The purpose of the present study was to estimate the qualitative dynamics of bone tissue under denture base caused by lack of self-cleaning as a result of coverage by denture base, utilizing double labeling technique with bone markers and contact microradiography.
The experimental denture base was designed to make contact with molar region of the palate of rat and to transmit no occlusal forceto the tissues under the denture base. The denture base was not removed throughout the experimental period. This procedure caused lack of self-cleaning, and it also caused continuous pressure to be applied to palatal tissues under the denture base by the accumulation of exfoliative horny cells, which induced bone resorption and formation under the denture base.
The results were as follows:
1. Two to three weeks after the insertion of the denture base, number of osteoclasts and Howship's lacunae were observed on the palatal surface of hard palate bone tissue under the denture base. In the same observation period, increased bone formation was observed on the nasal surface.
2. Four to six weeks after the insertion of the denture base, increased bone formation was observed on the palatal surface of hard palate bone tissue under the denture base. Bone formationwas observed mainly in Howship's lacunae, and only slight bone formation was observed in other region. 3. The first one week and from seven to ten weeks after the insertion of the denture base, bone formation was suppressed on the palatal surface of hard palate bone tissue under the denture base.