CLINICAL REPORT

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Digital capture, design, and manufacturing of a facialprosthesis: Clinical report on a pediatric patient

Gerald T. Grant, DMD, MS,a Cynthia Aita-Holmes, DMD,b Peter Liacouras, PhD,c Johnathan Garnes,d andWilliam O. Wilson, Jr, DDS, MSe

ABSTRACTA digitally captured, designed, and fabricated facial prosthesis is presented as an alternative tocustomary maxillofacial prosthodontics fabrication techniques, where a facial moulage and patientcooperation may be difficult. (J Prosthet Dent 2015;114:138-141)

Facial prosthesis fabrication forchildren can be a difficult andlengthy process. Conventionalfacial impression techniquesoften require that young chil-

dren and infants undergo general anesthesia or areheavily sedated, resulting in multiple modifications in thefabrication and delivery of the prosthesis. A method thatwould require minimal contact from impression to de-livery of a well-fitting prosthesis would be preferred.

Digital capture technology using photogrammetrytechniques has proven to be an accurate alternativemethod for image capture for the digital design of facialprostheses.1,2 Digital capture systems are traditionallywhite light or laser scanning technologies, which can takeseveral seconds, are sensitive to movement, and wouldbe contraindicated for small children and infants. Ad-vances in photogrammetry technology with digital cam-eras have made available commercial systems that allowfor image capture in fractions of a second, eliminating theissue of scanning movement.3 The speed of camera-based digital capture is ideal for children and is usedroutinely to evaluate cranial deformities, soft tissuechanges, and the results of surgical interventions.4-6

Once a digital image has been captured and3-dimensional (3D) soft tissue geometry created, theycan be used to digitally design the prosthesis and manu-facture a mold, or directly print the prosthesis.1 Although

he views expressed in this article are those of the authors and do not nectment of Defense, nor the U.S. Government.Director, Dental Corps, United States Navy Craniofacial Imaging Researchrtment of Radiology, Walter Reed National Military Medical Center, BethesProsthetics Fellow, Naval Postgraduate Dental School, Bethesda, Md.ervices, 3D Medical Applications Center, Department of Radiology, Walteraxillofacial Prosthetics Laboratory School, Naval Postgraduate Dental Schrogram Director, Maxillofacial Prosthetics, Naval Postgraduate Dental Scho

directly printing the prosthesis would be the preferredmethod, the current additive manufacturing technologiesin materials and coloring do have some limitations.7

CLINICAL REPORT

A 4-year-old girl was referred for the fabrication of anasal-facial prosthesis. As the result of an explosion, herleft arm had been amputated below the elbow, she hadsevere facial trauma leading to bilateral enucleation of theeyes, and she had lost her entire nose. An examination ofthe patient revealed that she had a conformer in the rightanophthalmic socket in preparation for an ocular pros-thesis, a soft tissue flap to the midface, a missing nose,and a missing globe and palpebra in the left eye. She didnot speak English, and all communications were throughan interpreter. An adhesively retained, silicone nasalprosthesis was indicated, possibly with the help of eye-glasses to provide auxiliary retention. The eyeglassescould be heavily shaded or mirrored to camouflage theleft eye, which cannot presently receive an ocular pros-thesis. The patient was very cooperative during the initialconsultation. She was excited to meet new people and

essarily reflect the official policy or position of the Department of the Navy,

; and Service Chief, Naval Postgraduate Dental School, 3D Medical Applicationsda, Md.

Reed National Military Medical Center, Bethesda, Md.ool, Bethesda, Md.ol, Bethesda, Md.

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Figure 1. Photograph and patient digital image. Figure 2. Patient and template donor 3D images.

Figure 3. 3D approximation registered patient/donor images.

Figure 4. Definitive digital prosthesis and mold design; spacer wasadded to ensure space for breathing.

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was very friendly. However, because of the anticipatedlack of cooperation for a moulage impression and thedifficulties of communicating with such a young patient,a digital workflow was planned to fabricate the nasal-facial prosthesis.

