Objectives: The aim of this study was to describe inequalities in tooth loss and dissatisfaction with teeth related to time-invariant and time-variant socio-demographic characteristics and use of dental care across the middle and older life course and to assess whether oral health inequalities remain stable, widen or narrow from age 50 to 75.

Materials and methods: In 1992, 6346 residents, aged 50, consented to participate in a prospective cohort study including postal questionnaire follow-ups every fifth year until age 75. Tooth loss and dissatisfaction with teeth were assessed at each survey wave in addition to socio-demographic factors and use of dental care. Multivariable logistic regression, generalised estimating equations, GEE, and random intercept logistic mixed models were used for estimation of population-averaged and person-specific odds ratio. Interaction terms of each covariate with the time indicator were added to test whether inequalities changed across time.

Results: Person-specific OR and 95% CI estimates for tooth loss varied from 1.29 (1.09-1.53) (unmarried vs married) to 9.20 (6.07-13.94) (foreign country vs native). Estimated ORs for tooth dissatisfaction ranged from 1.33 (1.15-1.55) (unmarried vs married) to 2.59 (2.15-3.11) (smoking vs no smoking). Inequalities in tooth loss according to sex, educational level and country of birth were smaller in magnitude in 2017 than in 1992. Inequality estimates in dissatisfaction with teeth according to use of dental care and perceived health were, respectively, smaller and greater at older than at younger age.

Conclusion: Socio-demographic inequalities in oral health persisted from age 50 to 75 and varied in magnitude across time. Both convergence and widening of disparities in oral health occurred towards older ages.