Comparison of extraction versus nonextraction orthodontic treatment outcomes for borderline Chinese patients.
BACKGROUND
The purpose of this study was to compare orthodontic treatment outcomes in Chinese patients with borderline problems treated with and without extractions.


METHODS
Records of 39 borderline patients treated at the Faculty Clinic of the Peking University Orthodontic Department were evaluated retrospectively by 5 associate professors. Sixteen patients had been treated without extractions, and 23 had 4 first or second premolars extracted. Each judge evaluated the posttreatment records independently for tooth alignment, overbite, overjet, midline symmetry, lateral occlusion, and facial profile, and rated them on a scale from 1 to 5.


RESULTS
The only statistically significant difference between the extraction and nonextraction groups was for facial profile, with the judges preferring the extraction profiles. Fifteen soft-tissue cephalometric variables were measured to determine the source of the difference, and 6 showed statistically significant differences. When profile changes from pretreatment to posttreatment were examined, significant differences in treatment-associated changes between extraction and nonextraction groups were all related to the lower lip and chin.


CONCLUSIONS
In this sample of Chinese borderline orthodontic patients, Chinese clinicians had a statistically significant preference for the facial profiles of the extraction patients, but no statistically significant preferences for tooth alignment, overbite, overjet, midline symmetry, or posterior occlusion. Extraction treatment increases the inclination of the chin and reduces protrusion of the lower lip compared with nonextraction treatment, and this might explain the difference.
Xu
Tian-Min
TM
Department of Orthodontics, School of Stomatology, Peking University, Beijing, China. tmxu@vip.sina.com
Liu
Yan
Y
Yang
Min-Zhi
MZ
Huang
Wei
W