Perception of smile attractiveness by dentistry professionals, dental students and laypeople before and after esthetic procedures

Dentist community needs to understand the esthetic perception of laypeople and correlate the standards of dental esthetics to avoid unnecessary treatment. Thus, the aim was to compare the perception of smile attractiveness before and after performing esthetic dental procedures by general practitioners (GP), periodontists (P), restorative dentistry (RD), undergraduate students (UGrad), and laypeople (L). Two photographs of smile were taken, before (PSB) and after (PSA) the esthetic dental procedures. Photographs were exposed to 5 groups: GP (n = 20), P (n = 20), RD (n = 20), UGrad (n = 60), and L (n = 20). The smiles were evaluated using the visual scale with scores ranging from 1 (unattractive) to 10 (very attractive). Data were statistically evaluated (Kruskal-Wallis, Dunn, Mann Whitney). The PSA of the esthetic dental procedures was more attractive than PSB (p < 0.05). In PSB, P group presented the lowest values of smile attractiveness scores (p < 0.05). On the other hand, in PSA, RD group attributed lower values (p < 0.05). The perception of smile attractiveness after performing dental procedures was higher than before, and P and RD were more critical in evaluating the smiles before and after treatment, respectively.


Introduction
The emphasis in dentoalveolar esthetics has increased since 90s due to emotional, social well-being, desire, and pleasure of patient, factors that can result in a better life quality (Isiekwe et al., 2016). For dental clinicians, esthetic seeks physical beauty through correction of specific problems resulting in harmony of proportions and perfect shapes, awakening pleasant sensations and admirations (Alhammadi et al., 2018). Thus, initial smile analysis aims to establish the diagnosis, prognosis, and treatment plan (Pinzan-Vercelino et al. 2020). For this evaluation, periodontal and dental factors are considered, especially in relation to position, shape, size, proportion, symmetry, and parallelism of structures involved (Koidou et al., 2017;Koidou et al., 2018). Current smile patterns have been based in scientific evidence established to overcome the subjectivity of smile analysis (Pinzan-Vercelino et al., 2020). However, the esthetic perception may be individual and influenced by judgments of those with whom the patient interacts (Pinzan-Vercelino et al., 2020;Jørnung & Fardal, 2007;Van der Geld et al. 2007).
Furthermore, patterns have been changeable in a temporal variation and may be imperceptible to laypeople in area (Parrini et al. 2016).
Thus, dentist community needs to understand the esthetic perception of laypeople and correlate the standards of dental esthetics to specialists in different areas of Dentistryas well as general practitioners and dental studentsin order to avoid unnecessary treatment that may be not recognized by patients as details in dental and periodontal contours (Witt & Flores-Mir 2011).
Thus, the present study aimed compare the smile attractiveness before and after the performance of esthetic dental procedures by general practitioners, periodontists, restorative dentistry specialists, undergraduate students, and laypeople. The null hypothesis tested was that would be no difference in perception of smile attractiveness between before and after esthetic dental procedures and among the evaluated groups.
A clinical case of periodontal esthetic surgery was performed to increase the clinical crown of right and left upper central incisor and right and left upper lateral incisor, followed by direct composite veneers.
The smiles before (Fig. 1) and after (Fig. 2) the intervention was photographed, and the images were manipulated using computer software (Photoshop CS5; Adobe Systems). The images were sized to provide images with measurements similar to those measured in a real patient. Most of nose, chin, and cheeks were removed to reduce the number of variables in images. The final images were presented in a standardized color and format with a resolution of 300 dots per inch (dpi).  Volunteers totalized 140 participants. Five groups evaluated the images (Table 1): GP -general practitioners (n = 20); P -periodontists (n = 20); RD -restorative dentistry specialists (n = 20); UGrad -undergraduate students in Dentistry (n = 60); and L -laypeople in Dentistry (n = 20). The inclusion criteria for general practitioners was to have a degree in Dentistry and to be enrolled in Regional Dentistry Council. For specialists, the inclusion criteria referred only to conclusion of their courses before the questionnaire application. Undergraduate students from third, fourth, and final years of Dentistry course were included. The population of students was defined by undergraduate which already have earlier knowledge about restorative dentistry and periodontics. Inclusion criteria for laypeople were to have an undergraduate education, not related with dental training; not be associated with artistic activities; and have no direct contact with dentists, including the partner or children of dentists and/or oral hygiene technicians.
A single researcher presented printed images to volunteers with time observation controlled in 40 s. Volunteers were approached at two different point times, with an interval of at least 15 days. Initial case photo was evaluated in first approach and the final case photo in second approach; however, they were unaware that the photographs are from the same patient. Each volunteer viewed the image only once.
Prior to their evaluation, each volunteer received a brief explanation of study and was asked to evaluate the attractiveness of smile in images using the visual scale with scores. Scale consisted of a horizontal line of 100 mm marked with "unattractive" printed in one end and "very attractive" printed in other end, and had 10 symmetrical points along its line. The evaluators marked with a "X" at the point in scale that stood for their esthetic perceptions of each smile. Afterwards, scores from 1 to 10 were attributed in an increasing way from "unattractive" to "very attractive". Data were statistically analyzed by nonparametric Kruskal-Wallis test with Dunn's post-test for comparison between Research, Society and Development, v. 10, n. 3, e50010313690, 2021 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v10i3.13690 groups, and Mann Whitney's post-test for comparison between before and after for each group. The significance level of 5% was determined for all tests. SPSS program (Chicago, USA) performed all statistical tests.

