Dynamic smiles of different smile lines evaluated by orthodontists, plastic surgeons, dentists and laypeople

The purpose of this study was to evaluate esthetic outcomes of dynamic smiles of different smile lines using Facial Action Coding System (FACS) by orthodontists, plastic surgeons, dentists and laypeople. FACS is a method used for standardization of facial muscle activities by categorizing each muscle and activity into Action Units (AU). Out of 11 models that were chosen, 3 male and 3 female models with low, normal and high smile lines met the inclusion criteria. Models were asked to produce 7 different smiles with the help of FACS which include different combinations of muscles such as zygomaticus major (AU12), orbicularis oculi (AU6), zygomaticus minor (AU11), levator labii superioris (AU10), risorius (AU20) muscles and mouth opening action unit (AU25). Models were asked to produce their own posed smile as the 7th smile. Smiles were evaluated by 193 evaluators (48 orthodontists, 48 plastic surgeons, 49 dentists and 48 laypeople) with different age groups, and gender using Visual Analog Scale (VAS). The results revealed that there is no correlation between the esthetic values and occupations. Male model with low smile line (52.96±18.14), and female model with high smile line (52.83±17.91) were given the highest values, whereas male model with high smile line (37.97±18.86) and female model with low smile line (39.27±18.50) were given the lowest. As the amount of visible gingiva seen increases, the esthetic values are decreased. When the age was considered, 30-39 age group was the most strict, giving the lowest scores, while the 60+ group gave the highest. Different smiles are found more esthetic compared to the posed smiles of the models, which can suggest that a better smile can be produced in social life compared to the adopted posed smile. Key words: Dynamic Smile, Facial Action Coding System, Action Unit, Smile Line, Visual Analog Scale