A few days later, the patient was escorted to theCraniofacial Imaging department to obtain a full-headdigital image captured with a stereophotogrammetrydevice (3dMDcranial system; 3dMD). This method ofacquiring an impression was chosen because the imagecapture takes fractions of a second with minimal personalcontact by the operator. The image was sent to the 3DMedical Applications Center at the Walter Reed NationalMilitary Medical Center for the design and fabrication ofthe prosthesis (Fig. 1). The library of templates did notinclude a model nose for a young girl; therefore, a digital

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image of a staff member’s 6-year-old daughter was ac-quired (Fig. 2). The 2 sets of 3-dimensional data wereimported and manually registered in digital software(Fig. 3). The nasal and mid-face soft tissue geometry wasthen isolated from the staff member’s daughter (Magics;Materialise). The young patient and the model nose withsurrounding soft tissue geometry was imported intosoftware that allowed for the free-form manipulation oforganically shaped objects with a haptic device (Free-form; Geomagic); the nose brim was reduced, and theprosthetic soft tissue borders were created (Fig. 4). Afterthe replacement nose was finalized, a mold wasdesigned, manufactured by using a binder jetting additivemanufacturing technique (ProJet 460 plus; 3D Systems),infiltrated with cyanoacrylate resin (Apollo 5005 Cyano-acrylate; Cyberbond), and sealed with 2 coats of mattefinish, clear acrylic resin sealer (Clear acrylic sealer; PlaidEnterprises, Inc).1,2

The patient was visited in the hospital a second time toselect a silicone base shade. At this visit, a prototype sil-icone nose was brought to allow the patient to touch itand become familiarized with the feel of the material. She

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Figure 5. Technician painting first layer of silicone into mold.

Figure 6. Processed prosthesis with base shade as recovered from mold.

Figure 7. Completed prosthesis.

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was curious about it and was looking forward to having aprosthetic nose. The patient was happy to have visitors,and the visit was a positive experience for the child.

Once the base shade and notes of characterizationhad been established, the molds were prepared with amold release spray (Silicone Spray; Dentsply Intl), and asmall amount of Part A and B A-2000 silicone (Factor II,Inc) without pigment was mixed in a 1:1 volume ratioand de-aired in a vacuum chamber for 1 rise and fallevolution. A layer approximately 1-mm thick of the clearsilicone was applied to the margin area of the futureprosthesis on both the cope and drag (upper and lowerparts of the mold) to help camouflage the margins(Fig. 5). The separate molds were placed in a polymer-izing oven for 5 minutes at 49�C to increase the viscosityof the silicone, but without allowing it to completelypolymerize. Additional silicone was mixed in an amountsufficient to pack the mold and allow for excess siliconeto extrude from the junction of the cope and drag whilepressing. Flocking and intrinsic pigments (FunctionalIntrinsic II; Factor II) were added to match the base skintone and the silicone was de-aired for 1 rise and fallevolution. The colored silicone was transferred to a sy-ringe and injected into the cope and drag, avoiding theclear silicone margins. Once the cope and drag had beenfilled to the desired amount, the colored silicone wascarefully painted over the clear silicone to form a gradualtransition from color to transparent. The cope was placedover the drag, and hand pressure was applied to createintimate contact on all sides. The invested molds wereprocessed in a hydraulic heat press (Carver, Inc) under345 psi, at 49�C for 40 minutes. The silicone nasalprosthesis was removed from the mold, and the marginswere trimmed with scissors (Fig. 6).

The definitive characterization and delivery of theprosthesis were delayed for 2 weeks, because of the pa-tient’s outpatient status. When she returned, she hadbeen placed in foster care with a new caretaker and was

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seen in the Maxillofacial Prosthetics Clinic to verify fitand esthetics. Extrinsic characterization was applied tothe prosthesis with the patient present to better matchskin tones. Once the color and characterization wereacceptable, an outer layer of silicone (A-100 silicone;Factor II, Inc) was applied to seal extrinsic modifications,and the prosthesis was applied with adhesive (Daro;Factor II, Inc). The family was happy with the estheticsand fit of the prosthesis, and the patient eagerly partici-pated in the positioning and adhesion of the prosthesis,insisting on holding it until it felt secure. The caretakerswere given postoperative instructions on how to applythe prosthesis as well as homecare and maintenance(Fig. 7). In a follow-up email, the foster mother reportedthat the nose had given the child a lot of freedom, and forthe first time they were able to go out without any

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problems. She stated: “We were out all weekend for every-thing, shopping, restaurant, parks, and playing outdoors.”

