title: Overview of registered studies in orthodontics: Evaluation of the ClinicalTrials.gov registry.
abstract: BACKGROUND
  The Food and Drug Administration Modernization Act of 1997 made it mandatory for all phase II through IV trials regulated by this Act to be registered. After this, the National Institutes of Health created ClinicalTrials.gov, which is a registry of publicly and privately supported clinical studies of human participants. The objective of this study was to examine the characteristics of registered studies in orthodontics.
  
  
  METHODS
  The ClinicalTrials.gov Web site was used to query all registered orthodontic studies. The search term used was "orthodontics." No limitations were placed for the time period. All registered studies regardless of their recruitment status, study results, and study type were selected for analysis.
  
  
  RESULTS
  A total of 64 orthodontic studies were registered as of January 1, 2014. Of these, 52 were interventional, and 12 were observational. Close to 60% of the interventional studies and 66.7% of the observational studies had sample sizes of 50 or fewer subjects. About 21.2% of the interventional studies and 16.7% of the observational studies had sample sizes greater than 100. Only 1 study was funded by the National Institutes of Health, and the rest were funded by "other" or "industry" sources. Close to 87.7% of the interventional studies were randomized. Interventional model assignments included factorial assignment (3.9%), parallel assignments (74.5%), crossover assignment (7.8%), and single-group assignment (13.7%). Most studies were treatment oriented (80.4%). The types of masking used by the interventional studies included open label (28.9%), single blind (44.2%), and double blind (26.9%). Outcome assessors were blinded in only 6 studies.
  
  
  CONCLUSIONS
  Orthodontic studies registered in ClinicalTrials.gov are dominated by small single-center studies. There are wide variations with regard to treatment allocation approaches and randomization methods in the studies. These results also indicate the need for multicenter clinical studies in orthodontics.
authors.affiliation: Associate professor, Department of Orthodontics, College of Dentistry, University of Iowa, Iowa City, Iowa. Electronic address: Veerasathpurush-Allareddy@uiowa.edu.
authors.forename: Veerasathpurush
authors.initials: V
authors.lastname: Allareddy
authors.affiliation: Graduate student, University of Nebraska Medical Center, Omaha, Neb.
authors.forename: Sankeerth
authors.initials: S
authors.lastname: Rampa
authors.affiliation: Director of orthodontics, Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Mass.
authors.forename: Mohamed I
authors.initials: MI
authors.lastname: Masoud
authors.affiliation: Postgraduate student, Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Mass.
authors.forename: Min Kyeong
authors.initials: MK
authors.lastname: Lee
authors.affiliation: Instructor, Office of Global Health, Harvard School of Dental Medicine, Boston, Mass.
authors.forename: Romesh
authors.initials: R
authors.lastname: Nalliah
authors.affiliation: Assistant professor, Department of Pediatric Critical Care and Pharmacology, Rainbow Babies and Children's Hospital, University Hospitals, Case Medical Center, Cleveland, Ohio.
authors.forename: Veerajalandhar
authors.initials: V
authors.lastname: Allareddy
mesh_terms: D000328:Adult; D000367:Age Factors; D002648:Child; D002986:Clinical Trials as Topic; D018592:Cross-Over Studies; D016208:Databases, Factual; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D009316:National Institutes of Health (U.S.); D064887:Observational Studies as Topic; D009970:Orthodontics; D016032:Randomized Controlled Trials as Topic; D012042:Registries; D012107:Research Design; D012109:Research Support as Topic; D018401:Sample Size; D012737:Sex Factors; D016037:Single-Blind Method; D014481:United States; D014486:United States Food and Drug Administration / Q000331:legislation & jurisprudence