抄録
This study tested the hypothesis of whether the lack of tooth eruption would affect the masticatory function. For this purpose, we recorded the jaw movement trajectory in the three dimensions and electromyographic (EMG) activity of MAS and DIG muscles in freely behaving osteopetrotic (op/op) and normal mice. A masticatory sequence was divided into food intake and mastication periods, and 10 cycles in the latter stage were selected for analysis. Mean values of total cycle duration, closing phase duration and opening phase duration were obtained from the jaw movement and those of onset time, time duration and amplitude were obtained from the EMGs of the MAS and DIG muscles. The protruding phase coincided with the power stroke lacked in the op/op mouse. The total cycle duration and opening phase duration were longer in the op/op mouse than normal mouse. The pattern of MAS muscle activity in op/op mice was similar to that in normal mice while the duration of the DIG muscle was longer in op/op mice than normal mice. Our results indicate that the periodontal receptors play an important role in the completion of masticatory function.
