COMPARISON IN MANDIBULAR MOVEMENTS BETWEEN SUBJECTS WITH DEEP BITE AND NORMAL OCCLUSION

Introduction: Orthodontic treatment in-deep bite subjects has generally been focused on the correction of excessive vertical coverage (overbite); however, the impact on functional problems following treatment has not been well evaluated. This study aimed to investigate the differences in mandibular movements between deep bite and normal occlusion, and to compare the functional changes of mandible in the subjects with deep bite before and after treatment. Methods: This study included students from School of Dentistry, China Medical University (CMU), and employees from CMU Hospital. The participants were categorized into normal bite (n = 11) and deep bite (n = 16) groups. Considering the clinical practicability, convenience and affordability, Digi Gnatho software (Japan), was used to analyze mandibular movements recorded by digital video camera. Results: No significant difference was observed in the left side masticatory movements between two groups. Significant difference was only detected in the horizontal direction of right side mastication. All of the velocities and masticatory cycle duration of both sides showed no difference. In the mandibular border movements, protrusive movements in deep-bite group were distinct from normal occlusion group. Normal occlusion group had a larger range of mandibular movements compared to deep bite group. Conclusions: Different degrees of vertical coverage of the incisors not only presented differences in the ranges of masticatory movements and border movements, but also had an impact on the final occlusal phase of mastication.