Vol. 113 No. 3 March 2012

CAD/CAM and rapid prototyped titanium for reconstruction oframus defect and condylar fracture caused by mandibularreductionGuosong Wang, DDS, Jihua Li, MD, PhD, Ashish Khadka, DDS, Yuchun Hsu, DDS, Wenyang Li, DDS, andJing Hu, MD, PhD, Chengdu, ChinaWEST CHINA COLLEGE OF STOMATOLOGY

Fracture or defect of the mandible is a serious complication of mandibular angleplasty, and precise reconstructionfor such defect is still a huge challenge. This case report provides a new method based on CAD/CAM and rapid prototypedtitanium for individual design, fabrication, and implantation of a mandibular ramus and angle. A 25-year-old woman with asquare-shaped face, who had undergone mandibular outer cortex split ostectomy (MOCSO) 3 months earlier, was afflicted bya series of symptoms: asymmetric face, collapse of the right face, masticatory problems, deviation during mouth opening,malocclusion, and TMJ clicks. These symptoms were caused by unintentional removal of the fractured ramus during MOCSO.By means of CT scan data, rapid prototyping, reverse engineering, 3D display, and CAD/CAM, the individualized titaniumimplant was designed and fabricated. The 3D demo system of operative scheme demonstrated the operative procedure, anddetermined the position of the implant so as to obtain a perfect fit. Postoperatively, the patient regained satisfactorymorphologic symmetry, facial appearance, occlusion, and TMJ functions. (Oral Surg Oral Med Oral Pathol Oral Radiol 2012;

113:356-361)

In East Asians, a square face is considered unappealing,as it imparts a coarse and masculine look. Asian womenprefer to have an ovoid and slender facial contour,which is thought to be more feminine and attractive.Mandibular contouring surgery has become a com-monly performed procedure1-4; however, there aresome serious complications reported. One complicationis a fracture or defect in the mandibular ramus andcondyle,5,6 which might occur during mandibular outercortex split ostectomy (MOCSO) when the horizontalostectomy line is too deep or the ramus is too thin.During splitting, if the surgeon is unaware of the fullhorizontal fracture, the split ramus might be inadver-tently pulled out. Here, we report a case of applicationof computer-aided design/computer-aided manufactur-ing (CAD/CAM) and rapid prototyped titanium recon-struction for such a ramus defect and condylar fracturecreated during MOCSO.

CASE REPORTA 25-year-old woman with a square-shaped face under-

went MOCSO. The right mandibular angle and the posteriorborder of mandibular ramus were ostectomized and freed.However, an unusually large bony segment was pulled out

Research Fellow, The State Key Laboratory of Oral Diseases andFaculty, Orthognathic Surgery, West China College of Stomatology,Sichuan University, Chengdu, China.Received for publication Feb 20, 2011; accepted for publication Mar15, 2011.© 2012 Elsevier Inc. All rights reserved.2212-4403/$ - see front matter

doi:10.1016/j.tripleo.2011.03.034

356

unintentionally. As the surgeon could not cope with thisdaunting task, another surgeon fixed the free mandibularcondyle by pulling it antero-inferiorly, to the stump of theramus under direct vision by approaching through the ex-tended preauricular incision.

The patient visited our hospital 3 months after the ill-fatedoperation. She complained of a variety of symptoms, such asreduction of masticatory efficiency, deviation of mouth, col-lapse of the right face, malocclusion, and temporomandibularjoint (TMJ) clicks soon after the operation. We discoveredthat the loss of the right mandibular ramus and shortening ofthe right ramus led to these symptoms. The occlusion wasbarely acceptable, and the maximal mouth opening was 22mm and mouth-opening deviation was 8 mm (Fig. 1). Com-puted tomography (CT) scan showed that the right defectivemandibular ramus appeared irregular. Because of antero-inferior displacement and oblique position, the condyle wasnot completely located in the glenoid fossa. The coronoidprocess had also shifted anterosuperiorly. A mini plate hadbeen used to fix the condyle and the ramus (Fig. 2).

