Influence of soft diet feeding on development of masticatory function

Stomatognathic function is developed in steps from the latter half of infancy up to childhood. This period is thought to be critical for stomatognathic function acquisition. In this study, we investigated how the consistency of the daily diet after weaning affects the development of stomatognathic function in mice. C3H mice were divided into liquid- and solid-diet group. Three-dimensional jaw-movement tracking and jaw-muscle electromyography (EMG) were recorded simultaneously during chewing of pellet and bread at 11 weeks of age. As a result, we found that (1) The masseter activity was larger in the liquid-diet group than the solid-diet group. (2) Total cycle duration indicating chewing rhythm and gape size indicating burst pattern were significantly longer and larger during pellet chewing than bread chewing in the solid-diet group. On the other hand, there was no significant difference in both parameters in the liquid-diet group. These results suggest that greater EMG bursts are necessary, since the masticatory muscles are weaker in mice fed with liquid diet, and that the capacity to perceive the consistency of diet is reduced in these mice. The development of the mechanism to regulate chewing rhythm and pattern is considered to be impeded when raised on soft diet