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Table 4 Adjusted prevalence ratios (PRs) and 95% confidence intervals (CIs) for dental caries in relation to smoking in the household of 20,703 schoolchildren, RYUCHS, Japan

From: Household smoking and dental caries in schoolchildren: the Ryukyus Child Health Study

  Deciduous subgroup (n = 13,872) Permanent subgroup (n = 20,253)
  Adjusted PR1 (95% CI) Adjusted PR1 (95% CI)
Decayed and/or filled teeth   
   Smoking in household   
   Never 1.00 1.00
   Former 1.02 (0.99, 1.06) 1.03 (1.00, 1.06)
   Current <152 1.04 (1.02, 1.06) 1.05 (1.02, 1.07)
   Current ≥152 1.06 (1.04, 1.08) 1.03 (1.00, 1.06)
   P for trend < 0.0001 0.01
Pack-years of passive smoking in household  
   None 1.00 1.00
   0.1-2.9 1.03 (1.01, 1.06) 1.05 (1.02, 1.08)
   3.0-6.9 1.05 (1.03, 1.07) 1.02 (0.99, 1.05)
   ≥7.0 1.05 (1.03, 1.08) 1.04 (1.01, 1.07)
   P for trend <0.0001 0.006
Decayed teeth   
   Smoking in household   
   Never 1.00 1.00
   Former 1.06 (1.00, 1.12) 1.09 (1.01, 1.17)
   Current <152 1.08 (1.04, 1.12) 1.19 (1.13, 1.25)
   Current ≥152 1.12 (1.07, 1.16) 1.16 (1.10, 1.23)
   P for trend < 0.0001 < 0.0001
   Pack-years of passive smoking in household  
   None 1.00 1.00
   0.1-2.9 1.04 (1.00, 1.09) 1.12 (1.06, 1.20)
   3.0-6.9 1.12 (1.07, 1.17) 1.18 (1.12, 1.26)
   ≥7.0 1.11 (1.06, 1.16) 1.17 (1.11, 1.24)
   P for trend <0.0001 <0.0001
Filled teeth   
   Smoking in household   
   Never 1.00 1.00
   Former 1.00 (0.95, 1.04) 1.01 (0.96, 1.06)
   Current <152 1.03 (1.00, 1.06) 0.99 (0.96, 1.03)
   Current ≥152 1.05 (1.01, 1.09) 0.97 (0.93, 1.01)
   P for trend 0.003 0.19
   Pack-years of passive smoking in household  
   None 1.00 1.00
   0.1-2.9 1.04 (1.01, 1.07) 1.02 (0.98, 1.07)
   3.0-6.9 1.02 (0.98, 1.05) 0.96 (0.92, 1.00)
   ≥7.0 1.04 (1.00, 1.08) 0.99 (0.96, 1.03)
   P for trend 0.06 0.26
  1. 1 Adjustment for sex, age, region of residence, toothbrushing frequency, use of fluoride, sugar intake, and paternal and maternal educational level.
  2. 2 Number of cigarettes smoked in the household per day.