Abstract: PURPOSE: To explore the intervention effect of probiotics combined with conventional treatment on patients with peri-implant diseases, focusing on analyzing its impact on clinical indicators [probe depth (PD), clinical attachment level (CAL), bleeding on probing (BOP)] and the structure of the oral microbial community, so as to provide evidence-based basis for clinical treatment. METHODS: A total of 111 patients with peri-implant diseases admitted to Cangzhou People's Hospital from January 2022 to December 2023 were selected and divided into the probiotic group (n=55) and control group (n=56) using a randomized controlled design. Both groups received mechanical cleaning + ultrasonic subgingival scaling. On this basis, the probiotic group took a probiotic preparation containing Lactobacillus and Bifidobacterium daily (2×10⁹ CFU/d), while the control group took a placebo. The treatment course for both groups was 12 weeks. Before and after treatment, PD, CAL, and BOP were measured; the microbial communities in saliva and subgingival plaque were analyzed via 16S rRNA high-throughput sequencing; meanwhile, the levels of inflammatory factors (IL-1β, TNF-α, CRP) in gingival crevicular fluid and saliva were detected, and adverse reactions were recorded. RESULTS: After 12 weeks of treatment, PD in the probiotic group decreased from (4.7±0.8) mm to (3.1±0.5) mm, while PD in the control group decreased from (4.6±0.7) mm to (3.7±0.6) mm, with significant difference (P<0.01). CAL in the probiotic group improved from (5.5±1.0) mm to (4.1±0.8) mm, while CAL in the control group improved from (5.4±1.1) mm to (4.7±0.9) mm, with a statistically significant difference (P<0.05); the rate of BOP in the probiotic group decreased from 65% to 25%, while the rate of BOP in the control group decreased from 67% to 40%, with significant difference (P<0.01). The results of microbial community analysis showed that the proportion of pathogenic bacteria in the probiotic group decreased significantly, while the proportion of beneficial bacteria increased significantly (P<0.01). In terms of inflammatory factors, the levels of IL-1β, TNF-α, and CRP in the probiotic group decreased significantly after treatment (P<0.01), and were significantly lower than those in the control group (P<0.01). No severe adverse reactions occurred in either group. CONCLUSIONS: Probiotics combined with conventional treatment can significantly improve the clinical symptoms of patients with peri-implant diseases, optimize the structure of oral microbial community, inhibit the inflammatory response with good safety, which has high clinical application value.

Key words: Probiotics, Peri-implant disease, Probing depth, Clinical attachment level, Microbial community, 16S rRNA, Inflammatory factors