Acceptable deviation of labial tubercle and anterior tooth midlines relative to facial midline in smile aesthetics: A retrospective observational study. Issue 41 (14th October 2022)

• Record Type: Journal Article
• Authors: Wang, Xiuhong; Long, Jinlie; Mei, Mei; Huang, Jin; Chen, Yuan; Zhou, Yuanzhong; Zhang, Jiangtao
• Is Part Of: Medicine. Volume 101:Issue 41(2022)
• Page Start: e30983
• Publication Date: 2022-10-14
• Subjects: acceptable deviation -- anterior tooth midline -- facial midline -- labial tubercle midline -- smile aesthetics; Medicine -- Periodicals; Medicine -- Periodicals; Médecine -- Périodiques; Geneeskunde; Medicine; Periodicals; Periodicals; 610.5
• DOI: 10.1097/MD.0000000000030983
• Languages: English
• ISSNs: 0025-7974

Abstract

Abstract : Smile aesthetics are mainly influenced by the relative position of facial midline (FC-line), anterior tooth midline (AT-line) and labial tubercle midline (LT-line). However, the acceptable deviation of LT-line and AT-line relative to FC-line is unknown. This study aims to fill the critical gap. We adopted the method of cross-sectional study, the frontal full-face smile photographs of 1 subject set (1 male) were enrolled. Taking the FC-line as the center line, twelve images with 1-mm increment relative to FC-line (right or left deviation, the maximum deviation distance was 3-mm) in LT-line deviation model or LT + AT-line deviation model (LT-line coincided with AT-line basing on LT-line deviation model) were produced. Basing on Q-sort assessment, the images were evaluated by 160 dentists, 165 orthodontic patients and 163 freshmen. And the collected Q-sort scores were subjected to nonparametric comparative analysis using SPSS 18.0. There were significant differences in Q-sort scores among different groups ( P < .01). When the deviation distance was 1 mm in dentist and orthodontic patient or 2 mm in freshman group, there was no significant difference in smile attractiveness scores between the LT line deviation model and the LT + AT line deviation model ( P > .05). We also found that the score of male dentist significantly higher than female dentist ( P < .05). However, the scores of right deviation in dentists and orthodontic patients were significantly lower than those in left deviation ( P < .05). The acceptable deviation of LT-line and AT-line relative to FC-line should be kept within 2 mm. Besides, raters' occupation and gender, and deviation direction of model may influence the smile aesthetics.