We constructed a covariance structural model from factors such as the temporomandibular joint, dentition and the jaw movement for acquired open bite. From this model, we analyzed the possible underlying factors for acquired open bite.
Methods: The study involved 20 patients with both malocclusion and osteoarthritis. They were recruited from April 2004 - March 2006. We carried out medical interviews, and examined subsequent intra-oral and X-ray findings. In addition, we measured and analyzed the resultant dental model and jaw movement of the acquired open bite patients. We then classified the subsequent findings by factor analysis (SPSS 12.0). The causation between each factor was evaluated through structural equation modeling (Amos 7.0).
Results: The exploratory factor analysis revealed 26 findings and five factors (Factor 1: temporomandibular joint, Factor 2: tapping, Factor 3: occlusion of incisor, Factor 4: intercuspal position, Factor 5: dental arch form). In structural equation modeling, acquired open bite displayed a strong significant path toward the latent variable of the temporomandibular joint, tapping, the occlusion of the incisor, and the stability of the intercuspal position (Standardized regression coefficients 0.75, 0.65 and 0.64 and -0.47). The path along the latent variable for the dental arch form was deleted, as the cause of the path coefficient was deemed non-significant. The model fit to data was fair to good, as evidenced by GFI=0.776, AGFI=0.636, CFI=0.995.
Conclusion: From these results, it was suggested that the cause of the acquired open bite could not only be due to the deformation of the condyle, but as result of a multitude of factors.