1Robine JM,Vaupel JW,Jeune B,et al.Longevity:to the limits and beyond[M].Berlin:Springer Verlag,1997:4-175.
2Danner DD,Snowdon DA,Friesen WV.Positive emotions in early life and longevity:findings from the nun study[J].J Pers Soc Psychol,2001;80(5):804-13.
3Harker L,Keltner D.Expressions of positive emotion in women′s college yearbook pictures and their relationship to personality and life outcomes across adulthood[J].J Pers Soc Psychol,2001;80(1):112-24.
4Hertenstein MJ,Hansel CA,Butts AM,et al.Smile intensity in photographs predicts divorce later in life[J].Motiv Emot,2009;33(2):99-105.
5Abel EL,Kruger ML.Smile intensity in photographs predicts longevity[J].Psychol Sci,2010;21(4):542-4.
6Freese J,Meland S,Irwin W.Expressions of positive emotion in photographs,personality,and later-life marital and health outcomes[J].J Res Persp,2007;41(2):488-97.
7Keltner D,Gross JJ.Functional accounts of emotions[J].Cogn Emot,1999;13(5):467-80.
8Fredrickson BL,Losada M.Positive affect and the complex dynamics of human flourishing[J].Am Psychol,2005;60(3):678-86.
3David C, Havens J, Namara J,et al. The role of the posed smile in overall facial esthetics [ J ]. Angle Orthod ,2010,80 ( 2 ) : 322 - 328.
4David M, Sarver M, Ackerman B. Evolution of the concept and dy- namic records for smile capture [ J ]. Am J Orthod,2003,124 ( 1 ) : 4 -12.
5Vander Geld P, Oosterveld P, Kujjpers-Jagtman A. Age-related changes of the dental aesthetic zone at rest and during spontane- ous smiling and speech. [J]. Eur J Orthod. 2008,30(4) :366 - 373.
6Durgekar S, KN, Naik V. The ideal smile and its orthodontic im- plications [ J ]. World J Orthod ,2010,11 ( 3 ) : 211 - 220.
7David C,Havens J,Namara J,et al.The role of the posed smile in overall facial esthetics[J].Angle Orthod,2010,80(2):322-328.
8Cristina B,Adriana M,Azucena G.Smiling is fun:a Coping with Stress and Emotion Regulation Program[J].SHTI,2012,181:123-127.