IMPT Journal

Winter 2007 Vol 10. ISSN 1366–4697

The Journalof MAXILLOFACIALP R O S T H E T I C S& T E C H N O L O G Y

The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10 iii

The Journal of Maxillofacial Prosthetics & Technology

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PUBLICATION:THE JOURNAL OF MAXILLOFACIAL PROSTHETICS & TECHNOLOGYis published by:Type Script, 7 Carmelite Way, Hartley, Kent DA3 8BP, UK.Tel: 01474 707896 E-mail: [email protected]

ADVERTISING SALES:Contact Dr M. Anwar Bamber,Dept. of Oral and Maxillofacial Surgery,UCL Eastman Dental Institute,University of London,London WCIX 8LD, UK.E-mail: [email protected]: 0044 (0)20 7915 1226

COPYRIGHT:ISSN 1366-4697© The Institute of Maxillofacial Prosthetists & Technologists, 2006. No part of this publication may be reproduced without the express permission of the Editor.Permission is not required to copy abstracts on condition that a full reference to the sourceis shown.

SUBSCRIPTIONS:Members are reminded that if their subscriptions to The Institute of MaxillofacialProsthetists & Technologists are out of date, the Journal cannot be supplied.Subscriptions for the Journal cost £40 per issue. Cheques should be made payable to The Institute of Maxillofacial Prosthetists & Technologists and sent to: 7 Carmelite Way,Hartley, Kent DA3 8BP, UK.

MEMBERSHIP & CHANGE OF ADDRESS:All matters relating to the membership ofThe Institute of Maxillofacial Prosthetists& Technologists should be sent to:

The Honorary Registrar Mr M. Pilley,Prosthesis Clinic,Maxillofacial Unit,Leicester Royal Infirmary,Leicester LE1 5WW. Tel: 01162 585255

All queries regarding subscriptionshould be sent to:

Mr R. EggletonHonorary TreasurerDepartment of Medical Physics & Oncology,St. Luke’s Cancer Centre,Royal Surrey County Hospital,Edgerton Road,Guildford,Surrey GU2 7XX.Tel: 01483 406640

Internet website: http://www.impt.orgRegistered as a Charity. Registered in England under Charity Number 101 3059

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iv The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10


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EDITOR:DR M. ANWAR BAMBER

Department of Oral and Maxillofacial Surgery, UCL Eastman Dental Institute,University College London, University of London, London WCIX 8LD, UK.

EDITORIAL BOARD: ALAN BOCCA

Maxillofacial Unit, Morriston Hospital, Swansea SA6 6HLRICHARD BIBB

Medical Applications, PDR, UWIC, Western Avenue, Cardiff CF5 2YBSTEVE BAILEY

Maxillofacial Unit, Pilgrim Hospital, Sibsey Road, Boston,Lincolnshire PE21 9QSJASON WATSON

Maxillofacial Unit, Queens Medical Centre/University Hospital, West Block,B Floor, Derby Road, Nottingham NG72 UH

EDITORIAL ADVISORY BOARD:K. F. MOOS OBE – Scotland J. S. BROWN – EnglandI. COLLINS – England M. P. ROTHERA – England M. CUTLER – England P. EVANS – Wales N. SAPP – England A. TJELLSTRÖM – Sweden K. E. THOMAS – England F. P. JOHNSON – England G. GRANSTRÖM – Sweden A. VACHIRAMON – ThailandA. LINNEY – England C. HAYLOCK MBE – EnglandG. H. WILKES – Canada A. E. MARKUS – England C. MARYAN – England J. WOLFAARDT – Canada C. NACHER – Spain S. J. WORROLLO – England R. LEESON – England P. BARRETT – Wales V. SALIH – England D. BREWER – EnglandC. BETZ – Germany C.E. CLUFF – England

THE INSTITUTE OF MAXILLOFACIAL PROSTHETISTS & TECHNOLOGISTS COUNCIL 2007PRESIDENT S. FISHER FDSRCS, FRCS

PRESIDENT ELECT P. RAMSAY-BAGGS MB BCH BAO BDS FDS RCS(ENG) FFD RCSI FRCS(ED)CHAIRMAN S. PARKINSON

SECRETARY M. TOWNEND

HON. TREASURER R. EGGLETON

HON. REGISTRAR M. PILLEY

COUNCIL MEMBERS D. ALLEN K. PAGE MBE

M. BAMBER M. PILLEY

B. EDWARDS S. QUINN

R. EGGLETON M. TOWNEND

L. GILL F. WALKER

R. JENNER J. WATSON

The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10 v


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EDITORIAL

The Partnership: Patient, Public and the IMPT

Why should a membership organisation involve itself with the non-fee paying public?

Many years ago, the Institute successfully negotiated charitable status, which recognises its primary role infostering the education and training of Maxillofacial Prosthetists, as such it sets standards similar to many otherindependent organisations. Throughout its relatively short history, as many of you will know, the IMPT has beenkeen to have an open dialogue not only with its membership but also with those outside the medical and dentalprofessions. It is important for both patients and clinical practice that the public understand the possibilities andthe limitations of modern healthcare. Since the late-seventies, we have specifically welcomed those from withinand outside the medical profession to our forums to generate a mutually constructive dialogue.

Representatives of the IMPT have attended a series of meetings organised by various charities – targeted atpatients with a specific illness or condition. We have also contributed in meetings to introduce school childrento career options in allied healthcare professions. In collaboration with NHS Careers we published a useful seriesof fact sheets for prospective trainees, patients and for other members of the general public. We have hosted anumber of events to which those outside healthcare have been invited, either as part of the audience or as guestspeakers. Christine Piff from Let’s Face It addressed our conference audience to share her experiences as apatient with facial defect; this in turn inspired a number of other initiatives. Allowing the public as patientsbenefit from the superb educational opportunities we provide nationally and internationally to members andnon-members across all disciplines.

But to comply with the new Charities Act, we now need to put this engagement with the public on a more formal,statutory footing. Although the Act itself does not clearly define ‘public benefit’, guidance from the CharityCommission identifies two key principles charities must satisfy: there must be an identifiable benefit in acharity’s activities, and the benefit must be to the public or a section of the public. Factors such as activity hours,geographical location or not being a member of the charity in question should not restrict someone frombenefiting. The guidance also clearly specifies that people living in poverty must not be excluded from theopportunity to benefit. The commission will carry out spot checks to gauge a charities’ compliance from the endof the financial year 2008/09. The IMPT already aim for its provision for public benefit, but it now becomes astatutory requirement.

Perhaps the IMPT like some other organisations may need to set up a Public Engagement Group (PEG) whichmeets a few times a year on an ongoing basis. However, for this to be effective, this group would need to be madeup of patients, members of IMPT, the Council and outside organisations from non-medical backgrounds. Thegroup would need to explore a wide range of initiatives to increase our interaction with the public. These couldinclude a series of public debates on controversial topics such as the need for statutory registration, healthcarerationing, patients’ rights and patients’ responsibilities, and conventional versus implant supported prostheses.This group would also need to engage the media programme makers and broadcasters for public benefit.

vi The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10

These future seminars and exhibitions could be attended by Members and non-members alike, and some of theexhibitions planned for the year ahead could also be open to the public with no admission charge. We need tolook at making a number of free places available for prominent members of the public to attend certain meetingsand conferences. This would be in addition to making some events available for viewing online via our website.We ought to be looking into the idea of expanding our website content to develop e-bulletins that members ofthe public can elect to receive. If you have any ideas about initiatives to further engage with the public or if you’dlike to join and contribute please get in touch with an IMPT council member. The IMPT Council invites you toget engaged.

To have a ‘Maxillofacial Prosthetic service which is identifiable but integrated in the healthcare system’ wouldbe a laudable vision indeed. But is it feasible? Despite having been sidelined by some statutory authorities it mustbe right to adopt a positive view of the future. Surely the benefits for patients will become more visible soonerrather than later? The aims of the IMPT are comprehensive and fulfilling, although I might move the last –‘putting the patient at the focus of our work’ – further up the list.

Maybe the tide is turning in our favour in a funny sort of way, this presents an exciting challenge for the Counciland members alike!

Summer – such as it was – is over and the nights are fair drawing in as folk up in Scotland say. This would be agood time to turn your thoughts to the next journal for which the first call for papers has been issued.

M. Anwar BamberHon. Journal Editor

The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10 vii


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CONTENTS

PAGES

A WEIGHT COMPARISON OF SURGICAL PACKING MATERIALS USED FOR MAXILLECTOMY OBTURATION 1–4R. Jenner

MEASURING ADEQUACY OF RETENTION OF MINI DENTAL IMPLANT IN LOWER FULL DENTURES WITH FLAT RIDGES:AN IN VITRO STUDY 5–8C. B. Koay, C. C. Chee, J. Y. Sia, R. A. Rahman, C. L. Koay, M. N. Jabar

DIGITAL TECHNOLOGIES IN EXTRA-ORAL, SOFT TISSUE FACIAL PROSTHETICS: CURRENT STATE OF THE ART 9–16D. Eggbeer, R. Bibb and P. Evans

FLEXIBLE JAW EXERCISER: AN ALTERNATIVE APPLIANCE FOR TRISMUS REHABILITATION 17–22C. Orbaneja Botija

EXTERNAL HOLLOW BUTTOCK PROSTHESIS 23–26P. Kaur and D. Coppins

DIGITAL PHOTOGRAPHY IN MAXILLOFACIAL PROSTHETICS 27–30N. Caulfield and C. Maryan

TITANIUM CRANIOPLASTY IMPLANT CONSTRUCTION USING A SECTIONAL MOULD 31–33B.C. EDWARDS

ABSTRACTS 34–39

INSTRUCTIONS TO AUTHORS 41–42

> Precise models of patient anatomy built directly from

your CT or MRI data

> Our stereolithography models are transparent and strong

> Theatre models are available (Tested to USP 23 Class 6)

> Selective colouring of designated tissues is available

> Models for: cranioplasty plates, tumour reconstruction, siting osseointegrated

implants, osteotomy planning and symmetrical reconstruction

> PDR undertakes research and development projects in the application of

design and manufacturing technologies in reconstruction and rehabilitation

For further information, please contact Dr Dominic Eggbeer or Dr Richard Bibb:

Tel: 029 2041 6703 Fax: 029 2041 6973

email: [email protected] or [email protected]

Medical Applications Group

The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10 1

INTRODUCTION

Throughout recent literature there have been manydescriptions of the use and value of surgical obturators1–4.The functional importance of these devices cannot bestressed enough; they restore the patient’s masticatoryfunction, improve their speech and lend support to surgicaldressings whilst, at the same time, supporting thesurrounding facial tissues. The support of those surroundingtissues is especially important as these will help to restore thepatient’s self image at a delicate and stressful stage oftreatment. Lapointe, et al (1996)5, compared the merits ofimmediate and delayed obturator prosthesis placement inmaxillectomy patients. His retrospective study concludedthat immediate obturation benefited the patient and theirprogress to recovery.

In terms of material considerations, Gutta-Percha (GP) hasremained the favourite for surgical packing in maxillectomypatients. This inelastic natural latex, produced from the sap ofPallaquium trees bio-inert properties make it suitable forsurgical dental devices6. Steadman (1957)7 describes the useof an acrylic plate lined with gutta-percha to support a skingraft to the maxillary defect. Although a surgeon’s favourite,this choice of material has displayed disadvantages to thepatient. Namely it has a taste and smell not always pleasantfor the patient during the healing process, and once set, it isrigid and heavy in mass. With the lack of raw materials,resulting in a global shortage of GP, it is appropriate to lookat the alternatives available.

In 1984 Radcliffe et al8, presented the idea for a lightweightsurgical obturator with use of silastic foam as an alternativeto GP. Buckle (1998)9–10, also highlighted the use of silasticfoams for immediate obturation. He explained the advantagesof combining Nusil R 2370 and Med 6382 (Polymer SystemsTechnology Limited, Unit 2 Network 4, Cressex BusinessPark, Lincoln Road, High Wycombe) over the moretraditional material GP.

Addition silicones are widely used in the oral cavity as a highprecision impression material, they also act as good surgicaldressing material in obturation cases. It can provide stable,clean support to the surrounding healing tissues with accuratedetail of the cavity. This detail can subsequently assist in thenext process of temporary obturation, providing an excellentreplica of the defect.

METHOD AND MATERIALS

The original method was to compare the weight difference ofmaterials used in packing surgical obturator defects, based ondifferent sized defect cavities assessed as small, medium andlarge. It was felt that this required further definition; thereforeseveral maxillectomy classifications were considered11–12, 17–20.The final method used Class 2 Low alveolar maxillectomy,not including the orbital floor or contents. This isdescribed by Brown et al, as a modified classification forthe maxillectomy defect12–14. Brown’s approach topalatomaxillary reconstruction has become a usefulfunctional classification for maxillectomy defects.His system is based on both vertical and horizontaldimensions of a defect. All the cases chosen were edentulous.

A WEIGHT COMPARISON OF SURGICAL PACKING MATERIALS USED FORMAXILLECTOMY OBTURATION

R. Jenner

Rachel Jenner MIMPTMaxillofacial & Orthodontic LaboratoryKent & Canterbury HospitalEast Kent Hospitals NHS TrustCanterbury, Kent CT1 3NG

Key: maxillectomy, obturator, Gutta-percha, addition silicone, silastic foam, Taguchi Orthogonal Array.

The aim of this study is to compare the weight of packing materials used for immediate surgicalobturation. In addition to the weight of the obturator, an evaluation of material retention methodswas assessed.


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2 The Journal of Maxillofacial Prosthetics & Technology Winter 2007 Volume 10

When considering the design of the dressing plate, anotherfactor that can affect the overall weight could be the retentionaid used for locating or attaching the dressing material to theplate. Traditional techniques include a wire ‘goal post’ oracrylic stud shape added to the fitting surface. If looking forareas to reduce the overall weight, then perforations couldprovide the solution.

Within industry, Taguchi’s Orthogonal Arrays15 make itpossible to experiment with the component parts of a productduring the design stages of that product’s design andmanufacture. Factors such as variation in the chemical ratio,or the ingredients used, or even the ways in which the productis formed all contribute to the final product.

Orthogonal Arrays are a set of tables laid out by Taguchi tochart the design experiments.

The type of Orthogonal Array will differ depending on thenumber of variables to be considered, and how many levelsthose variables take. This method of analysis is used toprovide us with the best parameters for the optimum design.

The advantage of an Orthogonal Array is that it can beapplied to an experimental design involving a large numberof design factors. In the case of this experiment, to test eachcombination of size of defect, material used and method ofretention employed, twenty-seven separate samples wouldneed to be constructed. With Taguchi’s Orthogonal Array L9,only nine samples are needed (Table 1).

Replica Kaffir-D models were produced in triplicate for eachclassification. For the purpose of this experiment, it was notnecessary to incorporate circum-zygomatic retentioncomponents or aesthetic teeth onto the base plate. Thereforeclear edentulous acrylic base plates were constructed for thenine experimental models, Meadway Superclear Heatcure(MR Dental, 4 Manor Way, Old Woking, Surrey). Eachclassification set of base plates were trimmed and polished toensure that they weighed the same at this stage of theexperiment.

For each of the classification sets, one of three types ofobturator retention method were assigned; perforations(limited to 3), an acrylic stud or a wire goal post. Once thesewere applied to the base plates, the final factor was allocated.The three obturator packing materials were; Black GuttaPercha sheets, Epiform-flex an addition silicone (DreveDentamid GmbH, Max-Planck-Str.31, 59423 Unna,Germany) and Nusil R-2370 silastic foam (Polymer SystemsTechnology Limited, Unit 2 Network 4, Cressex BusinessPark, Lincoln Road, High Wycombe). This is illustrated inTable 1 (Fig. 1).

Each cavity was filled with the designated material andattached to the appropriate base plate. All handling instructionssupplied with the materials were followed carefully. All ninecases were then weighed individually; using an electronicbalance, the total weight of each appliance was recorded.

Fig. 1: Defect models and the application of the different materials.

Table 1: L9 Orthogonal Array Experiment Table; showing factors applied and levels measured (L1, 2, 3)

Number of Levels

Experiment No. (Parameters) Classification Retention Material

1 L1 – Class 2b L1 – Perforations L1 – GP

2 L1 – Class 2b L2 – Acrylic Stud L2 – Silicone

3 L1 – Class 2b L3 – Goal Post L3 – Foam

4 L2 – Class 2a L1 – Perforations L2 – Silicone

5 L2 – Class 2a L2 – Acrylic Stud L3 – Foam

6 L2 – Class 2a L3 – Goal Post L1 – GP

7 L3 – Class 2c L1 – Perforations L3 – Foam

8 L3 – Class 2c L2 – Acrylic Stud L1 – GP

9 L3 – Class 2c L3 – Goal Post L2 – Silicone


RESULTS

The results show that silicone is the lightest packing material,therefore more effective on weight reduction. The larger thedefect size, the greater the weight reduction when usingfoam. When assessing the retention components, perforationseliminate additional weight to the plate; the results help showthe impact back-up retention aids have on the overall weighton the appliance (Table 2).

The results for each factor; classification Class 2a, b and c,retention method and obturator material, were taken andadded together and divided by three to calculate their meanaverage (Table 3).

DISCUSSION

As expected, Silastic foam is more effective on weightreduction. From the authors’ experiences throughout thisexperiment, the foam was not always easy to handle. Themixing technique and time can be limiting, therefore it wouldbe advisable to practice with its application before working ina theatre environment or pressurised situation. One knownsurgical procedure when using this material involves theWebber Ferguson technique, which allows open access to thecavity. The manufacturers notes state the quantity of catalystcan affect the expansion, it is therefore important toaccurately measure both component parts. Additionally thetemperature of the working environment is an importantfactor to consider. The hospital theatre environment is likelyto be warmer than the laboratory and this could have an effectof reducing the setting and expansion time of the foam. Carehas to be taken when the foam is in final stages of expansion,if touched it is liable to implode resulting in some failure ofset. The R-2370 foam can be strengthened and lifetimeincreased by blending 75% R-2370 and 25% MED 63829.There is some concern around the length of time a foam

obturator can healthily stay in the cavity; this also highlightsthe patients issue around smell and taste.

