Dental caries prevalence and associated factors among schoolchildren aged 6–8 years in Macao: a cross-sectional study (2015–2020)

Dental caries is a highly prevalent non-communicable disease in children worldwide. However, recent epidemiological data specific to Macao are lacking. This study aimed to investigate the prevalence and associated factors of dental caries among schoolchildren aged 6–8 years in Macao during 2015 and 2020. A repeated cross-sectional study was conducted using data from the Macao Children Physical Fitness Surveillance Project in 2015 (n = 1,063) and 2020 (n = 808). Dental caries was diagnosed by calibrated dentists according to WHO criteria. Data on sociodemographics, oral hygiene behaviors, and physical activity were collected via guardian questionnaires. Multivariable binary logistic regression was used to identify factors associated with dental caries. The overall prevalence of dental caries was 57.4% in 2015 and 59.8% in 2020, with no significant change over time (P > 0.05). Multivariable analysis indicated that higher school grade was associated with increased caries risk (OR = 1.97 for 3rd vs. 1st grade). In contrast, more frequent physical activity, daily flossing (OR = 0.40), and higher BMI (OR = 0.93 per 1 kg/m² increase) were significantly associated with a lower prevalence of dental caries. The study reveals a persistently high burden of dental caries among children in Macao. Daily flossing and regular physical activity were significant protective factors, while a higher BMI showed a counterintuitive negative association with caries risk. These findings underscore the need for integrated public health interventions focusing on oral hygiene and physical activity, tailored to different grade levels.