Differences in the response of rodent oral mucosa and skin to repeated surface trauma.

The responses of oral mucosa and skin to daily application of controlled frictional stimuli were compared. In some respects, the epithelia of both oral mucosa and skin showed similar responses: Low levels of friction resulted in epithelial thickening, and higher levels resulted in ulceration. The mucosa, however, ulcerated more readily and, unlike the skin, failed to heal if friction was reapplied. The histologic appearance of the ulcers so produced was essentially similar to that of denture-induced traumatic ulcers. Healing of ulcerated skin was associated with the formation of a hard surface scab which protected the underlying healing tissues from further frictional damage. A similar protective scab was not formed over mucosal lesions, and a thickened epithelium resistant to further frictional damage was not re-formed. The low resistance of the oral mucosa to friction and its failure to heal if friction is reapplied suggest that an analogy between the responses to friction of oral mucosa and the skin does not form a sound basis for clinical therapy.