Induction of periodontal disease via retentive ligature, lipopolysaccharide injection, and their combination in a rat model

Periodontitis is a highly prevalent, chronic immune-inflammatory disease of the periodontium that results in the periodontium and alveolar bone loss's progressive destruction. In this study, the induction of periodontal disease via retentive ligature, lipopolysaccharide, and their combination at three different times were compared in a rat model. Seventy-two Sprague Dawley rats were distributed into four treatment groups: 1) control group with no treatment; 2) application of 4/0 nylon ligature around second maxillary molars; 3) combination of ligature and LPS injection (ligature-LPS); 4) intragingival injection of Porphyromonas gingivalis lipopolysaccharide (Pg-LPS) to the palatal mucosa of the second maxillary molars. Six rats were sacrificed from each group after 7, 14, and 30 days of periodontal disease induction. Alveolar bone loss, attachment loss, number of inflammatory cells, and blood vessels were evaluated histologically. A micro-CT scan was used as a parameter to know the rate of alveolar bone loss. Parametric data were analyzed using two-way ANOVA followed by Bonferroni correction with a significance set at 5%. Non-parametric data were analyzed using Kruskal-Wallis, followed by multiple comparisons with Bonferroni correction. The histological results revealed significant destructive changes in the periodontal tissues and alveolar bone following the ligature and ligature-LPS induction techniques. These changes were evident as early as seven days, maintained until 14 days post-treatment, and declined with time. The ligature technique was effective in inducing acute periodontal disease. The LPS injection technique did not induce alveolar bone loss, and its combination to ligature added insignificant effects.