摘要
關於微笑的分析，以往研究多著重於軟組織的觀察上，近來有研究欲探討當微笑（posed smile）時有過多的牙齦裸露（gummy smile），其硬組織在測顱分析上的特色，但往往因為蒐集樣本數在男性gummy smile組別極為缺乏而未能將男性和女性分開比較。本研究目的，除了探討gummy smile組和non-gummy smile組在測顱分析上的差異外，更分別探討男性和女性各自在gummy smile組和non-gummy smile組測顱分析上的差異；但主要是欲得知哪些測顱分析項目會影響gummy smile的發生。方法為以靜態正面觀微笑照片為主，臨床觀察為輔，蒐集男性、女性分別60人，其中各有30位為gummy smile和30位為non-gummy smile的病患，根據其測顱分析項目的數據，以JMP 9.0統計軟體，獨立樣本t檢定的方法比較gummy smile組和non-gummy smile組的測顱分析值，以及將男性和女性分開討論其各測顱分析值是否有顯著性差異。其次，利用ROC curve，探討各測顱分析項目對gummy smile的預測度，並利用逐步邏輯式廻歸的方法，評估主要影響gummy smile發生的測顱分析項目。最後的結果顯示，當男女分開討論時，男性測顱分析項目中，A-Nv、ANS-Me、tooth to lip會影響gummy smile的發生；女生測顱分析項目中，facial axis angle、anterior facial height、tooth to lip會影響gummy smile的發生。由此可知，影響gummy smile的測顱分析項目主要為垂直向的數值，隱約透露出垂直向生長過多而導致gummy smile的現象，尤其是休息狀態下上顎門牙相對於上唇的裸露量（tooth to lip），不管在男性或女性，均會影響gummy smile的發生。
關鍵字
posed smile ； gummy smile ； tooth to lip ； anterior facial height ； facial axis angle ； A-Nv ； ANS-Me.並列摘要
Studies on gummy smile used to put more stress on soft tissue analysis. Recently, some studies started to explore the relationship between soft tissue and underlying hard tissue. They tried to find out the hard tissue characteristics of gummy smile with cephalometric measurement, but often failed to compare the difference between males and females due to fewer male gummy smile individuals. In this study, we tried to find out the hard tissue characteristics of gummy smile in cephalometric measurement for males and females by clinical static posed smile photos and records used to define the gummy smile group and non-gummy smile groups. Finally, we used JMP 9.0 (two-sample t-test, and ROC curve, and stepwise logistic regression) for analysis of the cephalometric measurement, and found out the factors resulting in gummy smile in males and females. In males, the cephalometric factors are A-Nv, ANS-Me, and tooth to lip; in females, the cephalometric factors are facial axis angle, anterior facial height, and tooth to lip. We found that the vertical factor was the key to gummy smile, and the value of tooth to lip was important in clinical use.