title: Comparison of vacuum-formed and Hawley retainers: a systematic review.
abstract: BACKGROUND
  Hawley retainers (HRs) and vacuum-formed retainers (VFRs) are the 2 most commonly used retainers in orthodontics. However, the basis for selection of an appropriate retainer is still a matter of debate among orthodontists. In this systematic review, we evaluated the differences between VFRs and HRs.
  
  
  METHODS
  Electronic databases (PubMed, EMBASE, Cochrane Library, ISI Web of Science, LILACS, and Pro-Quest) were searched with no language restriction. The relevant orthodontic journals and reference lists were checked for all eligible studies. Two article reviewers independently screened the retrieved studies, extracted the data, and evaluated the quality of the primary studies.
  
  
  RESULTS
  A total of 89 articles were retrieved in the initial search. However, only 7 articles met the inclusion criteria. Some evidence suggested that no difference exists to distinguish between the HRs and VFRs with respect to changes in intercanine and intermolar widths after orthodontic retention. In terms of occlusal contacts, cost effectiveness, patient satisfaction, and survival time, there was insufficient evidence to support the use of VFRs over HRs.
  
  
  CONCLUSIONS
  Additional high-quality, randomized, controlled trials concerning these retainers are necessary to determine which retainer is better for orthodontic procedures.
authors.affiliation: Postgraduate student, Department of Orthodontics, College of Stomatology, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Wenjia
authors.initials: W
authors.lastname: Mai
authors.affiliation: Senior instructor, Department of Orthodontics, College of Stomatology, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Jin'an
authors.initials: J
authors.lastname: He
authors.affiliation: Postgraduate student, Department of Orthodontics, College of Stomatology, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Hongying
authors.initials: H
authors.lastname: Meng
authors.affiliation: Postgraduate student, Department of Orthodontics, College of Stomatology, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Postgraduate student, Department of Orthodontics, College of Stomatology, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Chaoxiao
authors.initials: C
authors.lastname: Huang
authors.affiliation: Postgraduate student, Department of Orthodontics, College of Stomatology, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.affiliation: Postgraduate student, Department of Orthodontics, College of Stomatology, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Kan
authors.initials: K
authors.lastname: Yuan
authors.affiliation: Associate professor and director, Department of Orthodontics, College of Stomatology, Guangxi Medical University, Nanning, Guangxi, China. Electronic address: kangna78@gmail.com.
authors.forename: Na
authors.initials: N
authors.lastname: Kang
mesh_terms: D003362:Cost-Benefit Analysis; D003724:Dental Arch / Q000033:anatomy & histology; D006801:Humans; D016382:Orthodontic Appliance Design; D018704:Orthodontic Retainers; D017060:Patient Satisfaction; D016019:Survival Analysis