1Assistant Professor, School of Dentistry, Tehran Islamic Azad University, Tehran, Iran
Smile line is one of the most important element of the smile esthetics. In an attractive smile, the maxillary anterior incisal curve is parallel to the lower lip. With the changes in face, lips and teeth muscles, which are caused by aging, this element (smile line) also changes. Aging causes smile line to move from its parallel position and in complete smile, formulate different shapes relative to the lower lip curve. Therefore thorough and accurate information about smile elements and anatomy seems to be essential for attractive smile restoration in various ages. A descriptive research on this issue has been done on 300 men and women between 20 to 70 years of age. Each subject was analyzed and evaluated by careful visual judgement. After the completion of information and evaluation of the results, findings based on the clinical observation on students and clients at Azad University – School of Dentistry have shown that, with the passing of age, the smile line gradually changes from parallel form to straight and then reverse form. Other elements of smile such as tooth lower lip position also changes their forms through aging, and different forms such as slightly covered and touching decline while not touching increases. In the position of lip line the high form declines whereas the low form increases.