title: Optimal force for maxillary protraction facemask therapy in the early treatment of class III malocclusion.
abstract: BACKGROUND
  The facemask is used to treat early class III malocclusion, in combination with expansion therapy. There is a great deal of controversy in literature regarding the effectiveness of protraction facemask treatment as studies report results anywhere from considerable changes to lack of any maxillary improvement. This controversy may be due to the fact that the process of placing the orthopaedic facemask on patients has, in part, been done empirically, without the use of literature containing the clinical parameters for facemask placement for maxillary protraction.
  
  
  OBJECTIVE
  To determine the optimal magnitude, duration, and direction that should be used in maxillary protraction facemask therapy.
  
  
  METHODS
  A systematic search was carried out in the following databases: Medline, Google Scholar, Embase, Cochrane, Lilacs, Scielo, with no restriction placed on the year of publication, in English and Spanish, using MeSH terms and free-text terms.
  
  
  METHODS
  Clinical trials, systematic reviews, meta-analysis, cohort studies, case-control studies, and cross-sectional studies were included, whereas literature reviews, case reports, case series, symposiums, compendiums, pilot studies, and expert opinions were excluded.
  
  
  METHODS
  Data selection and extraction were blinded and performed independently, and the methodology was evaluated using various scales.
  
  
  RESULTS
  A total of 223 articles were found. After eliminating repeated articles and those that did not meet the selection criteria, 14 remained for analysis. Regarding magnitude, there were values ranging from 180 to 800g per side; there were force vector direction values between 20 and 30 degrees below the occlusal plane or parallel to the occlusal plane; and a duration ranging from 10 to 24 hours of use per day.
  
  
  CONCLUSIONS
  There is no scientific evidence that would allow for the definition of adequate parameters for force magnitude, direction, and duration for maxillary protraction facemask treatment in class III patients.
authors.affiliation: Department of Orthodontics, Universidad Cooperativa de Colombia, Envigado, Colombia eliana.yepes@campusucc.edu.co.
authors.forename: Eliana
authors.initials: E
authors.lastname: Yepes
authors.affiliation: Department of Orthodontics, Universidad Cooperativa de Colombia, Envigado, Colombia.
authors.forename: Paula
authors.initials: P
authors.lastname: Quintero
authors.affiliation: Department of Orthodontics, Universidad Cooperativa de Colombia, Envigado, Colombia.
authors.forename: Zulma Vanessa
authors.initials: ZV
authors.lastname: Rueda
authors.affiliation: Department of Orthodontics, Universidad Cooperativa de Colombia, Envigado, Colombia.
authors.forename: Andrea
authors.initials: A
authors.lastname: Pedroza
mesh_terms: D005115:Extraoral Traction Appliances; D006801:Humans; D008313:Malocclusion, Angle Class III / Q000628:therapy*; D008437:Maxilla / Q000473:pathology; D013314:Stress, Mechanical; D016896:Treatment Outcome