Comparison of immediate vs. delayed guided tissue regeneration in Infrabony defect of second molars after adjacent third molar extraction: a retrospective study.

BACKGROUND: The distal aspect of the second molar (d-M2) often exhibits infrabony defects due to the adjacent third molar. Although the defects can be treated by guided tissue regeneration (GTR) after removing the third molar, the optimal timing remains uncertain following third molar removal in clinical decision-making. This study aimed to compare delayed and immediate GTR treatments to assist in clinical decision-making. METHODS: D-M2 infrabony defects with a minimum 1-year follow-up were collected and divided into three groups: Immediate GTR group, which underwent third molar extraction and received GTR simultaneously; Delayed GTR group, which underwent delayed GTR at least 3 months after third molar extraction; and Control group, which underwent only scaling and root planing during third molar extraction. The clinical and radiographic parameters related to the infrabony defect before GTR and post-surgery were evaluated using the Kruskal-Wallis test or one-way ANOVA, followed by post-hoc Dunn's test or the Bonferroni test for pairwise comparisons. RESULTS: A total of 109 d-M2 infrabony defects were assessed. No significant differences were found between the two GTR groups, although both of them showed significant reductions in infrabony defect depth: the immediate GTR group (2.77 ± 1.97 mm vs. 0.68 ± 1.03 mm, p < 0.001) and the delayed GTR group (2.98 ± 1.08 mm vs. 0.68 ± 1.03 mm, p < 0.001) compared to the control group. CONCLUSION: GTR can effectively improve d-M2 infrabony defects when the third molar is removed, whether simultaneously or delayed. Patients may experience less discomfort with immediate GTR treatment as it requires only one surgery.

[Characteristics of the immune status in aged mice with experimental periodontitis].

PURPOSE: To establish mice model with periodontitis by oral infection with Porphyromonas gingivalis, simulating human periodontal disease. The immune status of youth and aged mice were compared, and the cytokines expression of regulatory T cells and Th17 cells in this model were analyzed. METHODS: Entity microscope was used to evaluate the extent of periodontal bone resorption. H-E staining was used to observe infiltration of inflammatory cells in periodontal lesions. TRAP staining was used to observe osteoclastes in alveolar bone. The expression levels of TGF-ß1, IL-10, IL-17A and RANKL mRNA in periodontal tissues were detected by real-time quantitative PCR. SPSS 17.0 software package was used for statistical analysis. RESULTS: At 4-week after infection, the distance of cemento-enamel junction to the alveolar crest was significantly increased in the periodontal disease group compared with the normal control group (P<0.01); In the aged mice, the cemento-enamel junction to the alveolar crest distance significantly increased compared with youth mice (P<0.01). Periodontal tissues had inflammatory cell infiltration, and deep periodontal pockets. Moreover, the expression levels of TGF-ß1 and IL-10 mRNA were significantly decreased (P<0.01) and the expression levels of IL-17A, RANKL mRNA qsignificantly increased (P<0.01). CONCLUSIONS: The expression of inflammation mediator is abnormal in aged mice with more serious periodontal lesions than youth mice. It is suggested that the inflammatory status of periodontitis not only has a relationship with the decreased expression of inhibitory cytokines, but also relates to aging.