Periodontal treatment causes a longitudinal increase in nitrite‐producing bacteria

Background The oral microbiome‐dependent nitrate (NO 3 − )–nitrite (NO 2 − )–nitric oxide (NO) pathway may help regulate blood pressure. NO 2 − ‐producing bacteria in subgingival plaque are reduced in relative abundance in patients with untreated periodontitis compared with periodontally healthy patients. In periodontitis patients, the NO 2 − ‐producing bacteria increase several months after periodontal treatment. The early effects of periodontal treatment on NO 2 − ‐producing bacteria and the NO 3 − –NO 2 − –NO pathway remain unknown. The aim of this study was to determine how periodontal treatment affects the oral NO 2 − ‐producing microbiome and salivary NO 3 − and NO 2 − levels over time. Methods The subgingival microbiota of 38 periodontitis patients was analysed before (baseline [BL]) and 1, 7 and 90 days after periodontal treatment. Changes in NO 2 − ‐producing bacteria and periodontitis‐associated bacteria were determined by 16s rRNA Illumina sequencing. Saliva samples were collected at all‐time points to determine NO 3 − and NO 2 − levels using gas‐phase chemiluminescence. Results A significant increase was observed in the relative abundance of NO 2 − ‐producing species between BL and all subsequent timepoints (all p < 0.001). Periodontitis‐associated species decreased at all timepoints, relative to BL (all p < 0.02). NO 2 − ‐producing species negatively correlated with periodontitis‐associated species at all timepoints, with this relationship strongest 90 days post‐treatment ( ρ = −0.792, p < 0.001). Despite these findings, no significant changes were found in salivary NO 3 − and NO 2 − over time (all p > 0.05). Conclusions Periodontal treatment induced an immediate increase in the relative abundance of health‐associated NO 2 − ‐producing bacteria. This increase persisted throughout periodontal healing. Future studies should test the effect of periodontal treatment combined with NO 3 − intake on periodontal and cardiovascular health.