Orthodontic treatment effect on gingival recessions

Background The occurrence of gingival recessions (GR) after orthodontic treatment (OT) is well described in the literature. However, there is a lack of information about changes to pre-existing GR during OT. Methods The aim of this retrospective study was to examine the change of GR before and after OT. Intraoral photographs of 993 patients treated with fixed appliances between 2005 and 2017 were evaluated. Patients who had at least one GR on the vestibular surface of maxillary/mandibular teeth mesial to first molars were included. GR was measured on good quality plaster models before and after OT. The change of GR (T0-T1) was categorised into the three groups: worsened, did not change and improved (this group consisted of GR, which became better but did not disappear, and fully healed, which disappeared after OT)). The change by ≥0.5 mm was recorded. Statistical analysis was performed using SPSS Statistics (Version 22.0. Armonk, NY). Results Fifty-one (5.1%) patient had ≥1 GR before OT. Of them, 37 (72.5%) patients were included in the final analysis according to the inclusion criteria. GR before OT was found on 114 buccal/labial surfaces. The mean GR improvement was 0.51 (95% CI: 0.40, 0.63) mm (p<0.001). GR improved in 71 teeth (62.3%), did not change in 37 (32.4%), and worsened in 6 (5.3%). Of the 71 GR, which improved, full healing was observed in 15 (21.1%) teeth. GR had a greater chance of improvement in cases with a thick/normal gingival biotype compared with the thin biotype (OR 2.4; 95% CI: 1.07; 5.28) (p=0.03). There was a lower chance for GR improvement in cases with pre-treatment open bite (OR 3.29; 95% CI: 1.10; 9.81) (p=0.03) and Class III patients (OR 2.79; 95% CI: 1.14; 6.83) (p=0.03). Conclusions Based on the results of this retrospective study, we conclude that orthodontic treatment may change and even influence the healing of GR.