Accuracy of orthopantomograms in the assessment of implant position following alloplastic temporomandibular joint replacement.

Abstract

The aim of this study was to determine the accuracy of orthopantomograms (OPGs) when assessing post-operative temporomandibular joint (TMJ) implant position, compared with cone beam computerized tomography (CBCT). A retrospective analysis was undertaken on six adult patients who were implanted with a custom TMJ prosthesis due to end-stage TMJ disease. Post-operative CBCT was compared with post-operative OPGs. Overall magnification of each OPG was calculated and used to linearly rescale each image. Implant position was assessed by measuring the gonion angle and the distance between each surgical screw and the mandibular gonion (SG length). Mean magnification for OPGs was 24.2%. There were no significant differences (p > 0.05) in the gonion angle on OPGs compared with CBCT images. There was a mean decrease in SG lengths of 0.02mm on OPGs, corresponding to error level of 5.31%. The 95% limits of agreement between OPGs and CBCT images for SG lengths were 1.65mm and - 1.73mm. This study presents a clinically applicable and accurate first-line radiographic screening tool to assess TMJ implant position. When combined with clinical assessment, OPGs can help reduce the need for further imaging and radiation exposure post-operatively.