Oral Mucosal Response to Dental Prostheses

Oral mucosa is not optimally adapted to provide a foundation for prostheses and the provision of dentures requires it to function in a modified environment. Previous studies have used a rat model for examination of the histopathology of oral candidiasis or mucosal coverage with dental prostheses. Some studies have been complicated by the presence of accumulated food debris between mucosa and prostheses. The present study was undertaken to develop further the Wistar rat as a suitable animal model on which to study the effects of dentures and dental materials on oral mucosa, and was divided into two parts. The first part examined the effects of prostheses on oral mucosa while modifying the animals' diet. The second part examined the effects of materials used to modify prostheses. The first part of the study compared the effects of three dietary regimes upon debris accumulation and measurable epithelial parameters. Individual heat-cured acrylic appliances were constructed. Within each dietary group, animals were allocated to a control group, or one of two test groups, wearing an appliance for periods of either 7 or 14 days. Tissue was analysed using computerised planimetry. Results showed that a powdered diet used in a paste form gave the least accumulation of debris in appliance wearers. This dietary group exhibited the least differences between appliance wearers and controls. Unlike the other two groups, they showed no difference in the thickness of adherent keratin between the test and control animals. The second part of the study used the Wistar rat fed on the powdered diet in a paste form to analyse the effects of a resilient soft lining material and a hard "chairside" relining material upon the epithelium. The effect of relining in the experimental groups examined was to increase the thickness of keratin, while not increasing the total epithelial thickness. The use of the Wistar rat model utilising the paste diet is indicated for future investigation of the effect of prostheses on oral mucosa