Dental caries in a Norwegian adult population, the HUNT4 oral health study; prevalence, distribution and 45-year trends.

OBJECTIVE: To investigate dental caries prevalence amongst adults in Central Norway and assess changes over the last 45 years. MATERIALS AND METHODS: The cross-sectional HUNT4 Oral Health Study was conducted in 2017-2019. A random sample of 4913 participants aged >/=19 years answered questionnaires and underwent clinical and radiographic examinations. Data were compared to findings from previous studies in the same region conducted from 1973 to 2006. RESULTS: Mean number of decayed, missing and filled teeth (D(3-5)MFT) was 14.9 (95% CI 14.7, 15.1), 56% of adults had one or more carious teeth (D(3-5)T) and 11.8% had >/=4 D(3-5)T, with the mean number of 1.4 (95% CI 1.32, 1.42). For initial caries, mean D(1-2)S was 3.8 (95% CI 3.7, 3.9), being the highest for 19-24-year-olds at 8.6 (95% CI 7.9, 9.3). Comparisons with earlier studies showed a decline in mean D(3-5)MFT for 35-44-year-olds from 26.5 in 1973 to 10.8 in 2019. In 1973, 4.8% of 35-44-year-olds were edentulous, while in present study edentulousness was found only in individuals >65 years. CONCLUSIONS: Despite a substantial reduction in caries experience over the last 45 years, untreated dentine caries was common, evenly distributed across all age groups. Initial caries particularly affected younger individuals, indicating a need to evaluate prevention strategies and access to dental services.