Perforations in the base plate, as a method of retention, alsoprovide a reduction of the overall weight. Perforations areeasier to incorporate into the base plate during constructionand negate the need for auxiliary retention components, alsoeliminating additional weight. This is not a satisfactoryretention method for all the materials, if it is necessary tokeep the plate and obturator as one-piece.

With the exception of silastic foam there are limitations onthe use of dressing materials if using a one-stage packingprocess. The size, and specifically, the undercut areas of thedefect site can cause complications at removal of the surgicaldressing plate. Both Silicone and Gutta Percha althoughgiving a good supportive structure, can be difficult to removeonce they become locked into an undercut area, if an‘sectional impression’ technique has not been used!

Gutta Percha does have the properties that enablemodifications or additions, enabling the operator to remouldor build up areas. Once set, silicone does not allow theoperator to create a successful bond and enable them to addfurther material. Although having the ability to build-up insections, using silicone putty can be beneficial. The operatorwould be able to engage useful undercuts and ensure thateach section is removable.

In conclusion, Brown’s multidisciplinary (surgical andprosthodontic) classification describes the type and extents ofsurgery, but the overall volume of the defect is still variedwithin each classification boundary, as this depends on eachcase. It will ultimately be the operators’ decision as to themost suitable packing material and method used, dependanton the volume of defect.

Table 2: Total weight of immediate obturators (grams)

Experiment No. Classification Retention Material Total Weight (grams)

1 Class 2b Perforations Gutta-Percha 26.55

2 Class 2b Acrylic Stud Silicone 25.03

3 Class 2b Goal Post Foam 15.54

4 Class 2a Perforations Silicone 41.23

5 Class 2a Acrylic Stud Foam 19.29

6 Class 2a Goal Post Gutta-Percha 49.93

7 Class 2c Perforations Foam 32.41

8 Class 2c Acrylic Stud Gutta-Percha 77.50

9 Class 2c Goal Post Silicone 98.30

Table 3: Surgical obturation dressing methods – Mean Average weight calculated for each level and factor measured (grams)

Size (grams) Retention (grams) Material (grams)

Level 1 22.37 33.39 51.32

Level 2 36.81 40.60 54.85

Level 3 69.40 54.59 22.41

Biggest difference 47.03 21.2 32.44


Acknowledgements

I would like to thank Mr J. McKenzie, ConsultantMaxillofacial Surgeon, for his assistance in the compilationof this paper.

I also express my thanks to my colleagues at Kent &Canterbury Hospital for all their support; Mr S.J. Abbott andMr J.A. Couchman.

I would also like to thank Polymer Systems TechnologyLimited for their product guidance and for providing samplesto carry out this experiment.

References

1. Huryn J.M., Piro J.D. The maxillary immediate surgicalobturator prosthesis. J Prosthet Dent. 1989; Mar: Vol 61,No 3; 343–347.

2. Black W.B. Surgical obturation using a gated prosthesis.J Prosthet Dent. 1992: 68: 339–342.

3. Keyf F. Obturator prostheses for hemi-maxillectomypatients. J Oral Rehabil. 2001; Vol: 28, Issue 9; 821.

4. Freidline C.W. Immediate prosthetic obturation of thepartially resected maxilla in edentulous patients. J ProsthetDent. 1980; Vol: 44, No 1; 72–73.

5. Lapointe H.J., Lampe H.B., Taylor S.M. Comparison ofmaxillectomy patients with immediate versus delayedobturator prosthesis placement. J Otolaryngol. 1996;Oct: 25 (5); 308–12.

6. Anderson J.N. Applied Dental Materials, BlackwellScientific Publications. 1956.

7. Steadman B. St J. Construction of prosthesis after resectionof the maxilla. Int Dent J. 1957; 7; 560.

8. Radcliffe G.J., Mady S., Burr R., Cheeseman A.D., Wilson D.A new immediate temporary lightweight obturator formaxillectomy cavities. Br J Oral Maxillofac Surg. 1984;22: 50–53.

9. Buckle J.P. Adaption and application of silicone foams.J Maxillofac Prosthet Tech. 1998; Vol: 2 Issue: 1; 27–29.

10. Polymer Systems Technology Limited. Product Data Sheetfor R2370 and instruction booklet.

11. Okay D.J., Genden E., Buchbinder D., Urken M. Prostheticguidelines for surgical reconstruction of the maxilla:A Classification system of defects. J Prosthet Denti. 2001Vol: 86, No 4; 352–363.

12. Brown J.S., Rogers S.N., McNally D.N., Boyle M.A modified classification for the maxillectomy defect.Head & Neck. 2000 Jan: 22 (1); 17–26.

13. Brown J.S. Deep circumflex iliac artery free flap withinternal oblique muscle as a new method of immediatereconstruction of maxillectomy defect. Head & Neck. 1996Sept/Oct: 18; 412–421.

14. Rogers S.N., Lowe D., Brown J.S., Vaughan E.D. Health-related quality of life after maxillectomy: A comparisonbetween prosthetic obturation and free flap. J OralMaxillofac Surg. 2003: 61; 174–181.

15. Peace G. Taguchi Methods – A hands on approach.Addison-Welsey Publishing Group Inc. 1993: 122–127.

16. Cunningham R. A laboratory technique for the productionof immediate surgical appliances and ‘one-stage’ obturatorsfor the hemi-maxillectomy patient. Br J Oral MaxillofacSurg. 1990; 28: 59–61.

17. Koyama S., Sasaki K., Inai T., Watanbe M. Effects ofdefect configuration, size and remaining teeth onmasticatory function in post maxillectomy patients. J OralRehabil. 2005; Vol: 32, Issue 9; 635.

18. Cordeiro P.G., Santamaria E. A Classification System andAlgorithm for Reconstruction of Maxillectomy andMidfacial Defects. Plastic and Reconstr Surg. 2000:Vol: 105, No. 7; 2331–2346.

19. Aramany M.A. Basic principles of obturator design forpartially edentulous patients. Part I: classification.J Prosthet Dent. 1978; 40: 554–7.

20. Aramany M.A. Basic principles of obturator design forpartially edentulous patients. Part II: design principles.J Prosthet Dent. 1978; 40: 656–62.


MEASURING ADEQUACY OF RETENTION OF MINI DENTAL IMPLANT IN LOWERFULL DENTURES WITH FLAT RIDGES: AN IN VITRO STUDY

C. B. Koay, C. C. Chee, J. Y. Sia, R. A. Rahman, C. L. Koay, M. N. Jabar

Keywords: mini-implant, retention, retention measurement, Sendax, severely resorbed mandible.

Objectives: The aim of this study was to evaluate and report the retention force of the IMTEC SendaxMDI System.

Method and materials: The experimental model with four MDI Classic implants (1.8mm x 18mm)was used and the respective overdenture was prepared with the O-ring housing embedded. Tensilestrength tests (Micro 500) were performed to measure the maximum dislodging force (peak load) ofthe overdenture with 4 O-rings, 2 O-rings and 1 O-ring attached. The test was repeated ten times foreach group at a speed of 50mm/min. Data were analysed to calculate the mean, standard deviationand mean confidence interval at 95%.

Results: Results showed mean force of 2.790 ± 0.095 N for 1 O-ring attached, 5.527 ± 0.178 N for2 O-rings and 8.946 ± 0.847 N for 4 O-rings. The peak load of 2 O-rings appeared to be twice thatof 1 O-ring. However, the peak load of 4 O-rings was less than four times the peak load of 1 O-ring.

Discussion: Lehmann & Arnim recommends 5 to 7 N as the minimum force required for overdenturestabilisation. The peak load (8.946 N) of the overdenture with four O-rings has exceeded thisrecommendation.

Conclusion: Based on the study, the O-ball prosthetic head of the IMTEC Sendax MDI provideadequate in vitro retention for lower full dentures when used in flat, severely resorbed mandible.It can be considered as adjunct or as long-term measure to address the lower overdenture retentiveproblem in cases where inadequate bone volume in supporting standard-diameter implant is present.However, further research is needed to further verify their in vivo use and success.

Dr Chee Chu Cheet and Dr Sia Jye Yen Dental OfficerMinistry of HealthMALAYSIA

Dr Roslan Abdul Rahman (Associate Professor)Dept of Oral and Maxillofacial Surgery,Universiti Kebangsaan Malaysia Medical Centre [UKMMC]Jalan Yaacob Latif, Cheras56000 Kuala LumpurMALAYSIA

Dr Koay Chuan LekPrivate Dental PractitionerMALAYSIA

Dr Mohd Nazimi Abd Jabar (to address all correspondence and mailing)Dept of Oral and Maxillofacial Surgery,Universiti Kebangsaan Malaysia Medical Centre [UKMMC]Jalan Yaacob Latif, Cheras56000 Kuala LumpurMALAYSIA

Dr Koay Choon BokDental OfficerDept of Oral and Maxillofacial Surgery,Universiti Kebangsaan Malaysia Medical Centre [UKMMC]Jalan Yaacob Latif, Cheras56000 Kuala LumpurMALAYSIA


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INTRODUCTION

The IMTEC Sendax Mini Dental Implant (MDI) System wasapproved for long-term use by the United States Food andDrug Administration (FDA) in 2003. It is the first and onlyreduced-diameter implant system to receive approval forlong-term use. The device permits immediate splinting abilityand long-term fixation of new and existing crown and bridgeinstallations, for full partial edentulism, and employsminimally invasive surgical intervention1.

There are four MDI designs available: Classic, Classic MAX,Collared, and Collared MAX. The standard design has adiameter of 1.8mm while the MAX design has a 2.4mmdesign. They each have four lengths: 10, 13, 15 and 18mmand two attachment systems: O-ball and square prosthetichead2.

Following success in the temporary prosthetic stabilisationduring the healing period of standard diameter implant3,4,their use has been extended in orthodontic anchorage5, intemporary fixation of transplanted teeth6, periodontaltherapy7 and more recently in the long-term fixed andremovable prosthetics8–10.

As there have been many studies and publications previouslyconducted to the various attachment systems of the standard-diameter implants in lower full dentures, we sought toevaluate the adequacy of MDI retention force when used toretain overdentures in this in vitro analysis. According toLehmann & Arnim, forces from 5 to 7 N should be sufficientto stabilise overdentures during function11.

MATERIALS AND METHODS

Specimen preparation

The experimental model was prepared with four 18mm MDIClassic with O-ball attachment system mounted according tothe patented insertion protocol2,12. The implants were placedin the inter-canine region. An overdenture with the O-ringmetal housing embedded corresponding to the model withimplants was manufactured (Fig. 1). No undercuts werepresent. The model was fixed to the universal testing machineusing a clamp while a device to attach the overdenture wasfabricated (Fig. 2).

Retention measurements

The peak load (maximum dislodging force) was measured inN using a universal testing machine (Micro 500) with acomputer interface. Traction was applied at 50mm/min,which was reported to approximate the speed of themovement of the denture away from the ridge duringmastication13. The peak load was measured 10 times with4 O-rings attached. Following completion, 2 rings wereremoved and the peak load was measured again 10 times.Finally, another ring was removed and the maximumdislodging force was again measured 10 times. Thisadditional test was carried out to ascertain whether thedislodging force has a proportionate increment with thenumber of mini implant used, although this could not

be feasible in an in vivo situation. A total of 30 tests wereconducted and the results of each test recorded automaticallyby the computer interface. The components removaland insertion were only performed along the long axis ofthe implants avoiding any unnecessary flexural or horizontalload.

Statistical analysis

The results of peak load of all groups were summarised andtabulated following the tests conducted. Statistic and analysiswas carried using Statistical Package for the Social Sciences(SPSS) version 11.0. Mean and standard deviation werecalculated to demonstrate the distribution of peak load testsperformed. Confidence interval was used to test the reliabilityof an estimate of the dislodging force.

Fig. 1: Four O-ring metal housing embedded into theoverdenture.

Fig. 2: The model attached to the testing machine.


RESULTS

The peak load tests results with statistical summaries arepresented in Table 1 and Fig. 3. Dislodging force ranged froma minimum of 7.553 to a maximum of 10.191 N foroverdentures with 4 O-rings attached; 5.132 to 5.809 N for 2O-rings; and 2.577 to 2.912 N for 1 O-ring.

Fig. 3: Mean values and 95% confidence interval (error bars) ofthe dislodging force of the 3 groups tested.

DISCUSSION

Retention can be considered as the force that resistswithdrawal along the path of insertion13. Since the path ofinsertion of a mini-implant retained overdenture lies alongthe long axis of the implants, this investigation studied thepeak load measurements along the long axis of the implants.Resistance to anterior-posterior dislodging force has alsobeen referred to as ‘stability’14, however was not studied inthis investigation.

The results showed that with only one ring in place, themaximum dislodging force is 2.79 N. With two rings inplace, the result showed a peak load of 5.527 N, which istwice the force of one ring. This result lies within theacceptable range for denture stabilisation recommended byLehmann & Arnim11. Nevertheless, it is not recommendedfor only two implants to be placed for this purpose.

The peak load of the overdenture with four rings in place(8.946 N) is lower than the expected value of four times themaximum dislodging force of one ring. However, this may bebeneficial for patients who have difficulty inserting andremoving the overdenture such as patients with poor manualdexterity. The maximum dislodging force also exceeded therecommendation by Lehmann & Arnim11 of 5 to 7 N requiredfor denture stabilisation during function.

The IMTEC Sendax MDI Classic has a diameter of 1.8mm.This allows it to be placed when inadequate bone is present(e.g. edentulous arches with flat ridges) without the need forthe added costs and trauma of bone grafting and otherinvasive procedures usually associated with conventionalstandard-diameter implants15. The minimally invasiveprocedures also means that MDIs may be placed in patientswho are medically compromised when standard-diameterimplants may not be a viable option.

The MDI surgical protocol is a much simplified procedure,most of the time not requiring the raising of a mucoperiostealflap2. The armamentarium for MDI placement consists ofonly five components (Fig. 4). This simple procedure makesit easier for implant placement and a shorter time required.It is also possible for immediate loading of the MDIs andhence, immediate improvement in denture retention andfunction.

The ball attachment system, which is utilised by the IMTECSendax MDI, is favoured by some authors to retainmandibular overdentures due to the favourable ratio betweenthe supporting bone structures and the forces acting duringfunction and parafunction16.

Fig. 4: Armamentarium for placement of IMTEC Sendax MDI

STUDY LIMITATION

The testing was done in specific and limited mechanicalconditions. As such, this in vitro testing does not entirelyreplicate the function of dentures in the complex environmentof the oral cavity. Additional experimentation should involvemultidirectional force application (anterior-posterior andoblique), various fluids and thermal environments, fatigueeffects and clinical trials to evaluate the attachment systemthat was investigated here.

8.000

6.000

4.000

2.000

1 Ring

Max

imum

Dis

lodg

ing

Forc

e(N

)

2 Rings

O-Rings

4 Rings

Table 1: Results of peak load tests of all groups

Group Dislodging Force (N) Maximum (N) Minimum (N)

4 O-rings 8.946 ± 0.847 10.191 7.553

2 O-rings 5.527 ± 0.178 5.809 5.132

1 O-ring 2.790 ± 0.095 2.912 2.577


CONCLUSIONS

The maximum dislodging force was determined along thelong axis of the implants for 4 O-rings, 2 O-rings and1 O-ring. Based on the results of this study, it could beconcluded that:

1. The O-ball prosthetic head of the IMTEC Sendax MDIprovide adequate in vitro retention for lower full dentureswhen used in flat, severely resorbed mandible.

2. The use of the MDI could be considered as adjunct or aslong-term measure to address the lower overdentureretentive problem in cases where inadequate bone volumein supporting standard-diameter implant is present.

3. The use of the MDI could be an alternative option topatients who do not desire invasive implant surgicalprocedures or in patients who are medically or surgicallycompromised, or even in patients who are financiallychallenged.

However, further research is needed to further verify thein vivo use and success of the IMTEC Sendax MDI inmaintaining the retention of full dentures in flat mandibularridges.

DISCLOSURE

None of the authors have any financial interests in the miniimplants mentioned in this article.

References

1. Food and Drug Administration. IMTEC Sendax MDI andMDI Plus. U.S 510(k) Premarket Notification K031106.

2. IMTEC Corporation. IMTEC MDI Sendax:Long Term Denture Stabilisation. http://www.imtec.com/cgi-bin/janus.cgi?ID=MDI4.pdf

3. El Attar M.S., El Shazly D., Osman S. et al. Study of theeffect of using mini-transitional implants as temporaryabutments in implant overdenture cases. Implant Dent.1999; 8: 152–158.

4. Petrungaro P.S., Windmiller N. Using transitional implantsduring the healing phase of implant reconstruction.Gen Dent. 2001; 49: 46–51.

5. Kanomi R. Mini-implant for orthodontic anchorage.J Clin Orthod. 1997; 31: 763–767.

6. Nagata M., Nagaoka S. Mini-implant is effective as atransitional fixation anchorage for transplantation of teeth.Jap J Cons Dent. 2002; 45: 69.

7. Nagata M., Nagaoka S. Preservation of the natural teethand arch integrity by the use of transitional mini-implants.J Periodontol. 2000; 71: 1910.

8. Ahn M.R., An K.N., Cho J.H. et al. Immediate loadingwith mini dental implants in the fully edentulous mandible.Implant Dent. 2004; 13: 367–372.

9. Mazor Z., Steigmann M., Leshem R. et al. Mini-implantsto reconstruct missing teeth in severe ridge deficiency andsmall interdental space: a 5-year case series. Implant Dent.2004; 13: 336–341.

10. Bulard R.A., Vance J.B. Multi-clinic evaluation usingmini-dental implants for long-term denture stabilisation: apreliminary biometric evaluation. Compend Contin EducDent. 2005; 26: 892–897.

11. Lehmann K.M., Arnim F.V. Studies on the retention forcesof snap-on attachments. Quintes Dent Technol. 1978;7: 45–48.

12. Sendax V.I. Dental implantation. U.S. Patent 5749732May 12, 1998.

13. Sarnat A.E. The efficiency of cobalt samarium (Co5Sm)magnets as retentive units for overdentures. J Dent. 1983;11: 324–333.

14. Petropoulos V.C., Smith W. Maximum dislodging forcesof implant overdenture stud attachments. Int J OralMaxillofac Implants. 2002; 17: 526–535.