Results
The Table 1 shows the demographic data of the volunteers. Female (69.3%) and male (30.7%) participants were aged between 16 and 40 years old.   In general, the smile was more attractive after performing the esthetic procedures, with a statistically significant difference between the initial photo and the final photo for each evaluated group (p < 0.05).
For comparison between the groups, in photo before the esthetic interventions, the P group differed statistically from GP, RD, and L groups, presenting lower values of smile attractiveness scores (p < 0.05). The comparison between P group and UGrad group did not differ (p > 0.05), as well as the comparison between UGrad group and GP, RD, and L groups (p > 0.05).
On the other hand, in photo after the esthetic interventions, the RD group was statistically different from the UGrad and L groups (p < 0.05), presenting the lowest value of smile attractiveness scores (p <0.05). The other groups did not show statistically significant differences (p > 0.05).

Discussion
This research compared the perception of smile attractiveness before and after esthetic procedures by dental clinicians in different specialties, general practitioners, undergraduate students, and laypeople. The null hypothesis was not accepted because the smile was considered more attractive after esthetic procedures; before esthetic procedures, periodontists presented the lowest scores; after treatments, restorative dentistry specialists presented the lowest scores.
The face and its expressions play an important role that can affect multiple aspects of patients' life (Schmidt et al., 2012). Currently, photo-based activity on social networking sites contributes to body image concerns, including body and smile dissatisfaction (Tiggemann et al., 2018;Sampson et al., 2020). Considering these demands, dental clinicians may improve shape, color, position, and size characteristics of teeth and the architecture of soft gum tissue (Goyal et al., 2013;Censi et al., 2014).
In clinical case presented, a slight periodontal esthetic surgery was performed in order to increase the clinical crown.
Afterwards, direct composite veneers were performed in superior canine to canine teeth to replace an unsatisfactory adhesive restoration and to improve esthetic. The median scores values before treatments was around 6-7, which is considered satisfactory. Despite difference between before and after of treatment be subtle, statistical difference was observed for all groups, because after esthetic treatment, the median scores values ranged from 8 to 9. This observation may highlight the current high esthetic demand regarding to attractiveness of the smile.
Literature has shown that specialists may be more critical in clinical case evaluation (Pinzan-Vercelino et al., 2020;Nomura et al., 2018). Pinzan-Vercelino et al. (2020) compared the influence of gingival display on perceived smile esthetics among restorative dentistry specialists, orthodontists, prosthodontists, periodontists, and laypeople (Pinzan-Vercelino et al., 2020). They observed that dental specialists were more sensitive about changes in gingival display compared to laypeople (Pinzan-Vercelino et al., 2020). Corroborating with Nomura et al. (2018) that evaluated the smile attractiveness of different gingival zeniths by general dentists, orthodontists, and laypeople (Nomura et al., 2018). Also, they have reported that laypeople observed asymmetric changes in gingival zeniths only superior to 1 mm. In the present study, periodontists and restorative dentistry specialists attributed lower scores before and after, respectively, the procedures (Nomura et al., 2018). However, differently, laypeople presented a trend similar to dental class (Nomura et al., 2018). Pinzan-Vercelino et al. (2020) justified the critical analysis for periodontists because in their specialty, the periodontal tissues are constantly evaluated (Pinzan-Vercelino et al., 2020). Researches evaluating the perception of dentists and other specialists have reported in the literature; however, the perception of periodontists is scarce. Lima et al. (2019) evaluated the perception of orthodontists, maxillofacial surgeons, and periodontists regarding to gingival exposure, the periodontists attributed better scores when there is no gingival exposure (0 mm), differing from other specialists in dentistry (Lima et al., 2019).
On the other hand, after esthetic procedures, periodontists assigned score 9 and restorative dentistry specialists score 8. Same line of thought to justify the result may be given, since the level of esthetic demand of these professionals after treatment is remarkably high. There is a trend to use ceramic veneers instead of composite resin ones due to its excellent esthetic results and more predictable longevity (Gresnigt et al., 2013; Alothman & Bamasoud 2018). However, direct composite veneers may be considered as a good conservative option, but surface quality changes are more frequently (Gresnigt et al., 2013;Alothman & Bamasoud 2018). In this case, the direct composite veneers were opted due to the age of patience (19 years), the reduced cost to improve the clinical case, and the possibility of none wear of the dental structure.

Conclusion
According to results obtained in this study, the perception of smile attractiveness after performing esthetic dental procedures was higher compared to before, and periodontists and restorative dentistry specialists were more critical in evaluating the smiles before and after treatment, respectively.
This study shows important data to the literature about how subtle changes in the smile can influence the attractiveness of the smile from laymen to specialized professionals. Thus, the triad beautiful and healthy smile, personal social insertion and physical, psychological and emotional well-being discussion comes up in an interesting way. However, we must always take into account the maleficence of over-indication of some aesthetic dental procedures. Based on the results presented, as future perspectives, it is suggested that further research on smile attractiveness be carried out in order to perceive the limits between the improvement of the patients' smile and the over-indication of treatments.