Autogenous bone graft is the most commonly acceptedmethod for reconstruction of bone defects; however, it hassome drawbacks, such as exploration of a second surgicalsite, donor site morbidity, poor abrasion resistance, and boneresorption. More importantly, it is difficult to obtain satisfac-tory restoration of facial contour and TMJ functions. Atpresent, a new method based on CAD/CAM and rapid pro-totyped titanium provides a promising solution.7

The data of the CT scan acquired with a 0.1-mm slicethickness was imported into 3DMSR software (Beijing Gim-mafei Science and Technology Development Co., Ltd, Bei-jing, China). The craniofacial skeleton was visualized with aslice reconstruction interval of 0.5 mm in a 3-dimensional(3D) display for evaluation of the defect. Pro/E (PTC Corp.,

Needham, MA, USA), Solidworks (Dassault Systemes S.A.,

OOOO ORIGINAL ARTICLEVolume 113, Number 3 Wang et al. 357

Velizy, France), and Geomagic software (Raindrop; Geo-magic, Research Triangle Park, NC, USA) were used toreconstruct the right missing segment by mirroring the lefthealthy ramus. After reverse engineering, it was shown thatthe right digitalized individualized titanium mesh and the lefthealthy ramus were absolutely symmetric. Then, the datawere converted to a mesh-based surface representation (STL)format and was downloaded to a CAM machine to fabricate

Fig. 1. a, Preoperative anterior view of the patient: note thetoward the right during mouth opening. Preoperative lateralgonial area (c), left side (d).

the skull replica and the digitalized titanium mesh in the My

Center-3XiF laser prototyping system (Beijing Gimmafei Sci-ence and Technology Development Co., Ltd, Beijing, China).

Placing the titanium implant in the correct position and replacingthe condyle in the glenoid fossa is a key procedure in restoring thedefective ramus to improve preexisting problems, such as facialasymmetry, malocclusion, and mouth-opening deviation. The 3Ddisplay was used to locate the titanium mesh, which ensured thelocation of the titanium implant in complete concordance with the

asymmetry. b, maximal mouth opening: note the deviationof the patient: right side, note the collapse of the ramus and

facialviews

original bone (Fig. 3).

ORAL AND MAXILLOFACIAL SURGERY OOOO358 Wang et al. March 2012

Fig. 2. Visualized 3D display based on helical CT: a, the dorso-ventral view; b, the right lateral view. The right posterior borderof ramus was missing, the condyle was fixed antero-inferiorly to the stump of the ramus, and the coronoid process was positioned

antero-superiorly because of temporal muscle pull.

Fig. 3. a, The CAD display shows orientation of implant by surgical guides. b, CAD/CAM and rapid prototyped titanium implant.The implant was inserted into the defective area and fixed using miniscrews. c, The view from the extended preauricular incision,note the condyle and coronoid process reset and fixed at the exact normal position by the implant. d, The view from the intraoral

incision.

OOOO ORIGINAL ARTICLEVolume 113, Number 3 Wang et al. 359

Stable occlusion was obtained by intermaxillary fixation(IMF) with dental arch splints before surgery. The completeexposure of the TMJ area and the defective ramus wasachieved through the intraoral route and preexisting preauric-ular scar. The 3D demo system of operative scheme was also

Fig. 4. Views of the patient at follow-up, 6 months after thethe marked decrease in deviation during mouth opening. The lcontour.

developed to determine the position of the mesh, and also to

observe the amount of contralateral mandibular angle to beresected to obtain facial symmetry. The condylar segmentwas mobilized postero-superiorly� and coronoid segment an-tero-superiorly back to their original location. The titaniumimplant was then placed in the defect site reestablishing the

tion. a, The anterior view. b, Maximal mouth opening, noteiews: c, right side; d, left side, note the symmetry of the facial

operaateral v

connection between the condylar and the coronoid segment

ORAL AND MAXILLOFACIAL SURGERY OOOO360 Wang et al. March 2012

and the mandibular body. The titanium mesh was fixed at thedesignated position using screws (Fig. 3). Mouth openingtraining was performed for 3 months postoperatively as perthe methods of Kun Hwang et al.6 During the follow-upperiod of 6 months, correction of facial asymmetry was

Fig. 5. a, Preoperative occlusion. Note the malocclusion withpremature contact on the right side. b, Views of the occlusionat the follow-up assessment 6 months after the operation.

Fig. 6. Helical CT showing the reconstructed defect 6 monthsthe digitalized titanium implant oriented at the designated po

the exact normal position by the titanium implant.

ultimately achieved, with maximal mouth opening increasingto 40 mm, and mouth-opening deviation decreasing to 2 mm.There was disappearance of TMJ pain and acceptable occlu-sion was achieved postoperatively (Figs. 4 and 5). The 3D-CTalso showed the ramus defect well reconstructed by the dig-italized titanium mesh. The implant was oriented at the des-ignated position and the condyle and coronoid process werereset and fixed at the exact normal position by the implant(Fig. 6).

