[Esthetic proportions of maxillary anterior tooth among 300 normal occlusion college students in Shanxi province].

Objective: To explore the relationship between the width ratios of maxillary anterior teeth, the width/height ratios of maxillary central incisor and the esthetic proportions among individual normal occlusion, and to provide reference for the esthetic design of anterior teeth. Methods: A total of 300 Shanxi Medical University students who were residents from Shanxi province with normal occlusion (110 males, 190 females, aged 18-30 years) were recruited in this study from October 2020 to March 2021. Standardized digital photographs of the maxillary anterior tooth in natural head position were obtained, the perceived width of the maxillary anterior teeth (maxillary central incisors, lateral incisors and canines) on the left and right sides and height of maxillary central incisor were measured on the standardized digital photographs, then the width ratios of adjacent maxillary anterior teeth including the lateral incisor/central incisor width ratio (LI∶CI), the canine/lateral incisor width ratio (C∶LI), and the width/height ratios (W/H ratio) of the maxillary central incisor were calculated. The independent sample t test was used to compare the sex differences of each measurement project, Single sample t test was used to compare the difference of adjacent maxillary anterior teeth width ratios with golden proportion (0.618 and 0.618), Preston proportion (0.66 and 0.84), the recurring esthetic dental (RED) proportion (0.70 and 0.70). The percentage of anterior tooth width/intercanine width was calculated, the number and proportion of teeth conforming to golden percentage (25%, 15%, 10%)±1% or modified golden percentage (22.5%, 15.0%, 12.5%)±1% were calculated. The number and proportion of width/height ratio of maxillary central incisor ranged from 0.75 to 0.85 was counted. Results: The widths of maxillary central incisor, lateral incisor and canine were (8.50±0.52), (6.23±0.53) and (5.18±0.55) mm, respectively, the corresponding tooth of male [(8.74±0.49), (6.37±0.52), (5.41±0.47) mm] was significantly higher than that of female [(8.37±0.50), (6.15±0.52), (5.04±0.54) mm] (t=6.40, 3.55, 6.23,P<0.05). The width ratio of maxillary lateral incisor/central incisor was 0.73±0.05, and there was no significant difference between genders (t=-1.06, P>0.05). The width ratio of canine/lateral incisor was 0.84±0.10, and it was significantly higher in male (0.85±0.10) than in female (0.82±0.10) (t=2.42, P<0.05). Two width ratios of maxillary anterior teeth were significantly different from golden proportion and the RED proportion (t=38.50, 35.74, 11.48, 22.20, P<0.05). The lateral incisor/central incisor was significantly different from that of Preston proportion (t=24.66, P<0.05), while the canine/lateral incisor was not significantly different from that of Preston proportion (t=-0.92, P>0.05). In this study, a total of 0% (0/600) of central incisors, 63.0% (378/600) of lateral incisors and 5.8% (35/600) of canines met the golden percentage±1%. There were 42.8% (257/600) of central incisors, 63.0% (378/600) of lateral incisors and 56.7% (340/600) of canines met the modified golden percentage±1%. The width/height ratio of maxillary central incisors was 0.86±0.08, and there was no significant difference between genders (t=-0.88, P>0.05). Only 36.3% (218/600) of the subjects in this study ranged from 0.75 to 0.85. Conclusions: Gender differences should be considered in the esthetic design of anterior teeth; for the width ratios of maxillary anterior teeth, the golden proportion, the RED proportion and golden percentage do not accord with the natural tooth morphological characteristics of Shanxi nationality college students in normal occlusion. Preston proportion and modified golden percentage are of more reference value. The width/height ratio of maxillary central incisors is different from 0.75-0.85.目的： 探讨山西省个别正常(牙合)高校学生上前牙宽度比、上颌中切牙宽长比与美学比例的契合程度，为前牙美学设计提供参考。 方法： 2020年10月至2021年3月于山西医科大学学生中选取山西籍个别正常(牙合)志愿者300名（男性110名，女性190名，18~30岁）。拍摄受试者自然头位前牙列正面照片，测量上颌双侧中切牙、侧切牙和尖牙宽度和上颌中切牙高度，计算上前牙宽度比（侧切牙与中切牙宽度比、尖牙与侧切牙宽度比）以及上颌中切牙宽长比。独立样本t检验比较各测量项目的性别差异，单样本t检验比较两项上前牙宽度比与黄金分割比例（0.618和0.618）、Preston比例（0.66和0.84）、重复性美学比例（0.70和0.70）的差异；统计上前牙各牙位宽度占前牙总宽度的百分比符合黄金百分比（25%、15%、10%）±1%或改良黄金百分比（22.5%、15.0%、12.5%）±1%的牙数及占比；统计上颌中切牙宽长比在0.75~0.85内的牙数及占比。 结果： 上颌中切牙、侧切牙、尖牙宽度分别为（8.50±0.52）、（6.23±0.53）、（5.18±0.55）mm，男性各牙位［分别为（8.74±0.49）、（6.37±0.52）、（5.41±0.47）mm］均显著大于女性相应牙位［分别为（8.37±0.50）、（6.15±0.52）、（5.04±0.54）mm］（t=6.40、3.55、6.23，P<0.05）。侧切牙与中切牙宽度比为0.73±0.05，性别差异无统计学意义（t=-1.06，P>0.05），尖牙与侧切牙宽度比为0.84±0.10，男性（0.85±0.10）显著大于女性（0.82±0.10）（t=2.42，P<0.05）。两项上前牙宽度比与黄金分割比例、重复性美学比例的差异均有统计学意义（t=38.50、35.74、11.48、22.20，P<0.05）。侧切牙与中切牙宽度比与Preston比例的差异有统计学意义（t=24.66，P<0.05），而尖牙与侧切牙宽度比与Preston比例的差异无统计学意义（t=-0.92，P>0.05）。本组受试者共0%（0/600）的中切牙、63.0%（378/600）的侧切牙和5.8%（35/600）的尖牙符合黄金百分比±1%；共42.8%（257/600）的中切牙、63.0%（378/600）的侧切牙和56.7%（340/600）的尖牙符合改良黄金百分比±1%。上颌中切牙宽长比为0.86±0.08，性别差异无统计学意义（t=-0.88，P>0.05），36.3%（218/600）的上颌中切牙宽长比在0.75~0.85范围内。 结论： 前牙美学设计时需考虑性别差异；对于上前牙宽度比，山西籍个别正常(牙合)高校学生人群天然牙形态特征与黄金分割比例、重复性美学比例、黄金百分比不契合，而与Preston比例、改良黄金百分比更契合。上颌中切牙宽长比与0.75~0.85有一定的差别。.