DISCUSSION

Because of the age of the child, the recent trauma, andher limited communication skills, the use of digital im-aging, digital design, and additive manufacturing of theprosthetic mold, with minimal direct patient contact, waschosen for the fabrication of the prosthesis. It wasevident at the time of the initial evaluation that this pa-tient would not have been able to tolerate a moulageimpression technique without sedation. Digital imagingtechniques provided the accurate capture of the soft tis-sue in a more normal patient position, reducing capturetime and the subsequent modifications in fabrication anddelivery that must be anticipated with conventionalcontact impression techniques. In order to approximatean age-appropriate prosthesis, the image of another childof similar age and size was used as a template to evaluateand design the prosthesis. Now that the design has beenestablished, future prosthetic designs can be fabricated byresizing and reshaping to the new image of the child asshe grows.

Although a 5-pod image capture system was used,any device that can capture the midface and provide a fileformat suitable for 3D design (.stl, .obj, .vrml, .amf, andso on) could be used, including the tissue surface of acomputed tomography (CT) scan. Technology to fabricatethe surface of the face of a patient is available in a varietyof medical 3D software, and a facial cast can be manu-factured in a number of materials, with a number ofdifferent additive manufacturing techniques.7 However,the registration of the images, development of theprosthesis, and design of the molds for fabrication dorequire more than 1 software package, in that a singlesoftware package does not provide everything needed toaddress the 3D files and the mold workflow.2

The molds were fabricated from a bonded gypsummaterial. Although the surface roughness was ideal forreproducing the skin surfaces, when heat is used topolymerize the silicone under a press, after 2 uses, theybegin to fracture and deteriorate. This may not be anissue if only a limited number of prostheses need to befabricated; for long-term use, a different mold materialmay be more appropriate. However, the molds can bestored as digital files, reducing physical storage andallowing easy modification as required.

Grant et al

SUMMARY

A clinical report is presented on the application of digitaltechnologies in the fabrication of a nasal-facial prosthesisfor a child. The fabrication of a facial prosthesis is adifficult process for both the provider and the patient,regardless of age. It requires several visits involvingpotentially uncomfortable and stressful procedures thatare even more demanding for a child with minimalcommunication skills. The procedure presented involved3 sessions of brief physical interaction with the patientand resulted in a well-fitting, esthetic prosthesis. Inaddition, the process allows for the continued fabricationof prostheses as the child grows, requiring only a 3Ddigital image that can be used to resize the prosthesis,fabricate a new mold, and process a new prosthesis.Additive manufacturing technologies have advanced toinclude recent improvements in limited color printing ofsoft materials. This development may provide a way ofdirectly printing a prosthesis in multiple materials thatwould closely match the color shades of the patient.These advances may eventually lead to the ideal work-flow of digital image capture, digital design, and directprinting of prostheses.

REFERENCES

1. Sabol JV, Grant GT, Liacouras P, Rouse S. Digital image capture and rapidprototyping of the maxillofacial defect. J Prosthodont 2011;20:310-4.

2. Liacouras P, Garnes J, Roman N, Petrich A, Grant GT. Designing andmanufacturing an auricular prosthesis using computed tomography, 3-dimensional photographic imaging, and additive manufacturing: a clinicalreport. J Prosthet Dent 2011;105:78-82.

3. Kau CH. Creation of the virtual Patient for the study of facial morphology 3Dimaging technologies for facial plastic surgery. Facial Plast Surg Clin North Am2011;19:615-22.

4. Atmosukarto I, Shapiro LG, Starr JR,HeikeCL,Collett B,CunninghamML, et al.3D head shape quantification for infants with and without deformational pla-giocephaly. Cleft Palate Craniofac J 2010;47:368-77.

5. Bugaighis I, Mattick C, Tiddeman B, Hobson R. Three-dimensional genderdifferences in facial form of children in the North East of England. Eur JOrthod 2013;35:295-304.

6. Brons S, van Beusichem ME, Maal TJ, Plooij TJ, Bronkhorst EM, Bergé SJ, et al.Development and reproducibility of a 3D stereophotogrammetric referenceframe for facial soft tissue growth of babies and young children with andwithout orofacial clefts. Int J Oral Maxillofac Surg 2013;42:2-8.

7. Grant GT, Liacouras P, Santiago G, Rakan MA, Murphy R, Armand M, et al.Restoration of the donor face after facial allotransplantation: digitalmanufacturing techniques. Ann Plast Surg 2014;72:720-4.

Corresponding author:Dr Gerald T. GrantWalter Reed National Military Medical Center8901 Wisconsin AveBethesda, MD 20889Email: gerald.t.grant.mil@mail.mil

Copyright © 2015 by the Editorial Council for The Journal of Prosthetic Dentistry.

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