Effects on human maximum bite force of biting on a softer or harder object.

A recent study concluded that the pulps of human incisor teeth may contain mechanoreceptors. These provide the input for a protective mechanism that reflexly limits the maximum bite force by monitoring the stress on compressed dentine. In separate experiments it was later shown that individuals can accurately detect whether they are biting on a harder or softer surface when it seemed that the only receptors which could have detected the difference must have been in the tooth pulps. Thus, pulpal mechanoreceptors may be used subconsciously to limit the maximum bite force and consciously to detect differences in hardness. If these conclusions are correct the maximum bite force should be larger when incising on a soft (rubber) surface than on a hard (acrylic) surface because when the teeth sink into the rubber the bite force is spread over a larger area, thereby reducing the local stress. A reduction in stress allows an increase in bite force. But if the tooth were previously covered with an acrylic crown, which would already reduce the stress by distributing the bite force over a large area of the incisor crown, there would be little or no difference in the maximum bite force whether biting on rubber or acrylic. The results of experiments on 15 participants confirm these predictions and support the hypothesis that the pulps of human incisors contain high-threshold mechanoreceptors.