15. Christensen G.J. The ‘mini’-implant has arrived. J AmDent. Assoc Mar 2006; 137: 387–390.

16. Svetlize C.A, Bodereau E.F. Comparative study of retentiveanchor systems for overdentures. Quintessence Int. 2004;35: 443–448.


INTRODUCTION

The field of Maxillofacial Prosthetics & Technology is facedwith increasing patient numbers within an increasingly cost-constrained healthcare system leading to a desire to explorewhether computer-aided, Digital Technology (DT)techniques can achieve cost or delivery time savings1. DigitalTechnologies such as Computer-Aided Design (CAD), 3Dscanning and Rapid Prototyping (RP) have found limitedapplication in extra-oral, maxillofacial prosthetics and therehave been a number of research studies exploring theirapplication. However, the majority of the previous researchhas relied on single case studies2–9. Consequently,conclusions on the wider implications for quality, economicand clinical impact have not been possible.

This paper summarises 4 years of research into theapplication of DTs in soft tissue, extra-oral prosthetics.Technological capabilities have been critically evaluated inmultiple case studies and a number of complementaryexperiments. The article presents conclusions on the currentcapabilities, limitations and future developments.

METHODS

This research involved conducting a number of clinical casestudies carried out through the Centre for AppliedReconstructive Techniques in Surgery (CARTIS). CARTIS is

a unique collaboration between The National Centre forProduct Design & Development Research (PDR) and theMaxillofacial Unit of Morriston Hospital, Swansea(www.cartis.org). This collaboration provided clinicalexpertise and access to state of the art computer-aidedproduct development technologies, such as 3D scanning,Computer-Aided Design and Rapid Prototyping.

An Action Research (AR) approach was used in theimplementation of the case studies. Case studies have beendescribed as an “empirical inquiry that investigates acontemporary phenomenon within its real-life context”10.They are particularly useful when the boundaries betweenphenomenon and context are not clearly evident9. ARmethods involve iterative stages of research design, researchimplementation and evaluation. Case study and AR methodsare typically applied to the social sciences and involvetechniques that are appropriate for studying “real life”situations where the researcher cannot control all of thevariables or the research environment. Typically, theseinvolve complex, changing situations and small samples. Theparticipatory approach helps to produce realistic and validresults. A number of the case studies demonstrated the needto incorporate flexibility and adapt to unforeseen challenges.Throughout the research, a small number of complementaryexperiments were carried out to establish technicalcapabilities that informed subsequent case studies and did notrequire clinical investigation.

DIGITAL TECHNOLOGIES IN EXTRA-ORAL, SOFT TISSUE, FACIAL PROSTHETICS:CURRENT STATE OF THE ART

D. Eggbeer, R. Bibb and P. Evans

Keywords: 3D scanning, computer-aided design, digital, design, prosthesis, rapid prototyping.

An Action Research approach was taken utilising multiple case studies to evaluate the currentcapabilities of digital technologies in maxillofacial prosthetics. The research sought to establishquality, economic, technological and clinical implications. This article summarises the research andprovides a discussion of the findings and implications for the field of Maxillofacial Prosthetics &Technology. Conclusions on the current capabilities and future developments are made.

Peter Evans MIMPTMaxillofacial UnitMorriston HospitalSwansea SA6 6NL

Dominic Eggbeer AIMPT (corresponding author) and Richard Bibb PhD AIMPTThe National Centre for Product Design and DevelopmentResearchUniversity of Wales Institute, CardiffWestern AvenueCardiff CF5 2YB


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RESULTS

1. Pilot Case Study – Orbital prosthesis

This pilot study intended to utilise appropriate digital methodsthat had been identified in the literature and was subsequentlypublished11. Digital Technologies utilised included ComputedTomography (CT), FreeForm Modelling Plus Computer-Aided Design software (SensAble Technologies Inc.), andThermoJet rapid prototyping (3D Systems Inc.). These werecombined with conventional fitting and finishing techniquesto produce the final prosthesis. This case demonstrated thatCT data was sufficient to capture the facial anatomy, but itcould not capture fine details such as texture and wrinkles.The case also indicated that FreeForm could be successfullyused to design the basic shape of a prosthesis. The ThermoJetrapid prototyping process successfully manufactured the basicprosthesis design in a wax material that was shown to besuitable for modifying and moulding using conventionalmaxillofacial laboratory techniques. The wax prosthesis wastherefore suitable for use in fitting sessions with the patientpresent (Fig. 1).

Fig. 1: Trial fitting of the ThermoJet wax pattern following edgemodification and ocular unit positioning.

2. Texture Experiment

Rather than a case study, this experiment aimed to identifymethods that were capable of capturing, utilising andphysically reproducing convincing skin textures. This studywas subsequently published in 200612,13. The experimentutilised a 3D scanning technology that a survey of availabletechnologies had indicated would be capable of capturingtexture as well as gross facial anatomical shape (BreuckmannGmbH). As in the pilot case study, FreeForm CAD(SensAble Technologies Inc.) and ThermoJet technologieswere utilised. This experiment confirmed that FreeForm wascapable of generating three-dimensional textures that couldbe incorporated into prosthesis designs. ThermoJet wasfound to be capable of physically reproducing fine texturesthat would produce a convincing skin texture. Thisexperiment indicated that the optical scanning technologywas limited in its ability to capture skin textures. Figure 2shows a sample skin texture embossed on a compound,curved test surface in FreeForm.

Fig. 2: A skin-like texture embossed on a surface in FreeForm CAD.

3. Case Study – Auricular prosthesis A

A review of the literature identified that digital techniqueshad not been applied to the design of all of the componentsof a maxillofacial prosthesis. Therefore, this case study wasdesigned to investigate how digital techniques could be usedto produce a prosthesis design that incorporated magneticretention (Technovent UK). The case study was published in200614. This case explored the application of 3D scanning ofa plaster replica of the patient’s defect site and contralateralear (Steinbichler Optotechnik GmbH). Once again, FreeFormCAD and ThermoJet technologies were combined withstandard hand finishing techniques. This study indicated thatmagnetic retention could be incorporated into digitalprosthesis design. As with the pilot case study, modificationof the wax prosthesis design was required using traditionaltechniques in order to achieve a satisfactory fit. Figure 3shows the modified wax pattern.

Fig. 3: The modified wax pattern:a) trial fitted on the patient;b) the magnets incorporated directly into the wax pattern.

4. Case Study – Auricular prosthesis B

This followed the previous case but explored the use of DTsin the design of bar and clip retention and was publishedin 200615. This project combined two 3D scanningtechnologies. Computed Tomography scan data was used tocapture the contralateral ear whilst optical scanning of the


patient’s defect site was attempted (Konica-Minolta Vivid900 laser scanner). Additionally, an alternative 3D scanningprocess was also used to scan a plaster replica of the defectsite (Steinbichler Optotechnik GmbH). The ThermoJetprocess was used to produce a wax pattern of the earprosthesis whilst Stereolithography (3D-Systems Inc.)produced the sub-structure incorporating the retentive clips.A new metal-based rapid prototyping process, SelectiveLaser Melting was utilised to produce the bar (SLM, MCP-HEK GmbH). The computer-aided design of thecomponents is shown in Figure 4. This study identifiedsome significant limitations in the 3D scanning methodswhen attempting to capture data that would enable thedesign of implant retention components.

Fig. 4: CAD models of a scanned replica cast, bar,clip/sub-structure and auricular prosthesis form.

5. Case Study – Nasal prosthesis

This case explored the design and manufacture of a nasalprosthesis incorporating magnetic retention. The mainpurpose of the study was to apply the process knowledgeobtained from the previous cases and compare them toentirely conventional methods. Technologies used included3D scanning (Roland LPX–1200 desktop laser scanner,Roland DG Corp.), FreeForm CAD, Stereolithography (forthe sub-structure) and ThermoJet (wax prosthesis patternproduction). It was identified that there were significantdifferences in the quality that could be achieved by digitaltechniques (combined with conventional fitting andfinishing) and entirely conventionally designed andmanufactured prosthesis. This case demonstrated that digitalmethods (combined with conventional fitting and finishing)were capable of producing a clinically acceptable prosthesis.However, this was achieved using a 3D scan of the patientsstone defect model rather than scanning the defect directly.This case demonstrated that there were no significantdifferences in the positional accuracy and shape achieved byboth techniques. However, the digitally produced prosthesiswas found to be significantly inferior in edge qualitycompared to the conventionally produced prosthesis.

This study was also used to consider the economicimplications of digital methods by measuring and comparingthe design and construction times for each technique. Resultssuggested that reductions in the overall design andconstruction time were possible.

Fig. 5: a) The conventionally produced prosthesis.b) The digitally designed prosthesis.

6. Case Study – Direct RP production of bar

This experiment aimed to explore further digital design anddirect manufacture of prosthesis retention bars. This caseutilised touch probe scanning (Roland Pix–30), FreeFormCAD and Selective Laser Melting. Here, a new SLMmachine specifically designed to produce small, accurateparts was used to manufacture the bar directly from CADdata (MCP-HEK GmbH, SLM–100). The bar produced wasshown to be a good fit when attached to the replica castabutments (Fig. 6).

Fig. 6: A digitally designed, SLM produced bar based upon atouch probe scan of a replica cast with abutments.

DISCUSSION

The results of the case studies were used to consider threeprimary factors, quality, economic impact and clinicalimplications.

Quality aspects included fit (marginal integrity of theprosthesis against the skin and fit between components),accuracy (anatomical position), resolution (reproduction offolds, wrinkles, texture, and substructure components), andmaterials (mechanical and chemical properties).


Fit

Prosthesis fit was defined as the distance between theindividual components and between the prosthesis marginsand the anatomy. According to clinical best practice, thereshould be no visible gap between the prosthesis margin andthe anatomy. When possible, the margin should form a sealthat remains in contact with the skin during changing facialexpressions and functions (talking, drinking, eating etc.).In conventional techniques, careful contouring of the waxpattern, modifying the mould and the inherent flash from themoulding process help to form extremely thin margins edges.These thin margins are soft and pliable enough to adapt to theskin surface and may maintain contact during facialmovements.

The thickness of fine margins produced using traditionaltechniques was measured to range from 40µm to 130µm. Bestpractice over many years has demonstrated that edges withinthis range achieve a good aesthetic result.

The results of this research found that margins with a 260µmthickness could be achieved using FreeForm CAD. Whilstsome RP technologies are capable of producing very thinlayers, most could not produce parts in a suitable material.Whilst the ThermoJet process proved capable of producingpatterns in an appropriate wax material, it was not able toreproduce edges thin enough to produce good margins andsubsequent adaptation was required during moulding.

When it comes to assessing the fit between components, whatconstitutes a ‘satisfactory’ fit has been discussed16–18.However, no conclusive method of evaluating passivity hasbeen established. Clinical methods often rely on visuallyassessing movement in the frame (i.e. a rocker action). To besatisfactory a bar should be able to locate on two abutmentswithout noticeable movement when pressed and there shouldbe no visible gaps.

Each stage in the process from data capture to barmanufacture introduces incremental errors resulting in anaccumulation of tolerances. This creates difficulties whenattempting to design and manufacture a bar that will fitabutments fitted to a patient.

This was apparent from the findings from case study 4indicated that designing bar structures was difficult whenusing data from optical scanners which produced insufficientdata resolution. The use of a touch probe scanner to scan aplaster replica in case study 6 showed that improved resultscould be achieved. However, further studies are required tovalidate whether digital methods are capable of producing aclinically acceptable bar via rapid prototyping methods.

Accuracy

Assessing the accuracy of a maxillofacial prosthesis issubjective but can be considered according to two criteria,accurate location in relation to the contralateral appearanceand the positional accuracy in relation to anatomicallandmarks.

Conventional methods require the patient to attend clinics sothat measurements can be taken. These typically involve theuse of rulers, callipers and protractors to assess the positionof a prosthesis. The aim is always to locate the prosthesisto produce a convincing visual appearance and thesemeasurements are used to assist location in conjunction withvisual inspection. Digital methods enabled location to bemanipulated and adjusted at will any number of timeswithout necessarily having the patient present. This alonemay provide a number of advantages for both the patient andprosthetist in terms of number and duration of clinics,reduced travel and flexibility in the prosthetist workscheduling. In addition, it was noted that the use of digitalmethods enabled angles of view and sectional views to beused that would be impossible or at least extremely difficultto achieve when dealing with the actual patient.

Due to the subjective nature of assessing facial appearance itis very difficult to define quantifiable standards of fit.However, the case studies undertaken resulted in prostheseswith good location and produced results as good as would beproduced when using conventional techniques.

Resolution and texture

Conventional techniques utilise impression techniques totransfer existing textures and fine details from the patientonto the prosthesis. These techniques, typically using siliconematerials produce an extremely faithful reproduction of smallfeatures. Digital Technologies however rely in data points todescribe three-dimensional shapes. The number of datapoints per unit area is a variable that is entirely dependent onthe technology being used. The cases illustrated that manyscanning technologies can provide a sufficient density of datapoints to adequately describe overall anatomical shape.Whilst CT, laser and structured white light scanning werefound to describe overall anatomical shape adequately theywere very limited in their ability to record small facialfeatures such as folds, wrinkles and skin texture.

In addition, the case studies indicated that these scanningtechnologies also had difficulty in capturing implantabutments, which made scanning defect sites incorporatingabutments problematic. Touch probe scanners were shown tobe able to capture sufficiently dense data points to captureabutments but these are not capable of scanning the patientdirectly. The case studies showed that combiningconventional impression and replication techniques and usingtouch probe scanners to digitise the replicas could producesufficiently good data to enable the design of an implantretained prosthesis using digital techniques.

As an alternative to recording the patient’s skin textures,experiment 2 demonstrated that digital techniques could beused to create and reproduce appropriate details such as skintexture and wrinkles12,13. The results of experiment 2suggested that in order to capture, describe and reproduceconvincing skin texture DTs must be capable of working toresolutions around one point per 0.03mm in all axes.However, whilst the experiment was successful on smallsamples the amount of data required was very large. Scalingthis data requirement to a whole prosthesis, particularly one


covering a large area would require such large data files thatcurrent technologies would struggle to cope. This iscompounded by the fact that many rapid prototypingtechnologies rely on the STL file format, which is quiteinefficient when describing highly detailed surfaces. Whilstthe rapid development of computer capability will increase tomeet this challenge, there is also scope for the developmentof more efficient data file formats.

Whilst the suitability of available rapid prototypingtechnologies for prosthetics has other requirements, mostnotably material properties, the ability to reproduce finedetails such as skin texture is also an issue. Experiment 2demonstrated that the ThermoJet process was capable ofreproducing skin textures in the range 0.1mm to 0.8mm.In order to reproduce texture details on a prosthesis pattern,RP technologies must have the ability to build in the 10s ofmicrons level. Whilst some RP technologies are approachingthis level of detail, the materials they use are not compatiblewith current prosthetic techniques.

Retention

Retention is typically achieved using gold bar and clips ormagnets. Bar and clip methods provide higher retentiveforces and the retention strength can be altered by adjustingthe compression of the clips or increasing the number ofclips. Attempts to incorporate retention clips intosubstructures manufactured using RP techniques provedunsuccessful. The materials used in the case studies providedretention, but the retention strength was poor and they worerapidly reducing retention strength still further. As prosthesesare likely to be applied and removed twice a day, a twelve-month period equates to 1,460 cycles of the retentivecomponents and the case studies indicated that the RP clipsincorporated into the substructures would not provide asufficient service life.

The bars must also be able to withstand the force ofapplication and removal. Due to their small size, a relativelystiff, typically metal material is required. Gold is typicallyused, but biocompatible alloys such as Cobalt-Chrome orTitanium, are viable alternatives. The availability of metal RPprocesses enabled the investigation of direct digitalmanufacture of retention bars. Bars were attempted using316L Stainless Steel and Cobalt-Chrome. Experiment 6 andpublished literature in similar applications have shown thatSelective Laser Melting can be used to manufacture barcomponents15 and that they may also be successfully castfrom Stereolithography patterns19.

Silicone has long been acknowledged as the optimummaterial for the body of the prosthesis. It has excellentphysical properties and can be colour-matched to produce ahighly convincing visual appearance. Currently no RPtechnology is capable of producing a prosthesis with therequired properties. In these cases, wax patterns wereproduced that were successfully incorporated into theconventional prosthetic production process.

Economic impact

Digital techniques can potentially have direct, indirect andopportunity impacts. Direct costs are associated with the costof care, treatment, materials, etc. Indirect economic costs areassociated with technology costs (purchasing, maintenance)and overheads. Opportunity costs are those costs that couldbe accrued from alternative approaches to those taken. Thiscan be associated with both the delivery of treatment and forthe patient. Treatment opportunity costs could be representedby missed appointments, longer clinics, etc. Opportunitycosts for the patient could include lost earnings, travel time,overnight stays, etc. This was an area of particular interestsince previous publications and advocates of DTs suggestthat their application can lead to reduced production times.

A detailed comparison of the time and cost implications of theimplementation of the digital techniques is shown in theflowchart in Table 1. The detail was gathered from timed casesand techniques used in the case studies were judged to beclinically viable in the near future. The flowchart shows thestages, staff and resources required for prosthesis constructionand it indicates the economic opportunities and additionalindirect costs associated with the introduction of DTs.

Economic impacts are difficult to measure and quantifybecause cases vary from patient to patient and costs varyregionally. In addition, many costs are hidden in overheadsand fixed costs. Whilst the cases indicated that DTs mightproduce economic benefits, more work is needed to establishthat the benefits are widely achievable and significant.However, the cases indicated that many of the benefits arerepresented by opportunities.

The case studies suggested that given current circumstancesthe investment required would probably not yield sufficienttime savings to make economic sense. Considering that amajor regional Maxillofacial Unit in the UK will fabricateapproximately 10 to 20 new facial prostheses per year (inpersonal communications with Maxillofacial Labs atMorriston Hospital, Queen Victoria Hospital and QueenElizabeth Hospital in the UK), the return on investmentwould be poor.

A strategy for addressing this issue is to invest intechnologies that have wider applications within a hospitalwould help to spread the investment costs. For example, 3Dscanning technologies may also be used to assist in burnssplint fabrication or craniofacial surgery planning. CAD andCT data preparation software could also be used to incomputer-aided surgical planning, implant design and thedesign of custom-fitting surgical guides and templates.

