| Description |
Several morphometric and cellular parameters were studied in the rice rat (Oryzomys palustris). When fed a soft, high carbohydrate diet, a severe periodontal disease occurred, with significant alterations in the morphometric and cellular endpoints observed. Weaned animals were placed on a high carbohydrate diet for periods of, 12 or 18 weeks. There was a linear, rapid loss of bone by 18 weeks, approaching a 75% loss of original bone. Vascular spaces decreased as the remaining connective tissue became fibrotic in character. The percentage of the inter-dental test site which was destroyed by periodontal disease increased dramatically over the time of the experiment. The numbers of fibroblasts per mm of bone surface increased slightly at the 18 week period; osteoblasts were unchanged at any period. The numbers of osteoclast nuclei rose dramatically by 12 weeks, and these cell nuclei remained at increased levels at 18 weeks. Also, the numbers of inflammatory cells residing at the bone surface increased greatly by 18 weeks time. Finally, the number of 3H-TdR labeled periodontal ligament (PDL) fibroblasts increased significantly at both 12 and 18 weeks time. These cellular changes and their relation to the bone lose due to periodontal disease are discussed. The effects of a diphosphonate, dichloromethylene diphosphonate (C1[2]MDP) were also studied, using the rice rate as a model of periodontal bone loss. C1[2]MDP was given in daily subcutaneous injections at dosages of 0 (control), 0.1, 1.0, or 10.0 mg/kg/day; these treatments were continued for periods of 6, 12, or 18 weeks. The amount of alveolar bone was increased over age matched controls at the 1.0 and 10.0 mg/kg/day doses at 6 weeks; at 12 and 18 weeks, all doses showed increases in bone over control. Due to increase connective tissue fibrosis, the C1[2]MDP treated animals had fewer vascular spaces. Also, the amount of destroyed tissue in the inter-dental test site was increased in animals given 10.0 mg/kg/day of C1[2]MDP. The number of fibroblasts per mm of bone surface decreases slightly at 6 weeks, but was otherwise not different from controls, in treated animals at 12 and 18 weeks. Numbers of osteoblasts decreased greatly at all doses, at both 12 and 18 weeks time. There were no significant differences between treated and control animals of osteoclast nuclei per mm bone surface. Also, the numbers of inflammatory cells residing at the bone surface increased at all time periods in the 10.0 mg/kg/day dose group. Finally, the proliferative activity of PDL fibroblasts decreased dramatically at all time periods in the 10.0 mg/kg/day dose group. The response of the proximal tibia to C1[2]MDP was compared to the alveolar bone response in these animals. |
