The influence of craniofacial morphology on mandibular border movements.

Although they are widely used as diagnostic signs of temporomandibular disorders, mandibular border movements reflect not only condylar movement, but also other factors. In the present study, the authors investigated the effect of craniofacial morphology on three different mandibular border movements: maximum jaw opening, maximum jaw protrusion, and maximum jaw laterotrusion. One hundred female subjects were selected from outpatients visiting the orthodontic clinic of Okayama University Hospital. The mandibular border movements were measured using an optical recording system in three dimensions as six degrees of freedom. The craniofacial morphology was evaluated using lateral cephalograms. The results suggest that craniofacial morphology had different influences on each mandibular border movement. In particular, during maximum jaw laterotrusion, lower incisor movement strongly reflected condylar movement, and the influence of craniofacial morphology on mandibular border movement was minimal. Therefore, lower incisor movement during maximum jaw laterotrusion appears suitable to evaluate condylar movement.