Short-term effect of removal of fixed orthodontic appliances on gingival health and subgingival microbiota: A prospective cohort study

Abstract

Objective. The aim of this prospective longitudinal study was to assess and compare the microbiological and clinical parameters of patients wearing a fixed orthodontic appliance, as opposed to 10 days after the bracket had been removed following treatment. Materials and methods. In total, 122 patients participated in this study; 61 of the subjects were assessed at baseline (wearing a fixed orthodontic appliance: T1) and 10 days after bracket removal (T2). The other 61 individuals had never worn an orthodontic appliance before and these subjects served as controls (CT). Subgingival plaque samples were assessed for bleeding on probing (GBI) and plaque index (VPI). PCR of 16s rDNA, followed by reverse species-specific hybridization for Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia and Treponema denticola were performed. A descriptive analysis was conducted; chi-squared, Student’s matched and unmatched t-tests, the point biserial correlation coefficient and the McNemar test were used to test for differences between groups (p < 0.05). Results. The GBI and VPI clinical parameters showed statistical differences (p < 0.05) between T1–T2, T1–CT and T2–CT. The prevalence of T. denticola had significantly decreased (p = 0.039) 10 days after appliance removal. At T2, a significant positive correlation was found between GBI and A. actinomycetemcomitans (p < 0.01) and between clinical parameters and P. intermedia. In patients without a fixed orthodontic appliance (T2 and CT), there was a significant positive correlation between T. forsythia and VPI. Conclusion. Local factors associated with the wearing of a fixed orthodontic appliance influence changes in subgingival plaque that leads to more inflammation and bleeding.