Dental caries among over 1.5 million records of schoolchildren in Singapore, 2007 - 2019: age-period-cohort effect analyses.

Abstract

This study aimed to examine the effects of age, period (historical events), and cohort (generational impact) - APC on caries prevalence and mean DMFT among Singapore schoolchildren from 2007 to 2019. Anonymized records of all 6-year-old Primary 1 (P1), 11-year-old Primary 6 (P6), and 14-year-old Secondary 3 (S3) students before the start of each school year between 2007 and 2019 were extracted from the Integrated Dental Electronic Assessment System (IDEAS), categorised by school level, ethnicity, and sex. Poisson regression and Partial Least Squares (PLS) regressions were applied to estimate APC effects. In total, 502339 P1, 535579 P6, and 496725 S3 records were included from 2007 to 2019, with 1058589 (69.0%) Chinese, 187948 (12.2%) Malay, and 152618 (9.9%) Indian students; 245447 (48.8%) P1, 259389 (48.4%) P6, and 243941 (49.1%) S3 students were girls. Overall, the APC effects on caries prevalence and mean DMFT showed a strong age effect, with the lowest prevalence in the youngest P1 group and the highest in the oldest S3 group. Period and cohort effects were identified, with the prevalence decreasing among those born after 1995 and the lowest prevalence rate in 2013. Similarly, period and cohort effects on mean DMFT were also detected, with decreased mean DMFT after period 2009 and the highest mean DMFT (0.72 in P6 and 1.13 in S3) in cohort 1995. Caries prevalence and DMFT increased with age. While both decreased in individuals born after 1995, mean DMFT began to rise again in those born after 2003.