Abstract: Abstract:Objective To survey aesthetics cognition for smiling beauty in young people smile. Methods Smile model was established. The middle incisor width/length ratio, lateral incisor and middle incisor width ratio, difference of lateral incisor and the middle incisor gingival level, gingiva exposure, buccal corridor width and smile line radian were used as variable values to change respectively. A total of 200 young people were selected to evaluate results. The differences in index of ideal value and acceptable range between different dender groups were calculated. Results The ideal value of middle incisor width/length ratio was 0.75, and acceptable range was 0.65-0.85. The ideal value of lateral incisor and middle incisor width ratio was 0.618, and acceptable range was 0.518- 0.718. The ideal value of lateral incisor and the middle incisor gingival level difference was -0.5 mm, and the acceptable range was -1-0 mm. The ideal value of gingiva exposure was 0 mm, and the acceptable range was 0-2 mm. The ideal value of buccal corridor was 0.09, and the acceptable range was 0.05-0.21. Coordinate smile was ideal smile line (value= 1), and the acceptable range was 0.5-1. There were no statistically significant differences in smile esthetics of six ideal value indicators and acceptable ranges between different gender groups. Conclusion The ideal values and acceptable ranges of six indexes of quantitative criteria can be used for clinical treatment.

Key words: esthetics, dental, questionnaires, sex factors, smile esthetics, gingival exposure, buccal corridor, smile line