Histopathological Study of the Effect of Periodontopathic Bacterial Lipopolysaccharide on Changes in Rat Periodontal Tissue after Penetration through the Gingival Sulcus.

Abstract

This study was performed to clarify the in vivo damage to periodontal tissue induced by lipopolysaccharide (LPS) from Actinobacillus actinomycetemcomitans Y 4 and Porphyromonas gingivalis 381, which penetrate the junctional epithelium. Each LPS solution (5 mg/ml) was continuously dropped into the gingival sulcus of the lower first molar of a Lewis rat for 30min every 24h. The animals were sacrificed 30min after the 1st, 3 rd, 7th, 10th and 15th administration and their mandibles were examined histopathologically and histomorphometrically (n=25 in each group). A gradual increase in inflammatory findings was observed in both LPS groups. However, A. actinomycetemcomitans LPS induced more marked inflammation and degeneration of periodontal tissue. Loss of connective tissue attachment and rete peg elongation were significantly greater in rats administered with A. actinomycetemcomitans LPS compared to those administered with P. gingivalis LPS. Degeneration of junctional epithelium and subepithelial connective tissue was found at the 1st and 3rd administrations. At the 7th and 10th administrations, epithelial cells and collagen fibers were detached from root surfaces. Rete pegs showed deep invasion toward alveolar bone and epithelial detachment downward migration. At the 15 th administration, osteoclastic bone resorption was in some cases observed on the alveolar bone crest in the A. actinomycetemcomitans LPS group. These findings suggest that A. actinomycetemcomitans LPS had a greater effect on periodontal tissue destruction than P. gingivalis LPS.