RECOMMENDATIONS

3D Scanning

Where available, use of CT data obtained pre or post-operatively should be used. This may remove the need to scanthe anatomy using optical methods and assist in the designstage by providing a form based on the patients originalanatomy.


Where adhesive retention is used, the anatomy is simpler tocapture since there are fewer undercuts caused by retentivecomponents blocking the scanners line of sight. Where thenose is missing, the reflective mucosal layer is unlikely tocapture well, but this will not affect the subsequent designstages as long as the margins are captured in detail andwithout distortion. It is particularly difficult to capture behindthe ear, which may make it necessary to take an impressionand scan a replica cast of the contralateral ear. A significantadvantage of using non-contact scanning methods is that thatthe eyes can be captured whilst open. This allows details fromthe unaffected side to be mirrored to form the basis of theprosthesis design. The eye globe is unlikely to captureaccurately due to its reflectivity and translucency.

The fine detail and reflective surfaces of implant retentioncomponents makes them difficult to capture using opticalbased scanning technologies. This may be addressed byapplying a light coloured, matt, opaque coating. However, dueto the accuracy and resolution limitations of current light-basedscanners it has been shown to be more productive to produce areplica cast of the defect site. The advantages of this approachare that the replica can be kept perfectly still and held at anyangle desired. This enables slower but more accurate scanningtechnologies to be used, including light-based or touch probescanners. The replica can be covered in a matt white powder toimprove scanning without inconvenience to the patient.

Prosthesis Design

FreeForm CAD has been demonstrated to be the mostappropriate CAD tool for prosthesis design in all of thesecase studies and also in previously publishedliterature7, 8, 11–15. It has been shown to be the most appropriateway to manipulate anatomical forms and is alsocomparatively intuitive for prosthetists to learn to use. Whenconsidering the investment required, research has shown thatFreeForm can be used in many other applications in themaxillofacial lab in other ways including: cranioplastycontouring20, creating burns pressure splints21, surgical guidedesign22 and removable partial denture frameworkdesign19–28.

Fabrication

ThermoJet 3D printing has been shown to be suitable forphysically producing wax prosthesis patterns. The waxmaterial, although not exactly the same as the wax typicallyused in the lab, can be altered using conventional labtechniques. The process is comparatively rapid, requiresminimal clean up, is easy to use and has been shown to beable to produce patterns with skin textures. Conventionalproduction of the final prosthesis body in silicone stillrepresents the only, clinically viable option.

Table 1: Cost implications of the implementation of the digital techniques

Conventional People Direct resource Digital economic Addition indirect costsstage involved costs opportunity of digital technology

Patient consultation Patient Clinic room No difference No differenceSurgeon Waiting roomProsthetistNurseReceptionist

Impression taking Patient Lab and clinic Reduced time if patient is Scanner hardware.Prosthetist room scanned directly instead Additional time if indirect

scanning of a cast is required

Create stone replicas Prosthetist Lab Possible stage removal – CAD softwarereduced time

Bar/substructure Prosthetist Lab Free up lab space CAD software.design and fabrication Additional RP fabrication

time and cost

Hand carve pattern Prosthetist Lab and clinic Reduced design time. CAD software.Patient for final room Removal of patient: Additional RP fabrication fitting of pattern – No travel time time and cost

– Capacity to work/go to school– Removal of potential non-attendance– Free up clinic space

Flasking of pattern Patient Lab and clinic No difference No differenceProsthetist room

Boil out pattern and Prosthetist Lab No difference No differencemould clean up

Colour matching Prosthetist Clinic room No difference No differencePatient

Curing time None Lab No difference No difference

Removal from mould, Prosthetist Lab and clinic No difference No differencefitting and extrinsic Patientcolouring


Selective laser melting has demonstrated potential to producebar structures, but further research is required to validate thedimensional accuracy, material compatibility and clinicalviability.

Sub-structures and base plates may be fabricated usingStereolithography. Other RP processes such as PerfactoryDigital Light Processing or Objet three-dimensional printing,ideally in a polymer material with a flexural modulus equalto, or greater than 1,720 MPa (value of DSM Somos 10110,epoxy Stereolithography resin) also show potential.

ILLUSTRATION OF THE CURRENTSTATE OF THE ART USING DIGITALTECHNOLOGIES

In order to attempt the digital design and fabrication ofmaxillofacial prostheses the following technologies arerequired.

l 3D Scanner to capture the facial anatomy (light-based).

l Software to process scan data and output-good qualitySTL data.

l Software to process CT data and convert to good qualitySTL data.

l Haptic sculpting CAD software to design the prosthesisbody and sub-structure.

l Wax printing RP technology to produce the prosthesispattern.

l RP technology to produce stiff sub-structure components.

Table 2 illustrates the workflow possible with current DTs inthe design and fabrication of magnet-retained prostheses.

CONCLUSIONS

Hospitals and Universities undertaking research in DTs aredriving developments and improving accessibility leading towider application. However, whilst some units are exploringthe application of DTs, access remains limited. Furtherresearch is required to develop technologies that are moreaffordable and easier to use. The research has highlighted thefact that DTs have not been developed towards the needs ofmaxillofacial prosthetics, which may hinder adoption further.Introducing DT to training courses and integrating thembetter with the whole treatment process may help to improvetheir adoption into hospital laboratories and clinics.

It is clear that DTs have enormous potential. However, thecases summarised here have illustrated that although DTs canbe successfully applied to many aspects of prosthesisconstruction, they are not yet sufficiently well developed todesign and manufacture maxillofacial prostheses efficiently.For example, 3D scanning does not yet offer sufficientresolution to capture fine texture detail over an entire face.Although FreeForm has been shown to be a suitable designtechnology, issues remain when combining geometriccomponents with anatomical data. In addition, it is not yetpossible to assign skin colours necessary for a facialprosthesis in this CAD environment.

Despite the success of producing prosthesis components andwax patterns achieved in these cases, the application of DTswill be restricted by the lack of any technology capable ofbuilding a colour matched, silicone prosthesis body.

In addition to the technical limitations of DTs, the casestudies indicated that in their current state they do not makea convincing economic case on the grounds of increasedspeed or efficiency. It is likely that until costs come downsignificantly DTs would only be viable for large, busy unitswhere other applications could also be found.

References

1. Wolfaardt J., Sugar A., Wilkes G. Advanced technologyand the future of facial prosthetics in head and neckreconstruction, Int J Oral Maxillofac Surg. 2003; 32(2):121–3.

2. Chen L.H., Tsutsumi S., Iizuka T. A CAD/CAM techniquefor fabricating facial prostheses: a preliminary report. Int JProsthodont. 1997; 10(5): 467–72.

Stage

Place the matt coatedmagnets on the abutments

Non-contact scan the patient

Process scan data

Design the pattern andsub-structure if required

Fabricate the patternand sub-structure

Try the pattern on

Refine the pattern

Flask the pattern

Remove the prosthesis and trim

Extrinsic colour and detailing

Undertake colour matching

Pack mould and cure the silicone

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Patient consultation As per conventional methods

Coat the magnets in a matt,light coloured finish toreduce the reflectivity

Scan, capturing the entiresub-structure surface and areaof face required to undertake

the design

Use FreeFrom to design theprosthesis form and

sub-structure (where requiredfor magnet-retained cases)

Use ThermoJet printing to produce the pattern. Use Stereolithographyor alternative RP proces to produce

the sub-stucture in a suitableresin-based material

As per conventional methods

Note: the patient may or may notbe in attendance during flasking

and silicone curing. This will dependif the prosthesis can be completed

in a single day. If not, either ofthese processes may be undertaken

without the patient present

Fill holes and removenoise if required

Details

Table 2: Workflow based on the current capabilities of digitaltechnologies in the design of a magnet-retained prosthesis


3. Bibb R., Freeman P., Brown R., Sugar A., Evans P., Bocca A.An investigation of three-dimensional scanning of humanbody surfaces and its use in the design and manufacture ofprostheses. Proc Inst Mech Eng [H]. 2000; 214(6): 589–94.

4. Chua C.K., Chou S.M., Lin S.C., Lee S.T., Saw C.A.Facial prosthetic model fabrication using rapid prototypingtools. Inte Manufac Sys. 2000; 11(1): 42–53.

5. Cheah C.M., Chua C.K., Tan K.H., Teo C.K. Integration oflaser surface digitizing with CAD/CAM techniques fordeveloping facial prostheses Part 1: Design and fabricationof prosthesis replicas. Int J Prosthodont. 2003; 16(4):435–41.

6. Cheah C.M., Chua C.K., Tan K.H. Integration of lasersurface digitizing with CAD/CAM techniques fordeveloping facial prostheses Part 2: Development ofmolding techniques for casting prosthetic parts.Int J Prosthodont. 2003; 16(5): 543–8.

7. Verdonck H.W.D., Poukens J., Overveld H.V., Riediger D.Computer-Assisted Maxillofacial Prosthodontics: A newtreatment protocol. Int J Prosthodont. 2003; 16(3): 326–8.

8. Sykes L.M., Parrott A.M., Owen P., Snaddon R.Applications of rapid prototyping technology inmaxillofacial prosthetics. Int J Prosthodont 2004;17(4): 454–9.

9. Chandra A., Watson J., Rowson J.E., Holland J., HarrisR.A., Williams D.J. Application of rapid manufacturingtechniques in support of maxillofacial treatment: evidenceof the requirements of clinical application. Proc Inst MechEng [B]. 2005; 219(6): 469–76.

10. Yin R.K. Case study research: Design and methods,3rd ed., Sage Publishing. 2003.

11. Evans P., Eggbeer D., Bibb R. Orbital Prosthesis waxPattern Production using Computer-Aided Design andRapid Prototyping Techniques. J Maxillofac Prosthet Tech.2004; 7: 11–5.

12. Eggbeer D., Evans P., Bibb R. A pilot study in theapplication of texture relief for digitally designed facialprostheses. Proc Inst Mech Eng [H]. 2006; 220(6): 705–14.

13. Bibb R. Medical modelling: the application of advanceddesign and development technologies in medicine.Woodhead Publishing Ltd., Cambridge, UK, 2006.ISBN: 1–84569–138–5, 262–75.

14. Eggbeer D., Bibb R., Evans P. Assessment of digitaltechnologies in the design of a magnetic retained auricularprosthesis. J Maxillofac Prosthet Tech. 2006; 9: 1–4.

15. Eggbeer D., Bibb R., Evans P. Towards Identifyingspecification requirements for digital bone anchoredprosthesis design incorporating substructure fabrication:a pilot study. Int J Prosthodont. 2006; 19(3): 258–63.

16. Brånemark P.I. Osseointegration and its experimentalbackground. J Prosthet Dent. 1983; 50: 399–410.

17. Jemt T. Failures and complications in 391 consecutivelyinserted fixed prostheses supported by Brånemark implantin the edentulous jaw: a study of treatment from the time ofprosthesis placement to the first annual check up. Int J OralMaxillofac Implants. 1991; 6(3): 270–6.

18. Kan J.Y., Rungcharassaeng K., Bohsali K., Goodacre C.J.,Lang B.R. Clinical methods for evaluating implantframework fit. J Prosthet Dent. 1999; 81(1); 7–13.

19. Eggbeer D., Bibb R., Williams R. The Computer-AidedDesign and Rapid prototyping of Removable PartialDenture Frameworks. Proc Inst Mech Eng [H]. 2005;219(3): 195–202.

20. Bibb R., Bocca A., Evans P. An Appropriate Approach toComputer-Aided Design and Manufacture of CranioplastyPlates. J Maxillofac Prosthet Tech. 2002; 5(1): 28–31.

21. Bibb R., Bocca A., Hartles F. “Producing Burns TherapyConformers Using Non-Contact Scanning and RapidPrototyping” Proceedings of the 6th InternationalSymposium on Computer Methods in Biomechanics &Biomedical Engineering, Madrid, Spain, February 2004.ISBN: 0–9549670-0–3 (Published on CD-ROM byFirst Numerics Ltd. Cardiff, UK).

22. Bibb R., Eggbeer D., Bocca A., Sugar A., “Rapid designand manufacture of custom fitting stainless steel surgicalguides”, in 6th National Conference on Rapid Design,Prototyping & Manufacture, eds Bocking C.E., Rennie A.,Jacobson D. 2005, CRDM/Lancaster University, 65–72.

23. Williams R.J., Bibb R., Eggbeer D. CAD/CAM in theFabrication of Removable Partial Denture Frameworks:A Virtual Method of Surveying 3D Scanned Dental Casts.Quintess J Dent Tech. 2004; 2: 268–76.

24. Eggbeer D., Williams R.J., Bibb R. A Digital Method ofDesign and Manufacture of Sacrificial Patterns forRemovable Partial Denture Metal Frameworks.Quintess J Dental Tech. 2004; 2: 490–9.

25. Bibb R., Eggbeer D., Williams R. Rapid manufacture ofremovable partial denture frameworks. Rap Proto J. 2006;12(2): 95–9.

26. Williams R.J., Bibb R., Eggbeer D., Collis J. Use ofCAD/CAM technology to fabricate a removable partialdenture framework. J Prosthet Dent. 2006; 96(2): 96–9.

27. Williams R.J., Bibb R., Eggbeer D., Woodward A.A Patient-fitted removable partial denture frameworkfabricated from a CAD/CAM-produced sacrificial pattern.Quintess J Dent Tech. 2006; 4(3): 200–4.

28. Bibb R.J., Eggbeer D., Williams R.J., Woodward A.Trial fitting of a removable partial denture frameworkmade using computer-aided design and rapid prototypingtechniques. Proc Inst Mech Eng [H]. 2006; 220(7): 793–7.


INTRODUCTION

Trismus is defined as a contraction of the masticationmuscles which generates restriction of mouth opening1. It canoccur immediately post surgery involving the maxilla ormandible and post radiotherapy at any time. Early treatmentcan minimise complications, with prophylactic managementin appropriate cases further reducing the number of patientsexperiencing this condition.

The diagnosis is often overlooked by a number ofprofessionals as it is not life threatening, and unless informedpre-operatively, patients may assume that the mouth openingreduction is ‘normal’ and will recover with time.Unfortunately, the trismus is likely to worsen if not treated,with immobile joints suffering degenerative changes1.

A study from Boston reported that the normal maximummouth opening is 48.9mm, which may be assessed bypositioning three fingers vertically aligned between the upperand the lower central incisors up to the first distalinterphalyngeal folds2.

Trismus can be caused by trauma, nerve damage, radiationtreatment, TMJ problems, central nervous system dysfunctionor a combination of them1. The passive motion of using a jawexerciser allows the TMJ to stay relaxed, while the devicemoves the joints by increasing mouth opening. The jawexerciser keeps the joints healthy without activating painfulmuscles and reduces TMJ inflammation and muscle pain1.

AETIOLOGY

A lack of success using conventional trismus screws ortongue depressors in patients groups (including those whohave had an maxillectomy, some edentulous patients,gingival problems and post-radiotherapy), led to therequirement for an alternative device in the Department ofMaxillofacial Prosthetics in Poole Hospital NHS.

In post radiotherapy patients, the tissue is particularlysensitive and may not tolerate a hard surface against it witheven minimal pressure. The TheraBite appliance has beenshown to be beneficial in this group of patients, but it isrelatively expensive (£221.43 per device)3.

Fig. 1: Photographs oftongue depressors, acrylatedTrismus screw and aTheraBite4.

FLEXIBLE JAW EXERCISER: AN ALTERNATIVE APPLIANCE FORTRISMUS REHABILITATION

C. Orbaneja Botija

Carmen Orbaneja Botija MIMPTMaxillofacial Prosthetics ServicePoole Hospital NHS TrustLongfleet RoadPooleDorset BH15 2JB

Keywords: Trismus, Flexible jaw exerciser, Protocol, Information leaflet.

This paper highlights the importance of mouth opening recovery in patients who do not tolerate thehardness and/or shape of a conventional trismus appliance.The construction of a flexible jaw exerciser as an economical and straightforward to produce devicefor temporo-mandibular joint problems was considered to be a treatment alternative. A protocol formand patient information leaflet were written to establish an accurate and easy to follow treatment.


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The flexible jaw exerciser can also benefit patientsundergoing radiotherapy. It is advisable to monitor fortrismus by checking for pain or weakness in the masticatingmuscles in the radiation field. Problems can arise as a resultof collagen deposition causing further tissue fibrosis5.

The patients can also be instructed to prophylacticallyexercise the muscles of mastication 3 times daily, opening themouth as much as possible without pain, 20 times, withoutthe need of any appliance6.

Contraindications to the use of the flexible jaw exerciserinclude:

l Patients with new skin flaps in the area of application ofthe exerciser.

l Patients with possible fracture in the maxilla, mandible orany weaknesses of the surrounding bones.

l Patients with osteoradionecrosis of the jaw or infectionsincluding osteomyelitis7.

PROBLEMS CAUSED BY TRISMUS

1. Maxillofacial

Difficulty in re-examination leading to problems indiagnosing recurrent disease.

Complicated management of surgical site: surgery itself,impression taking, obturation of the defect area,rehabilitation.

2. Dietetics

Reduced mouth opening can result in reduced oral intake,weight loss and considerable nutritional deficit, which cancompromise the recovery from surgery, radiotherapy and/orchemotherapy.

It may also make mastication more complex as a result in acompromised airway clearance1.

3. Speech and Language

Reduced mouth opening can impact speech with a decreasedsize of the resonating oral cavity reducing the quality of thevoice1.

4. Dentistry

Oral hygiene could be compromised, leading to dentalcaries and/or infection if not treated. The situation worsensby the difficulty in placing dental restorations and doingextractions8.

5. Cosmesis

Cosmetic appearance while talking may change because ofopening restrictions.

6. Psychology

The discomfort and occasional bleeding of the tissue whenusing hard trismus screws or tongue depressors maydemotivate patients. This may result in poor compliance of

the prescribed treatment routine. Trismus if untreated canworsen and affect the quality of life due to difficulty in dailytasks such as speech, mastication, taste and hygiene. Patient’smental strength may weaken, making the overall recoveryslower, especially for those who have received or arecurrently receiving radiotherapy.

