title: Grinding is effective in early orthodontic treatment of unilateral posterior crossbite.
abstract: METHODS
  PubMed and the Cochrane Controlled Clinical Trials Register were searched. Reference lists from retrieved articles were also searched by hand for additional studies.
  
  
  METHODS
  For inclusion, an article had to satisfy the following criteria: cases in primary and early mixed dentition with unilateral posterior crossbite; be a randomised controlled trials (RCT) or prospective and retrospective studies with concurrent untreated as well as normal controls; clinical trials must have compared at least two treatment strategies without any untreated or normal control group involved; and be written in English, German, French or a Scandinavian language.
  
  
  METHODS
  Data extraction was carried out independently and in duplicate. Quality of the studies was assessed and categorised as low, medium and high. Interexaminer conflicts were resolved by discussion to reach a consensus.
  
  
  RESULTS
  The search identified 1001 articles, of which 12 met the inclusion criteria. Only two RCT of early treatment of crossbite have been performed, and these two studies support grinding as treatment in the primary dentition. As treatment strategies, quad-helix (QH), expansion plates and rapid maxillary expansion (RME) are effective in the early mixed dentition with high success rates. There is, however, no scientific evidence available that shows which of the treatment modalities, that is, grinding, QH, expansion plates or RME, is the most effective.
  
  
  CONCLUSIONS
  Most of the studies have the serious drawback of lack of power because of small sample size, bias and confounding variables, lack of method error analysis and blinding in measurements, and deficient or lack of statistical methods. Thus, the studies were not of high enough quality level to draw any evidence-based conclusions. Better-controlled RCT with sufficient sample sizes are needed to obtain reliable scientific evidence identifying which treatment is the most effective for early correction of unilateral posterior crossbite. Future studies should also include assessments of long-term stability as well as analysis of costs and side-effects of the interventions.
authors.affiliation: Faculty of Medicine and Dentistry, Dentistry/Pharmacy Center, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Carlos
authors.initials: C
authors.lastname: Flores-Mir