Changes in dental status and dental care utilization in the Swedish population over three decades: age, period, or cohort effects?

Objectives: In cross-sectional data, cohort effects give a false impression of changes in edentulousness over age and time. This study, therefore, corroborated cross-sectional data with corresponding longitudinal analyses. Complete or partial edentulousness and yearly dental care utilization were studied from 1968 to 2002. Results: A nationally representative Swedish panel study allowed repeated cross-sectional comparisons of ages 18-75 (5 waves n approximate to 5000), and ages 77+ at later waves (2 waves n approximate to 500). Cross-sectional 10-year age group differences in 5 waves, time-lag differences between waves for age groups, and within-cohort differences between waves for 10-year birth cohorts were examined. Regular over time analysis revealed large decreases in edentulousness between waves. While cross-sectional differences indicated an exponential curve-linear age-dependency, longitudinal differences revealed little decline, contradicting cross-sectional results. Following the cohorts showed little change within cohorts but large differences between cohorts. Care utilization increased between 1968 and 2002 in older age groups but decreased somewhat in younger ones. In 1968, utilization was highly age-related with lower utilization rates among older age groups. By 2000/2002, this had almost reversed. However, all cohorts had aged with little change in their rates of care utilization, while at the same time great between-cohort differences were demonstrated. Conclusions: For both edentulousness and dental care utilization, almost all variation originated before 1968. These cohort effects are probably the consequences of changes in dentistry going back several decades and they demonstrate the early socialization of health behavior.