Exploring socioeconomic inequality in caries experience in an adult Norwegian population; the HUNT4 Oral Health Study

Objectives: To investigate socioeconomic inequality in caries experience in an adult Norwegian population. Methods: This population-based study included 4549 dentate participants aged 25-94 years from the cross-sectional HUNT4 Oral Health Study conducted in Central Norway in 2017-2019. Participants were randomly sampled from the larger HUNT4 Survey and answered questionnaires and underwent clinical and radiographic examinations. Caries experience was measured as numbers of decayed, missing and filled teeth (DMFT index) and socioeconomic position was denoted by education and household income. Negative binomial regression models were used to estimate associations between caries experience and socioeconomic position. Results: Lower levels of both education and income were associated with higher caries experience, particularly pronounced for missing teeth. Socioeconomic gradients were observed for all outcomes DMFT, DT, MT and FT (p-value linear trends <.001). Gradients were similar for both income and education and were apparent for all age groups but were most evident in middle-aged and older individuals. High level of education was associated with a 50% lower mean number of missing teeth compared with basic level education, whereas high income was associated with a 24% lower mean number of decayed teeth and a 15% higher mean number of filled teeth than low income. Conclusions: There was a socioeconomic gradient for caries experience in the study population that was present from early adulthood and increased with age. The gradient was particularly pronounced for missing teeth. Findings indicate that inequality was more associated with treatment given than with untreated disease.