Abstract: PURPOSE: To investigate the osteosclerin level and bacterial distribution in periodontitis patients at different stages, and to analyze the correlation between osteosclerin and the parameters of conventional periodontal examination. METHODS: Patients with periodontitis admitted to Guangzhou Huadu Maternal and Child Health Hospital from March 2017 to June 2019 were selected and divided into stage Ⅱ group (n=27), stage Ⅲ group (n=42) and stage Ⅳ group (n=22) according to the severity of periodontitis; meanwhile, 30 healthy individuals underwent physical examination in our hospital during the same period were selected as control group. Gingival crevicular fluid and plaque at buccal and lingual sites were collected for bacterial culture. The expression of osteosclerotin in gingival crevicular fluid was detected by enzyme-linked immunosorbent assay. The data were processed by SPSS 23.0 software package. Spearman correlation analysis was used to analyze the correlation between BI grade and osteosclerin, and correlation between PD, CAL and osteosclerin was determined by Pearson analysis. RESULTS: The mean PD and mean CAL of patients in stage Ⅱ group before and after treatment were significantly smaller than those in stage Ⅲ and Ⅳ group (P<0.05). The mean CAL of stage Ⅳ group before treatment was significantly greater than that of stage Ⅲ group (P<0.05). After treatment, the mean PD and mean CAL of three groups were all significantly smaller than those before treatment (P<0.05). The mean PD in stage Ⅲ group was significantly lower than that in stage Ⅳ group after treatment (P<0.05). Before treatment, the proportion of BI grade 2 in stage Ⅱ group was significantly higher than that in stage Ⅲ and Ⅳ group (85.19%, 19.05%, 18.18%, P<0.05). Before treatment, the proportion of BI grade 3 in stage Ⅲ group was significantly higher than that in stage Ⅱ group (64.29%, 14.81%, P<0.05). Before the treatment, the expression of osteosclerosis protein in stage Ⅱ group was significantly lower than that in stage Ⅲ and Ⅳ group (P<0.05). The levels of osteosclerin expression of three groups after treatment were all significantly lower than those before treatment (P<0.05). The expression of osteosclerosis protein in stage Ⅱ group was significantly lower than that in stage Ⅲ and Ⅳ group after treatment (P<0.05). PD, CAL and BI of patients with different stages of periodontitis were positively correlated with osclerosin in gingival crevicular fluid before and after treatment (P<0.05). The number of bacteria detected in stage Ⅳ group was significantly higher than that in stage Ⅲ group and stage Ⅱ group. The main bacteria in each group were anaerobic bacteria. The dominant bacteria were Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetes, Fusobacterium nucleatum, and Prevotella melaninogenicus. CONCLUSIONS: The expression level of osteosclerosin is closely related to PD, CAL and BI grades in patients with periodontitis, and bacterial colonization levels in gingival crevicular fluid and dental plaque in patients with periodontitis at different stages are different. Detection of osclerosin level and identification of periodontal microorganism culture have high clinical value in clinical diagnosis of periodontitis severity and can provide reference for selection of subsequent treatment plan.

Key words: Osteosclerotin, Bacterial culture, Periodontitis