Age-related periodontitis and alveolar bone loss in rice rats

Objective: To characterize in rice rats: (a) periodontitis (PD) progress with feeding of standard laboratory rat chow (STD) during ages 4-80 weeks; and (b) PD progress with feeding of a high sucrose-casein (H-SC) diet during young adulthood. Methods: One group (N = 12) was euthanized at age 4 weeks (Baseline). Four groups (N = 8-16) consumed a STD diet from baseline and were necropsied at ages 22, 30, 52, and 80 weeks. Three groups (N = 10-16) consumed an H-SC diet from baseline. Two were necropsied at ages 22 and 30 weeks, respectively. The third switched to the STD diet at age 22 weeks and was necropsied at age 30 weeks. All mandibles/maxillae were assessed by histometry for degree of periodontal inflammation (PD Score), alveolar crest height (ACH, mm), and horizontal alveolar bone height (hABH, mm(2)). Results: In STD diet rats aged >= 30 weeks, all endpoints were worse (P < 0.05) than at Baseline. In H-SC diet rats aged >= 22 weeks, all endpoints were worse than at Baseline (P < 0.05). At age 22 weeks, all endpoints were worse in the H-SC group than in the STD group (P < 0.05). By age 30 weeks, the STD and H-SC groups did not differ. Conclusions: 1) STD diet fed rice rats develop moderate/severe PD by age 30 weeks; 2) an H-SC diet accelerates moderate/severe PD development; and 3) switching to a STD diet does not halt/reverse PD that was accelerated by an H-SC diet. These data further clarify use of the rice rat as a PD model. (C) 2016 Elsevier Ltd. All rights reserved.