Effects of buccal corridors on smile esthetics in Japanese

To test the hypothesis that the amount of buccal corridor has no influence on smile evaluations of Japanese orthodontists and dental students.

One photograph of a smiling female, displaying first molar to first molar, was constructed. Buccal corridors were modified digitally in 5% increments, from 0% to 25% buccal corridor compared with the inner commissural width. Using a visual analog scale (VAS), 32 Japanese orthodontists and 55 Japanese dental students rated the attractiveness of six smiles with altered buccal corridors. The Wilcoxon rank-sum test was conducted to compare the distributions of the median scores between the male and female raters for each of the rater groups. Differences in the median esthetic scores were analyzed using the Kruskal-Wallis test. We used 15% VAS difference to determine the clinical significance of the esthetic scores.

There was no significant difference in judging the effects of buccal corridors on the smile attractiveness between the male and female raters for both the orthodontists and dental students. There were significant differences in the median esthetic scores for both the orthodontists and dental students. The median esthetic score decreased to become clinically significant from 10% to 25% buccal corridor for both the orthodontists and dental students.

The hypothesis was rejected. Both the orthodontists and dental students preferred broader smiles to medium or narrow smiles.