Objectives: Sensory information from periodontal mechanoreceptors is used to control the magnitude of bite forces when subjects use low forces to manipulate and hold food between anterior teeth. The purpose of the present study was to analyze if periodontal mechanoreceptors have an influence also on the jaw-power actions during the split of a morsel in a hold-and-split task. Methods: 10 subjects (ages 20-25 years) participated in the study. Instructions were given to hold a morsel between a pair of opposing central incisors for ca 3 seconds, and then to split it. The force applied by the teeth was continuously monitored by a transducer-equipped bar on which the morsel rested. Each session consisted of 3 series with different conditions; “normal”, “blind” (without vision) and “anesthesia” (with local anesthesia of the periodontium). In each series, 15 biscuits and 15 peanuts were presented in a semi-random order. Results: The mean split forces was for biscuits 9.9N and for peanuts 20.1N and did not differ between the different conditions. In the “normal” condition, the mean force rate during the split phase differed significantly between biscuits (47N/s +-19) and peanuts (76N/s +-24). This difference decreased for the “blind” condition (biscuits 45N/s +-19 and peanuts 68N/s +-27), and for the “anesthesia” condition (biscuits 44N/s +-28 and peanuts 58N/s +-24). In the “normal” condition, the difference between biscuits and peanuts in the force increase during the split phase could be seen as early as after 70 ms. Conclusions: Sensory information from periodontal mechanoreceptors is used to regulate the force rate when splitting morsels of different hardness. Vision seems to be of minor importance for this regulation.
This study has been supported by the Swedish Dental Society.