Effect of continuous pressure on histopathological changes in denture-supporting tissues

The histopathological changes in denture-supporting tissues were studied in relation to continuous pressure exerted through an experimental denture base. The experimental dentures were designed to load continuous pressures (1·5, 3·4 or 4·9 kPa) to the palate of molar region of rat. Histopathological changes caused by the continuous pressure were observed, and the intensity of the pressure was also estimated. A high correlation was observed between the histopathological changes under the denture base and the intensity of the continuous pressure. In groups exposed to 4·9 and 3·4 kPa, the continuous mechanical pressure caused bone resorption; in 1·5 kPa group, no evidence of bone resorption was observed. The epithelium and lamina propria mucosa under the denture base, which were compressed by the continuous pressure, recovered histopathologically depending on the decrease of the pressure caused by bone resorption; no quantitative recovery of the absorbed bone tissue was observed. No inflammatory change was induced by the continuous pressure. From the histopathological results observed in this study, the possibility of the existence of a threshold for bone resorption induced by continuous pressure was suggested.