Methods: Four healthy volunteers (aged 19 to 23 years) performed masticatory trials on a purpose built simulator while mechanical orthogonal stimuli were applied to the upper left central incisor tooth each time the jaw passed through the mid-open position. These trials were repeated after anaesthetising the incisor to isolate any contribution by the periodontal mechanoreceptors.
Results: Strong inhibitory reflexes originating from the periodontal mechanoreceptors were noted under static conditions, consistent with previous studies. Dynamic condition trials showed that the inhibitory reflex decreased considerably (p<0.05) during jaw opening, whereas it remained relatively constant during jaw closure (p>0.05).
Conclusions: Inhibitory reflexes, activated by strong forces, serve to prevent teeth and their surrounding structures from being injured during mastication. Modulation of periodontal mechanoreceptor response was noted in human subjects during jaw movement, supporting previous findings in experimental animals. Future studies are planned with a larger sample of subjects and using different bite force levels.
The authors would like to thank the Australian Dental Research Foundation for its support.