关键词: 拔牙, 非拔牙, 牙弓宽度, 微笑美学

Abstract: ABSTRACT Objective:To compare the changes of arch width as well as smile esthetics in patients treated by extraction and nonextraction procedures. Methods: Dental casts of 30 patients treated with extraction and 30 patients without extraction of four first premolars were randomly selected. Arch widths were measured from the cusp tips of the canines, premolars, and molars. Posttreatment arch widths were also measured in the midline at a constant arch depth from the most labial surfaces of the incisors. Standardized frontal photographs of the face taken during smiling of extraction and nonextraction treated subjects were evaluated. Twenty orthodontic doctors judged the esthetics of the smiles. Results: Intercanine width increased less than one mm in both groups, and there was no difference between the two groups. The interpremolar and intermolar distance in both arches decreased significantly in theextraction sample, whereas the interpret molar and intermolar widths increased significantly in the nonextraction sample. When arch widths of both groups were measured from the most labial surfaces of the teeth at a constant depth, the average arch width of both arches was significantly wider in the extraction sample. The mean esthetic score and the number of teeth displayed during a smile did not differ between the groups. Conclusion: The results indicate that arch width is not decreased at a constant arch depth because of extraction treatment,and smile esthetics are the same in both groups of patients.

Key words: Extraction, Nonextraction, Arch width, Smiles Esthetics