title: Gingival condition associated with two types of orthodontic fixed retainers: a meta-analysis.
abstract: BACKGROUND
  The maintenance of gingival health around orthodontic fixed retainers (FRs) is difficult and different designs have been proposed.
  
  
  OBJECTIVE
  The goal of this systematic review was to analyse whether FR designs that allow unobstructed interproximal flossing, compared with the ones that do not, improve gingival parameters.
  
  
  METHODS
  Detailed individual database search strategies for Cochrane Library, 'Latin' American and 'Caribbean' Health Sciences Literature, PubMed, Scopus, and Web of Science were developed. Grey literature was also considered.
  
  
  METHODS
  Clinical trials and cross-sectional studies that compared two types of FRs (plain and waved) were included and evaluated.
  
  
  METHODS
  Study selection, data extraction, and risk of bias (RoB) assessment were performed individually and in duplicate. The methodology quality was assessed using the MAStARI RoB tool.
  
  
  RESULTS
  Four studies met the inclusion criteria, and all presented moderate RoB. While two of those studies found a statistically significant difference in gingival parameters, the other two did not report differences. A meta-analysis was conducted based on two of the selected studies, which performed evaluations of plaque index (PI) and calculus index (CI). The results revealed no differences on PI between wave FR and plain FR of 0.46 (0.24 to 0.69) and no differences on CI of 0.12 (-0.10 to 0.33). Regarding comfort, no clear differences were identified.
  
  
  CONCLUSIONS
  There is not enough scientific evidence to support or not an association between FR design and gingival health, flossing frequency, or patient comfort.
  
  
  BACKGROUND
  PROSPERO - CRD42016030059.
authors.affiliation: Department of Dentistry, Latin American Institute of Dental Research & Education, Curitiba, Paraná.
authors.forename: Leandro Nicolao
authors.initials: LN
authors.lastname: Buzatta
authors.affiliation: Section of Orthodontics, Department of Dentistry, ILAPEO and Tuiuti University of Paraná, Curitiba.
authors.forename: Roberto Hideo
authors.initials: RH
authors.lastname: Shimizu
authors.affiliation: School of Health and Biosciences, Pontifícal Catholic University of Paraná, Curitiba, Brazil.
authors.forename: Isabela Almeida
authors.initials: IA
authors.lastname: Shimizu
authors.affiliation: School of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada.
authors.forename: Camila
authors.initials: C
authors.lastname: Pachêco-Pereira
authors.affiliation: School of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada.
authors.forename: Carlos
authors.initials: C
authors.lastname: Flores-Mir
authors.affiliation: School of Dentistry, University of São Paulo, Ribeirão Preto.
authors.forename: Mario
authors.initials: M
authors.lastname: Taba
authors.affiliation: Brazilian Centre for Evidence-Based Research, Department of Dentistry, Federal University of Santa Catarina, Florianopolis, Brazil.
authors.forename: André Luís
authors.initials: AL
authors.lastname: Porporatti
authors.affiliation: School of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada.|Brazilian Centre for Evidence-Based Research, Department of Dentistry, Federal University of Santa Catarina, Florianopolis, Brazil.
authors.forename: Graziela
authors.initials: G
authors.lastname: De Luca Canto
mesh_terms: D003430:Cross-Sectional Studies; D003742:Dental Devices, Home Care; D003774:Dental Plaque Index; D005882:Gingival Diseases / Q000209:etiology* / Q000517:prevention & control; D006801:Humans; D009910:Oral Hygiene; D016382:Orthodontic Appliance Design; D018704:Orthodontic Retainers / Q000009:adverse effects*