The Evaluation of Smile Design by Lay People and Dentists in the UAE

Background and Objectives: Esthetics is characterized primarily by the smile, however, the smile comprises much more than the dental arch. Dental smile design preferences differ from one person to other based on different factors such as: social level, economic level, education level and ethnic origin. There is a lack of similar studies in the UAE. The purpose of this study is to determine which features of a smile are attractive as rated by lay people and dental professionals in the UAE. Material and Methods: A questionnaire survey of standardized images of smiles was distributed to 190 dental professionals including under-graduate students at Sharjah University and 190 lay people (teachers, employers, workers and patients relatives). A sample size calculation determined the sample as 380. The participants were not randomly selected and were not a representative sample of the UAE population but a convenience sample. The participants were all adults above the age of 17 years. The questionnaire had 7 separate aesthetic features with between 3 to 6 different standardized computer generated images for each feature. The different features included amount of tooth exposed, lip line height, buccal corridor and midline position. Results: There were a total of 380 participants with a mean age of 28.6 years (SD 7.9) of which 228 (60%) were female. Significantly more females compared to males preferred a convex smile irrespective of whether or not the upper teeth contacted the lower lip (p<0.01). Females tended to prefer low lip line compared to males but this was at the borderline of significance (p=0.067). Interestingly, more married respondents preferred the low lip line whereas unmarried respondents were evenly distributed between those liking an average and low lip line (p<0.05). The coincidence of dental and facial midlines would be expected as the preferred choice for both dental professionals and lay people but significantly more lay people preferred the smile that deviated to the right whereas dentists preferred midlines to be coincident (p<0.001). Furthermore, residents of Abu Dhabi, Dubai and Sharjah preferred the coincidence of midlines whereas the lay people from Fujairah preferred the right deviation of the dental midline. Over half the unmarried respondents had a significantly greater preference for midline coincidence but married respondents were more evenly split regarding this aspect of smile design (p<0.05). There were no preference differences for most of the smile design features as judged by dentists and lay people. Conclusion: There is general agreement between dentists and lay people regarding the most pleasing features of smile design. Females prefer a convex incisal curve that follows lip curvature and tend to prefer a low lip line. Coincidence of facial and dental midlines was expected to be preferred by both dentists and lay people but surprisingly this was not the case as lay people, married respondents and residents from Fujairah prefer a right deviation. Why should this preference for a smile with a deviated dental midline be regarded as attractive requires further research but may be influenced by tribal or other cultural factors.