[Perception of asymmetry smile: Attempt to evaluation through Photoshop]

In the labial palliative surgery of facial paralysis, it can persist asymmetry smile.

Evaluate the impact of an augmentation or reduction of the commissural course on the perception of a smile anomaly, and determine from which asymmetry threshold, the smile is estimated unsightly.

We took a picture of two people with a smile not forced; including one with a "cuspid smile", and the another one with a "Mona Lisa" smile. The pictures obtained were modified by the Photoshop software, to simulate an asymmetry labial smile. The changes were related to the move of the left labial commissure, the left nasolabial furrow, and the left cheek using under-correction and overcorrection, every 4 mm. Three pictures with under-correction and four pictures with over-correction were obtained. These smiles were shown to three groups of five people, which included doctors in smile specialties, doctors in other specialties, and non-doctors. Participants were then asked to indicate on which of the pictures, the smile seemed abnormal.

Between -8 mm under-correction, and +8 mm over-correction, the asymmetry of the commissural course does not hinder the perception of smile.

In the labial palliative surgery of facial paralysis, in the case of persistent asymmetry, there is a tolerance in the perception of "normality" of smile concerning the amplitude of the commissural course going up to 8 mm of asymmetric with under-correction or over-correction.