Table 4 Logistic regression for the dental caries status

Gender

 Boy (ref)

–

–

–

–

 Girl

1.14 (1.03, 1.27)

0.01

1.12 (1.01, 1.25)

0.04

Only Child

 Yes (ref)

–

–

 No

1.06 (0.95, 1.17)

0.32

Father's education level

 Middle school and below (ref)

–

–

 High school

1.00 (0.85, 1.18)

0.99

 Junior college

1.07 (0.90, 1.27)

0.45

 Bachelor and above

0.90 (0.77, 1.05)

0.18

Mother's education level

 Middle school and below (ref)

–

–

–

–

 High school

1.23 (1.04, 1.44)

0.01

1.15 (0.98, 1.36)

0.09

 Junior college

1.13 (0.96, 1.33)

0.13

1.03 (0.87, 1.22)

0.74

 Bachelor and above

0.99 (0.86, 1.15)

0.91

0.91 (0.77, 1.07)

0.24

Tooth brushing frequency

 ≥ 2 times a day (ref)

–

–

–

–

 Once a day

1.36 (0.61, 3.17)

0.46

1.51 (0.66, 3.60)

0.33

 Not every day

1.85 (0.86, 4.18)

0.12

1.97 (0.90, 4.54)

0.10

 Seldom or never

2.18 (1.02, 4.92)

0.05

2.36 (1.08, 5.44)

0.04

Time since last dental visit

 Never (ref)

–

–

–

–

 More than 1 year

1.88 (1.61, 2.20)

< 0.001

1.58 (1.35, 1.86)

< 0.001

 Less than 1 year

1.85 (1.62, 2.11)

< 0.001

1.50 (1.29, 1.73)

< 0.001

Dessert

 < 1 time/day (ref)

–

–

–

–

 ≥ 1 time/day

1.23 (1.08, 1.38)

0.001

1.14 (1.00, 1.29)

0.04

Soft drinks

 < 1 time/day (ref)

–

–

–

–

 ≥ 1 time/day

1.16 (1.04, 1.30)

0.008

1.21 (1.07, 1.36)

0.002

Beverage with sugar

 < 1 time/day (ref)

–

–

 ≥ 1 time/day

1.08 (0.97, 1.20)

0.17

Tooth pain in the past 12 months

 Always (ref)

–

–

–

–

 Occasionally

1.10 (0.76, 1.58)

0.62

1.07 (0.73, 1.55)

0.73

 Never

0.52 (0.36, 0.74)

< 0.001

0.55 (0.38, 0.80)

0.002

 Don't remember

0.93 (0.58, 1.49)

0.76

0.96 (0.59, 1.55)

0.86

Parents’ oral health knowledge

 Score 0–3 (ref)

–

–

 Score 4–6

0.92 (0.80, 1.06)

0.26

 Score 7–9

1.05 (0.82, 1.35)

0.68

Parents’ oral health attitude

 Score 0–2 (ref)

–

–

 Score 3–4

0.99 (0.72, 1.37)

0.97