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Table 3 Bi-variate analysis of each risk factor and TF score (as five categories and dichotomised)

From: Dental fluorosis in populations from Chiang Mai, Thailand with different fluoride exposures – Paper 1: assessing fluorosis risk, predictors of fluorosis and the potential role of food preparation

Explanatory Variables : Water Continuous Data obtained by water sample analysis (ppm F)

TF score (5 categories)

TF 0–2 versus 3+

ANOVA

Binary Logistic Regression

F-ratio

df

p-value

Odds ratio

p-value

(95% CI)

Drinking water

11.31

4, 555

<0.001

2.71*

<0.001

(1.75, 4.18)

Cooking water

22.27

4, 555

<0.001

1.67*

<0.001

(1.39, 2.01)

Explanatory Variables: Water Interval Data (ppm F)

Cross Tabulations

Binary Logistic Regression

χ 2

df

p-value

Odds ratio

p-value

(95% CI)

Drinking water (ref <0.20)

45.97

12

<0.001

   

0.2 to 0.59

   

1.26

0.41

(0.73, 2.20)

0.6 to 0.89

   

1.33

0.47

(0.61, 2.94)

0.9+

   

4.02

<0.001

(2.12, 7.63)

Cooking water (ref <0.20)

93.33

16

<0.001

   

0.2 to 0.59

   

1.36

0.55

(0.50, 3.71)

0.6 to 0.89

   

2.20

0.94

(0.87, 5.33)

0.9 to 1.59

   

3.58

0.005

(1.47, 8.77)

1.6+

   

6.77

<0.001

(2.86, 16.02)

Drinking water (ref <0.20)

34.62

8

<0.001

   

(Age 3) 0.2 to 0.59

   

0.99

0.98

(0.52, 1.88)

0.6+

   

2.47

0.002

(1.40, 4.34)

Cooking water (ref <0.20)

83.582

16

<0.001

   

(Age 3) 0.2 to 0.59

   

1.16

0.74

(0.47, 2.87)

0.6 to 0.89

   

1.87

0.15

(0.80, 4.39)

0.9 to 1.59

   

3.27

0.005

(1.43, 7.50)

1.6+

   

6.28

<0.001

(2.82, 13.96)

Water formula (ref <0.20)

40.74

16

= 0.001

   

0.2 to 0.59

   

1.27

0.58

(0.55, 2.93)

0.6 to 0.89

   

1.35

0.55

(0.50, 3.65)

0.9 to 1.59

   

3.30

0.12

(1.30, 8.38)

1.6+

   

5.45

<0.001

(2.10, 14.11)

Water infant food (ref <0.20)

87.13

16

<0.001

   

0.2 to 0.59

   

1.26

0.57

(0.57, 2.77)

0.6 to 0.89

   

1.56

0.29

(0.69, 3.54)

0.9 to 1.59

   

3.10

0.004

(1.42, 6.74)

1.6+

   

5.77

<0.001

(2.76, 12.05)

Explanatory Variables : Oral Hygiene Practices

χ 2

df

p-value

Odds ratio

p-value

(95% CI)

Age toothbrush starts (ref 4 years+)

11.18

16

0.80

   

3-4 years

   

1.37

0.42

(0.64, 2.96)

2-3 years

   

1.15

0.72

(0.50, 2.45)

1-2 years

   

1.12

0.79

(0.54, 2.48)

0-1 year

   

1.24

0.73

(0.36, 4.36)

Toothbrushing frequency (ref once per day)

6.63

8

0.58

   

2

   

0.90

0.331

(0.53, 1.55)

3+

   

1.46

0.309

(0.71, 3.00)

Fluoride content of paste (ref < 1000 ppm)

9.69

4

0.46

   

1000 ppmF

   

0.55

0.06

(0.29, 1.04)

Other explanatory variables

χ 2

df

p-value

Odds ratio

p-value

(95% CI)

Feeding pattern (ref Breast alone)

12.87

8

0.12

   

Breast & formula

   

0.61

0.61

(0.37, 1.01)

Formula only

   

1.33

0.43

(0.66, 2.69)

Gender (ref male)

2.04

4

0.729

   

female

   

0.95

0.83

(0.61, 1.48)

  1. * odds ratios reported, but residuals strongly related to the fluoride levels for both variables.