GAP Australasian-Dentist-Mar Apr 2019

Category 96 AustrAlAsiAn Dentist surgery, his mouth opening was measured at 34mm inter-incisal distance (fig. 14) which the patient was very pleased with. CASE 3 A 44 yo lady presented to the author with an 8 year history of bilateral tMJ pain and crepitus and gradual deterioration in her mouth opening (fig. 15) which made visits to her dentist almost impossible. After many years of splint therapy and medications, including a period of chronic pain management, the patient was referred to the author by her General Medical Practitioner who felt that the patient was unable to cope any more with her jaw symptoms. Her GP had already done the usual screening for rheumatoid and other autoimmune disorders which came back negative. the author ordered update OPG and cone-beam Ct scans which clearly demonstrated advanced tMJ osteoarthritis in both tMJ’s (fig. 16). Having exhausted her non-surgical treatment options, and armed with a clear diagnosis of bilateral tMJ osteoarthritis, the patient was keen to proceed with bilateral custom tMJ prosthetic total joint replacement surgery. the custom joints were built on her Ct-scans (fig.17) and delivered 3 weeks later, ready to implant in the patient (fig. 18). since the joint prostheses were fully customized to fit the patient’s own bony anatomy, there was no bone preparation required as each component just slid into place which speeded up the surgery and her recovery time. she was out of hospital in 4 days and back to work 4 weeks after her surgery. On her 2 year review following surgery (fig. 19) she reported no pain in the tMJ’s and significantly improved function (fig. 20), which included eating a wide range of food. Her quality of life had improved enormously and she was grateful that the custom fit, print-to-order technology was available to treat her chronic condition (fig. 21). DISCUSSION the 3 cases described clearly demonstrate the benefits of customized tMJ implants which simplify and improve the accuracy of the surgery. the close adaptation of the implant to the bone contours means no bone preparation is required (apart from resection of the arthritic condyle). the custom fit also speeds up the surgical procedure by eliminating the guess work in sizing and positioning of the implant which plagued the off-the-shelf stock devices. Prior to the advent of the OMX Custom tMJ prosthesis, the author used stock tMJ prostheses that came in a multitude of different sizes that required the laborious and time-consuming action prostheses by OMX solutions (fig. 12) to help improve the accuracy and speed of the jaw resection and the reconstruction. He underwent bilateral gap arthroplasties and reconstruction with custom OMX prosthetic tMJ’s together with bilateral coronoidectomies and temporalis tendon release to improve mouth opening (fig. 13). His recovery was uneventful and post-operative jaw physiotherapy was an indispensable requirement for success in this case as the patient’s masticatory muscles had atrophied over the last 20 years because of his restricted mouth opening. On his 2 year review following was the severely restricted mouth opening that made access for dental treatment almost impossible, in addition to his limited diet and difficult intubations whenever he required an operation. Detailed Ct scans were taken of the jaws and facial skeleton and 3D dynamic images were reconstructed. surgical planning of the proposed gap arthroplasties to remove the ankylosis in both tMJ’s was conducted on the 3D images (fig. 11) and stereolithic 3D nylon models of the patient. Customized surgical cutting and drilling guides were designed and 3D printed together with customized tMJ lInICal Figure 9 – Image of the patient’s jaws based on his CT scans showing extensive bony ankylosis (fusion) of the right TMJ/condyle Figure 11 – The shaded red area shows the planned extent of the surgical resection required to release the ankylosis which the surgeon could view from any angle. Surgical cutting guides were also provided by OMX Solutions to help the surgeon make the precise bony cuts as planned. Figure 13 – Frontal facial x-ray view showing the custom prosthetic TMJ implants secured with bicortical screws in the mandibular ramus. Figure 12 – The TMJ implants were designed around the planned resection whilst preserving the existing occlusion. The position of the ID nerve is shown as a pink line to avoid being damage by screws. Figure 14 – The 2 year follow up review shows a very good mouth opening which the patient has been able to maintain since his bilateral TMJ ankylosis release and OMX TMJ custom implants. Figure 10 – On his first visit, the patient could only open 8mm inter-incisal distance.