Histopathological initial changes in denture supporting tissues, in relation to the changes in intensity of occlusal pressure exerted through the experimental denture base, was studied. The denture base was applied to the palate of the molar region of the rat, and was installed to cover the palatal mucosa without any pressure unless occlusal force was exerted. The defined amount of occlusal pressure was transmitted to denture supporting tissue by allowing the denture base to subside the specified amount into palatal mucosa. The intensity of the occlusal pressure measured immediately after the insertion of the denture were 79.7, 31.7 and 10.7kPa. The animals were sacrificed at 2, 4, 7, 10 and 14 days after the insertion of the denture. Histopathological changes caused by the occlusal pressure were observed, and the changes in intensity of the occlusal pressure was also measured on every histopathological observation periods.
Histopathological changes of the denture supporting tissues showed dependence on the intensity of the occlusal pressure, and also showed high correlation with the subsequent gradual changes of the pressure. Compression of lamina propria mucosa, shortening of epithelial ridges, osteoclastic bone resorption, compression of epithelial tissue except for epithelial ridges and inflammatory cell infiltration in the lamina propria mucosa were observed with the elapse of time. These tissue changes came out early and became severe by increasing the occlusal pressure.