Functional reversibility of temporomandibular joint mechanoreceptors

Objective: Previous studies have reported that the maturation of temporomandibular joint (TMJ) mechanoreceptors occurs during the early stages of mastication, and indicated that TMJ mechanoreceptors lose their function when masticatory loading is decreased. The purpose of the present study was to investigate whether the resumption of proper TMJ loading during the early growth period could restore TMJ mechanoreceptor function.

Designs: Ninety-nine 2-week-old male Wistar rats were divided into two groups and fed either pellets [control group (n=33)] or a liquid diet [experimental group (n=66)]. At 5 weeks of age, the experimental group was split into changing-diet (n=33) and liquid-diet (n=33) groups; the former was fed pellets instead of a liquid diet. TMJ mechanoreceptor activities were recorded from the trigeminal ganglion at 5, 7 and 9 weeks. The firing threshold and maximum instantaneous firing frequency of single TMJ units were measured in each group.

Results: In the changing-diet group, the firing properties of TMJ units were recovered at 7 weeks.

Conclusions: Proper TMJ loading during the early growth period can lead to the restoration of TMJ mechanoreceptor function.