Dental caries among 12-year-old adolescents in shanghai: a cross-sectional study on prevalence, severity, and associated risk factors

This study aimed to assess the prevalence, severity, and associated factors of dental caries in permanent teeth among 12-year-old adolescents in Shanghai, China. A cross-sectional study was conducted in 2021 among 1,305 adolescents from six randomly selected districts. Clinical examinations recorded dental caries (DMFT index), gingival bleeding, dental calculus, pit-and-fissure sealant, and dental crowding. Questionnaires collected data on sociodemographics, oral hygiene, sugar intake, and dental service use. A zero-inflated negative binomial regression model was used to identify factors associated with caries prevalence and severity. Caries prevalence was 27.9% (mean DMFT = 0.61 ± 1.26), with 72.1% caries-free and 17.1% having untreated decay. Caries burden was highly polarized: the top 10% accounted for 60% of total DMFT. In the multivariable ZINB model, female sex, dental crowding, gingival bleeding, and occasional toothache were associated with higher odds of having caries, while pit-and-fissure sealants and positive oral health attitudes were associated with being caries-free. Among affected adolescents, daily flossing, moderate-frequency sugar intake, poor self-rated oral health, and dental calculus were linked to greater caries severity. Caries prevalence among 12-year-olds in Shanghai has continued to decline over the past four decades, yet substantial untreated cases and polarization remain. Future strategies should strengthen monitoring and follow-up care for high-risk adolescents, while scaling up sealant coverage and promoting healthy dietary and oral hygiene practices.