UCSF

Introduction: Positional and morphological changes of the condyles and subsequent changes in the temporomandibular joint (TMJ) space are often observed following orthognathic surgery. The purpose of this study was to present and validate a novel semi-automated method for three-dimensional evaluation of the TMJ space using cone-beam computed tomographic (CBCT) data and clinically apply this method to evaluate the post-operative changes in the TMJ space in orthognathic surgery patients and compare the results to the conventional two-dimensional analysis of the CBCT multiplanar cross-sections.

Methods: Three-dimensional TMJ space analysis using Stratovan Checkpoint software (Stratovan Corporation, Sacramento, CA) and two-dimensional TMJ space analysis using Invivo5 software (Anatomage Inc., San Jose, CA) were repeated by an investigator to assess the analyses' reliability. The analyses were further applied to pre-operative, immediate post-operative, and follow-up CBCT scans from nine orthognathic surgery patients to evaluate the joint space change caused by positional and/or morphological changes of the TMJ.

Results: For three-dimensional and two-dimensional analyses, the mean intra-observer difference was small and within the clinically accepted margin of error. The two analyses gave concurring results for the majority of the joint spaces when applied to evaluate the longitudinal TMJ space change in orthognathic patients, demonstrating general increase in the joint space immediately after surgery followed by a decrease in the measurements at follow-up. However, the three-dimensional analysis offered far more morphological information compared to the conventional two-dimensional analysis.

Conclusions: This novel semi-automatic method is a reliable tool for the three-dimensional analysis of the TMJ space, allowing longitudinal assessment of the joint changes after orthognathic surgery.