GAP Australasian-Dentist Issue 80 Jul-Aug 19

Category 92 AustrÀlÀsiÀn Dentist n aÀ ramus osteotomy can be safely performed without interfering with either the conventional bone cuts or the split (figs. 9, 18). Alternatively, the full customization of the OMX ÀMJ prosthesis means the prosthesis itself can also be designed to advance the mandible and correct the occlusion without the need to perform a mandibular sagittal split osteotomy. Àhe surgical complexity of combined Orthognathic and ÀMJ prosthetic total joint replacements makes it virtually impossible to accurately plan precise movements in all three dimensions without the aid of digital technology 5 . Àhe precision of digital tools allows for more accurate placement and positioning of the jaws and implants that is facilitated by cutting and drilling guides which help guide and improve the accuracy of the surgery. Digital platforms also allow for greater customization of medical devices than has ever been possible in the past. Customized implants in the form of custom bone plates (fig. 17) and prosthetic joints provides the surgeon with a level of confidence that eliminates the need for years of experience in guessing where the bones should be cut, positioned or placed (figs. 7, 8). Combined Orthognathic and ÀMJ surgery is tremendously difficult surgery involving many complex steps that can test even the most experienced surgeons in this field 2 . Àophisticated software used in the pre-surgical planning stages is essential to not only work out the desired surgical movements, but to also facilitate the manufacture of accurate cutting and drilling guides together with fully customized bone plates and joint replacements that will be used by the surgeon. Àltimately, the advantages of using digital tools in complex surgery are numerous and include increased safety, reduced operating times, precise positioning of bones, improved accuracy of implant placement and simplified surgery. Àhis, in turn, leads to better patient outcomes in terms of recovery and patient satisfaction. u All Correspondence: Dr George Dimitroulis Suite 5, 10th Floor, 20 Collins Street Melbourne Vic 3000 Tel: +61 03 9654 3799 Fax: +61 03 9650 3845 Mob: +61 0409 505 146 e-mail: geodim25@gmail.com ACKNOWLEDGEMENTS: Àhe author would like to thank Dr David Ackland and Professor Peter VÀ Àee from the Biomedical Àngineering Department at the Àniversity of Melbourne who were involved in the early development of the Melbourne ÀMJ prosthesis, now referred to as the OMX ÀMJ Àystem. Àhe contribution of biomedical engineers at OMX Àolutions (www.omx-solutions. com) who helped design, develop and produce the OMX ÀMJ prosthesis, custom plates and surgical guides is also gratefully acknowledged. Àhe orthodontics for both patients presented in this article was undertaken by Dr Peter Àcott whose work is gratefully acknowledge. DECLARATION: Dr George Dimitroulis is a practicing Oral & Maxillofacial Àurgeon and Managing Director of OMX Àolutions Pty Àtd, (www. omx-solutions.com ) a Melbourne based Med-tech Company which developed and manufactured the OMX ÀMJ prosthetic total joint replacement system as well as the custom plates and guides described in this article. Àhe OMX ÀMJ prosthesis is approved for clinical use by the Australian Àherapeutic Goods Administration (ÀGA) as a Class b implantable medical device (AÀ G listing 276176) and is listed on the Prosthesis Àchedule. References 1.À odhi A, Àaik À, Pai A, Anuradha A. Àheumatoid arthritis affecting temporomandibular joint. Contemp Clin Dent. 2015 Jan-Mar;6(1):124-7 2.À Chigurupati À, Mehra P. Àurgical Management of Àdiopathic Condylar Àesorption: Orthognathic Àurgery Versus Àemporomandibular Àotal Joint Àeplacement. Oral Maxillofac Àurg Clin Àorth Am. 2018; 30:355-367. 3.À Andrews BÀ, Àakin GÀ, Bradley JP, Kawamoto HK Jr. Orthognathic surgery for obstructive sleep apnea: applying the principles to new horizons in craniofacial surgery. J Craniofac Àurg. 2012 Àov;23(7 Àuppl 1):2028-41 4.À Kau CH, Bejemir MP. Application of virtual three-dimensional surgery planning in management of open bite with idiopathic condylar resorption. Ann Maxillofac Àurg. 2015 Jul-Dec;5(2):249-54 5.À Farronato G, Galbiati G, Àsposito À, Mortellaro C, Zanoni F, Maspero C. À hree-Dimensional Virtual Àreatment Planning: Presurgical Àvaluation. J Craniofac Àurg. 2018 Jul;29(5):e433-e437 TABLE 2 – SURGICAL SEQUENCE 1.À LeFort 1 Maxillary Osteotomy a.À Cutting and drilling guide used for osteotomies and screw hole positions b.À Complete down fracture / remove bony interferences c.À Use custom maxillary plate to line up with pre-drilled screw holes and secure to new position with screws (no intermediate splint required) d.À Suture up maxillary incision 2.À Placement of Bilateral TMJ Prosthetic Joints a.À Surgical exposure of right TMJ via preauricular incision À i.À Perform discectomy and low condylectomy À ii.À Place custom fossa with aid of drilling guide and secure with 2mm screws À iii.À Temporary closure of wound b.À Surgical exposure of left TMJ via preauricular incision À i.À Perform discectomy and low condylectomy À ii.À Place custom fossa with aid of drilling guide and secure with 2mm screws c.À Maxillo-mandibular fixation using intermediate splint À i.À Isolate field with sterile sheet À ii.À Change gloves when finished with oral cavity d.À Surgical exposure of left mandibular ramus via neck incision À i.À Use drilling guide for screw positions À ii.À Place condylar prosthesis to line up with pre-drilled holes and secure in place with 2.5mm wide screws À iii.À Wound closure of left neck (suction drains) and preauricular incisions e.À Surgical exposure of right mandibular ramus via neck incision À i.À Use drilling guide for screw positions À ii.À Place condylar prosthesis to line up with pre-drilled holes and secure in place with 2.5mm wide screws À iii.À Wound closure of right neck (suction drains) and preauricular incisions f.À Release MMF and remove intermediate splint 3.À Bilateral Sagittal Split Mandibular Osteotomy a.À Conventional BSSO surgery and 2mm screw and plate fixation b.À Place into final occlusion with the aid of final occlusal surgical splint 4.À Genioplasty a.À Optional +/- 3D printed custom chin plate