MATERIALS AND METHODS

A master model was fabricated in lab putty which could betrimmed easily and quickly, using a grinder to give flatsurfaces. The wedge with a handle had a narrow section of10mm to accommodate patients who had a much decreasedmouth opening (up to 13mm). According to the Boston studypreviously mentioned in the introduction, it was decided toconstruct the widest section at 50mm.

Vertical lines were incorporated on one side every 10mm sothe patient could easily assess the mouth opening during thetreatment. These lines were made with a saw and round bladein the lab putty master model.

A mould of the putty master model was made using a metalflask, Crystacal R hard plaster and the conventional two partmould technique and separating agent.

Once the plaster was set, the master model was removedand the void filled with an addition cure silicone(more commonly known as Platinum cure silicone) whileeither dermatologically tested or medical grade silicone wereused to avoid any reaction when in contact with tissue. Thesilicone was mixed with a standard catalyst along with athixotropic agent for easy control when transferred into themould, adding white pigment Factor II9.

The types of silicone used for the construction of theseappliances were:

l Elastomer 42 by Technovent whose shore hardness is A42with the Factor II thixotropic agent A 300-810.

l Maxillofacial Rubber M511 with hard catalyst M516 byCosmesil whose shore hardness is A35-40 with antislump agent M514.

When cured, the silicone wedge was removed from themould and minor trimming was carried out.

Fig. 2: Photograph of a flexible jaw exerciser4.


The flexible jaw exerciser was provided together with aflexible plastic ruler so that the patient could measure theopening weekly. This was also made in the laboratory bycopying and pasting a 50mm long ruler on an A4 sheet whichwas used to make an acetate copy. Then it was trimmed toobtain individual rulers.

Each flexible jaw exerciser was customised to the patientneeds in terms of opening, shape and material used.

PROTOCOL AND PATIENTINFORMATION LEAFLET(Both enclosed as appendix at the end of this paper)

A protocol was filled out and signed by either a consultant ora specialist registrar. Specified application of heat on theaffected area before or after the treatment11 instructions ofhow to use the device, type of treatment recommended,storage, modifications and cautions would be given verballyas well as written. A patient evolution record chart was alsoprovided and the patient was asked to bring it to everyappointment with the prescriber as a method ofencouragement to follow the treatment, which may be longand seem tedious.

Initial opening was measured and recorded at the start of thejaw exerciser treatment. A patient information leaflet wasprovided, in which basic definition of trismus, its problemsand how and when to use the flexible jaw exerciser weredescribed.

Patients should be followed up closely, ensuring the correctfrequency and adequate procedure of its use. This allowsearly identification of any problems due to misuse of thedevice.

RESULT

Cosmesil Maxillofacial Rubber M511 with hard catalyst hasbeen selected for the construction of future flexible jawexercisers as patients found it softer, more comfortable andmore compliant with the therapy.

The flexible jaw exerciser can be particularly helpful whenused in conjunction with the written protocol.

Patient progress records as well as periodic reviews (of 1 to 2weeks) were beneficial in encouraging patients to follow theprescribed treatment.

Patient information leaflets could facilitate the rehabilitationprocess by ensuring adequate awareness of the condition andallowing treatment to be conducted accurately.

CONCLUSION

l Awareness of trismus and its prophylactic treatmentscould minimise the number of patients affected by it.

l Improvement in mouth opening can be related to thepatient compliance.

l Information and follow up was considered to enhancepatient co-operation.

Acknowledgements

I would like to thank the following colleagues:

Mr Mark Townend, Maxillofacial Prosthetist Head ofService, and Mrs Heidi Silk, Principle MaxillofacialProsthetist, both at Poole Hospital NHS Trust for theirconstant support not only in this paper.

Mr Parkash Ramchandani, Consultant Oral andMaxillofacial/Head and Neck Surgeon at Poole HospitalNHS Trust for his collaboration in this paper.

Mrs. Penny Scott, Senior Specialist Speech and LanguageTherapist and Miss Abbie Smith, Specialist Speech andLanguage Therapist, Poole Hospital NHS Foundation Trust.

Miss Pamela Cartwright, Oncology Dietician, Poole HospitalNHS Foundation Trust.

References

1. What is Trismus? 1–4www.oralcancerfoundation.org/dental/trismus.htm© 2001–2007, OCF Inc.

2. Zawawi K.H., Al-Badawi E.A., Lobo Lobo S., Mellis M.,Mehta N.R. 0873 An Index for the Measurement of NormalMaximum Mouth Opening. Tufts University School ofDental Medicine, Boston, MA, USA. March 2000Available at http://iadr.confex.com/iadr/2002SanDiego/techprogram/abstract_16576.htm

3. Information obtained by ATOS medical representant duringa telephone conversation on 05/01/2007.

4. Pictures taken by Medical Photography at Poole HospitalNHS Trust. 2007.

5. Srithavaj T., Thaworanunta S., Bunnang J. Modifieddenture plates using bilateral technique manipulation intrismus-induced head and neck irradiated patients: A pilotstudy. Mahidol Dent J 2006; 26: 229. Available athttp://www.dt.mahidol.ac.th/eng/eresources/journal/PDF26(3)/DENT26(3)227.pdf

6. National Institute of Dental and Craniofacial Research.Oncology Reference Guide to Oral Health. 1.Available at http://www.nidcr.nih.gov/HealthInformation/DiseasesAndConditions/CancerTreatmentAndOralHealth/OncologyReferenceGuide.htmThis information is not copyrighted. Updated Jul. 2002.


7. Atos Medical. Treatment Regimens. Available athttp://www.atosmedical.com/Products/Mouth_Jaw/The_TheraBite_System/Treatment%20Regimens.aspx.Updated Nov. 2006. © 2006 Atos Medical.

8. Thomas D. Taylor. Clin Maxillofac Prost. 43. © 2000Quintessence Publishing Co, Inc.

9. Thomas K.F. Techniques and Materials Guide forSuccessful Facial and Somato Prosthetic Rehabilitation.164. © 2006 K.F. Thomas.

10. Technovent Product Catalogue 2007; 10–11.www.technovent.com

11. Peters W.J. Consultant. Poole Hospital NHS Trust. PatientInformation Leaflet: Training to Obtain Correct JawFunction. Reviewed 01/2007.


WHAT IS THE JAW EXERCISER?

The Jaw Exerciser is a device that may be supplied to you tohelp increase the amount your mouth opens if this becomesmore difficult than normal.

WHAT IS TRISMUS?

It is a restriction of mouth opening because the lower jaw isnot functioning as normal. Various things can lead to trismusincluding:

• Trauma.• Radiation therapy. • Surgery. • Stroke.• Extraction of the wisdom teeth. • Problems with the joint of the lower jaw. • A combination of the above.

WHAT ARE THE PROBLEMS THATTRISMUS CAN CAUSE?

If your mouth cannot open normally it may not be able tocreate normal sounds and therefore you may find it difficultto speak. Reduced mouth opening can also cause problemswith things such as:

• Eating.• Tooth brushing.• Putting in and taking out dentures.• Specialist dental examinations and treatments.• Cosmetic appearance whilst talking.

Overall the problem of trismus can be an added stress to youwhen you are already undergoing other treatment.

THE TREATMENT OF TRISMUS

The Jaw Exerciser

The majority of patients can use a Jaw Exerciser although thedesign of the device may vary depending on your particularsituation, i.e. if you have some teeth missing.

To avoid the problems described it is best to start jawexercising as soon as your Specialist is happy that it is safefor you to do so, i.e. not immediately after your operation.

Your Specialist will advise that you start jaw exercising andone of the team will then discuss and demonstrate thetreatment to you. A device and printed instructions will begiven to you and your mouth opening will be measured whenyou start the treatment and as you continue.

What the Jaw Exerciser should and should not do

The Jaw Exerciser should apply constant pressure when youuse it. You will be advised to undertake daily regular constantsessions.

The Jaw Exerciser should not cause you pain as this cancause an opposite effect and make the trismus worse.

The Jaw Exerciser should allow the joint of your lower jaw tobe relaxed but moving as the Jaw Exerciser opens yourmouth.

Success with the Jaw Exerciser

Success with the Jaw Exerciser is achieved by using itregularly over a period of time, i.e. weeks not days. You willbe shown how to monitor your own progress with a simplemeasure and regular review appointments will be arrangedfor you, normally when you are due to see the Head and NeckTeam anyway. You will need to continue using the JawExerciser until advised otherwise by the Team or yourtrismus may return.

Problems with the Jaw Exerciser

If during the treatment you notice any of the following,please stop the treatment immediately and contact the Headand Neck Team, details are on the cover of this leaflet:

• Redness/itching of your skin/gums – Allergy.• Prolonged discomfort/pain.• Swelling of your mouth or neck.• Sensitivity of your teeth/gums.

For more detailed information

Oral Cancer Foundationwww.oralcancerfoundation.org/dental/trismus.htm

National Institute of Dental and Craniofacial Researchwww.nidcr.nih.gov

APPENDIX 1

PATIENT INFORMATION LEAFLET


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INSTRUCTIONS

Your mouth opening will be measured and recorded beforestarting the treatment. You will be able to monitor your ownprogress by using the ruler provided and filling in the PatientProgress Record on this form. When and how to measure willbe demonstrated to you.

Treatment for patients with limited jaw mobility:8-5-8-7

• Sit with your head straight.• Place the Jaw Exerciser in the centre of the mouth until

the muscles are stretched. • Avoid bringing your lower jaw backwards.• Maintain this position for 8 seconds.• Rest for 5 seconds.• Repeat this exercise 8 times per session.• Perform 7 sessions a day.

Treatment for patients with jaw pain: 30-5-5-5

• Sit with your head straight.• Place the Jaw Exerciser in the centre of the mouth until

the muscles are stretched.• Avoid bringing your lower jaw backwards.• Maintain this position for 30 seconds.• Rest for 5 seconds.• Repeat this exercise 5 times per session.• Perform 5 sessions a day.

Notes

• If you have been supplied with a flexible Jaw Exerciser, pushit in after it has been positioned in the centre of the mouth.

• If you have been supplied with a plastic trismus screw,rotate it round instead of pushing it in.

OTHER TREATMENT RECOMMENDED:

___________________________________________

Storage

Wash the Jaw Exerciser after every session with warm waterand washing up liquid and dry it.

Store it in a dry environment.

Do not expose to high temperatures.

Modifications and replacements

These devices can be modified as required i.e. made shorteras your mouth opening increases.

Replacement due to loss or breakage is provided, as continuousrehabilitation is very important. Please contact the Team.

Cautions

The Jaw Exerciser is only for your use, please handle it withcare. If you notice any of the following, please stop yourtreatment and contact the Team, details are on the cover ofthis form:

• Redness/itching of your skin/gums – Allergy.• Prolonged discomfort/pain.• Swelling of your mouth or neck.• Sensitivity of your teeth/gums.

Treatment Advised

Type of Jaw Exerciser

Plastic trismus screw nn Flexible Jaw Exerciser nn

Treatment recommended: 8-5-8-7 nn 30-5-5-5 nn

nn Other (please specify) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Application of heat on the affected area Yes nn No nn

Before treatment nn During treatment nnAfter treatment nn

Duration of heat application

5 minutes nn 10 minutes nn 15 minutes nn

Consultant nn SPR nn Other nn

Name _________________________________________

Title ________________________ Date_____________

APPENDIX 2

THE JAW EXERCISER: PROTOCOL FORM


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Patient Progress Record

Date Time Measurement of Period Comments (ie. pain,jaw opening of time swelling…)

Before After


INTRODUCTION

An external buttock prosthesis maybe used in the prostheticrehabilitation treatment of congenital deformities orsyndromes, burns, trauma and tumour excision.

The management of burns to the buttock area are difficultbecause of difficulty in securing the dressings, risk of faecalsoilage leading to wound infection and poor graft take.

Potokar et al1 states that isolated buttock burns are oftensuperficial, they consist of a different aetiology in adults andchildren and are often a result of contact burns. Burns fromhot water scalds are usually superficial partial thickness orfull thickness burns and they require treatment.

The current available treatments for burns in the buttock areaare grafting of buttock burns1 and silicone gluteal implants

that can be placed in the defect area to assist with thecontouring of the deformity caused by the burn injury2.Gluteal augmentation can also be used, which uses implantsand a combination of liposuction/lipo-injection procedures3.Gluteal implants are reported to have a higher success rate incomparison to liposuction and lipo-injection procedures,which require vast experience in Coleman fat injection3.

Tissue expansion is another clinical procedure that can beused in the reconstruction and management of extensive burnscars, however there is a risk of complications caused whenthe serial expansion of the same tissues is performedrepeatedly or if the expanders are located in the lowerextremities4. Buttock augmentation has reported to have postsurgical complications and presents great challenges with theincidence, diagnosis, management, and prevention ofcomplications post surgery5.

EXTERNAL HOLLOW BUTTOCK PROSTHESIS

P. Kaur and D. Coppins

Paramjit Kaur BSc (Hons) MIMPTMaxillofacial ProsthetistCraniofacial Prosthetics UnitDental InstituteKings College Hospital NHS Foundation TrustBessemer Road London SE5 9RS

Key: buttock prosthesis, hollow, burns, rehabilitation of patient.

Introduction: This paper describes a methodology for the fabrication of a custom-made externalhollow buttock prosthesis for a burns patient, and details the treatment options and the selectedchoice of treatment.

Method: An impression of the defect was taken and a wax-sculpt pattern shaped and fitted to assessthe conformity of functional movements. A mould was prepared, allowing for the void in the waxpattern and packed with a silicone elastomer.

Conclusion: The prosthesis allows the patient to walk and sit comfortably and gain confidence bywearing the external hollow buttock prosthesis for a successful outcome. The advantages of thecustom-made external hollow buttock prosthesis over a conventional solid prosthesis are that it fitsvery well to the patient’s skin, the prosthesis was not visible and it was light in weight. Beingnon-invasive the procedures avoid surgical and multiple surgical reconstruction.

This case was undertaken at the Department of Anaplastology and Maxillofacial Surgery at theNorthern General Hospital in Sheffield.

David Coppins BSc (Hons), LCGI, MIMPTConsultant AnaplastologistDepartment of Anaplastology Burns, Plastic Surgery and Oral DirectorateSheffield Teaching Hospitals Foundation NHS TrustNorthern General HospitalHerries RoadSheffield S5 7AU


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CASE HISTORY

A 42-year-old female sustained a scald as a one-day old babywhen she was in hospital. The patient presented a long scaracross the right buttock and had completely lostsubcutaneous fat in the area. This resulted in a significantdefect with a deficit of almost half a kilo of fat.

The patient had managed to date with the use of pieces offoam inserted under her clothing in order to maintain hercontour.

The patient presented superficial partial thickness burns anddid not require skin grafting. She did not wish to have anysurgery for placement for implants, serial excision of the scaror tissue expansion for the correction of the contourdeformity.

METHOD

Following standard clinical procedure the patient wasinstructed to sit in an upright position and an impression ofthe defect area was taken using alginate impression material(Cavex Holland BV, PO BOX 852, 2003 RW Haarlem, TheNetherlands) with plaster of Paris backing (John Winters &Co. Ltd., PO BOX 21, Washer Lane Works, Halifax, HX27DP). This was cast in Crystacal ‘R’ dental IV stone material(John Winters & Co. Ltd., PO BOX 21, Washer Lane Works,Halifax, HX2 7DP) and allowed to set.

The defect area was waxed up to reproduce the naturalcontours of the buttock area and to fill out within the confinesof her support underwear.

The final waxed-up pattern was then hollowed out on thefitting surface of the wax pattern from the centre outwardsleaving 2 inches around the circumference of the wax pattern.

WAX/TRY-IN STAGE

For the wax try-in procedure the patient was shown how toinsert the wax pattern into her underwear and then asked towalk in order to observe how noticeable the wax pattern wasand whether it needed to be extended or shaped according tothe conformity of functional movements. The patient wasalso assessed in gaits and seated positions, to determine thecomfort of the wax pattern and whether it was noticeable.The wax pattern was adjusted and re-contoured accordinglyand then re-fitted to determine the final fit.

FABRICATION OF THE HOLLOWBUTTOCK PROSTHESIS

The void of the hollowed wax pattern on the cast impressionmodel was filled with a mixture of Crystacal ‘R’ and waterand allowed to set. A circular groove 20mm in diameter and20mm deep was then ground into the middle of the castimpression model. This was done to allow compressibility ofthe prosthesis when the patient is in a seated position. Thewaxed up pattern was then sealed onto the cast model andUnifol separating medium (Bracon Limited, High Street,

Etchingham, East Sussex, TN19 7AL) was applied onto thestone surfaces. The waxed-up pattern was invested in amixture of type IV dental stone material of Crystacal ‘R’ andwater. Following the setting stage the mould was boiled out,separated and left to bench cool. Unifol separating mediumwas then applied to the mould and allowed to dry.

Fig. 1: Shows two-part mould ready for packing for the externalbuttock prosthesis.

The selected material of choice material was A-588 Realisticsilicone elastomer material (Technovent Limited, HeadingleyHouse, 39 St. Michael’s Lane, Leeds, LS6 3BR, UK) as it isa translucent platinum cured silicone elastomer. Fourhundred grams of this silicone elastomer material was mixedwith a small amount of intrinsic colour in order to obtain atranslucent buttock prosthesis and catalysed with 40 grams ofA-588-3 catalyst (Technovent, Headingley House, 39 St.Michael’s Lane, Leeds, LS6 3BR, UK). This strength of thecatalyst was used to ensure flexibility and firmness of theprosthesis, which was required for this type of prosthesis.The properties of the Realistic Silicone elastomer are shownin the Table 1 below.

Table 1 shows the physical properties of A-588 RealisticSilicone Elastomer Materials, (Technovent, HeadingleyHouse, 39 St. Michael’s Lane, Leeds, LS6 3BR, UK,manufacturing instructions).

Table 1: The physical properties of A-588 Realistic SiliconeElastomer Materials

Durometer Shore A 29

Tensile Strength (psi) 600

Tear Strength (ppi) 40

Elongation 325

Viscosity 85,000 cps

The material works well with A-300-1 Thixo Agent,(Technovent, Headingley House, 39 St. Michael’s Lane,Leeds, LS6 3BR, UK), which helps eliminate the need forvacuum deairation in a speed mixing machine and alsoincreases the viscosity of the material to a mixture which willno longer pour, so ease of packing is achieved.

