Evaluation of the attractiveness of different gingival zeniths in smile esthetics

ABSTRACT Objective: To evaluate the smile attractiveness of different gingival zeniths by general dentists, orthodontists and laypersons and the esthetic perception in the symmetric and asymmetric changes in gingival zeniths. Methods: Posed photographs of five patients were taken and digitally manipulated in Keynote software, in the gingival zenith region, in increments of 0.5 to 1mm in maxillary central and lateral incisors, symmetrically and asymmetrically, in nine different ways for each patient. The photos were then uploaded to a website, where evaluators (general dentists, orthodontists and laypersons) could observe and vote according to their esthetic perception, scoring from 1 to 10, 1 being the least attractive and 10 the more attractive. Kruskal-Wallis and Mann-Whitney tests were used for comparison. Results: Asymmetric gingival zeniths were less attractive than symmetrical gingival zeniths; gingival zenith differences greater than 1mm were perceptible in the smile attractiveness, both by laypersons, general dentists and orthodontists. When comparing maxillary central incisors with maxillary lateral incisors, the aesthetic change performed in the central incisors are more perceptible than those performed in lateral incisors, both symmetrical and asymmetrical. In a general way, orthodontists and general dentists are more critical in the evaluation and perception of gingival zenith changes, with the laypersons perceiving this change only from 1mm of maxillary right central incisor asymmetrical change. Conclusions: Asymmetric gingival zeniths are less attractive than symmetrical ones. Gingival zenith differences greater than 1mm are perceptible in the smile attractiveness. Orthodontists and general dentists are more critical in evaluating smile esthetics.

摘要
研究目的：评估不同牙龈顶点（gingival zenith）在全科牙医、正畸医生与普通人群中的微笑吸引力，以及牙龈顶点对称与不对称变化带来的美学感知差异。
研究方法：拍摄5名患者的摆拍微笑照片，使用Keynote软件对上颌中切牙与侧切牙的牙龈顶点区域进行数字化调整，以0.5至1mm为调整增量，分别采用对称与不对称两种方式，为每位患者设置9种不同的调整方案。随后将处理后的照片上传至网站，评估者（全科牙医、正畸医生及普通人群）可根据自身美学感知对照片进行观察并评分，评分区间为1至10分，其中1分代表吸引力最低，10分代表吸引力最高。统计分析采用Kruskal-Wallis检验与Mann-Whitney检验进行组间比较。
研究结果：不对称牙龈顶点的微笑吸引力显著低于对称牙龈顶点；当牙龈顶点差异超过1mm时，普通人群、全科牙医与正畸医生均可感知其对微笑吸引力的影响。对比上颌中切牙与侧切牙的调整效果，无论对称或不对称调整，中切牙的美学变化均比侧切牙更易被识别。总体而言，正畸医生与全科牙医对牙龈顶点变化的评估更为严苛，普通人群仅在上颌右侧中切牙不对称调整量达1mm时，才可感知该美学变化。
研究结论：不对称牙龈顶点的微笑吸引力低于对称牙龈顶点；牙龈顶点差异超过1mm时，可被感知其对微笑吸引力的影响；正畸医生与全科牙医在评估微笑美学时更为严苛。