Relationship between the direction of mandibular growth and masseter muscle conduction velocity.

Introduction: The purpose of this study was to investigate the relationship between muscle conduction velocity (MCV) of the masseter muscle and the direction of mandibular growth. Methods: Longitudinal cephalometric X-rays taken at the prepubertal and postpubertal periods of 16 Japanese girls were analyzed. MCV was calculated from the delay in myoelectric signals obtained by using multiple surface electrode arrays placed along the fibers of the left masseter muscle in the postpubertal period. The direction of mandibular growth was evaluated by superimposition of the lateral cephalometric X-rays at the prepubertal and postpubertal periods. The relationship between MCV and the direction of mandibular growth was analyzed statistically. Results: MCV was significantly correlated with the vertical facial height at the postpubertal period and the direction of mandibular condyle growth. Conclusions: If the relationship between prepubertal and postpubertal of MCV is clarified, it might be possible to predict the direction of mandibular growth and the vertical facial proportions at the postpubertal period from MCV of the masseter muscle at the prepubertal period.