The Unifol separating medium on the mould was allowed todry and then catalysed silicone elastomer was carefullypacked into the mould using a spatula to eliminate any airtrapping during the packing procedure. The mould waspressure clamped and processed at room temperature for24 hours.


Following the curing process, the mould was unclamped, theprosthesis removed and the excess material at the edgestrimmed. The prosthesis was finally cleaned with a soapywater solution.

Fig. 2: Shows the fit of the finished external hollow buttockprosthesis on the mould.

FITTING OF THE EXTERNAL HOLLOWBUTTOCK PROSTHESIS

During the fitting procedure the patient was asked to try theprosthesis by inserting it into her underwear and asked towalk and sit down with the prosthesis fitted as previouslydescribed. Thus, compliance of patient/prosthesis isdetermined.

Fig. 3: Shows the finished external buttock prosthesis.

The finished prosthesis weighed 352 grams, thus allowingcomfort for the patient and reduces the risk of drag of theprosthesis as it is light, and the hollow aspect, allowed for thecompressibility of the prosthesis for when the patient was ina seating or lying position.

Fig. 4: Shows the fitting surface of the finished external hollowbuttock prosthesis.

The patient was initially reviewed one month post fitting andsubsequently at 6 month intervals.

It is important that reviews are maintained, thus patientexpectations, requirements and prosthetic and clinicalgovernance outcomes can be monitored.

The patient did not consent to allowing any clinicalphotography.

DISCUSSION

There are various surgical options available as a method oftreatment, which involve serial excision of the scar or tissueexpansion. However, the patient was keen to explore a moreconservative approach and custom-made prosthesis wasoffered as a prosthetic rehabilitation option. There are twoforms of prostheses available with this treatment, a completeor a hollow custom-made prosthesis. The selected choice wasclear hollow silicone buttock prosthesis. The hollow aspectreduces the weight of the prosthesis, which is an importantfactor in the functionality and comfort of the prosthesis forthe patient. This was achieved by 35% of the prosthesis beinghollowed.

CONCLUSION

The advantages of custom-made external hollow buttockprosthesis over a conventional solid prosthesis are that itconformed well to the patient’s skin and was far less visiblethrough the patient’s clothing. Being non-invasive theprocedures avoid surgical and multiple surgicalreconstruction and if the patient does not wish or require touse the prosthesis at anytime in the future then it can be easilydiscarded without any subsequent trauma. When wearing theexternal hollow buttock prosthesis, the patient was able towalk and sit comfortably and gained confidence, andpresented a successful prosthetic outcome.

New treatment materials are continually evolving. Siliconeand gel silicones could be used for this kind of treatment,however further research in this area is recommended.


References

1. Potaker T., Ramaswamy R., Dickson W.A. Isolated buttockburns: epidemiology and management. Burns. 2001; 27:629–634.

2. Vergara R., Marcos M. Intramuscular gluteal implants.Aesthet Plas Surg. 1996; 20(3): 259–62.

3. Harrison D., Selvaggi G. Gluteal augmentation surgery:indications and surgical management. J Plastic Recon &Aesthet Surg. 2007; 60: 922–928.

4. LoGiudice J., Gosain A.K. Paediatric tissue expansion:Indications and complications. J Craniofac Surg. 2003; 6:866–872.

5. Bruner T.W., Roberts T.L. 3rd, Nguyen K. Complicationsof buttocks augmentation: diagnosis, management andprevention. Clin Plas Surg. 2006; 3: 449–466.

The photographic pictures were taken from SheffieldTeaching Hospital NHS Trust Database.


INTRODUCTION

Maxillofacial Prosthetists in the modern NHS are required byclinical governance to provide clinical documentation. Theseinclude medical records, monitoring patient progress1 andmedico-legal reports. They may be used to provide patienteducation, case presentations, teaching and treatment audits2.A review of the literature shows there to be many issues toconsider when using digital photography within the practiceof Maxillofacial Technology such as; costs, usability, imagestorage, and potential advantages over existing recordsystems.

Using a questionnaire this article highlights how MPT’s areusing digital photography in their workplaces and highlightsthe relevant issues and considerations that should be takeninto account with using digital photography within thepractice of Maxillofacial Technology.

LITERATURE REVIEW

Digital photography is used in many trades and professionssuch as Estate Agents, Advertising Agencies, Police andMedia3. Its use has been investigated by Dentists4, Physiciansand Otolaryngologists5.

Existing literature is mostly focused on using digitalphotography in dental practice4, orthodontic practices2,3, orcomparing different cameras and their associatedadvantages/disadvantages.

USAGE AND REGULATORY ISSUES

The associated issues when using digital photography arepresented in Table 1 and this article will highlight the moreimportant: standardisation; management; storage; consentand data protection.

DIGITAL PHOTOGRAPHY IN MAXILLOFACIAL PROSTHETICS

N. Caulfield and C. Maryan

Keywords: Maxillofacial Technology, digital photography, purchase considerations, security, consent,Data Protection Act 1998.

Health care professionals need to be aware of their responsibilities in relation to patient rights, dataprotection and a professional manner in relation to taking and storage of photographic images,particularly digital images.

Purpose: The purpose of the study was to review aspects of these regulations and how they impactupon Maxillofacial Prosthetists & Technologists (MPT).

Method: A survey of MPT’s practice and a literature review was undertaken.

Results: The survey identified a high level of awareness and competence by many MPT’s however anumber of MPT’s were not aware of or adhering to Department of Health guidelines.

Conclusions: All MPT’s should be aware of legal and professional issues of consent, the efficientuse of digital photography and data storage. Every unit using this technology within their practiceshould produce an agreed protocol for image capture and storage. Alternatively, medical illustrationonly should be used as required.

Christopher Maryan BSc (Hons), LCGI, FIMPT Head of Centre and Principal LecturerSchool of Biology, Chemistry & Health Science,Manchester Metropolitan UniversityAll Saints BuildingAll SaintsManchester M15 6BH

Natalie Caulfield BSc (Hons), Dip PS, MIMPT,LOTA, Maxillofacial ProsthetistMaxillofacial Unit 1st FloorDental Institute,Kings College HospitalDenmark HillLondon SE5 9RS


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Table 1: Associated issues when using digital photography

Number of pixels Publishing

Light and flash Internet and e-mail

Digital ‘v’ film Management and storage

Projection Standardisation

Manipulation Data protection and consent

Printing Security

STANDARDISATION

Standardisation is an important factor in photographyespecially when the photographs are to be used forcomparisons6. Using photographs for comparative purposesrequires an initial point of reference. If the light, subjectposition and distance from the subject differ, an unbiasedcomparison cannot be made. The pictures in Figure 1 showthe subject in good light, good position and eyes level to theFrankfort plane. The second and third show tilting,shadowing and differing ratio of the subject making acomparison difficult.

Fig. 1: Illustrates difference in light and positioning on animage. Pictures copyright of University Hospital Birmingham.

Principles for light and flash use are largely the same indigital photography as in standard film photography.Exposure is critical for a good picture7. To capture a goodpicture the amount of light entering the camera must beadjusted to suit the sensitivity of the sensor7. Too much lightand delicate areas of the picture are converted to white andlost, too little light and shadow areas become solid areas ofblack. The user must adjust the shutter speed higher to allowmore or slower to allow less light through to the sensor.A digital camera contains a metering system designed tomeasure the amount of light entering the camera. This will belinked to an auto exposure mechanism to alter the apertureand shutter to suit the light available7. Digital cameras alsohave various settings for various lighting conditionsi.e. indoor/outdoors, snow scene, night, fluorescent light.If these are present in the camera it will automatically adjustthe light source to the setting selected.

In some cameras there are light indicators (red and green) toalert the operator if there is enough light or not, so a flash unitmay be added6.

STORAGE AND MANAGEMENT

Storage refers to the medium on which your images arestored. This may be a hard drive, CD, DVD or compactmedia. Whereas management is how they are retrieved oncesaved onto the appropriate medium, e.g. a database where thepatient details such as name, hospital number, date of birth,prosthesis type can be added for use later for statisticalpurposes.

SECURITY

Within the NHS, protection and security of images is apriority to ensure patient confidentiality. Using your trust’smedical illustration department ensures the images arestored, backed-up and accessed appropriately.

Images should never be stored on a laptop computer as thereis a risk of the images being lost or stolen and used bypersons outside the consent they were given.

DATA PROTECTION AND CONSENT

The Data Protection Act (DPA) 19988 governs protection ofpersonal data by companies and organisations in the UK. Theact allows personnel involved in the patients care to accessthem but not remove them from the Trust, data should berelevant for the purpose for which it is taken and be of theminimum amount necessary.

The Caldicott report (1997)9 identified six key principles tooutline justification, use, access and responsibilities withpatient information for all healthcare professionals.

Both of these can be found easily on the internet and withinall NHS Hospitals. As healthcare professionals, it is eachindividuals responsibility to familiarise themselves withthese documents.

METHOD

Twenty maxillofacial units were contacted by telephone toevaluate their use of digital photography in their work.Additional information such as camera cost, consent,protection and security of digital images was also gathered.The participants were all picked randomly and assuredanonymity.

RESULTS

The questionnaire showed that 80% of MPT’s questionedalready owned and used a digital camera in the managementof their patients.

The most common use for the photographs was for records,and a mixture of the following; construction; teaching anddiscussion aids; pre-post operative comparison; presentations;planning research and recording unusual or interestingprosthesis. Figure 2 illustrates these responses in detail.


Fig. 2: Uses of digital photography in maxillofacial prosthetics.

Factors that MPT’s considered when purchasing theircameras are shown in Figure 3. The results show that 100%of respondents consider resolution important, 79% considerease of use and 86% consider Macro features are more orvery important considerations.

Fig. 3: Camera purchase considerations.

Figure 4 shows how medical photographs were stored byMPT’s. Twenty-one per cent of respondents were using adatabase, 43% answered software package, 7% use the PChospital Hard Drive and 50% are using Windows application.

Fig. 4: Storage of images.

Respondents were questioned with regards to consent, ifconsent was sought and if it was recorded. The results areshown in Figure 5. All of the MPT’s using digitalphotography did seek consent and 79% always recordconsent. However 21% do not have consent recorded.

Fig. 5: Seeking and recording patient consent.

Final questions asked whether Maxillofacial Prosthetistswere aware of security guidelines. This intended to determinethe understanding and knowledge of the Data Protection Act(DPA) and the Caldicott report outlining the responsibilityan NHS professional has for the images they are taking.Eighty-six per cent said ‘yes’, they were aware of theissues/guidelines but only 50%, when questioned further,could name either the Caldicott or DPA 1998.

DISCUSSION

This study outlines the various issues related to the use ofdigital photography that MPT’s should take intoconsideration. It is clear from the questionnaire thatProsthetists have a wide use for digital photography inMaxillofacial Prosthetics, from planning and research toteaching aids.

Before purchasing a camera it is advisable to identify how itwill be used. The camera should be considered on how itperforms and it’s suitability for use, price is obviously aconsideration in a purchase but should not be the definingreason to buy. Resolution and macro are importantconsiderations with regards to the image quality. If thepictures are going to be used for a presentation, it may be thatlarger images are required. Therefore a picture at close rangewill be complimented by the detail from a high-resolutioncamera with good detail and colour. Ease of use is animportant factor with electrical and technical goods as a morecomplicated camera to use may cause the operator difficultiesin achieving the desired images. Operator difficultiesincreases the likelihood that the camera may not be used toits full potential. Fifty per cent of the responding MPT’sconsidered colleagues’ opinions and recommendationsbefore purchasing. This can be useful to identify whichcameras may suit the requirements for MaxillofacialProsthetic work before committing, only to find the camerayou chose may not be what was required.

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Do you seek patient consent for images? Is the consent recorded?

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The questionnaire highlights storage of images as anuncertain area, as to where and how the images should bestored. Respondents were asked how they stored the images,only one MPT answered on the PC hard drive, which isbacked-up by the Trusts IT department. None of the otherresponses were related to image storage, rather what softwareis used to access the images. It could be that the question waseither not understood by the MPT’s or the MPT questionedmay not understand the term ‘storage’. However, if anotherstudy were to be taken, this question would be revised.

Images should always be stored on a hospital main server,which is secure and backed-up regularly. In addition, imagesshould never be left on laptop computers or mobile phoneswhere they are at risk of loss or theft6.

Differing opinions and understanding of how photographicrecords should be taken, stored and used was apparent.Patient confidentiality is essential in the NHS. The DPA 1998and the Caldicott report outline measures for clinicians tofollow ensuring that any images are lawfully taken, storedand used appropriately.

Although there are guidelines for consent issued by the DOH,individual Trust’s and the Institute of Medical Illustrators,opinion on consent appears to remain fairly subjective.Advice sought from the Medical Illustration departmentconfirmed that for photographic and video recordings, fortreatment or patient assessment, must not be used for anypurpose other than the patient’s care or audit of that carewithout the consent of the patient. Recordings forpublication, research or education purposes must haveconsent in writing6.

From the questionnaire, some MPT’s did reveal not havingread these documents or knowing about them. As HealthCare Professionals it is a part of our responsibility to knowand understand the importance of these policies. Having nounderstanding of them could also mean that these MPT’smay be breaking data protection laws. Breaching rules aboutpatient confidentiality in the NHS is very serious and treatedin certain cases as professional misconduct with consequentdisciplinary action by the Trust and professional bodies6. Tomeet with the regulations that these two reports outline,consent must be given by the patient with full understandingfor the use of the images. This should be filed in the patient’snotes and may be withdrawn by the patient at any time.

CONCLUSIONS

This study has highlighted, including planning the use ofdigital photography within maxillofacial prosthetics andinvestigating the specifications required of the camera.

Determining the use of the images and the most appropriatemethod for taking, storing and archiving them.

The study highlights that while many MPT’s are wellinformed of issues of storage and archiving, security andconsent, some however are not.

When photographs are needed or have been taken, always beaware of consent issues and policies and ensure they arefollowed; find and read the latest information on consent, theDPA 1998 and the Caldicott Report from your Trust.

MPT’s should always have consent for the photographs inwriting before they are taken and ensure they are kept secureby agreement with the employing Trust, and in any doubtseek advice from your Medial Illustration Department.

When implementing a protocol for using digital photographyensure all staff are aware of it to ensure that correct protocolfor taking, storage and use of images are adhered to. All staffshould sign and date the protocol once in place.

Acknowledgements

I would like to express my thanks to all persons involvedwith answering the questionnaire. Medical Illustration atPortsmouth Hospital and University Hospital Birmingham,and Cristina Nacher, Maxillofacial Prosthetics manager,Kings College Hospital, for their help in writing this article.

Photographs in Figure 1 are copyright of University HospitalBirmingham and have been consented for publication.

References

1. France I. 2003. Managing Medical Photographs – The Key Issues. 17th March. Available at:www.ibase.com/PDFdownloads/Technical/Medical.pdfaccessed on 25 July 2003.

2. Hutchinson I., Ireland A.J., Stephens C.D. 1999. Dig CamOrthodont: An Overview. Dental Update; 26: 144–149.

3. Sandler P.J., Murray A.M., Bearn D. 2002. Dig RecOrthodont. Dental Update; 29: 18–24.

4. Dunn and Beckler, 2001. Digital photography Technologyoffers Unique Capabilities, Advantages and Challenges toDental Practices. J Californ Dent Assoc. Available at:www.cda.org/member/pubs/journal/jour2001/technology.html accessed on 23/7/03.

5. Smith R.V. 2002. The Digital Camera in Clinical Practice.Otolaryngologic Clinics of North America; 35: 1175–1189.

6. Charters S. 2003. Personal communication. MedicalPhotographer, Department of Medical Illustration,Queen Alexandra Hospital Portsmouth.

7. Andrews P. 2000. The Digital Photography manual.An introduction to the equipment and creative techniquesof digital photography. Carlton Books Ltd, London.

8. Data Protection Act 1998. Available [online]http://www.opsi.gov.uk/acts/acts1998/ukpga_19980029_en_1 accessed on 23/07/03

9. Caldicott F. 1997. Report on the review of Patientidentifiable information. Available [online]http://www.doh.gov.uk/ipu/confiden/report/crep.htmlaccessed on 11/10/03.


INTRODUCTION

A 23 year old male presented to the Hurstwood ParkNeurological Centre, Princess Royal Hospital, HaywardsHeath, West Sussex RH16 4EX following a road traffic accidentwith a large frontal cranial defect involving left and rightTemporal and Sphenoid bones. Cranioplasty using a Titaniumimplant was prescribed by the neurosurgeon. Literature reviewsindicated favourable infection rates using Titanium whencompared to other methods of cranioplasty implantreconstruction1–3. A Computerised Tomographic (CT) scan wassent to the Maxillofacial Laboratory at East Grinstead.A Stereolithographic model (SLA) was produced from a CTscan which were dimensionally accurate, negate patientattendance for impression taking and aesthetic results followingcranioplasty implant insertion were excellent4. Once the SLAmodel was fabricated, the procedure for the production of aTitanium cranioplasty implant was planned (Fig. 1).

Fig. 1: Stereolithographic model.

METHOD

First procedure of implant construction was to infill the defectarea, apparent on the SLA model, using Tenatex red wax,(Bracon Ltd, High Street, Etchingham, East Sussex TN197AL) building this up to restore an appropriate skull contour.The recontoured skull model was duplicated and a DentsoneKD, (Bracon Ltd, see above) stone model was poured and theduplicate model was inserted into one half of a large aluminummaxillofacial flask (Fig. 2). This case presented significantundercut areas about the temporal and sphenoid regions. Suchundercut areas, if poured up in the usual manner, willirremovably lock the flask halves together. Additionally, ifundercut areas are surveyed and blocked out followingstandard procedure, mould detail will be compromised bydetail lost and therefore an inaccurate implant formed. In orderto avoid locking the flask halves by using standard procedurea sectional mould was designed. This incorporates removablemould components that enable the Titanium plate to be swagedinto all undercut areas, and therefore counter the detail lost.

Fig. 2: Duplicate model in one flask half.

TITANIUM CRANIOPLASTY IMPLANT CONSTRUCTION USING A SECTIONAL MOULD

B.C. Edwards

B.C. Edwards MIMPTMaxillofacial ProsthetistQueen Victoria HospitalHoltye RoadEast GrinsteadWest Sussex RH19 3DZ

Keywords: Cranioplasty, Titanium, Skull Defect, Reconstruction.

