Table 3 Associations between D₃MFS (decayed, missing, filled surfaces) in the caries surface-based susceptibility hierarchy groups and their potential determinants, according to univariable and multivariable linear regression models with robust confidence intervals (95%CI) and significance (p values) among 35–74-year-olds (N = 946)

Socio-demographic characteristics

Fluoride level in drinking water

Lower-level < 0.7 ppm

Ref

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Ref

Ref

Ref

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Ref

Ref

Higher-level ≥ 0.7 ppm

− 0.15, 0.194

(− 0.38; 0.09)

− 0.23, 0.035

(− 0.44; − 0.001)

− 0.13, 0.615

(− 0.61; 0.36)

− 0.44, 0.034

(− 0.82; − 0.07)

− 0.49, 0.267

(− 1.4; 0.38)

− 1.14, 0.002

(− 1.88; − 0.41)

− 3.21, 0.098

(− 7.02; 0.59)

− 6.28, 0.001

(− 9.29; − 3.30)

Age/10 years

Continuous

0.29, 0.0001

(0.22; 0.36)

0.28, 0.001

(0.20; 0.36)

2.00, 0.0001

(1.05; 1.35)

1.20, 0.001

(1.05; 1.35)

2.47, 0.0001

(2.21; 2.74)

2.42, 0.001

(2.16; 2.66)

12.29, 0.0001

(11.21; 13.36)

12.05, 0.001

(10.84; 13.23)

Sex

Males

Ref

Ref

Ref

Ref

Ref

Ref

Ref

Ref

Females

0.47, 0.0001

(0.28; 0.65)

0.50, 0.001

(0.30; 0.72)

1.17, 0.0001

(0.76; 1.59)

1.28, 0.001

(0.86; 1.73)

1.61, 0.0001

(0.86; 2.35)

1.80, 0.001

(1.11; 2.47)

3.94, 0.018

(0.67; 7.22)

4.98, 0.003

(2.36; 7.95)

Education

Higher: 4 years or more

Ref

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Ref

Ref

Ref

Ref

Ref

Ref

Higher: < 4 years

0.36, 0.009

(0.09; 0.64)

0.12, 0.408

(− 0.16; 0.40)

0.89, 0.005

(0.28; 1.51)

− 0.12, 0.691

(− 0.73; 0.49)

2.38, 0.0001

(1.30; 3.47)

0.36, 0.426

(− 0.62; 1.35)

7.91, 0.001

(3.18; 12.65)

− 2.09, 0.231

(− 5.58; 1.42)

Secondary school or less

0.50, 0.001

(0.22; 0.79)

0.23, 0.141

(− 0.11; 0.57)

1.46, 0.0001

(0.82; 2.10)

0.24, 0.403

(− 0.45; 0.93)

3.80, 0.0001

(2.67; 4.93)

1.23, 0.025

(0.06; 2.31)

16.17, 0.0001

(11.25; 21.09)

2.80, 0.158

(− 1.55; 6.93)

Residency

Peri-urban/rural

Ref

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Ref

Ref

Ref

Ref

Ref

Ref

Urban

− 0.33, 0.001

(− 0.52; − 0.13)

− 0.12. 0.283

(− 0.09; 0.30)

− 0.73, 0.002

(− 1.19; − 0.28)

− 0.08, 0.690

(− 0.50; 0.33)

− 1.67, 0.0001

(− 2.48; − 0.87)

− 0.37, 0.317

(− 1.08; 0.31)

− 6.75, 0.0001

(− 10.27; − 3.23)

− 1.35, 0.406

(− 4.43; 1.71)

Oral health-related behaviors

Tooth brushing frequency

Twice a day or more

Ref

Ref

Ref

Ref

Ref

Ref

Ref

Ref

Once a day or less

0.07, 0.446

(− 0.11; 0.24)

0.10, 0.283

(− 0.9; 0.30)

0.32, 0.116

(− 0.08; 0.72)

0.40, 0.028

(0.05; 0.75)

0.78, 0.030 (0.07; 1.49)

0.63, 0.060

(− 0.02; 1.30)

4.24, 0.007

(1.15; 7.33)

2.21, 0.094

(− 0.71; 4.96)

Using fluoridated toothpaste

Yes

Ref

Ref

Ref

Ref

Ref

Ref

Ref

Ref

No

0.06, 0.668

(− 0.20; 0.31)

− 0.04, 0.708

(− 0.27; 0.18)

0.49, 0.095

(− 0.09; 1.07)

0.09, 0.704

(− 0.41; 0.59)

1.02, 0.053

(− 0.01; 2.05)

0.11, 0.808

(− 0.72; 0.94)

8.68, 0.0001

(4.21; 13.16)

4.23, 0.029

(0.52; 8.21)

Don’t know

0.10, 0.302

(− 0.09; 0.30)

0.03, 0.767

(− 0.15; 0.21)

0.17, 0.469

(− 0.28; 0.61)

− 0.12, 0.569

(− 0.52; 0.28)

0.51, 0.208

(− 0.29; 1.31)

− 0.09, 0.820

(− 0.71; 0.52)

4.46, 0.010

(1.10; 8.02))

1.73, 0.230

(− 0.98; 4.66)

Consumption of sugar- containing foods

Low

Ref

Ref

Ref

Ref

Ref

Ref

Ref

Ref

Moderate

− 0.01, 0.994

(− 0.21; 0.21)

0.09, 0.406

(− 0.11; 0.29)

− 0.08, 0.784

(− 0.56; 0.41)

0.23, 0.307

(− 0.21; 0.60)

− 0.23, 0.595

(− 1.10; 0.63)

0.45, 0.226

(− 0.27; 1.12)

0.50, 0.794

(0− 3.27; 4.27))

4.06, 0.007

(0.72; 7.17)

High

0.07, 0.586

(− 0.17; 0.30)

0.23, 0.067

(0.00; 0.46)

− 0.04, 0.894

(− 0.57; 0.50)

0.55, 0.038

(0.02; 1.08)

− 0.17, 0.734

(− 1.12; 0.79)

0.96, 0.031

(0.07; 1.76)

− 0.49, 0.818

(− 4.65; 3.67)

4.67, 0.011

(1.33; 8.10)

Last dental visit

12 months ago or less

Ref

Ref

Ref

Ref

Ref

Ref

Ref

Ref

More than 12 months ago

0.04, 0.682

(− 0.16; 0.24)

0.11, 0.302

(− 0.08; 0.31)

0.02, 0.925

(− 0.43; 0.47)

0.35, 0.119

(− 0.07; 0.80)

− 0.22, 0.591

(− 1.02; 0.58)

0.49, 0.174

(− 0.17; 1.09)

− 5.50, 0.002

(− 8.97; − 2.04)

− 1.87, 0.230

(− 4.97; 0.91)

R²

0.102

0.247

0.310

0.310

0.387