Comparative Histomorphometric Evaluation of Healthy and Ankylosed Mandibular Condylar Process.

Background: Temporomandibular joint (TMJ) ankylosis is one of the most disruptive maladies afflicting the masticatory system. The characteristic feature is the formation of bony mass bridging condyle with glenoid fossa. The exact pathogenesis is, however, not completely understood.

Purpose: To investigate and compare histomorphometric features of ankylosed condylar specimen with normal condylar process.

Materials and Methods: Group I included 17 post-traumatic unilateral TMJ ankylosis patients managed by excision of ankylosed mass and interpositional arthroplasty. Group II included 13 condylar head fracture patients managed by surgical debridement. The bony specimens of both the groups were subjected to histomorphometric examination for assessment of percentage of bone in trabeculae area (%BONE), osteocyte cell density (OSTCD), the presence of inflammation and fibrosis.

Results: The mean %BONE, OSTCD, %inflammation, %fibrosis was 60.4%, 340.9 mm2 , 52.9 and 58.8% in group I and 29.6%, 202.6 mm2 , 31 and 0% in group II.  %BONE, OSTCD and fibrosis in cases of TMJ ankylosis were significantly higher than the controls while no significant difference was observed in the presence of inflammation.

Conclusion: The persistence of joint inflammation following condylar head fracture causes aggressive reparative process leading to ankylosis.