Contrasting Patterns for Missing Third Molars in the United States and Sweden.

PURPOSE: 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. MATERIALS AND 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). CONCLUSION: 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.