Influence of trauma from occlusion on progression of experimental periodontitis in the beagle dog.

The experiments were performed in six beagle dogs fed a soft diet which allowed dental plaque formation. During a pre-experimental period of 7 weeks, periodontitis was induced by (1) surgically creating a bony pocket and (2) adapting a copper band to the exposed tooth surface. Two dogs were sacrificed at the end of this period and tissue sections were prepared for histological examination. In the remaining four dogs, trauma from occlusion was produced on the left niandibular fourth premolar by the installation of a cap splint and a bar device. The contralateral premolar served as a control. At the start of, and at regular intervals during, an experimental period of 180 days, tooth mobility, gingival inflammation and plaque accumulation were assessed. After sacrifice, radiographs were taken of test and control tooth regions and histological sections analysed regarding the width of the marginal periodontal ligament space and the degree of apical downgrowth of the gingival pocket epithelium. Only the test teeth showed a gradually increasing horizontal mobility, but gingival inflammation and Plaque Index scores were similar on test and control sides. Radiographs revealed (1) horizontal bone loss in both test and control areas, and (2) angular bone destruction only in test areas. Histological sections showed that the degree of apical proliferation of the pocket epithelium was more pronounced in test than in control regions. Experiments carried out in different laboramay alter the path of spread of gingival tories have demonstrated that it is possible inflammation and thereby facilitate direct in dogs and monkeys to induce a gingival penetration into the periodontal ligament inflammation which develops into perio(Macapanpan & Weinman 1954), enhancing dontitis by allowing the accumulation of angular bone resorptioti and infrabony plaque and calculus (Saxe et al. 1967, pocket formation (Glickman & Smulow Lindhe et al. 1973, Kennedy & Poison 1962, 1965). 1973). It has been suggested (for review see In animals, periodontal tissue changes Posselt 1966, Glickman 1967) that trauma due to trauma from occlusion resemble from occlusion in the presence of periothose found in human autopsy material (for dontal inflammation may be an important review see Posselt 1966). Objections have contributory factor in the pathogenesis of been raised, however, concerning the valiperiodontal disease. Thus, occlusal forces dity of conclusions made from autopsy