Assessment of bone remodeling in the temporomandibular joint by serial uptake measurement of technetium 99m-labeled methylene diphosphonate with a cadmium telluride probe.

Regional uptake of technetium 99m-labeled methylene diphosphonate was measured serially over time to follow the healing course of surgically generated lesions, induced unilaterally in the condyles of beagles. A small portable cadmium telluride probe was used for radiation detection, with and without a gold collimator attached. Radioactivity was measured at six periarticular sites on both the operated and the contralateral control sides and expressed as a ratio with respect to a reference site over the sagittal suture. The use of a collimator was crucial to separate the activity associated with bone mineralization in the condylar head from that arising in the adjoining bones. The uptake in the condylar region increased 2 weeks after surgery and remained at a constant level above the presurgery baseline (p less than 0.05) until termination of the study (10 weeks). Postmortem histologic examinations confirmed the high bone turnover level by revealing newly formed bone as well as the presence of osteoclasts. The time course of nuclide uptake in the temporomandibular joint is different from the general pattern of rise and fall of activity displayed in other bones and indicates the persistence of bone remodeling processes during a prolonged period of at least 10 weeks.