Periodontal repair in dogs: evaluation of the natural disease model

Abstract Animal models are frequently consulted for histometric analysis of periodontal reconstructive therapy. Such models include surgical, periodontitis‐simulating and natural disease defects in canines or non‐human primates. Our studies suggest that homogeneity in defect height is critical for sensitivity of surgical and periodontitis‐simulating supraalveolar defect models in discriminating treatment effects. We herein evaluate this model aspect for natural disease defects. Buccal‐lingual histologic sections from the 2nd, 3rd, and 4th mandibular premolar teeth (P2, P3, P4) from 6 aged beagle dogs with advanced natural periodontal disease were used. Defect heights from the reduced alveolar bone to the cemento‐enamel junction were recorded in central step‐serial sections at the buccal and lingual surfaces of the mesial and distal roots for the premolar teeth. Mean defect height, standard deviation and coefficient of variation were calculated for tooth types and jaw quadrants, separately, and for all teeth. Confidence intervals were calculated for teeth in left and right jaw quadrants. Mean defect height and standard deviation for left and right jaw quadrants was 3.6±0.9 and 3.3±0.6 mm for P2. 3.3±.9 and 2.3±0.9 mm for P3, and 3.3±1.0 and 4.5±1.6 mm for P4. respectively. Coefficient of variation for defects for left and right jaw quadrants was 26 and 40%, respectively. Using 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 as statistically significant (p≤0.05, N=6). With the apparent variation in defect baseline, it is suggested that natural disease defects have limited potential in discriminating treatment effects following periodontal reconstructive therapy.