Table 4 Combined effect between Ca intake and physical activity on dental caries in age, obesity, and total sugar intake subgroups

Age

< 12 years old (n = 4002)

≥ 12 years old (n = 1915)

 Ca reach recommendation level & physical activity = 7

Ref

Ref

 Ca reach recommendation level & physical activity < 7

1.24 (0.91–1.70)

0.165

1.04 (0.52–2.07)

0.910

 Ca not reach recommendation level & physical activity = 7

1.45 (1.12–1.88)

0.006

0.94 (0.40–2.18)

0.880

 Ca not reach recommendation level & physical activity < 7

1.62 (1.23–2.14)

0.001

1.56 (0.65–3.73)

0.312

 P for trend

0.001

0.068

Obesity

No (n = 4635)

Yes (n = 1282)

 Ca reach recommendation level & physical activity = 7

Ref

Ref

 Ca reach recommendation level & physical activity < 7

1.26 (0.98–1.62)

0.069

0.97 (0.44–2.12)

0.930

 Ca not reach recommendation level & physical activity = 7

1.47 (1.14–1.89)

0.004

0.93 (0.55–1.57)

0.789

 Ca not reach recommendation level & physical activity < 7

1.88 (1.49–2.35)

< 0.001

1.28 (0.60–2.75)

0.511

 P for trend

< 0.001

0.248

Total sugar intake

≤ 98 gm (n = 3010)

> 98 gm (n = 2907)

 Ca reach recommendation level & physical activity = 7

Ref

Ref

 Ca reach recommendation level & physical activity < 7

2.02 (1.24–3.30)

0.006

0.94 (0.66–1.36)

0.751

 Ca not reach recommendation level & physical activity = 7

2.06 (1.36–3.14)

0.001

1.11 (0.80–1.55)

0.524

 Ca not reach recommendation level & physical activity < 7

2.71 (1.70–4.32)

< 0.001

1.39 (1.02–1.89)

0.038

 P for trend

< 0.001

0.006