Temporal change in the occlusal vertical dimension and its involvement in modulation of jaw movement in bite-reduced animals

The occlusal vertical dimension (OVD) in guinea pigs is maintained by tooth eruption and grinding. It has been reported that the experimentally raised OVD recovers to the innate OVD within a few days in guinea pigs. However, the mechanisms underlying OVD adjustment are not entirely understood. This study thus aimed to clarify whether the experimentally reduced OVD would recover. Bite-reduced guinea pigs were created by applying bilateral intermaxillary elastics for 10 days. Guinea pigs without elastics were used as a control. The OVD after removal of the elastics in the experimental group was compared with that of the control group. Jaw movement during chewing was also compared between the experimental and control groups. After removal of the elastics, the experimentally reduced OVD did not recover fully and a significant difference was observed between the experimental and control groups for up to 25 days during the recording period. The minimum closed position during chewing was significantly higher in the experimental group than in the control group, whereas the maximum open position was no different between the groups. The present findings indicated that the experimentally reduced OVD could not be fully recovered, suggesting that reduction of the OVD may have limited influence on jaw movement.