CLINICAL REPORT

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Fixation of a severely resorbed mandible for complete archscrew-retained rehabilitation: A clinical report

Vinicius Fabris, DDS, MSDa and Atais Bacchi, DDS, MSD, PhDb

ABSTRACTSeverely resorbed mandibles with placed endosteal dental implants can fracture. Therefore, tech-niques to reduce the risk or minimize the consequences of these fractures are needed. This clinicalreport presents a technique for placing a titanium plate in a severely resorbed mandible subjectedto complete-arch implant therapy. The titanium plate is placed in the same surgical procedure asthe implants, allowing immediate implant loading. This technique provides safe implant-supportedtreatment for patients with severe mandibular resorption. (J Prosthet Dent 2016;115:537-540)

Rehabilitation of edentulouspatients with complete-archscrew-retained prostheses hasbeen considered an optimaltreatment choice. The pros-thesis provides the greatestsatisfaction and oral health-related quality of life because

of its retention and stablity.1,2 An implant survival rateof 100% after 5 years3 and 97.7% after a mean time of8 years4 has been reported in patients with adequatebone support. However, a considerable number of frac-tures have been reported related to severely resorbedmandibles treated with endosteal dental implants.5-7 Oneof the most affected populations is postmenopausalwomen.6,8-12

The mandibular fracture might occur during implantplacement10 or later during function13 because the im-plant’s presence weakens an already compromisedmandible.5 When a fracture occurs during implantplacement, the mandible requires immediate fixation,and the implant therapy is generally interrupted. If afracture occurs during function, in addition to a surgicalprocedure for mandibular reduction and immobilization,the solution generally involves implant removal andprosthesis loss because the fracture typically occurs at theimplant-bone interface. As the risk of mandibular frac-ture is difficult to eliminate in patients with severeresorption, a fixation technique was developed. Thistechnique uses a titanium plate to immobilize theimplant region. The titanium plate is placed during thesame surgical procedure as the implant therapy. Withthis technique, several of the consequences mentionedpreviously can be avoided.

fessor, Department of Oral Surgery, Meridional Faculty, Rio Grande do Sulfessor, Department of Prosthodontics, Meridional Faculty, Rio Grande do S

L OF PROSTHETIC DENTISTRY

CLINICAL REPORT

A healthy, 56-year-old woman sought treatment for theabsence of retention and stability in her mandibularcomplete denture and for related masticatory pain.Upon initial examination, the patient presented bothmaxillary and mandibular edentulous ridges (Fig. 1)supporting conventional complete dentures. The pano-ramic radiographic examination (Fig. 2) revealed aresorbed mandible at the “D” level of the Misch classi-fication (severe resorption e bone only at basal level).14

The maxillary ridge presented moderate resorption,which according to the patient provided adequateretention and stability for the complete denture. Noadditional pathology was diagnosed in the hard or softtissues.

Computed tomography was used to measure theheight of the mandible. The anterior region betweenthe mental foramina had a mean height of 12 mm, whichpresented a risk of fracture during implant placementor during function. Additionally, the mental foraminawere superficial at the ridge crest, which may havecaused her masticatory pain.

Treatment options were discussed with the patient,and a complete-arch screw-retained mandibular pros-thesis with a maxillary complete denture was chosen.15

, Brazil.ul, Brazil.

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Figure 1. Pretreatment condition of edentulous ridges. Figure 2. Initial panoramic radiograph view.

Figure 3. Mandibular prototype obtained for implant planning and formodeling titanium plate.

Figure 4. Extraoral incision.

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A mandibular fixation before implant therapy was plan-ned because of the risk of mandibular fracture. Amandibular prototype (Bioparts) was fabricated for sur-gical planning based on the computed tomography(Fig. 3). The mandibular prototype also allowed for themodeling of the 10-hole, commercially pure titanium(TiCP) plate (Ø 2.4×80 mm, Ref 449400; Synthes;Johnson & Johnson) used for mandibular fixation (Fig. 3).

Before the surgical procedure, impressions of theedentulous arches were made with irreversible hydro-colloid (Cavex ColorChange; Cavex Holland BV) andpoured with Type IV dental stone (Fujirock; GC Corp).Custom trays were made in autopolymerizing acrylicresin (Clas Mold; Classico Dental Products) for a defini-tive impression. Border molding was obtained withmodeling plastic impression compound (ImpressionCompound; Kerr Corp), and the definitive impressionwas made with polyether impression material (Impregumsoft; 3M ESPE) and poured in Type IV dental stone(Fujirock; GC Corp). Record bases with occlusion rimswere made and adjusted according to esthetic andfunctional principles. A centric relation interocclusal

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record was obtained, and the casts were mounted on asemi-adjustable articulator (A7 Fix; BioArt). Artificialteeth (Trilux; VIPI Dental Products) were arranged andevaluated in the mouth to verify the esthetics (midline,occlusal plane, relation to high lip), lip support, occlusalvertical dimension, maximum intercuspation, and pho-netics. The surgical template for the mandibular arch wasmade in transparent autopolymerizing acrylic resin (ClasMold; Classico Dental Products) by duplicating thearrangement of the teeth.

