美容牙科是非常的主觀的,在這篇文章中會討論到的幾項主題：1. Smile type (high, average, low); 2.Paralleism of the maxillary incisal curve with the lower lip; 3. Position of the incisal curve relative to touching the lower lip; 4. The number of teeth displayed in a smile.
首先作者群先定義出high-露出連續牙肉, average-75~100%上顎前牙和low smile-小於75%上顎前牙.
作者群在454位20-30歲(207男247女)的牙醫學院學生正面笑容的照片中做統計分析, 結果如下：
Smile type: High smile 10.57%, Average smile 68.94%, Low smile 20.48%
Parallelism of the maxillary incisal curve with lower lip: 84.8% Parallel, 13.88% Straight, 1.32% Reverse
Position of the incisal curve relative to touching the lower lip: 46.61% touch lower lip, 34.62% not total touch lower lip, 15.76% covered by lower lip
The number of teeth displayed in a smile: Six anteriors only: 7.01%, Six anteriors and first premolar: 48.6%, Six anteriors and first &second premolars: 40.65%, Six anteriors and first& second premolars and first molar: 3.74%
所以整體來說一個漂亮的笑容（或說是平均的笑容）需要露出上顎前牙75~100%而不漏出過多牙肉, 上顎前牙的曲線要配合下唇曲線, 且稍微或完全碰觸到下唇, 第一或第二小臼齒也要露出, 中線要在笑容的中間（所以要配合上唇）
這雖然是一群美國人的研究, 但是我看到的研究多半大同小異,所以這篇研究值得參考
yehc 