title: Contrasting Patterns for Missing Third Molars in the United States and Sweden.
abstract: OBJECTIVE
  The purpose of this study was to compare the prevalence of third molars from the US National Health and Nutrition Examination Survey (NHANES) and the Swedish survey.
  
  
  METHODS
  This cross-sectional study involved the comparison of the only published data on third molar prevalence. The number of visible third molars in the NHANES of 2011 through 2012 were assessed in nonclinical settings by trained, calibrated dental hygienists and reported by age decade (approximately 5,000 patients). Similar data were reported for the Swedish population with data collected in clinical settings (approximately 700 patients). The primary outcome variable was the number of third molars (0 to 4); the predictor variables were age cohorts (20 to 29 through 70 to 79 yr). Outcome data were reported with descriptive statistics.
  
  
  RESULTS
  In the youngest cohort (20 to 29 yr), having no visible third molars was more likely in the US population than in the Swedish population (47 vs 2%, respectively). By 50 to 59 years, outcomes for no third molars were similar in the United States and Sweden (53 and 57%, respectively).
  
  
  CONCLUSIONS
  The presence or absence of third molars reported from the US and Swedish populations presented contrasting patterns, particularly in the younger cohorts. More comprehensive and detailed data are required in future surveys as population studies on third molars become more important for clinicians and other stakeholders.
authors.affiliation: Resident, Department of Oral and Maxillofacial Surgery, School of Dentistry, University of North Carolina, Chapel Hill, NC.
authors.forename: Caitlin B L
authors.initials: CBL
authors.lastname: Magraw
authors.affiliation: Principal Surgeon, Copenhagen Clinic for Oral Surgery, Orthodontics & Implants, Copenhagen, Denmark.
authors.forename: Lars
authors.initials: L
authors.lastname: Pallesen
authors.affiliation: Research Applications Specialist, Department of Periodontology, School of Dentistry, University of North Carolina, Chapel Hill, NC.
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Moss
authors.affiliation: Adjunct Assistant Professor, Department of Oral and Maxillofacial Surgery, School of Dentistry, University of North Carolina, Chapel Hill, NC.
authors.forename: Elda L
authors.initials: EL
authors.lastname: Fisher
authors.affiliation: Chair and Kenan Distinguished Professor, Department of Periodontology, School of Dentistry, University of North Carolina, Chapel Hill, NC.
authors.forename: Steven
authors.initials: S
authors.lastname: Offenbacher
authors.affiliation: Dalton L. McMichael Distinguished Professor, Department of Oral and Maxillofacial Surgery, School of Dentistry, University of North Carolina, Chapel Hill, NC. Electronic address: ray_white@dentistry.unc.edu.
authors.forename: Raymond P
authors.initials: RP
authors.lastname: White
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008964:Molar, Third / Q000033:anatomy & histology*; D009749:Nutrition Surveys; D015995:Prevalence; D013548:Sweden; D014481:United States