The ideal smile and its orthodontic implications.

Aim: To determine the parameters for an ideal smile.

Methods: Ten laypersons classified frontal photographs of 62 smiling individuals between 18 and 25 years of age into five categories: 1, poor; 2, fair; 3, good; 4, very good; and 5, excellent. The scores obtained for each smile were averaged. The five smiles with each the highest and lowest scores were analyzed for seven parameters: buccal corridor, smile index, smile symmetry, smile line ratio, upper lip line, smile arc, and upper lip curvature.

Results: The five smiles with the highest scores were symmetrical with an average upper lip line and a consonant smile arc. Three of the five had an upward upper lip curvature. The smile line ratio, buccal corridor, and smile index for all five subjects ranged from 1.0 to 1.3 mm, 9.0% to 11.0%, and 4.0 to 6.0 mm, respectively. Two of the five smiles with the lowest scores were asymmetrical and three had a high upper lip line and a downward curvature, but all five had a nonconsonant smile arc. The smile line ratio, buccal corridor, and smile index for all five subjects ranged from -1.0 to 1.3 mm, 18.0% to 22.0%, and 7.0 to 10.0 mm, respectively.

Conclusion: The seven investigated smile parameters can define characteristics of an ideal smile. These smile components should be included in the orthodontic problem list to help clinicians select the appropriate mechanotherapy.