DISCUSSIONFracture or defect of the mandibular ramus, which isconsidered a serious complication of mandibular reduc-tion, is still a daunting task, largely because surgeonshave trouble reforming the original morphologic sym-metry along with restoration of the various TMJ func-tions.5,6 To date, autogenous bone graft is the goldstandard for reconstruction of mandibular ramus andcondyle. However, there are some inevitable disadvan-tages, such as exploration of the second surgical site,donor site morbidity, poor abrasion resistance, boneresorption, and difficultly in reshaping. Even more de-manding is the difficulty in regaining an exact mandib-ular contour.7-9

In view of the imperfection of the traditional meth-ods for reconstruction of mandibular ramus defect andcondylar fracture, we should explore new ways thathave obvious superiority. Titanium is known for itsbiostability, biosafety, and biocompatibility. In thiscase, the digitalized individualized titanium implantwas designed on the basis of the patient’s CT scan data,which were input into reverse engineering software to

he operation: a, dorso-ventral view; b, right lateral view. Noteand the condyle and the coronoid process reset and fixed at

after tsition,

OOOO ORIGINAL ARTICLEVolume 113, Number 3 Wang et al. 361

reconstruct the defective ramus through the mirror im-aging of the left part, thus providing exact facial sym-metry.7,10 The digitalized implant was made accordingto the virtual data with rapid prototyping technique. CTscan, rapid prototyping, reverse engineering, and com-puter modeling are the determinants of simplification,acceleration, and perfection of surgical planning, man-ufacturing of customized mesh, and immediate recon-struction. Likewise, autogenous mandibular angle bonegraft obtained from MOCSO of the contralateral sidecan avoid the second surgical site and donor morbidity.These techniques similarly ensure less surgical time,fewer operational errors, more precise fit, and muchbetter stability postoperatively.11,12 This method alsohelps achieve preoperative mesh fit testing and defini-tion of the desired location of the mesh, resulting innear perfect implantation.

REFERENCES1. Baek SM, Kim SS, Bindiger A. The prominent mandibular angle:

preoperative management, operative technique, and results in 42patients. Plast Reconstr Surg 1989;83:272-8.

2. Yang DB, Park CG. Mandibular contouring surgery for purelyaesthetic reasons. Aesthet Plast Surg 1991;15:53-60.

3. Park SH, Kim HS, Kin JT. New approach of mandibular angleresection. J Korean Soc Aesthetic Plast Surg 1998;4:72-9.

4. Deguchi M, Iio Y, Kobayashi K, Shirakabe T. Angle-splittingostectomy for reducing the width of the lower face. Plast Recon-

str Surg 1997;99:1831-9.

5. Oh YW, Han KT, Ahn ST. The complication of mandibular anglereduction. J Korean Soc Plast Reconstr Surg 1990;17:645-52.

6. Kun Hwang, Jin Yi Han, Kil MS, Lee SI. Treatment of condylefracture caused by mandibular angle ostectomy. J Craniofac Surg2002;3:709-12.

7. Eufinger H, Wehmoller M, Machtens E, Heuser L, Harders A,Kruse D. Reconstruction of craniofacial bone defects with indi-vidual alloplastic implants based on CAD/CAM-manipulatedCT-data. J Craniomaxillofac Surg 1995;23:175-81.

8. Morris CL, Barber RF, Day R. Orofacial prosthesis design andfabrication using stereolithography. Aust Dent J 2000;45:250-3.

9. Winder J, Cooke RS, Gray J, Fannin T, Fegan T. Medical rapidprototyping and 3D CT in the manufacture of custom madecranial titanium plates. J Med Eng Technol 1999;23:26-8.

10. Samman N, Luk WK, Chow TW, Cheung LK, Tideman H, ClarkRK, et al. Custom-made titanium mandibular reconstruction tray.Aust Dent J 1999;44:195-9.

11. Gibson I, Cheung LK, Chow SP, Cheung WL, Beh SL, SavalaniM. The use of rapid prototyping to assist medical applications.Rapid Prototyping J 2006;12:53-8.

12. Cesarano J, Dellinger JG, Saavedra MP, Gill DD, Jamison RD,Grosser BA. Customization of load-bearing hydroxyapatite latticescaffolds. Int J Appl Ceram Technol 2005;2:212-20.

Reprint requests:

Jihua Li, MD, PhDThe State Key Laboratory of Oral Diseases and OrthognathicSurgerySichuan UniversityWest China College of StomatologyChengdu, China 610064

leejimwa6698@sohu.com

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