关键词: 粪肠球菌, 溶血素, 根尖周炎, 肿瘤坏死因子-α(TNF-α), 大鼠

Abstract: Objective: To compare the inflammatory progress and the expression of TNF-α in rat-reinfected periapical periodontitis models induced by different genotypes of Enterococcus faecalis (E. faecalis). Methods: After pulp exposure of the bilateral maxillary first molars of rats for 3 weeks, the molars were divided to 4 groups: disinfection group, chronic apical inflammation group, hemolytic E. faecalis reinfected group and nonhemolytic E. faecalis reinfected group. Then the hematoxylin-eosin staining and immumohistochemical staining of TNF-α were conducted. Results: The inflammation degree of the disinfection group was 0. After 1 week in both reinfected groups, the inflammation degree reached to 3, and it lasted to the 3rd week. When E. faecalis was reinfected at the 4th week, the inflammation degree was dropped to 2. It was noticed that the inflammation degree of the nonhemolytic group at the 6th week was reduced to 1 which was the same as chronic apical inflammation group, while the degree of the hemolytic group maintained at level 2 at the same time. The expression of TNF-α was the lowest in the disinfection group. The expression of TNF-α in both reinfected groups was higher than that of the chronic group. At the second week, the expression of TNF-α in both reinfected groups reached the climax, and then decreased. The expression of TNF-α in hemolytic group was higher than that in nonhemolytic group at all time points. Conclusion: Cytolysin (Cyl) may influence the healing progress of E. faecalis reinfected periapical periodontitis and prolong the inflammation process. The expression of TNF-α was related to the inflammation progression of E. faecalis reinfected periapical periodontitis.

Key words: Enterococcus faecalis, Apical paradentitis, Cytolysin, Tumor necrosis factor α, Rat