Fine structural observations on the mechanism of loss of attachment during experimental periodontal disease in the rat

Severe periodontal destruction was produced unilaterally in rats by placing a wire/Concise appliance to encourage plaque accumulation, and then feeding the animals a high carbohydrate diet for up to five months. Electron microscopic examination of the specimens, which comprised maxillary first and second molar periodontium, at the ligament‐cementum interface revealed distinct zones in the destructive process. These included a zone of complete loss of ligament attachment to cementum just apical to the crevicular epithelium, and leading into a zone of partial loss of attachment where the destruction was occurring. Fibroblasts in this zone of partial loss were observed to resorb ligament fibrils inserted into cementum by phagocytosis and intracellular degradation. The same cells appeared to be phagocytosing the substance of the cementum as well. The remainder of the ligament apical to the zone of partial loss comprised the third zone and represented a more normal attachment apparatus.