Display of the incisors as functions of age and gender.

Background: Older subjects usually show less of their upper incisors and more of their lower incisors than younger subjects.

Objectives: To determine how much of the upper and lower central incisor crowns are visible in Brazilian subjects with their lips at rest.

Methods: The subjects were 240 white Brazilian subjects divided into four age groups: Group 1, 12 to 15 years of age; Group 2, 20 to 30 years of age; Group 3, 31 to 50 years of age and Group 4, 51 years of age and older. Each group contained 30 males and 30 females. The vertical display of the incisors was measured in millimetres from the midpoints of the incisal edges of the upper and lower central incisors to the borders of the upper and lower lips.

Results: In females, the mean upper central incisor display reduced from 4.45 mm in Group 1 to 1.32 mm in Group 4, and in males it reduced from 3.35 mm in Group 1 to 0.57 mm in Group 4. Less of the lower central incisor crowns were displayed in Group 1 females (Mean: 0.47 mm) than in Group 4 females (Mean: 2.22 mm), and in Group 1 males (Mean: 0.61 mm) than in Group 4 males (Mean: 3.05 mm). Brazilian women showed significantly more of their upper incisor crowns than Brazilian men in Groups 1, 2 and 4, whereas Brazilian men showed significantly more of their lower central incisors than Brazilian women in Group 4.

Conclusions: With the lips at rest, older Brazilians display less of their upper central incisors and more of their lower central incisors than young Brazilians. Women show more of their upper incisors than men, while men display more of their lower central incisors than women.