Synthesis of Mandibular Movements from Basic Motion Modes Considering Dynamic Profile of Masticatory Muscles

Abstract

Mandibular movement is performed by many masticatory muscles. It is important to estimate muscular activities in mastication for examining mechanical function of the movement. However, the estimation method has not yet been established. This study proposes a new method to clarify the cooperative change of muscular lengths using our patient-specific 3-D mandibular motion display system. The method reproduces a mandibular movement from several basic motion modes. The motion modes are expressed by periodic functions with different peak times. The proposed method provides comprehensible information even in a complex mandibular movement. Time series of the muscular lengths are also obtained from the 3-D motion display system. This study discusses a relationship between incisor trajectories and muscular lengths in mandibular movements. We succeeded in reproduction of chewing movements by synthesizing the basic motion modes. With the proposed method, dynamic profiles of masticatory movement show a clear relation to characteristics of the incisor trajectories. We also found all masticatory muscles are cooperatively controlled during mandibular movement. Bilateral difference of contractile muscular lengths and the timings obviously affect the trajectory pattern.

Keywords

• mandibular movement
• display system
• masticatory muscles
• incisor trajectory