Effect of chronic stress on ligature-induced periodontitis in inbred and noninbred rats: a radiographic study.

AIM: The aim was to compare the effect of chronic stress on ligature-induced periodontitis in inbred and noninbred female rats by means of a radiographic study. MATERIALS AND METHODS: Adult Lewis (inbred) and Wistar (non-inbred) rats were used and divided into the following groups: Ligature/Stress Lewis Group (LSLG, n = 8); Ligature/Stress Wistar Group (LSWG, n = 8); Ligature Lewis Group (LLG, n = 8) and Ligature Wistar Group (LWG, n = 8). The animals were anesthetized and a silk thread was continuously kept around their second upper right molar. Then, groups LSLG and LSWG were subjected to physical stress test (physical restraint for 12 hours). After 15 days of ligature placement, the animals were euthanized. The right hemimaxilla was kept in formalin solution for 48 hours. Radiographs of the hemimaxillae were obtained using the parallelism technique and subsequently submitted to a standardized radiographic processing. The examiner was blinded to the groups and calibrated. The bone height level was measured and the data were subjected to statistical analysis (ANOVA, Tukey, p < 0.05). RESULTS: LSWG showed bone destruction significantly higher than that of LSLG (32.1 +/- 1.45 mm and 23.6 mm +/- 2.13, respectively). Similarly, LWG showed bone destruction significantly higher than that of LLG (28.6 +/- 1.18 mm and 25.2 +/- 2.76 mm, respectively). CONCLUSION: Inbred rats (Lewis) are less susceptible to the effects of chronic stress than are noninbred rats (Wistar) in relation to ligature-induced periodontitis. CLINICAL SIGNIFICANCE: Epidemiological studies have shown a relationship between stress and periodontitis. One of the major difficulties of this type of research is the bias of the exact diagnosis of the patient's emotional state. Inbred lines animals have standards-specific neuroendocrine, this allows answers about the susceptibility of periodontal disease, making knowledge applicable in future clinical trials.