Abstract: Objective: To explore the effects of periodontal inflammation on the formation of macrophage extracellular traps (METs) in gingivae. Methods: 29 patients with periodontitis who finished periodontal non-surgical treatment and needed flap surgery and 20 periodontal healthy patients who needed crown lengthening surgery were recruited. Before surgeries, clinical periodontal parameters, including plaque index (PI), gingival index (GI), probing depth (PD) and clinical attachment loss (CAL), were recorded and gingival crevicular fluid (GCF) was collected. In patients with periodontitis, gingival samples from the most serious sites were collected during flap surgeries, while healthy gingivea were collected during crowning lengthening surgeries. METs were observed by laser confocal microscopy and the levels of TNF-α and IL-9 in GCF were measured by ELISA. Correlations between the scores of METs formation and periodontal clinical parameters, the levels of TNF-α, IL-9 were analyzed. Results: Clinical periodontal parameters, including PLI, GI, PD and CAL, the scores of METs formation and the levels of TNF-α and IL-9 in periodontitis group were higher than those in control group (P<0.05). The scores of METs formation were positively correlated with PD and CAL (P<0.05). Conclusions: Inflammatory destruction in periodontal tissues might contribute to the formation of METs.

Key words: periodontitis, macrophage extracellular traps, clinical periodontal parameters, TNF-α, IL-9