Clinical, microbiologic, and immunologic factors of orthodontic treatment-induced gingival enlargement

The aim of this study was to investigate the microbiologic and immunologic factors related to orthodontic treatment-induced gingival enlargement (GE).

Our study included 12 patients with GE undergoing fixed orthodontic treatment and 12 periodontally healthy controls. At baseline, periodontal variables, subgingival plaque samples, and gingival crevicular fluid (GCF) samples were taken from 2 preselected sites in both the GE and the control groups. The levels of Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Prevotella intermedia, Treponema denticola and Tannerella forsythia were determined by real-time polymerase chain reaction. GCF interleukin (IL)-1β and transforming growth factor-beta 1 (TGF-β1) were detected by enzyme-linked immunosorbent assay (Invitrogen, Camarillo, Calif). Periodontal therapy was given to the GE group, and all parameters were reassessed after 4 weeks.

At baseline, the GE group showed higher prevalences of the 5 periodontal pathogens than did the control group (P <0.05). IL-1β and TGF-β1 levels at the GE sites were also significantly higher than those at the control sites (P <0.05). Four weeks after periodontal therapy, the GE group showed significant improvements in the clinical parameters associated with significant reductions of P gingivalis, A actinomycetemcomitans, and T denticola. The levels of IL-1β decreased significantly compared with the baseline (P <0.05), whereas there was no significant change in TGF-β1 levels (P >0.05).

Periodontal pathogens might have a relationship with the initiation and development of orthodontic treatment-induced GE. Inflammatory cytokines (IL-1β and TGF-β1) can also be considered as contributing factors.