Objectives Dental caries is a leading noncommunicable disease worldwide; however, its association with occupational factors, particularly long working hours, has not been elucidated. This study examined the longitudinal association between long working hours and dental caries in a large Korean working-age cohort.

Methods Using data from the Kangbuk Samsung Health Study (2013–2024), we analyzed 1 136 767 person-visits of workers aged 20–64 years. Long working hours were defined as >52 hours per week. Dental caries was identified from clinical oral examinations performed by licensed dentists. Associations were estimated using generalized estimating equations adjusted for age, gender, and educational level. Subgroup and sensitivity analyses were also performed.

Results Long working hours were significantly associated with dental caries (odds ratio 1.024, 95% confidence interval 1.007–1.041). In the subgroup analyses, compared with their respective counterparts, the association between long working hours and dental caries was significantly stronger among women, individuals with a college-level education or higher, and those with proactive oral health behaviors such as dental visits and toothbrushing before sleep.

Conclusions Long working hours were independently associated with the risk of dental caries; women and highly educated workers exhibited a stronger association with dental caries. These findings suggest the potential value of integrating oral health strategies into occupational health policies, particularly among more vulnerable subgroups.

Key terms dental care; dental caries; dental cavity; Korea; long working hour; longitudinal study; occupational health; oral health; oral hygiene; teeth; tooth decay

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