## 4 Discussion
The use of subepithelial connective tissue grafts (SCTGs), together with a coronally advanced flap (CAF), or a tunneling approach for root coverage, and an improvement in the width and thickness of the gingiva, might be considered as the \"gold standard\" in terms of therapy. In sites without GR, the goal of therapy is periodontal soft tissue phenotype modification (STPM), with the primary aim of increasing the clinical attachment level, increasing the mucosal thickness, and improving the keratinized tissue width [24]. Be that as it may, STPM enhanced the thickening of the epithelial layer, as well as increased in the number and density of collagen bundles contained in the lamina propria [25]. The importance of changing a thin periodontal phenotype into a thick one has been demonstrated by several studies [26]. It has been highlighted that a minimum 1 mm thickness and 2 mm width of the attached gingiva is necessary to maintain the stability of the gingival margin over time. Soft tissue augmentation carried out before OT reduced the risk of additional attachment loss caused by deleterious tooth movements, outside the buccal alveolar bone envelope [26; 27; 28]. An interesting finding in our study was that the majority of orthodontists use the visualization method and 2D X-Ray imaging in evaluating soft and hard periodontal tissue, whereas periodontitis/oral surgeons chose the gingival transparency method and 3D X-Ray imaging. Using a periodontal probe is highly recommended to distinguish between thin (probe visible) and thick (probe not visible) gingiva, because it is a more standardized and reproducible way than the visual method [1]. Cone-beam computed tomography (CBCT) is not a mandatory examination in evaluating bone morphotype, because the correlation between the gingival thickness and buccal bone plate has been proven [29]. Moreover, the sensitivity of CBCT in detecting dehiscence is quite low, meaning that if a bone plate is visible in a CBCT, it most probably exists, but if it is not detected, there is no confidence that it is actually absent [30]. However, CBCT is a useful tool in determining the position of a tooth root within the alveolar bone envelope and for planning the direction and range of tooth movements. This study has some potential limitations. First of all, although the number of participants was enough to draw conclusions, the participants were not randomly selected from the population of polish dentists, but recruited from social media groups. Secondly, the multiple-choice character of the questionnaire could introduce bias into the results. Finally, the participants who were willing to participate in the study could be more educated and qualified in the area of the study's subject. In the future, it would be useful to perform a more comprehensive study, also in other regions of Europe or other continents. Orthodontic treatment can have adverse effects on periodontal tissue; however, it can also improve the status of soft and hard tissue when tooth movement is precisely planned, with respect to alveolar boundary conditions. In an increasingly demanding, but also litigious society, it is prudent to assess the risk of developing and aggravating GR during OT. In this regard, no OT should start without an evaluation of the periodontal phenotype. It is recommended to use the gingival transparency method, as an easy and reproducible way of assessing the gingival thickness. In patients with a thin phenotype, CBCT imaging is helpful in planning the OT with respect to the alveolar bone envelope. Cooperation between specialists is beneficial in the treatment of patients with malocclusion and mucogingival issues. The results of this study highlight the need for further studies on the prevention and treatment of GR in orthodontic patients, which could help establish guidelines for dental practitioners. Moreover, RCTs are desirable to compare surgical interventions before and after OT in patients with a thin phenotype.