This paper describes a method of Titanium cranioplasty implant fabrication where extensivecontouring of the implant material within the forming mould is necessary. Such a deep, threedimensionally contoured implant may be required when Temporal and Sphenoid bones arebilaterally absent and present a large frontal skull defect.


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DISCUSSION

A sectional design also allows trouble free separation of the(metal flask) mould; the Titanium plate may then be removed,trimmed and altered as it is formed. This method was firsttried using two individual stone sections to occupy theundercuts about the Sphenoid and Temporal areas, combinedwith a larger stone section over the frontal bone region.However, as the Titanium plate was swaged in the mould, itwas discovered that the smaller stone sections were fragileand crumbled upon removal from the mould. It was thendecided to make the smaller mould sections using PMMA(Fig. 3). In the two cases this technique was attempted, theremovable PMMA sections were able to withstand the forcesof the swaging process. The Titanium cranioplasty implantcould then be constructed in the following way.

Fig. 3: Flask halves with PMMA sections.

When designing a Titanium cranioplasty implant, factors thatmust be considered are skull profile and degree of overlapbetween the defect and implant plate margins. A degree ofoverlap is required so the implant maybe firmly affixed withscrews to skull bone and the defect maybe covered. Adequateimplant-defect overlap also affords the Neurosurgeon optionswhen deciding the best site for bone screw placement.However, an oversized implant will require a larger tissueflap be raised and additional soft tissue (Dura Mater) bestripped away from the boney defect margin prior to implantfixation; an unnecessary and time consuming contra-indication when planning cranioplasty of large defects5.

An overlap margin of 8mm is used for 0.5mm thicknessTitanium cranioplasty implant plates. In the Temporal region,guidance should be sought from the neurosurgeon regardingextent of the inferior margin of the implant as the Temporalis

maybe be raised and the implant inserted deep behind themuscle: less (or no) implant overlap maybe indicated due tothe presence of this muscle tissue.

The outline of the implant plate margin was marked upon theduplicate stone model, which was then incorporated into onehalf of a large aluminum flask to form the moulding implantdie (Fig. 2). Locating grooves or slots were cut into areas thatwill be filled with the removable (PMMA) mould sectionsand then separator was applied. Modeling or special trayPMMA was poured into the left and right undercut areas ofthe die half and allowed to polymerise. The frontal region andremovable PMMA sections are coated with petroleum jellyseparator and were then topped with stone in the second halfof the flask to form the counter-die (Fig. 4), 0.5mmcommercially pure (CP) Titanium plate, (DR Beven,Llangennith, Gower, Swansea SA31HU) is then drilled withTiN coated 2mm drill-bits while still flat. 2mm holes aredrilled into the Titanium plate except for the area of theimplant that will form the overlap margin. Relieving slots arethen cut into the Titanium plate using a cut-off disc, the slotsradiating from the plate margin towards the centre of the (stillflat) implant shape. Position of the relieving slots can bepredicted by using a similar shaped piece of card pressed intothe mould. The overlapping creases, apparent in the cardpattern, will act as a guide and show where the relieving slotsare required. After initial pressing, the Titanium implant wasremoved and edges trimmed to align with the marked implanton the model. Fixation holes are then drilled 2mm from theedge of the implant margin at 5–10mm intervals; diameter ofthese holes is dependent on the size of bone screws used bythe neurosurgeon. Numerous (fixation screw) holes willafford the neurosurgeon multiple fixation options. Thefixation screw holes are countersunk with a 13mm drill bitand checked using an appropriate Titanium fixation screw.

Fig. 4: PMMA sections in place.


The outer surface of the cranioplasty implant is polishedusing fine pumice and Titanium polishing compound. In ourexperience of fitting numerous Titanium cranioplastyimplants, we have found that it is easier to clean blood, tissuedebris and other (drying) fluids off of the implant when thedevice is being fitted in the operating theatre.

The implant was then marked with the patients name and therelevant medical device code using a laser under inert Argongas. It was then placed back into the mould and pressed untila passive fit is obtained when the implant is tried against theoriginal SLA model. When a passive fit is achieved theimplant is ready for sterilisation (Figs 5 and 6).

Figs. 5 and 6: Finished implant on SLA model showing left andright aspect.

Titanium cranioplasty implants, with deep three dimensionalcurves, may be formed, in the usual manner, using upper andlower flask halves and moulds. However, on removal fromthe mould an implant will require extensive modification,using hand tools, to recover contour accuracy and achieve apassive fit.

Larger cranioplasty implants, with deep three dimensionalcurves, maybe fabricated in sections and then fitted togetherin situ upon the patient in the operating theatre. Sectionaldesign implants may also be fabricated in separate moulds andco-joined by laser welding in the laboratory prior to fitting.

CONCLUSION

The technique described in this paper presents theMaxillofacial Prosthetist with a construction method thatprovides a uniform amount of force to the implant andaccuracy with regard to the fit of the implant device. Theimplant device is also fabricated and supplied as a simpleone-part device.

Acknowledgements

Sincere thanks to M. C. Cutler for help in the compilation ofthis article and Katie Salisbury of the photographicdepartment for providing the images.

References

1. Blake G.B., MacFarlane M.R., Hinton J.W. Titanium inreconstructive surgery of the skull and face. Br J Plas Surg.1990: 43: 528–35.

2. Eufinger H., Wehmoller M., Harders A., Heuser L.Prefabricated prostheses for the reconstruction of skulldefects. Int J Oral Maxillofac Surg. 1995: 24: 104–10.

3. Joffe J.M., Aghabeigi B., Davies E.H., Harris M.A retrospective study of 66 titanium cranioplasty. Br J Oral Maxillofac Surg. 1993: 31: 144–8.

4. Joffe J.M., Nicholl S.R., Richards R., Linney A.D., Harris M.Validation of computer assisted manufacture of titaniumplates for cranioplasty. Int J Oral Maxillofac Surg. 1999:28: 309–313.

5. Koppel D.A., Moos K.F., Walker F.S., Skull reconstructionwith a two part interlocking custom made interlockingplate. Br J Oral Maxillofac Surg. 1999: 37: 70–72.



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PRESENTATIONS

What do you need? Who can help you?Assessing the quality of life in individualpatients in routine clinical practice

Fisher SMaxillofacial Surgery, Faculty of Medicine and Health,University of Leeds

Our patients suffer not only the consequences of their diseaseor disorder and its diagnosis be that developmental, trauma orcancer related but the ongoing effects on important functions,such as speech and swallowing, challenges in terms ofappearance and resulting problems in resuming an activesocial life or a return to employment. It is these ‘impacts ofdisease’ areas which were highlighted in a recent major studyby Macmillan Cancer Support (the ‘Listening’ study) as themost important area for patients and carers.

My background is as an active maxillofacial oncologysurgeon in the period when free tissue transfer was becomingthe norm. In time, the decisions about what we should do (ornot) and how people coped with their disease became a majorfocus of my work and I moved to an academic appointmenthere in Leeds in 2000 to facilitate progress of head and neckrelated research.

This lecture will focus on my work to investigate the needs ofindividuals and to look at the way their needs might beidentified and met. We have used both touch-screen computertechnology and interviews and are currently evolving acommunication tool for use by all health professionals and theirpatients, for information, setting goals for progress together andfor monitoring needs, areas of difficulty and of progress.

Computer-Aided Design of orbital rimimplant

Pilley MLeicester Royal Infirmary

The use of Computer Aided Design (CAD), RapidPrototyping and Computer Aided Manufacture (CAM) canoptimize facial reconstruction. This case shows a patient whounderwent extended maxillectomy for ameloblastoma andhad several reconstructive operations but was left with anorbital rim and malar prominence deficit. CAD was used toreplicate the normal anatomical form of this site, mirroredfrom the opposite side, and a CAM wax pattern used toproduce a cast titanium implant. The steps in this process and

the difficulties in practically linking the technologies aredescribed.

CAD/CAM Technology in constructingmaxillofacial prostheses; Review of theliterature

Hatamleu M

Applications of the CAD/CAM system in maxillofacialprosthodontics include the fabrication of different facialprostheses of defect sites. Generally, the automatedfabrication of facial prosthesis follows the steps of takingfacial impression of the defect side using a laser scanner toprovide a 3D facial measurement. Then the data is sent to acomputer to generate a cast of the patient’s defective side forfabricating a physical prototype of the prosthesis using eitherrapid prototyping or Computer Numerically Controlledmilling (CNC).

This work reviews the different CAD/CAM techniques usedand the recent advances present till this date.

Conclusions on digital technologies in softtissues facial prosthesis designs

Eggbeer DPDR, Cardiff

There has been much discussion on the application of digitaltechnologies in extra-oral, facial prosthesis production,particularly in the last ten years. Much of the literature hasrelied upon the evaluation of a single case study or hasconcentrated on the engineering or the clinical aspects of theprocess. Thus coherent conclusions on how digitaltechnologies may be effectively integrated into health caresystems have not yet been made.

What was research is now becoming regular clinical practicein some major units. Critical evaluation of quality, clinicaleffectiveness and economics is vital to ensure that thedevelopment and integration of digital technologies meet thedemands of the maxillofacial prosthetics profession, patientsand the health care system.

This presentation will conclude the findings of a program ofdoctoral research into the application of digital, computer-aided technologies to facial prosthesis production. Criticalevaluations of currently available technologies andtechniques will be discussed and conclusions on how theymay be best applied to meet the needs of Prosthetists, patientsand the health care system given.

ABSTRACTS

23RD IMPT SCIENTIFIC CONGRESS 2007


The Face – a mirror of the soul

Schwipper V

Therapy of large basal cell carcinomas and the so-calledterebrans basal cell carcinoma often requires tumourresections which are mutilating, such as amputation of thenose, orbital exenteration, resection of large areas of facialskin, and/or amputation of midfacial bones. Frequently thepatients have refused any therapy for many years and havebeen living in social isolation.

One hundred and eight large skin tumours involving themidface were operated at Fachklinik Hornheide in a five-yearperiod. Individual psychological and psychosocial care wasnecessary for each of these patients prior to surgery andindividual surgical treatment plans had to be worked out.

Following surgical resection of the tumour, one step forrehabilitation of the individual patient consisted in surgicalrepair of the midfacial defects by local and distant flaps aswell as transfer of microsurgically anastomozed free flaps.The other important step was preparing individual implant-borne facial prostheses using magnetic or implant-barfixation. This type of fixation of modern craniofacialprostheses largely contributes to a patient’s private, social andprofessional rehabilitation.

Especially cases of orbital exenteration and those with a lackof surgical means to reconstruct the eyelids nicelydemonstrate the possibilities of modern facial prostheses.

Assessment of vascularity in irradiated andnon irradiated alveolar bone by laser DopplerFlowmetry, an animal study

Verdonk H

The purpose of this animal study was to confirm that LaserDoppler Flowmetry (LDF) is a reproducible method forassessing maxillary and mandibular alveolar bone vascularityand that maxillary and mandibular alveolar bone vascularityis less in irradiated bone when compared to non-irradiatedbone. All maxillary and mandibular premolars and molars of6 Gottingen minipigs were extracted. After a 3-monthhealing period, 3 minipigs received irradiation at a total doseof 24 Gy. At 3 months after irradiation, 5 holes were drilledin the residual alveolar ridge of each edentulous site of allminipigs. Local micro vascular blood flow around all 120holes was recorded by LDF, prior to implant placement. In 1irradiated and 1 non-irradiated minipig, an additional holewas drilled in the right edentulous maxillary site in order tobe able to perform repeated LDF recordings. The alveolarbone appeared less vascularised in irradiated than in non-irradiated minipigs. The effect of radiation showed to bemore pronounced in the mandible than in the maxilla. LDFwas demonstrated to be a reproducible method for assessingalveolar bone vascularity. However, recordings varied peredentulous site as well as per minipig. In order to be useful inhuman beings, normal values of vascularity of the variousalveolar sites should be known. These values may not onlyvary from person to person, but may also be depending on the

individual amount of local alveolar bone. Therefore, furtherresearch validating LDFs use in human beings; especially inthose who have undergone radiation therapy for head andneck cancer is necessary.

Maxillofacial Unit-Dhaka – Bangladesh

Gill L, Page KUniversity of Sheffield, Frenchay Hospital Bristol

In November 2005 we introduced the first trainingprogramme in Maxillofacial Prosthetics at DhakaCommunity Hospital. The Hospital was established in 1988and is a Trust-owned, non-profit-making organisationproviding health care for low income underprivileged people.The nutritional status and health care awareness of the peopleis poor, particularly in the rural areas, the women, childrenand elderly are often a substantial distance away from anymedical facility and as a consequence of this, it’s this groupthat suffer the most.

With this in mind we are returning to Dhaka in Novemberwith a larger team and aim to cover seven specialist areasfrom breast work to obturators. Our long term objectives areto return every year with a different team of specialists andwe have recently formed our own website and are in theprocess of forming a charity called MPT’s Abroad. Thiswebsite will be available shortly (mpt’sabroad.com) and willcontain lecture presentations, information/advice of workingabroad and contact details should you wish to join the team.

I would like to work overseas in a developingcountry

Haylock C

Following my early retirement from the NHS as a ConsultantMaxillofacial Prosthetist, it was my intention to work as anoverseas consultant in developing countries ‘the purpose ofthis short presentation is to identify some of the pitfalls thatmay arise with working overseas in developing countries andthe rewards should you be successful’.

Maxillofacial Prosthetist – a requirement

Chowdrey R

In recent years there has been much advancement in manyother disciplines in dentistry. There has been a progressiveworldwide demand for the specialised services personals.

Maxillofacial Prosthetist is one of them. But unfortunately inmany countries there is a severe shortage of suitable trained,qualified persons capable of providing this service for thepatients who require them. This paper will highlight thepresent status of maxillofacial prosthesis specialty in mycountry, the advancement in material science, social stigmathe patients suffer from, the amount of importance pertainingto maxillofacial prosthesis specialty given in dental educationcurriculum, and then finally an appeal to the congress forsuggestions and involvement for the betterment of thepatients of my country.


A comprehensive diploma programme inmaxillofacial prosthetics in the Indiansub-continent – need of the hour

Kheur M

India has the dubious distinction of having the largest numberof oro-facial cancer patients in the world. Oral canceraccounts for approximately 25 per cent of all cancer cases inthe subcontinent, as per latest studies.

Lack of awareness in the population, the socio-economicstatus of the affected and a compromised healthcare-deliverysystem (especially in the rural areas) usually result in patientsundertaking treatment in advanced stages of the disease andthus require extensive surgeries, followed by chemotherapyand/or radiotherapy. Thus the role of a maxillofacialProsthetist is critical in completing the overall rehabilitationof the patient.

Presently, maxillofacial prosthetic technology is taught aspart of the post-graduate curriculum in Prosthetic Dentistry.There is a greater emphasis on Intra-oral prosthetics only.The lack of materials (especially silicones and otherelastomers), lack of training in using the same, lack ofexpertise and experience is a big hurdle towards fabricatingextra-oral prostheses. The same is not covered in anyacademic curriculum in the country, including that of DentalTechnology and hence laboratory support is also lacking forthose few who wish to practice.

A lack of remuneration coupled with the reasons mentionedabove, does not make a full-time, dedicated Prosthetistprofession very viable, at this time.

There is an acute need to train the trainers in the subcontinenttowards Maxillofacial Prosthetics. The curriculum atinstitutes that run courses, such as Kings College, ChicagoDental School and Mahidol University can be used as ascaffold towards developing a program for the sub-continent.

This paper discusses the need and also presents an outline forsuch a program. The program would be tailor made to suit therequirements of the concerned personnel in the prevalentconditions and is aimed at advancing the noble science ofMaxillofacial Prosthetics via training of clinicians and dentaltechnicians, to enable them to treat and serve the patients.

Case study: Laboratory and surgicalApproach to complex Maxillary Hypoplasia –an unorthodox way forward

Paul PSouthern General Glasgow

A 48-year-old female was referred to our MaxillofacialDepartment after an unsuccessful Le Fort I osteotomy tocorrect Maxillary Hypoplasia. The bone graft had becomeinfected and she suffered Osteomyleitis and Sepsis for 3years postoperatively. Distraction Osteogenisis wasattempted to correct the deformity, however due to poor bonequality was unsuccessful.

Reconstruction is to be attempted using an OsteocutaneousFlap. I will present the complex laboratory surgery planning,and construction of templates for the correction of thispatient’s deformity.

The partial orbital prostheses

Brom JHeidelberg, Germany

Two cases of partial orbital defects are present. Both areprovided by a partial prostheses. The difficulties and theproblems of those prostheses are shown.

The use of silicone foam in prostheticrestoration of post surgical necrotizing faciitis

Payne GSouthern General Glasgow

Case study of a 62-year-old lady with postsurgicalNecrotizing Fasciitis.

A large excision of tissue was taken from right side of thechest wall and abdomen extending on to her back andanteriorly to the midline. The right breast was also removed.

I will describe the fabrication of an extensive body prosthesisusing Matrix M-3240 Silicone foam and the success ofretaining the prosthesis with a made-to-measure garment.

20 Years of craniofacial rehabilitation inSouth Wales

Evans PMorriston Hospital, Swansea

In 1987 the South Wales Facial and Audiological ImplantTeam (SWFAIT) treated their first prosthetic case. Over 200patients later we present the successes and lessons learnt overthe past 20 years in relation to planning, surgery, nursing andprosthetics. Finally the presentation looks at the future forCraniofacial Prosthetic rehabilitation in the UK.

Locator Locator Locator

Silk HPoole Hospital NHS Trust

Case presentation of patient with nasal collumella prosthesisand the use of a locator abutment for retention.

In-house custom-made TMJ implants

Bowman PNinewells Hospital, Dundee

There are custom made TMJ already available on the market.However, this lecture describes a developed method of in-house production of a two part TMJ joint implant built uponstereolithographic models, along with custom locationtemplates.

The results are promising, providing a reduction in implantcost and theatre time.


Becoming a member

Kearns AQueen Victoria Hospital, East Grinstead

Opinions on the Maxillofacial diploma, two years VocationalTraining and the AIB process are given through confidentialquestionnaires.

