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Table 3 Multivariable models for dental fluorosis

From: Hydrogeogenic fluoride in groundwater and dental fluorosis in Thai agrarian communities: a prevalence survey and case–control study

Variable Model 1, crude model (unadjusted) Model 2, adjusted for child’s demographic factors Model 3, adjusted for caregiver factors Model 4, adjusted for breastfeeding Model 5, adjusted for oral health behaviors Model 6, adjusted for all covariates
PR [95% CI] P-value PR [95% CI] P-value PR [95% CI] P-value PR [95% CI] P-value PR [95% CI] P-value PR [95% CI] P-value
Main exposure variable
Time-averaged fluoride concentration (ppm)*
 < 0.7 Reference Reference Reference Reference Reference Reference
 0.7–1.49 1.62 [0.78, 3.34] 0.195 1.62 [0.79, 3.32] 0.190 1.61 [0.28, 9.21] 0.592 3.08 [0.47, 20.04] 0.238 3.44 [0.48, 24.62] 0.218 1.64 [0.24, 11.24] 0.615
 ≥ 1.5 2.75 [1.42, 5.31] 0.003 2.78 [1.45, 5.32] 0.002 2.81 [0.51, 15.51] 0.235 5.30 [0.84, 33.45] 0.076 6.46 [0.94, 44.48] 0.058 2.85 [0.44, 18.52] 0.273
Child’s demographic factors
Sex
 Female    Reference        Reference
 Male    1.06 [0.86, 1.29] 0.596        1.07 [0.83, 1.37] 0.615
Age (year)
 < 8    Reference        Reference
 ≥ 8    1.19 [0.95, 1.50] 0.125        1.00 [0.75, 1.35] 0.976
Caregiver factors
Caregiver’s education
 ≥ Secondary school     Reference      Reference
 < Secondary school     1.25 [0.92, 1.69] 0.149      1.24 [0.91, 1.69] 0.178
Sufficiency of family income
 Sufficient      Reference      Reference
 Insufficient      0.84 [0.55, 1.30] 0.442      0.81 [0.51, 1.29] 0.378
Breastfeeding factor
Breastfeeding
 Yes        Reference    Reference
 No        1.28 [1.04, 1.57] 0.019    1.31 [0.97, 1.77] 0.078
Oral health behaviors
Brushing frequency before 2 years old
 No brushing          Reference Reference
 Once a day          1.29 [0.80, 2.08] 0.303 1.24 [0.76, 2.03] 0.397
 ≥ 2 times a day          0.94 [0.55, 1.59] 0.805 0.95 [0.55, 1.65] 0.854
Brushing frequency at ≥ 2 years old
 Once a day          Reference Reference
 ≥ 2 times a day          1.18 [0.89, 1.56] 0.253 1.16 [0.83, 1.63] 0.378
Fluoride toothpaste use
 No          Reference Reference
 Yes          1.06 [0.68, 1.65] 0.797 1.23 [0.46, 3.28] 0.685
Toothpaste size
 Pea-sized          Reference Reference
 > Pea-sized          1.20 [0.96, 1.50] 0.108 1.24 [0.94, 1.63] 0.130
  1. Multivariable models were estimated by Poisson regression with robust standard errors
  2. PR, Prevalence ratio
  3. *For each child, available measures of groundwater fluoride concentrations in drinking water sources supplying the child’s residence were time-averaged over the period of birth to the survey