Methods: C3H mice were used and divided into the liquid-diet group (n=7) and the solid- diet group (n=7). Three-dimensional jaw movements and masticatory muscle activities were recorded simultaneously during the chewing of pellet and bread in two groups at the stage of 11 weeks.
Results: (1) In the solid-diet group, total cycle duration was significantly longer during pellet chewing(229±34 ms) than during bread chewing(189±21 ms). However, in the liquid-diet group, there was no significant difference in the total cycle duration between the food(pellet-213±45 ms, bread-201±26 ms). (2) In the solid-diet group, the lateral excursion when chewing pellet(610±185 µm) was significantly smaller than when chewing bread (990±360 µm). However, in the liquid-diet group, there was no significant difference in the lateral excursion (pellet-670±374 µm, bread-730±282 µm). (3) The area of masseter activity in the liquid-diet group (0.0121±0.0049 mV-ms) was significantly larger than in the solid-diet group (0.0076±0.0021 mV-ms) during bread chewing.
Conclusion: Solid-diet mice showed a different masticatory rhythm and pattern when chewing on bread or pellet. On the other hand, liquid-diet mice showed a similar masticatory rhythm and pattern regardless of food consistency. It was suggested that daily diet of soft food after weaning influences the development of the mechanism to regulate chewing rhythm and pattern.