Perspectives given on the new structure to become a fullIMPT member through the people who have completed thisepic journey.

Positive and negative views are expressed; advice is given onhow to improve – not only lecturers and institutes, but linemanagers and senior colleagues.

‘Does my bung look big in this’

Jenner RKent and Canterbury Hospital

This study compares the weight of packing materials used forimmediate surgical Obturation. This study also offers anevaluation of material retention methods and a calculationof cost.

Pressure therapy and its effectiveness in theTreatment of keloid scars

Dimond JQueen Elizabeth Hospital, Birmingham

The aim of this study is to evaluate the effectiveness ofpressure therapy in the treatment of keloid scarring of thepinna. The study was conducted at the department ofmaxillofacial prosthetics at the Queen Elizabeth Hospital,Birmingham. 25 patients participated in the study over an18-month period. The results show that pressure therapy is aneffective treatment of keloidal scarring. However, patientcompliance is a major factor in achieving good results. A newpressure splint design was developed and trialed during thestudy, which received positive feedback from patients.

P G Tips an over view of the authorspreferred techniques

Garraway PRoyal West Sussex Trust, St Richards Hospital, Chichester

An over view of the authors preferred techniques forfabricating prosthetic nails, Ocular shell prostheses and ananti-TMJ dislocation appliance.

OTHER PRESENTERS WITHNO ABSTRACTS

Sliney DGeographical variables of sunlight resulting in higherincidence rates of age-related disease of the skin and eye.“Keynote speaker – BAOMS Sponsored lecture”

From Bond to Bones: Evolution of a novelcomposite for Craniomaxillofacialreconstruction

Professor Rudd CDean, Faculty of Engineering, University of Nottingham

Evolving concepts in chemo radiotherapy forHead and Neck Cancer

Dr Coyle C Clinical Oncologist, Leeds Teaching Hospitals NHS Trust.

Evolving aspects of of Oncology Surgery

Mr Ong T K Maxillofacial Surgeon, Leeds Teaching Hospitals NHS Trust

Working in the real world (registration, ethicsand litigation)

Maryan CManchester Metropolitan University

POSTER DISPLAYS

Review of lagopthalmos treatment

Orbanja CPoole Hospital NHS Trust

Review of different weight systems to correct paralysis of theorbiculari oculi muscle.

Studies on masticatory efficiency in patientsafter resections in maxillary region

Reitmeier B, Brom JDresden

The results of this study show that masticatory efficiency ofthe patients with resection prostheses was the lowest.

Based on the aforementioned results and the data from thenutrition reports, an attempt was made to develop nutritionalguideline for the patient with resection prostheses.


Investigations of water sorption and UVabsorbance to penetration depth of five clearheat-cured PMMA resins

Gill LUniversity of Sheffield

This work focuses on a comparison of five clear PMMAresins commonly used in the production of artificial eyeprosthesis.

Maxillofacial Prosthetics in Japan

Katsumata MMorriston Hospital, Swansea

Japan has a population of 125 million, we describe the facialand body prosthetic provision to this large populace, withdiscussion on how the service is funded and geographicaldistribution of clinics. Implant systems used along withmaterials are described and results illustrated.

Pull-out behaviour of glass fibres embeddedinto Biomedical Silicone in fibre reinforcedmaxillofacial prostheses

Hatamleh MTurner Dental School, Manchester

Fibre-reinforced maxillofacial prostheses have beenpresented recently in treating patients with facialdisfigurements. Such prostheses include the fabrication of aframework of glass fibres and injecting the silicone throughthe framework.

This study aimed to test the effect of embedding length ofglass fibres into heat vulcanised silicone through conductingpull-out mechanical test.

The use and need of patient informationleaflets

Moore YSouthern General Glasgow

A patients understanding of their treatment and care/wear oftheir prosthesis is needed to prolong the life span of theirprosthesis which in turn will help the patient maintainconfidence in their treatment helping to improve theirpsychological well being.

The aim of the research was to review the professional, legal,ethical and design issues relating to patient informationleaflets and their effectiveness.

This research will be used to determine a protocol for thewriting of leaflets.

For the maxillofacial prosthetics and technical service of theGlasgow Southern General.

The evolution of an intraoral trifocalmandibular transport disc distractor-conceptto clinical application

Walker F, Beale V R, Ayoub ASouthern General Glasgow

Introduction

A prototype intra-oral distraction device has been developedwhich can be used for trifocal distraction to reconstructmandibular segmental defects. The development of thisdevise will be discussed and the application of the distractordemonstrated using a clinical case.

Methods

The prototype distractor was custom-made in themaxillofacial laboratory. The device consists of a square-tapped threaded rod preshaped to match the desireddimensions of the new bone and tissues. It is attached to theposterior mandible on each side by 2 fixation plates whichprovide anchorage and stability. Anterior plates are attachedto the rod via a square sleeve and fixed to the osteotomisedbone transport segments. These are distracted after a 5 daylatency period by turning a nut behind the sleeve whichtransports the bone segments forward 0.5mm with eachcomplete turn following the vector determined by theposition and curvature of the rod until they meet. Thedevelopment of the devise and it’s use to recreate bone andsoft tissues in a longstanding anterior mandibular defectresulting from a childhood malignancy will be demonstrated.

Results

Approximately 6cm of anterior mandibular bone was formedvia trifocal transport disc distraction osteogenesis using thisdevice.

Conclusions

Transport disc distraction is a realistic option forreconstruction of segmental mandibular defects in selectedcases. This original design for a prototype distractor whichallows recreation of the anterior mandibular contour iscontained entirely intra orally. Further modifications to theprototype device are underway.

Hair control in Maxillofacial Surgery andProsthetics: back to the roots

Carter L.M1, Bartlett P2, Parsonage-Grant S3, Patterson A.R1,Wales C.J4, Chan W5

Aberford Road, Wakefield, West Yorkshire WF1 4DG.

1 Specialist Registrar2 Maxillofacial Prosthetist3 Senior House Officer, Oral and Maxillofacial Surgery, Leeds

Dental Institute, Leeds LS2 9LU4 Specialist Registrar, Oral and Maxillofacial Surgery, Aberdeen

Royal Infirmary, Foresterhill, Aberdeen AB9 2ZB 5 Senior House Officer, Plastic Surgery, Pinderfields General

Hospital


Many procedures in Maxillofacial Surgery and Prostheticsinvolve the hair bearing scalp or the hair bearing skin of theface. Effective hair control prevents hair from entering thesurgical wound or area for impression, thus limitinginterruptions from irritating hairs obstructing the operativefield, and allowing optimum wound closure by enabling goodvisualisation of wound edges.

Shaving the scalp or facial hair has been practised for overone hundred years. This produces a clear operating field butcan be associated with a higher risk of wound infection andcan cause psychological trauma and delays in rehabilitationby affecting the patient’s body image. Various alternative haircontrol techniques that obviate the need for shaving havebeen described.

The aim of this study was to illustrate and discuss the varioustechniques for scalp and facial hair control practised inMaxillofacial Surgery and Prosthetics.

Therefore a literature review of published methods of scalpand facial hair control was performed.

Numerous hair control techniques were identified which canbe classified into depilatory, parting, bundling/banding, anddraping techniques. Examples of the various techniquesinclude shaving, clipping, depilatory cream, gelling,braiding, banding/clasping with rubber bands/haemorrhoidligatures/urinary catheters/metal foil/cable ties/rollers, andcovering the hair with a swimming cap. Moustache hair canbe controlled in nasal procedures with the use of adhesivedrapes/dressings.

Careful management of scalp and facial hair in MaxillofacialSurgery and Prosthetics can allow a more efficient procedure,producing accurate and cosmetically pleasing results with noincreased risk of infection. The various methods areillustrated and discussed.

A novel modification in construction oftitanium cranioplasty for large craniofacialdefects

Carter L.M1, Bartlett P2, Russell J.L3

Oral and Maxillofacial Surgery, Leeds Dental Institute,Clarendon Way, Leeds LS2 9LU

1 Specialist Registrar2 Maxillofacial Prosthetist3 Consultant

Craniofacial bone loss due to traumatic injury, infectiveprocess or surgical resection of malignant disease is asignificant clinical problem. Reconstruction withcranioplasty must not only be aesthetically pleasing, but musthave adequate strength and dimensional stability to protectintracranial structures, and allow follow up with currentimaging techniques.

In large defects, harvest of autogenous bone is limited and canproduce unacceptable donor site morbidity. Titanium is strong,light, has similar thermal expansion to bone, is radiolucent andcan be fixed to surrounding bone easily. Methyl methacrylateis thicker yet mechanically inferior to titanium and is also

difficult to fix to surrounding bone. Resorbable osteoinductivescaffolds herald much promise for the future but are not yetready for routine clinical use, especially in large defects.Titanium is therefore the current material of choice forreconstruction of large craniofacial defects.

Our method for construction of titanium cranioplasty isindirect and is based on producing a model from thecraniectomy bone flap or from a stereolithographic model ofthe cranial vault defect using computed tomographic data. Acard template is then fashioned using this model, from whichthe cranioplasty cuts can be planned. The pre-cut titanium isthen swaged using a press and ball-peine hammer. As theplate is pressed into place, further cuts may be necessary.Perforations are then prepared which allow expansion anddrainage of cerebrospinal fluid and also allow fixation tosurrounding bone using titanium bone screws. Any sharpedges are smoothed and rounded off using a rubber wheel.The whole surface is pumiced and then bead blasted beforepassivation and anodising. This is widely believed to increasethe biocompatibility of the implant.

This method for construction of titanium cranioplasty forreconstruction of large craniofacial defects has proved simpleand inexpensive and is illustrated and discussed in this poster.

Prosthetic nasal reconstruction with ZygomaticImplants using drill guides from computergenerated models and direct production fromcomputer data

Hodder S, Evans P, Bocca AMorriston Hospital, Swansea

This poster will highlight the use of digital computertechnology for the replacement of zygomatic implants forprosthetic nasal retention. The development of drill guideshas:

1) Allowed avoidance of critical structures with minimalexposure of the facial skeleton.

2) Greatly reduced the operating time.

3) Gives a more favorable and predictable postoperativeposition of the implants and emergency profile of theimplant for placement of magnets or bars and clips forretention of the prosthesis.

4) Allowed a more biological nasal air flow.

5) Increased patient satisfaction.

6) Utilisation of CT data for construction of wax RapidPrototype prosthesis, dramatically reducing prostheticconstruction time.

Seventeen cases have been treated to date with a loss of onlytwo zygomatic implants in irradiated patients with recurrentmalignant diseased SCC’s of nose.


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This Journal is published annually and reaches a wide International audience which includes some of the

most influential leaders in the field. It is an important contributor to the development of this specialty.

The Journal covers all aspects of Maxillofacial Prosthetics and Technology including:

n Implantology n Splint Therapy

n Ocular Prosthetics n Psychological Issues

n Intra Oral Prosthetics n Orthognathic Planning

n Neurosurgical Appliances n Facial and Body Prosthetics

n Burns Pressure Therapy Appliances n 3D Technologies

Free to IMPT Members

The Journalof MAXILLOFACIALP R O S T H E T I C S& T E C H N O L O G Y

The Official Journal ofThe Institute of MaxillofacialProsthetists & Technologists

To order your copy, please complete the form below and return to:Type Script, 7 Carmelite Way, Hartley, Kent DA3 8BP, UK.Telephone: +44 (0)1474 707896 E-mail: [email protected]

Subscription form

Name:

Address:

Postcode:

Telephone: Fax:

Please send me copy/copies of the Journal of Maxillofacial Prosthetics &Technologists at £40.00 per copy (+ £5.00 per copy post and packaging for allinternational orders).

I enclose a cheque for £ (Please make cheques payable to ‘The Institute ofMaxillofacial Prosthetists and Technologists’, in Sterling only).

"



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Original articles, editorial correspondence and suggestionsfor review articles should be sent to Dr. M Anwar Bamber,Department of Oral and Maxillofacial Surgery, UCLEastman Dental Institute, University College London,University of London, London WCIX 8LD, UK.

Authors are requested to submit three hard copies of theirtypescript and illustrations. Each paper must also besubmitted on a computer disc or CD. Authors must keep onecopy for their reference.

The editor cannot accept responsibility for damage or loss oftypescripts or discs.

A paper is accepted for publication on the understanding thatit has not been published or submitted simultaneously toanother journal in the English language.

Rejected papers will be returned to the authors.

Typescripts that contain the results of human and/or animalstudies will only be considered for publication if it is made clearthat a high standard of ethics was applied in carrying out theinvestigations and an appropriate ethical approval was obtained.

The editor reserves the right to make editorial and literarycorrections. Any opinions expressed or policies advocated donot necessarily reflect the opinions or policies of the editor.

Copyright

In order for us to ensure maximum dissemination andcopyright protection of material published in the journal,copyright must be explicitly transferred from the author tothe Institute of Maxillofacial Prosthetists and Technologists.

The copyright transfer agreement will be sent to you by thepublisher with your proofs. A copy of the agreement must besigned by the principal author before any paper can bepublished.

We assure you that no limitation will be put on your personalfreedom to use material contained in the paper withoutrequesting permission, provided acknowledgement is madeto this journal as the original source of publication.

Presentation of Typescripts

These instructions are in accordance with the InternationalCommittee of Medical Journal Editors.

Uniform requirements for manuscripts submitted tobiomedical journals. Br Med J 1988; 296: 401–405 Papersshould be submitted in journal style. Failure to do so maylead to significant delays in publication. Papers should betyped in double spacing throughout on good, white A4 paperwith a margin of at least, 3cm all round. Type only on oneside of the paper. Three copies of the typescript andillustrations should be submitted and authors should retain acopy for reference.

Full Papers

Papers should be set out as follows, with each sectionbeginning on a separate sheet: title page, summary, text,acknowledgements, references, tables, captions toillustrations.

Title page – the title page should give the followinginformation: 1) title of the article, 2) initials, name (withdesignatory letters) and address of each author and positionsheld, 3) name, address, telephone number, fax number ande-mail of the author responsible for correspondence and towhom requests for offprints should be sent and 4) sources ofsupport in the form of grants.

Summary – this should consist of not more than 150 wordssummarising the contents of the article. Also a small numberof keywords should be included to accurately identify thesubject of your paper.

Text – headings should be appropriate to the nature of thepaper and it should be noted that the use of headingsenhances readability. Normally only two categories ofheadings should be used: major ones should be typed incapital letters in the centre of the page; minor ones should betyped in lower case (with an initial capital letter) at the lefthand margin.

References – the accuracy of references is the responsibilityof the author. References should be entered consecutively byArabic numerals as a superior in the text. The reference listshould be listed in numerical order on a separate sheet indouble or triple spacing. References to journals shouldinclude the author’s name and initials (list all authors when

INSTRUCTIONS TO AUTHORS


six or fewer; when seven or more, list only the first three andadd “et al”), full title of paper, journal title abbreviated usingIndex Medicus abbreviations, year publication, volumenumber, first and last page numbers (i.e. Vancouver style).

For example: Shaw S.M., Williams E.P., Allsop E.W.Laboratory testing of new prosthetic materials. Am J Med1994; 692: 231–240.

References to books should be set out as follows: GlennonA.W. The Science of Maxillofacial Prosthetics. 2nd ed.Philadelphia: Saunders W.B. 1995.

Tables – these should be double spaced on separate sheetsand contain only horizontal rules. Do not submit tables asphotographs. A short descriptive title should appear aboveeach table and any footnotes, suitably identified, below. Caremust be taken to ensure that all units are included. Ensure thateach table is cited in the text.

Illustrations – A maximum of 8 illustrations includingphotographs should be included with any one paper.Additional illustrations can be included at discretion of theeditor.

Line illustrations – should present a crisp black image on aneven white background (127 x 173mm (5 x 7in)).

Photographic illustrations and radiographs – should besubmitted as clear, lightly contrasted black and white prints(unmounted), sizes as above (or colour slides whereappropriate, for example, where facial or body prosthetics arebeing shown). Photomicrographs should have magnificationand details of staining techniques shown. Radiographs shouldbe submitted as photographic prints, carefully made to bringout the detail to be illustrated, with an overlay indicating thearea of importance. Photographs and illustrations submittedon disk should be saved in tif format scanned at a minimumresolution of 300 x 300 dpi. Figures should be submittedappropriately lettered in capitals. The size of the lettersshould be appropriate to that of the illustration, taking intoaccount the necessary size reduction. All illustrations shouldbe clearly marked (by label pasted on the back or by a softcrayon) with figure number and author’s name and the top ofthe figure should be indicated by an arrow. Never use ink ofany kind. Do not use paper clips as these can scratch or markillustrations.

Captions should be typed, double spaced, on separate sheetsfrom the typescript.

Patient confidentiality – where illustrations must includerecognisable individuals, living or dead and of whatever age,great care must be taken to ensure that consent forpublication has been given.

If identifiable features are not essential to the illustration,please indicate where the illustration can be cropped.

In cases where consent has not been obtained andrecognisable features may appear, it will be necessary toretouch the illustration to mask the eyes or otherwise renderthe individual “officially unrecognisable”.

Permission to reproduce borrowed illustrations or table oridentifiable clinical photographs – written permission toreproduce borrowed material (illustrations and tables must beobtained from the original publishers and/authors andsubmitted with the typescript. Borrowed material should beacknowledged in the captions in this, style: “Reproduced bythe kind permission of (publishers) from ... (reference)”.

If authors would like acknowledgement of where the paperwas initially presented, please include the details with thetext, immediately following the summary.

Page Proofs

Page proofs are sent to the author for checking. The proofs,with any minor corrections must be returned by fax or post tothe Editor within 48 hours of receipt.

Proprietary Names

Proprietary names of materials, instruments, etc. should beindicated by the use of initial capital letters. Initial capitalletter, followed by the full address in brackets in the text.

Abbreviations and Units

Avoid abbreviations in the title and abstract. All unusualabbreviations should be fully explained at their firstoccurrence in the text. All measurements should be expressedin SI units. Imperial units are acceptable from USAcontributors. For more detailed recommendations, authorsmay like to consult the Royal Society of Medicinepublication entitled Units, Symbols and Abbreviations:A Guide for Biological and Medical Editors and Authors.

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A PDF file of individual articles can be requested from TypeScript as no offprints are produced.

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