# The Impact of Orthodontic Treatment on Pre-Existing Gingival Recessions: A Retrospective Study
## 4 Discussion  
The present retrospective study aimed to evaluate the change of GRs, which were present before OT. As the focus on mucogingival factors is increasing in the orthodontic literature due to the increasing number of adult subjects in orthodontic practice, it is essential to analyze whether the improvement in GR may be influenced by OT. The present study is one of the very few studies in the field to assess changes of pre-treatment GRs and related factors retrospectively. The available literature is more focused on the factors inducing GR after OT rather than changes [20; 31; 32]. According to a recent systematic review, there is a greater chance for GR to develop in orthodontically treated patients, especially in retention period [33]. However, further, especially prospective studies are still needed. In the present study, only 5.1% of patients with pre-existing GR were identified from the 12-year clinical material of 2 orthodontists showing rather low prevalence. The included patients were different in the type of dental malocclusion, the number of gingival recessions and other variables, partly explaining the current scarcity of the prospective studies. Most of the included cases were adult patients (\(\geq\)18 years old) (n = 33), showing that GRs are more prevalent in adult patients and confirming findings in the literature [11]. GRs in young subjects (<18 years old) have been described to be associated with atypical tooth position; however, there were very few subjects <18 years in the present study (n = 4) [34]. The measurements of 114 GRs in 37 patients were performed calculating the distance between the most apical marginal gingival contour and cement-enamel junction using a digital caliper, which is more accurate than using a periodontal probe [35]. In the recent article, authors found that measurements on digital models were the most accurate; however, their caliper was not digital, and this could influence the results [35]. Other authors compared pre-treatment and post-treatment clinical crown heights; however, this kind of measurement in adults could be affected by incisal wear and/or restorations during OT [20; 36]. At tooth level, due to the small numbers of recession measurements, we recorded improvement only when it was clinically significant (change from T0 to T1 was \(\geq\)0.5 mm), so actual percentage with GR improvement could be higher. Changes of clinical periodontal variables are usually small and are in line with the findings of the present study [37]. The results of the present study revealed a positive impact of OT on the GR change. Change of GRs was similar at patient (0.45 mm) and tooth (0.55 mm) levels confirming that orthodontic movements to a more centered tooth positions in the alveolar bone are of major importance [21]. Possible confounding factors such as surgical treatment of GR during OT, periodontal disease and systemic disease or medication that could influence treatment outcome were excluded from the study. There were also no influences of sex, age or treatment duration on GR change. Furthermore, we found that GRs improved in more than half of the patients. A high percentage of improved GRs could be influenced by gingival enlargement during OT. However, gingival enlargement is mostly prevalent in teenagers with compromised oral hygiene; this study comprised mostly of adults with good oral hygiene, so the influence of this factor is not discussed. Tooth group was found to be important to GR changes. The present study showed the most significant amount of GR improvement in maxillary premolars and mandibular premolars. The study by [PERSON] et al. (2005) showed equal amounts of improved and worsened GRs (42.3%) [31]. It is worth mentioning that these authors examined recessions only on mandibular incisors, which improved in more than half in our study; however, none of them fully healed. Mandibular incisors might be described most frequently because of the highest prevalence of new GRs after OT on their labial surfaces.