Perceptions of midline deviations among different facial types

Abstract

With interest, I read about the study by Williams et al in the February 2014 issue of the AJO-DO.1Williams R.P. Rinchuse D.J. Zullo T.G. Perceptions of midline deviations among different facial types.Am J Orthod Dentofacial Orthop. 2014; 145: 249-255Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar I congratulate and appreciate the authors of this study for their efforts in bringing up the important issues regarding the perceptions of midline deviations among different facial types. I have 2 concerns about the study, focusing on the selection of the models who were photographed and the gender ratio of the evaluators. As shown in Figures 2 and 3, the evaluators thought that the female model gained significantly more attractiveness than the male model over all 5 levels of deviations. The threshold of acceptance for the woman was also higher than that of the man. These results may be attributed to the difference of overall full-face attractiveness between the female and the male models. The evaluators might have been distracted by the models' hairstyles, the black triangle space between the maxillary central incisors of the man, or other features not related to dental symmetry. The results of this research would be more persuasive if the male and female models selected as the experimental subjects had been determined by peers to be of average and equal attractiveness.2Springer N.C. Chang C. Fields H.W. Beck F.M. Firestone A.R. Rosenstiel S. et al.Smile esthetics from the layperson's perspective.Am J Orthod Dentofacial Orthop. 2011; 139: e91-e101Abstract Full Text Full Text PDF PubMed Scopus (85) Google Scholar What's more, the gender ratio of the evaluators was not taken into account. The effect of the evaluator's gender on the perception of midline deviation has been controversial. One possible reason would be that the age range of the evaluators was not clearly specified in previous studies that claimed no differences in the perception of smile esthetics based on the evaluators' gender.2Springer N.C. Chang C. Fields H.W. Beck F.M. Firestone A.R. Rosenstiel S. et al.Smile esthetics from the layperson's perspective.Am J Orthod Dentofacial Orthop. 2011; 139: e91-e101Abstract Full Text Full Text PDF PubMed Scopus (85) Google Scholar, 3Rodrigues Cde D. Magnani R. Machado M.S. Oliveira O.B. The perception of smile attractiveness.Angle Orthod. 2009; 79: 634-639Crossref PubMed Scopus (74) Google Scholar In this study, the evaluators' ages were specified to be similar to those of the subjects. This was consistent with a previous study that concluded that the gender of the evaluator did affect the perception of midline deviation.4Zhang Y. Xiao L. Li J. Peng Y. Zhao Z. Young people's esthetic perception of dental midline deviation.Angle Orthod. 2010; 80: 515-520Crossref PubMed Scopus (30) Google Scholar It seemed that the effect of the evaluator's gender on perceived smile esthetics would be more evident in a population of similar age. A balanced gender ratio might be essential in future studies. Thanks again for presenting this contribution. Perceptions of midline deviations among different facial typesAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 145Issue 2PreviewThe correction of a deviated midline can involve complicated mechanics and a protracted treatment. The threshold below which midline deviations are considered acceptable might depend on multiple factors. The objective of this study was to evaluate the effect of facial type on laypersons' perceptions of various degrees of midline deviation. Full-Text PDF Authors' responseAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 147Issue 1PreviewWe wish to thank Dr Yongwen Guo for his interest and thoughtful review of our article in the AJO-DO.1 The exposures or interventions we used in our study were facial type, sex of the target persons, and midline deviations, and the outcome measure was the level of attractiveness. The purpose of a target person or model as in this study was to control or neutralize all physical attributes except the exposures. The recruitment of suitable models for studies in the United States can often be challenging. Full-Text PDF