Can smile influence the lower anterior vertical facial height on frontal view in an adult Asian male subject? A cross-sectional study

Purposes: The goals of this study were to (1) determine the effect of a smile on different modified lower anterior facial height/total anterior facial height ratios (LAFH/TAFH) in frontal view and (2) compare the esthetic scores (ES) of raters for different facial vertical ratios at rest and on smile. Materials and Methods: Seventy-two raters evenly distributed across three panels of raters (orthodontic residents (OR), general dentists (GD), and laypersons (LP)) participated in this cross-sectional study.  The LAFH/TAFH ratios of photographs of an adult Asian male subject at rest and on smile were modified using a Photoshop software (Adobe Systems, San Jose, California).  Raters were given a visual analog scale (VAS) to make subjective assessments of facial attractiveness of the modified photographs.  Kruskal-Wallis test was used to compare ES among the raters and Mann-Whitney U test was employed to compare ES between the raters.  The ES between at rest and on smile were compared using Wilcoxon Signed Rank test. Results: The Kruskal-Wallis test revealed a statistically significant difference in ES among raters with +4% and +8% LAFH/TAFH ratios at rest (p = 0.001).  With smiling, however, there was a statistically significant difference among raters for the +8% LAFH/TAFH ratio (p = 0.01).  Using the Mann-Whitney U test, differences between raters for +4% and +8% at rest and +8% with a smile were shown to be statistically significant.  Comparison of raters’ ES between at rest and on smile revealed statistically significant differences for different LAFH/TAFH ratios. Conclusions: There was no discernible difference in facial attractiveness ratings based on the gender of the raters.  With a smile, normal LAFH/TAFH ratio and slightly lowered ratio (51%) were deemed the most appealing by all raters, but increased facial height was seen the least attractive.  All raters' opinions were positively affected by the esthetic smile.  The ”Smiloflage” properties of a smile helped to conceal the effects of modified LAFH.