Influence of a mandibular fixed orthodontic retainer on periodontal health

Objective: To investigate the impact of bonded mandibular orthodontic retainers on local periodontal health. Methods: Two groups of subjects were recruited and designated Group F+, individuals who were provided with a fixed wire lingual retainer in the mandibular anterior area following orthodontic treatment and Group F, individuals with no fixed wire and no clear sign of mandibular anterior malalignment. A clinical examination, a biochemical analysis, and a bacteriological analysis were performed at commencement baseline (BL) and at 1 week (T1), 4 weeks (T2), and at 8 weeks (T3) following retainer placement. The vertical position of the fixed wire relative to the clinical crown height in Group F+ was recorded and the subjects assigned to Subgroups Wi or Wg (the wire nearer or farther from the incisal edge, respectively). Results: Significant increases were found in gingival crevicular fluid (GCF) quantity, elastase activity, and protein content between T1 and T3 for both Group F+ and Group F-. A significant increase in F-Hb concentration was also found in Group F+. A comparison of the two groups identified significant differences for T3-BL in elastase activity and protein content. A Group Wi and Wg comparison showed significant baseline changes only in the F-Hb concentration at T2 and T3. Conclusions: There was no difference in the status of the periodontal tissue between individuals with and without fixed retainers. In addition, the vertical position of the fixed retainer wire did not appear to influence periodontal health. The result, however, was obtained in subjects who possessed good oral hygiene. Attention should be paid to a patient's oral hygiene when employing the fixed retainer.