PBM's effects on plaque microbiome for periodontal-orthodontic patients during retention

This pilot study aimed to determine whether adjunctive photobiomodulation (PBM) alters dental plaque microbiota and clinical parameters in periodontitis patients during orthodontic retention.

Six stage IV, grade C periodontitis patients entering orthodontic retention were enrolled in this split-mouth study. One arch side received monthly PBM therapy (GaAlAs diode laser) for six months; the contralateral side received sham irradiation. Periodontal examinations were performed. Supragingival and subgingival plaque samples were evaluated at appliance removal (T_i), 6 months (T_ii) and 12 months (T_iii) using 16S rRNA sequencing.

No significant differences were observed in periodontal clinical parameters between PBM and placebo sites at any time point (P > 0.05). Microbiome analysis showed similar alpha and beta diversity in supragingival and subgingival microbiota between the groups (P > 0.05). Exploratory genus-level differences were limited, with Treponema enriched in placebo supragingival plaque and Aggregatibacter in placebo subgingival plaque at T_ii, while Catonella differed in time-pooled supragingival comparisons. No headline differential genera were detected at T_i and T_iii.

Adjunctive PBM did not significantly alter overall plaque microbial community structure or clinical periodontal parameters. However, a few periodontitis-associated genera showed nominal, exploratory differences. These hypothesis-generating signals warrant confirmation in adequately powered trials.