The antibiotic cephalexin (500 mg) and the anti-inflammatory dexamethasone (4 mg) were administeredpreoperatively. The surgery was performed in a hospitalenvironment under general anesthesia and nasotrachealintubation. Local anesthesia with lidocaine 2% (1:200000) was used to improve vasoconstriction.

An extraoral incision was made according to thedemarcation in Figure 4. After the mandibular bonewas exposed, the titanium plate was fixed on the buccalsurface of the mandible with TiCP screws (Ø 2.0×8 mm,Ref 411908; Synthes; Johnson & Johnson) (Fig. 5).The plate and the screws were positioned considering

Fabris and Bacchi

Figure 5. Titanium plate fixation in frontal surface of mandible. Figure 6. Implant and abutment placement.

Figure 7. Panoramic radiograph after surgical procedure.

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the anatomic structures and the position of the futureimplants as previously planned.

Four external hexagon implants (Ø3.75×9 mm; Tita-maxTi Cortical; Neodent) were placed between themental foramina in the anterior mandibular region withan insertion torque of 45 Ncm. Mini conical abutments(Neodent) with a transmucosal height of 3.0 mm wereconnected to the implants (Fig. 6). A resorbable suture(Vicryl 4.0; Ethicon) was used in the periosteum andmuscular structures, and a nonresorbable suture wasused in the skin (mono-nylon 6.0; Ethicon).

Impression copings (Neodent) were screwed on themini conical abutments and joined to each other withmetal rods and autopolymerizing acrylic resin (PatternResin; GC Corp) to obtain a verification jig. The jigwas removed and connected to abutment analogs(Neodent) to obtain an implant position cast with TypeIV dental stone (FujiRock; GC Corp). The implant posi-tion cast was used to fabricate and evaluate the fit ofthe prosthetic framework, which was cast in cobalt-chromium alloy (Biosil F; Dentsply Intl) with the lost-wax technique.

New impression copings (Neodent) were connectedto the mini conical abutments (Neodent) and joined tothe surgical template with autopolymerizing acrylic resin(Pattern Resin; GC Corp). Polyvinyl siloxane impressionmaterial (Express XT; 3M ESPE) was inserted into thesurgical template. The centric relation record was refinedusing autopolymerizing acrylic resin (Pattern Resin; GCCorp) at 3 points of the surgical template, 1 anterior and2 posterior. The surgical template was unscrewed fromthe implants and removed from the patient’s mouth.Abutment analogs (Neodent) were connected to theimpression copings, and the definitive cast was poured inType IV dental stone (Fujirock; GC Corp). A siliconeputty index (Zetalabor; Zhermack) obtained from thebuccal surfaces of the initial arrangement of teeth wasused to guide the prosthetic waxing with the frameworkon the definitive cast, and both maxillary and mandibular

Fabris and Bacchi

prostheses were made with heat-polymerized acrylicresin (Classico; Classico Dental Products).

The complete-arch screw-retained mandibular pros-thesis was connected to the mini conical abutments,and the maxillary complete denture was adjusted anddelivered. The occlusion was adjusted, and instructionswere given to the patient, specifying that she eat onlysoft foods during the initial healing period. A panoramicradiograph was made (Fig. 7). The patient has been fol-lowed for 2 years without any complication (Fig. 8). Thelocation of the extraoral incision has shown no compli-cation or esthetic deficit.

DISCUSSION

The described treatment can improve the prognosis forcomplete-arch implant-supported prostheses in patientswith severe resorption of the mandible and risk of frac-ture. The technique was developed because of severalreports of mandibular fracture after treatment withendosteal dental implants.6,7,10 The mandibular atrophythat occurs after teeth are removed significantly reducesvertical and horizontal bone dimensions, increasing thebone’s susceptibility to fracture.5,6,11 This becomes more

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Figure 8. Intraoral view after two years follow-up.

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critical when associated with other local and systemicconditions, such as significant reduction in bone den-sity,6,8-13 implant placement where thin bone wallsremain,13 fixation penetrating the cortical basal re-gion,5,6,11,12 and periimplantitis.16 Prosthetic factors suchas excessive cantilevers also represent a risk of fracture.13

The titanium plate used for mandibular fixation in thepresent report is commonly used to immobilize fracturedmandibles. Using this rigid fixation, the risk of fractureduring implant placement and when the prosthesis is infunction should be reduced. However, if a fracture doesoccur, the complications can be assumed to be fewerbecause the fractured mandible will already be immobi-lized, averting the need for a new surgical intervention.

Overdentures retained by 2 implants are also effectivetreatment options for edentulous patients.17,18 However,this option was not the first choice for the current patientbecause of the position of the mental foramina on thecrest of the residual ridge. Thus, overdentures would notsolve the problem of mastication pain, as the denturewould still put pressure on the mental nerves.

