Change Of Subgingival Microbial Community Diversity Of Female Patients During The Early Stage Of Clear Aligner Treatment By 16s RDNA Gene Sequencing

Periodontal inflammation,such as gingival bleeding and hyperplasia,is a common complication of orthodontic treatment,which borders both orthodontists and patients.Traditional fixed orthodontic appliances,such as brackets,bands and ligature wires,increase the difficulty of cleaning the tooth surface,thereby causing the accumulation of dental plaque and periodontal tissue diseases.As a new type of orthodontic appliance,removable clear aligner is favored by patients because of its esthetic appearance,convenience and comfort.However,since it needs to be worn over 20 hours a day,the interference on the oral self-cleaning action may lead to the accumulation of both food residue and dental plaque,aggravating periodontal inflammation and damaging periodontal health.This study is to investigate the periodontal clinical index and the change of subgingival bacterial community diversity in the female patients during initial 3 months of clear aligner treatment.The relationship between subgingival microflora structure and periodontal health has been researched in order to avoid periodontal complications during clear aligner treatment.The periodontal clinical index of ten female patients undergoing clear aligner treatment were examined at three time points respectively,including before,1 month and 3months after the beginning of treatment(T0,T1 and T2),and the subgingival plaque of six patients were collected at the same time.The 16s rDNA gene sequencing were used to investigate the changes of subgingival microbial diversity and structure.The results show that there were no significant changes in PLI and BOP index in the early stage of clear aligner treatment while the PD index decreased significantly at the third month of treatment(P<0.05).The Miseq sequencing platform was used to sequence and analysis the microbial genomic DNA.The(?)ominant microbes at phylum level include Firmicutes,Proteobacteria,Bacteroidetes,Actinobacteria and Fusobacteria.The proportions of dominant bacteria are relatively stable during the first 3-months treatment.There is a correlation between the variation trend of periodontal disease-related bacteria and the changes of periodontal clinical indicators.In conclusion,clear aligner does not have a significant nagetive impact on periodontal health during the early stage of the treatment,which indicates that it has obvious advantages in oral hygiene maintenance.The eveness and diversity of subgingival bacteria increased during the treatment.Although the dominant bacteria of subgingival flora are relatively stable,the variation of both quantity and quality of subgingival bacterial community associated with gingival inflammation and periodontitis were found.There is also a correlation between some bacterial communities.