An improved cost-effective, reproducible method for evaluation of bone loss in a rodent model.

Aim: This study was designed to investigate the utility of two "new" definitions for assessment of bone loss in a rodent model of periodontitis.
Material and Methods: Eighteen rats were divided into three groups. Group 1 was infected by Aggregatibacter actinomycetemcomitans (Aa), group 2 was infected with an Aa leukotoxin knock-out, and group 3 received no Aa (controls). Microbial sampling and antibody titres were determined. Initially, two examiners measured the distance from the cemento-enamel-junction to alveolar bone crest using the three following methods; (1) total area of bone loss by radiograph, (2) linear bone loss by radiograph, (3) a direct visual measurement (DVM) of horizontal bone loss. Two "new" definitions were adopted; (1) any site in infected animals showing bone loss >2 standard deviations above the mean seen at that site in control animals was recorded as bone loss, (2) any animal with two or more sites in any quadrant affected by bone loss was considered as diseased.
Results: Using the "new" definitions both evaluators independently found that infected animals had significantly more disease than controls (DVM system; p<0.05).
Conclusions: The DVM method provides a simple, cost effective, and reproducible method for studying periodontal disease in rodents.