Analysis of the factors influencing the subjective smile evaluation in females after orthodontic treatment

Abstract

Objective To understand the factors influencing subjective smile evaluation and investigate the consistence between orthodontists and laypersons on smile evaluation.Methods 80 female patients with skeletal Class Ⅰ facial pattern (aged 14 to 27 years old) were included in the study after finishing orthodontic treatment.All subjects presented with Class Ⅰ canine and molar relationship,normal overbite and overjet and well-aligned teeth.The subjects were divided into extraction (42 subjects) and non-extraction groups(38 subjects).Posttreatment smile photographs of lower 1/3 of the face were taken.The smile photos were randomly numbered and distributed with a fixed sequence to 10 orthodontists and 10 laypersons for subjective smile evaluation (VAS).Results Significant difference was noted in smile scores when smile photographs were evaluated by orthodontists and laypersons.(P＜0.001).No significant difference was found in smile scores when smile photos in extraction group were compared with that in non-extraction group.Correlation analysis indicated that smile index was positively correlated with orthodontists and layperson's score,smile height,gingival exposure,canine width ratio,visible dentition width ratio was negatively correlated with their score.Conclusions Extraction or non-extraction decision itself might not significantly affect subjective smile evaluation of a patient.Gingival exposure may play a more important role in subjective evaluation of smile. Key words: Orthodontic patients; Smile; Evaluation