Abstract: Objective:?To investigate the effect of smoking on peri-implantitis in healthy population, and to provide theoretical basis for the effect of smoking on peri-implantitis. Methods:?Peri-implant gingival crevicular fluid samples were collected from smokers (n=10) and non-smokers (n=8), and the DNA samples of the bacterial flora were sequenced by metagenomic sequencing technology. The differences in the composition spectrum, number and species of microorganisms around implants between smokers and non-smokers were analyzed and their main biological functions were predicted. Results: There were significant differences in the microbial profiles between the non-smoking group and the smoking group. The number of specific microbial species was 203 in the non-smoking group and 373 in the smoking group（P＜0.05）. In terms of species, the dominant bacterial flora around the implant in the non-smoking group included Bacillus, Lactobacillus, Clostridium, Haemophilus and Actinomyces, while the dominant bacterial flora around the implant in the smoking group included Corynebacterium, Lactobacillus gingivalis, Anaerobes and Anaerobic cocci, Synbacteraceae, Desulfuria, and Actinomyces，Bacteroides genus and Anaerobic rope bacteria and other 19 kinds of bacteria （P＜0.05）. In terms of function, the dominant bacteria in the non-smoking group were mainly related to environmental information processing, signal transduction and immune response, while the dominant bacteria in the smoking group were mainly related to genetic material changes such as gene recombination and changes in metabolism-related pathways（P＜0.05）. Conclusions:?Smoking can increase the variety and number of peri-implant microbial flora by changing the genetic material and metabolism-related pathways.

Key words: smoking, microorganism, metagenomic sequencing, dental implant