2010 Volume 44 Issue 1 Pages 23-39
Establishing and maintaining stable occlusion is one of the most important challenges in orthodontic treatment. We investigated the correlation between centric occlusion and the temporomandibular joint (TMJ). Thirty-four male adult volunteers were enrolled in this study, presenting normal occlusion without subjective symptoms of TMJ disorders or any other abnormality in jaw function or masseter muscles. For occlusal force measurements, occlusal balance was determined by calculating the sum of the product of the area and the pressure at each occlusal contact on both sides of the mouth. A dynamic MRI was used for measurement of the TMJ space. The subjects were asked to achieve the maximum voluntary contraction (MVC) for 10 minutes and a set of 20 magnetic resonance images (MRI) were exposed on each side. The joint space dimensions were then measured on the images using image analysis software. We next investigated the relationship between occlusal balance and joint space dimension. In the group with greater occlusal force on the right side, the joint space dimension at the glenoid fossa (90°) on the left side showed a significant reduction during MVC, whereas in the bilateral equilibrium group the joint space dimension at the glenoid fossa (90°) on both sides showed a significant reduction (p<0.05). In the group with greater occlusal force on the left side, the joint space dimensions at the tuberculum articulare (45°) on the left side and at the glenoid fossa (90°) on the right side showed a significant reduction during MVC, whereas the joint space dimension at the glenoid fossa (90°) on the left side showed a significant increase (p<0.05). These findings indicate that poor balance between occlusal forces on the right and left sides can influence the TMJ. The findings also show the importance of balancing occlusal force in orthodontic treatment.
