The effect of different vertical patterns on smile in skeletal class I cases

The aim of this study was to evaluate the effect of different vertical patterns (hypodivergent-normodivergent-hyperdivergent) on smile characteristics in skeletal Class I malocclusions by comparing subjects who no need of orthodontic treatment. The study sample consisted of 90 patients with a normal sagittal skeletal pattern divided into three groups according to their vertical growth pattern: hypodivergent (15 women, 15 men; mean age, 20.38±3.76 years), normodivergent (18 women, 12 men; mean age, 19.36±2.83 years) and hyperdivergent (19 women, 11 men; mean age, 19.44±2.14 years) groups. The control group (20 women, 10 men, mean age, 20.95±1.90 years) consisted of 30 patients with no need of orthodontic treatment. Spontaneous smiles were elicited by watching a funny videos. The smile frames of smiling with maximum visibility of teeth and gingivae, referred to as the records, were recorded and analyzed with the help of the Image J® program. Analysis of variance (ANOVA) and post hoc "Honestly Significant Difference" (Tukey HSD) were performed to evaluate the changes with smile components among groups. Maximum incisor exposure (MxiD) (p≤0.05), maxillary incisal edges to lower lip (MxiLL) (p≤0.01), smile height (SH) (p≤0.001) and smile area (SA) (p≤0.01) measurements were found to be significantly reduced in the hypodivergent subjects. Visible dental width (VTW) (p≤0.01) and inter innercommissural width (İCW) (p≤0.05) was found to be significantly decreased in the hyperdivergent subjects in comparison to control group. Buccal corridor (BC-R, BC-L) (p≤0.001) measurements was found to be significantly lower in the hyperdivergent subjects. Smile index (SIx) (p≤0.001) was found to be significantly higher in the hypodivergent subjects. As a result, vertical pattern and gender affect smile components. Hyperdivergent subjects have more vertical smile than hypodivergent subjects. To obtain a more attractive smile, the effect of different vertical patterns on smile characteristics should be considered during orthodontic treatment planning. Key words: Analysis, Angle Class I, Esthetics, Smiling, Malocclusion