The clinical technique used has been followed for2 years without any complication. This technique hasalso been applied to 6 other patients who presentedwith similar bone conditions, and no complications havebeen found after a follow-up period of 5 years. All pa-tients reported satisfaction with the treatment, andnone related any episodes of functional pain, limitation,or discomfort.

SUMMARY

This clinical report describes the use of a titanium platefor fixation of severely resorbed mandibles that hadbeen subjected to endosteal dental implant therapy;the goal was to reduce the risk and consequences of

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trans- or postoperative fractures. This technique does notrequire an additional surgical procedure. It also preventssignificant complications from fractures during implantinstallation or during function and allows for immediateimplant loading.

REFERENCES

1. Felix GB, Nary Filho H, Padovani CR, Machado WM. A longitudinal study ofquality of life of elderly with mandibular implant-supported fixed prostheses.Clin Oral Implants Res 2008;19:704-8.

2. Da Cunha MC, Santos JF, Santos MB, Marchini L. Patient’s expectationbefore and satisfaction after full-arch fixed implant-prosthesis rehabilitation.J Oral Implant 2015;41:235-9.

3. Gallucci GO, Doughtie CB, Hwang JW, Fiorellini JP, Weber HP. Five-yearresults of fixed implant-supported rehabilitations with distal cantilevers forthe edentulous mandible. Clin Oral Implants Res 2009;20:601-7.

4. Priest G, Smith J, Wilson MG. Implant survival and prosthetic complicationsof mandibular metal-acrylic resin implant complete fixed dental prostheses.J Prosthet Dent 2014;111:466-75.

5. Chrcanovic BR, Custódio AL. Mandibular fractures associated with endostealimplants. Oral Maxillofac Surg 2009;13:231-8.

6. Almasri M, El-Hakim M. Fracture of the anterior segment of the atrophicmandible related to dental implants. Int J Oral Maxillofac Surg 2012;41:646-9.

7. Soehardi A, Meijer GJ, Manders R, Stoelnga PJ. An inventory of mandibularfractures associated with implants in atrophic edentulous mandibles: a surveyof Dutch oral and maxillofacial surgeons. Int J Oral Maxillofac Implants2011;26:1087-93.

8. Mason ME, Triplett RG, Van Sickels JE, Parel SM. Mandibular fracturethrough endosseous cylinder implants: Report of cases and review. J OralMaxillofac Surg 1990;48:311-7.

9. Shonberg DC, Stith HD, Jameson LM, Choi JY. Mandibular fracture throughan endosseous implant. Int J Oral Maxillofac Implants 1992;7:401-4.

10. Raghoebar GM, Stellingsma K, Batenburg RHK, Vissink A. Etiology andmanagement of mandibular fractures associated with endosteal implants inthe atrophic mandible. Oral Surg Oral Med Oral Pathol Oral Radiol Endod2000;89:553-8.

11. Romanos GE. Nonsurgical prosthetic management of mandibular fractureassociated with dental implant therapy: a case report. Int J Oral MaxillofacImplants 2009;24:143-6.

12. Oh WS, Roumanas ED, Beumer J. Mandibular fracture in conjunction withbicortical penetration, using wide-diameter endosseous dental implants.J Prosthodont 2010;19:625-9.

13. Manfro R, Fabris V, Garcia GF, Derech E, Felipe AF, Bortoluzzi MC. Mandibularfracture in a patient treated with a protocol prosthesis after 3 years of functiondue to biomechanical complications - clinical case report. Int J Dent Oral Health2015. 30 May 2015. http://dx.doi.org/10.16966/2378-7090.112.

14. Misch CE. Divisions of available bone in implant dentistry. In: Misch CE,editor. Contemporary implant dentistry. 2nd ed. Mosby: Madrid; 1999.

15. Tajbakhsh S, Rubenstein JE, Faine MP, Mancl LA, Raigrodski AJ. Selectionpatterns of dietary foods in edentulous participants rehabilitated withmaxillary complete dentures opposed by mandibular implant-supportedprostheses: a multicenter longitudinal assessment. J Prosthet Dent 2013;110:252-8.

16. Naval-Gíaz L, Rodriguez-Campo F, Naval-Parra B, Sastre-Pérez J. Patho-logical mandibular fracture: A severe complication of periimplantitis. J ClinExp Dent 2015;7:e328-32.

17. Dias R, Moghadam M, Kuyinu E, Jahangiri L. Patient’s satisfaction survey ofmandibular two-implant-retained overdentures in a pre-doctoral program.J Prosthet Dent 2013;110:76-81.

18. Boven GC, Raghoebar GM, Vissink A, Meijer HJ. Improving masticatoryperformance, bite force, nutritional state and patient’s satisfaction withimplant overdentures: a systematic review of the literature. J Oral Rehabil2015;42:220-33.

Corresponding author:Dr Atais BacchiRua Senador Pinheiro, 30299070-220, Passo Fundo, RSBRAZILEmail: atais_bacchi@yahoo.com.br

Copyright © 2016 by the Editorial Council for The Journal of Prosthetic Dentistry.

Fabris and Bacchi