title: [Effect of extraction and non-extraction treatment on frontal smiling esthetics: a meta-analysis].
abstract: OBJECTIVE
  To evaluate the effectiveness of tooth extraction and non-extraction orthodontic treatment on frontal smiling esthetics.
  
  
  METHODS
  A literature research was performed using Wanfang database, Chinese Biological Literature database, China National Knowledge Infrastructure, Chinese Scientific Journals Database of VIP, Medline and the Cochrane Library, dating from the establishment of the databases to 31st, August, 2014. Weighted mean difference (WMD) was calculated and meta analysis was performed by Review Manager 5.2.
  
  
  RESULTS
  A total of 8 controlled studies were included. The results of meta analysis showed no significant difference between extraction and non-extraction treatment on subjective evaluation of smile esthetics [5.74-7.05 for extraction; 5.53-7.02 for non-extraction; WMD=0.09, 95%CI (-0.28, 0.46), P=0.64], buccal corridor [0.12-0.19 for extraction; 0.11-0.18 for non-extraction; WMD=0.01, 95%CI (-0.00,0.02), P=0.09], maxillary visual arch width [26.3-52.17 mm for extraction; 25.43-52.37 mm for non-extraction; WMD=-0.13, 95%CI (-1.01, 0.75), P=0.77] and smile height [5.7-10.39 mm for extraction; 5.4-9.97 mm for non-extraction; WMD=0.38, 95%CI (-0.27, 1.03), P=0.25].
  
  
  CONCLUSIONS
  Based on the results of this meta analysis, it can't be concluded that extraction treatment could affect the frontal smiling esthetics based on the present clinic evidences. Given the small sample size and the potential heterogeneity, more well-designed prospective studies should be performed in future.
authors.affiliation: School of Stomatology, Shandong University. Jinan 250012, Shandong Province; China. E-mail:626851130@qq.com.
authors.forename: Mei-lu
authors.initials: ML
authors.lastname: Dai
authors.forename: Meng
authors.initials: M
authors.lastname: Xiao
authors.forename: Zhe
authors.initials: Z
authors.lastname: Yu
authors.forename: Dong-xu
authors.initials: DX
authors.lastname: Liu
mesh_terms: D002681:China; D004955:Esthetics, Dental; D006801:Humans; D008437:Maxilla; D011446:Prospective Studies; D012904:Smiling; D014081:Tooth Extraction