Objectives: The purpose of this study was to evaluate the effect of gingival pigmentations and anterior crown heights in conjunction with the maxillary gingival display on the perception of smile attractiveness assessed by orthodontists, dentists, and laypersons. Methods: Frontal intraoral photograph of ideally aligned teeth was modified to generate 3 levels of gingival smile exposure (2 mm, 3 mm, and 4 mm) with 4 different degrees of gingival pigmentation index according to DOPI and 5 different central incisors crown heights (7.7 mm, 8.7 mm, 9.7 mm, 10.7 mm, and 11.7 mm). Attractiveness of these 24 smiles was evaluated by orthodontists (n= 100), dentists (n= 100), and laypersons (n=100) using the visual analog scale. Two-way ANOVA was used to compare alterations on smile esthetics, and repeated measures ANOVA was used to evaluate the interaction between the variables. Bonferroni-adjusted pairwise comparisons were applied for determining the differences between the rater groups. Results: Orthodontists and dentists only tolerate a gummy smile of 2 mm while laypeople tolerate up to 3 mm. A gummy smile with gingival pigmentations is not tolerated by orthodontists. Dentists and laypeople only accept a 2 mm gummy smile with only the first degree of pigmentation (DOPI 2). Orthodontists and dentists accepted a 2 mm gummy smile with a central incisor of 9.7 mm and 10.7 mm. Laypeople accept a 2 mm gummy smile with central incisors ranging from 8.7 mm to 11.7 mm as for the 3 mm gummy smile, they only accept it with central incisors of 9.7 mm and 10.7 mm. Mean ages of all raters ranged between 25 and 30, therefore the sample was considered homogeneous in terms of age and years of experience. Female raters in general gave significantly lower scores than male raters and have, consecutively, lower thresholds of tolerance. Conclusions: Gingival pigmentations and disproportionate anterior crown height/width ratios decrease the tolerance threshold of a gummy smile.
Tannoury et al. (Wed,) studied this question.
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