Histopathology of periodontitis ('broken-mouth') in sheep: a further consideration

Histological observations of serial sections through the anterior teeth and periodontia of mature five-year-old sheep with 'broken-mouth' revealed two important histopathological features which advance the understanding of the disease mechanism. The periodontal pockets may extend not only in a vertical but also in a horizontal direction. The host response associated with microbial plaque at the advancing front and the more established regions showed obvious cellular differences. At the advancing front emigrating neutrophils are very evident, the pocket epithelium very thin, sometimes with microulceration. In the more established regions dense plasma cell infiltrates are common, with low numbers of neutrophils. It was concluded that broken-mouth periodontitis results from an active progression of plaque-forming oral microorganisms (of unknown species) advancing along the root surface between the cementum and periodontal tissues.