PERIODONTAL REPAIR IN DOGS - EVALUATION OF THE NATURAL DISEASE-MODEL

Animal models are frequently consulted for histometric analysis of per iodontal reconstructive therapy. Such models include surgical, periodo ntitis-simulating and natural disease defects in canines or non-human primates. Our studies suggest that homogeneity in defect height is cri tical for sensitivity of surgical and periodontitis-simulating supraal veolar defect models in discriminating treatment effects. We herein ev aluate this model aspect for natural disease defects. Buccal-lingual h istologic sections from the 2nd, 3rd, and 4th mandibular premolar teet h (P2, P3, P4) from 6 aged beagle dogs with advanced natural periodont al disease were used. Defect heights from the reduced alveolar bone to the cemento-enamel junction were recorded in central step-serial sect ions at the buccal and lingual surfaces of the mesial and distal roots for the premolar teeth. Mean defect height, standard deviation and co efficient of variation were calculated for tooth types and jaw quadran ts, separately, and for all teeth. Confidence intervals were calculate d for teeth in left and right jaw quadrants. Mean defect height and st andard deviation for left and right jaw quadrants was 3.6+/-0.9 and 3. 3+/-0.6 mm for P2, 3.3+/-0.9 and 2.3+/-0.9 mm for P3, and 3.3+/-1.0 an d 4.5+/-1.6 mm for P4, respectively. Coefficient of variation for defe cts for left and right jaw quadrants was 26 and 40%, respectively. Usi ng confidence intervals for mean differences between jaw quadrants, it was determined that a mean treatment effect may be as large as 0.8, 1 .1 and 1.9 mm for P2, P3 and P4, respectively, before being detected a s statistically significant (p less than or equal to 0.05; N=6). With the apparent variation in defect baseline, it is suggested that natura l disease defects have limited potential in discriminating treatment e ffects following periodontal reconstructive therapy.