Abstract
Purpose: Recently, the occurrence of acquired anterior open bite subsequent to temporomandibular joint (TMJ) closed lock (AAOB-SCL) has attracted attention. However, the actual state has not been clarified. The present study examined retrospectively the clinical characteristics of AAOB-SCL.
Methods: The subjects were 24 patients who were diagnosed as AAOB-SCL. Twenty-four TMJ closed-lock patients without AAOB-SCL also participated in this study as a control group. Patients with anterior open bite due to rheumatoid osteoarthrosis were excluded.
Results: Most cases of AAOB-SCL occurred more than three months after the emergence of TMJ closed lock.
For 5 patients of the AAOB-SCL group, an occlusal splint had not been applied and the rate of the cases without splint was not significantly different from that of the control group.
Posterior open bite was found except the most posterior tooth, more frequently on the contra-affected side, in addition to anterior teeth. The mean maximum mouth opening range was significantly larger than that in the control group.
Condyles on the affected side were deformed in all subjects and the rate of deformity was significantly larger than that in the control group.
Conclusions: It was suggested that AAOB-SCLs tended to appear in the chronic phase, i.e., the phase in which mouth-opening limitation improved or was improving, on the anterior teeth and posterior teeth more frequently on the contra-affected side except the most posterior tooth. An occlusal splint was not always used before the emergence of AAOB-SCL.
