Objectives: Information provided by periodontal mechanoreceptors is used to control the magnitude of bite forces used to hold and manipulate food particles between anterior teeth (Trulsson and Johansson, Exp Brain Res 107:486-496, 1996). In the present study, forces applied by anterior and posterior teeth and roles of periodontal receptors during a hold-and-split task will be analyzed.

Methods: 20 subjects with natural healthy teeth in both jaws participated in the study (ages 22-40 years). Each subject was instructed to hold half a peanut between two antagonistic teeth for ca 3 seconds, and then to split it. Each session consisted of 3 series in which the subjects performed the hold-and-split task 5 times using the upper right central incisor, the canine, the 2nd premolar and the 1st molar. Thus, each subject performed the hold-and-split task 15 times for each tooth. In addition, for 4 subjects, anesthesia of the upper and lower teeth on the right side was administrated and one series of hold-and-split tasks was performed.

Results: Significantly higher hold forces were observed for the premolar (1.15 +/- 0.72 N) and the molar (1.74N +/- 0.76 N) compared to the incisor (0.60 +/- 0.27 N) and the canine (0.77 +/- 0.45 N; P<0.001; ANOVA). No differences were found when the hold forces were compared between different series. Anesthesia of the teeth significantly increased the hold forces for all teeth.

Conclusions: Forces used to hold and manipulate food between the teeth increase distally along the dental arch suggesting a decreased sensitivity of the periodontal receptors at the posterior teeth. The higher hold forces produced during anesthesia attest the important role of periodontal receptors in specifying the level of the hold force.

This work was supported by the Swedish MRC, No. 13291.

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