Effect of occlusal pressure on the histopathological changes in denture supporting tissues.

Histopathological changes in the denture supporting tissues in relation to the occlusal pressure exerted through an experimental denture base were studied. An experimental denture, which prescribed the occlusal pressure by the amount of subsidence of the denture base (100, 50 and 13 microns), was constructed for the palate of the molar region of rat. Histopathological changes caused by the occlusal pressure were observed, and the intensity of the pressure was also estimated. In the 100 microns subsidence group, compression of epithelium and lamina propria mucosae, inflammatory change and bone resorption were caused by the occlusal pressure. In the 50 microns subsidence group, compression of epithelium and lamina propria mucosae and bone resorption were observed, while in the 13 microns subsidence group, no evidence of inflammatory change and bone resorption were observed. The epithelium and lamina propria mucosae recovered histopathologically depending on the gradual decrease of the occlusal pressure resulting from bone resorption, whereas no quantitative recovery of the resorbed bone tissue was observed in the 100 and 50 microns subsidence groups. From the results observed in this study, a high correlation was observed between the histopathological changes under a denture base and the intensity of the occlusal pressure, and the possibility of the existence of the threshold for bone resorption induced by occlusal pressure was suggested.