CATEGORY 88 AUSTRALASIAN DENTIST Declaration: Dr George Dimitroulis is a practicing Oral & Maxillofacial Surgeon and Founder of MAXONIQ Pty Ltd, (www.maxoniq.com) a Melbourne based Medtech Company which developed and manufactures the medical devices described in this article. Introduction There are many kinds of facial asymmetry resulting from multiple causes. The most common facial asymmetry, however, is the result of jaw deformities that may be developmental or posttraumatic that may involve the temporomandibular joint (TMJ). This results in the skewed appearance of the chin and lopsided smile line due to the cant of the maxillary teeth, especially if it first appears in a growing patient. The aim of this article is to show how we can surgically correct a complex facial asymmetry using current digital technologies. Case Report A 32yo male presented to the author with obvious lower facial asymmetry secondary to right side condylar hypoplasia resulting from juvenile arthritis of his left TMJ (figs. 1,2). His right condyle and ascending ramus were significantly smaller than the left side which resembled a type 1 hemifacial microsomia. The rudimentary condyle resulted in vertical shortening of his right ascending ramus of mandible which appears to have started in early childhood since his maxilla was also canted to the right side. He was not only conscious of his lopsided appearance but was also suffering from right TMJ and myofascial pain resulting from the skewed opening of his mandible with unbalanced masticatory muscles. Previous orthodontic treatment as a teenager meant his teeth were well aligned so he was spared the time and expense of presurgical orthodontics. Clinical photos and Dicom CT scans of his face and jaws clearly demonstrated the complexity of his lower facial asymmetry and degenerative nature of his right TMJ that had to be addressed as part of his treatment plan (figs. 1,2). Using Materialize software, biomedical engineers created a 3D rendering of his complete facial skeleton and the author was able to accurately plan the corrective jaw surgery that consisted of bimaxillary osteotomies, genioplasty and right TMJ prosthesis since the right TMJ was degenerative and deemed too unstable to preserve1. Additionally, a 3D designed and custom milled porous polyethylene (HDPE) onlay graft was used to build out the deficient right angle of mandible to match the symmetry of the left mandibular angle and body (figs. 3,4,5). The maxilla was down grafted on the right-side using cutting and drilling guides to accurately position the maxilla to correct the transverse cant. The maxilla was secured with custom 3D printed titanium bone plates and screws and iliac crest bone graft was used to fill the osteotomy gaps created by the maxilla’s new position. A right side TMJ custom prosthetic joint was implanted after the new mandibular position was secured to the maxilla with the additional aid of a left mandibular sagittal split osteotomy and right-side temporalis tendon release / coronoidotomy to allow vertical lengthening of the left ascending ramus of mandible (figs. 6,7). COMPLEX FACIAL ASYMMETRY: A Digital Approach to Corrective Jaw Surgery. By George Dimitroulis, Consultant Oral & Maxillofacial Surgeon, Epworth-Freemasons Hospital, East Melbourne Vic Fig.5 – Virtual Surgical Treatment Objective to correct lower facial asymmetry by combining bimaxillary osteotomies, genioplasty and right TMJ custom prosthesis with onlay synthetic graft to lower border of right mandible. Fig.3 – VSP showing Right TMJ custom prosthesis with Porous polyethylene onlay graft to angle and lower border of mandible Fig.4 – Lateral view showing additional maxillary ostetomy and genioplasty. Fig.2 – 3D Scan showing obvious lower facial asymmetry Fig.1 – Preoperative Frontal view LINICAL A right mandibular angle custom porous polyethylene (HDPE) prosthesis was secured with bicortical screws to the lower border of the mandible (figs. 3,4). Finally, an asymmetric genioplasty was performed to improve the chin projection and symmetry with the aid of cutting guides and 3D printed titanium chin plate. The patient was discharged after 3 nights in hospital. The arch bars which were used inlieu of orthodontic brackets and wires were removed after 6 weeks when the occlusion stabilized. A 12 month follow up of the patient showed a stable result with good facial symmetry (Figs. 8, 9, 10, 11).
RkJQdWJsaXNoZXIy MTc3NDk3Mw==