Smile expressions are generally divided into three. The first is sexy smile, the second is sophisticated smile, and the third is sporty smile. For a sexy smile, the central incisors (anterior teeth) should be noticeably longer than the rest of the teeth on the sides. Design your anterior teeth in this way gives you a young, dynamic and attractive smile. For a sophisticated smile, teeth aligned on a straight line (i.e. all have the same length) are needed. This smile gives a mature and wise expression to your face. For a sporty smile, your central incisors are required to be slightly longer than the rest of the incisor teeth on the sides. This smile will give you a sincere, extraordinary, and warm expression.