Effect of age and sex on dental esthetic zone during voluntary smile and at rest

A paramount objective of orthodontic therapy is the improvement of facial esthetics. Thus، it seems worthwhile to outline the common denominators of an esthetic smile. The aim of this study was to determine age and sex effects on the dental esthetic zone during posed smile and tooth display in the natural rest position in adults.

A total of 120 Iranians، from Isfahan، were randomly selected from three age cohorts of 20–25، 35–40 and 50–55، with equal distribution of the subjects. The subjects’ photographs were taken during posed smile and in the natural rest position. In addition a record of full dentition was made. Measurements were carried out and statistical analysis of the data was carried out using correlation analysis، analysis of variance، and post hoc Tukey tests (α = 0. 05).

With aging، maxillary lip line heights decreased significantly in the two situations of rest (p value = 0. 03) and posed smile (p value = 0. 02) to expose the teeth. In older participants، mandibular teeth were displayed only in the rest position (p value < 0. 01) but during posed smile mandibular lip line height and tooth display did not change with age (p value > 0. 05). Women had significantly greater average maxillary lip line height and tooth display than men in the two situations (p value = 0. 03). In contrast، men tended to show more of the mandibular anterior teeth than women at rest (p value < 0. 001). However، there were no significant differences between men and women during smile (p value > 0. 05).

The significant decrease in the upper lip line height and the resultant decrease in tooth display during rest and smiling indicate the significant effects of age on dental esthetic zone in which the differences between sexes are also involved. Therefore، the effect of two factors of age and sex should be included in orthodontic treatment planning.