Age–period–cohort analysis of trends in toothache prevalence among 15- to 64-yr-old Finns over a 25-yr period

Information on long-term trends in toothache prevalence is scarce. The aim of this study was to assess age-, period-, and cohort-related changes in toothache prevalence among 15- to 64-yr-old adults in Finland between 1990 and 2014 by using annual, representative postal surveys, albeit with decreasing response rates from 76% (n = 3,812) to 53% (n = 2,630). Age–period–cohort analysis of toothache prevalence during the past month was performed. Logistic regression analyses were conducted to account for other factors contributing to toothache. Toothache prevalence increased from 7% to 12% during the time period 1990 to 2014. Age–period–cohort analysis revealed that toothache prevalence increased from cohort to cohort, especially from the 1960 birth cohorts onwards (cohort effect). Adults under 30 yr of age had the highest toothache prevalence (~17%), while, in those over 30 yr of age, toothache prevalence decreased steadily according to age (to ~5% at age 64 yr, age effect). Toothache prevalence peaked at ~ 11% in the mid-2000s (period effect). Toothache was strongly associated with poorer perceived health and lower toothbrushing frequency and less strongly associated with higher educational level, a higher number of missing teeth, history of smoking, being single, separated, or divorced, and female gender. The increase in toothache prevalence occurred especially from 1990 to the mid-2000s, and mainly among younger age groups and more recent cohorts.