A retrospective study of orthodontic treatment with pre-treatment gingival recessions

Abstract Background: The development of gingival recessions (GR) after orthodontic treatment (OT) is well described in the literature. However, there is a lack of information about the changes in pre-existing GR during OT. Methods: This retrospective study aimed 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 of GR by ≥0.5 mm was recorded. Statistical analysis was performed using SPSS Statistics (Version 22.0. Armonk, NY, USA). 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.Significant improvement of mean GR at patient level was found between T0 and T1 (0.45 mm, 95% CI: 0.28, 0.62) (p<0.001). At tooth level the median GR improvement was 0.55 (Q1; Q3: 0.12; 0.96) mm (p<0.001). GR improved in 67 teeth (58.7%), did not change in 41 (36.0%), and worsened in 6 (5.3%). Of the 67 GR, which improved, full healing was observed in 15 (22.4%) teeth. There was a lower chance for GR improvement in cases with pre-treatment open bite (OR 3.35; 95% CI: 1.14, 9.84; p=0.03) and dental Class III patients (OR 2.20; 95% CI: 0.92, 5.28; p=0.03). Conclusions: There was an improvement of GR after orthodontic treatment in most cases. Class III malocclusion and reduced pre-treatment overbite had a negative impact on GR improvement.