Food-holding and -biting behavior in human subjects lacking periodontal receptors

Previous studies have suggested that information provided by periodontal mechanoreceptors is particularly important for the fine motor control of the mandible, i.e., when humans hold and carefully manipulate food particles between the teeth with low biting forces. In the present study, we further evaluated this hypothesis by comparing the performance of three age- and gender-matched groups of subjects for which the integrity of the periodontal sensory apparatus differed. Specifically, the subjects had either natural teeth (natural group), dental prostheses supported by oral mucosa (denture group), or dental prostheses supported by osseointegrated implants (implant group). Each subject was instructed to hold half a peanut between the upper and lower central incisors for ca. 3 sec, and then to split it. The force applied by the anterior teeth was continuously monitored by a transducer-equipped bar on which the morsel rested. While the peanut was held, the force generated by subjects in the denture and implant groups was more variable and averaged four times that generated by subjects in the natural group. The peanut was split by a distinct, rapid ramp-increase in force that was similar for all three groups. In subjects lacking periodontal receptors, the morsel frequently escaped from the incisal edges during both phases of the task. The results demonstrate a marked disturbance in the control of precisely directed, low biting forces in subjects lacking periodontal receptors and suggest that the receptors play a significant role in the specification of the level, direction, and point of attack of forces used to hold and manipulate food between the anterior teeth. Moreover, other types of mechanoreceptors can not fully compensate for the loss of periodontal receptors.