Abstract :

  Background and Aim: Excessive display of gum tissue during smiling is called gummy smile. This situation is caused by several factors including altered passive eruption. The purpose of this investigation is to determine the correlation between gummy smile and altered passive eruption (APE) in a young population of women in Esfahan.

  Materials and Methods : In this cross sectional study, 842 females aged between 20 and 30 were examined in Esfahan .

  They were asked to smile in voluntary and involuntary (emotional) states. Gingival display (more than 1mm during smiling) as well as length of the clinical crowns (short or normal) in anterior teeth were recorded in a table. Statistical analysis of the data was carried out using chi square.

  Results: Results revealed that 223 subjects exhibited short clinical crowns and 619 had normal clinical crowns. Gummy smile was reported in 128 subjects during voluntary state and in 556 subjects in involuntary state. 148 subject didn’t have gummy smile. Chi square analysis showed a correlation between short clinical crowns and the type of smile. In voluntary state, gummy smile was seen in 22.4% of the subjects with short clinical crowns and in 12.6% of the subjects with normal crown length ( P< 0.001 (

  Involuntary smiling resulted in gingival display in 68.6% of the subjects with short clinical crowns and in 66.7% with normal crown length (p= 0.61).

  Conclusion : There is a correlation between altered passive eruption and gummy smile during involuntary( emotional) smiling.