To investigate the influence of mechanical debridement on the subgingival microbiome in chronic periodontitis by 16S rRNA high-throughput sequencing.

Patients with generalized moderate to severe chronic periodontitis were recruited into this study and received oral hygiene instruction and supragingival scaling. One week later, they received ultrasonic and manual subgingival scaling and root planning. Clinical parameters were recorded and subgingival plaques were sampled at baseline and 3 months and 6 months after treatment. The comprehensive profiles of the subgingival microbiome were analyzed by sequencing the V3-4 region of 16S rRNA with the Illumina MiSeq platform.

Alpha diversity analysis showed that the richness and diversity of the subgingival community were consistent before and after treatment, but a significant difference in community structure was detected only between baseline and month 3 by principal coordinates analysis (PCoA). After 3 months, the clinical parameter as probing depth (PD) decreased significantly and the relative abundances of the genera related to periodontitis such as Porphyromonas, Treponema, Tannerella, and Filifactor decreased significantly. Meanwhile, the relative abundances of the genera associated with periodontal health increased, such as Capnocytophaga, Kingella. Six months later, however, less genera related to periodontitis decreased significantly from the baseline level, such as Filifactor. PD decreased significantly compared with baseline, but increased significantly compared with 3 months after treatment.

Mechanical debridement alone could relieve periodontal inflammation and balance microbial dysbiosis and the greater efficacy occurred 3 months after treatment.