Prospective Cohort Study of Thai Children
SECONDHAND SMOKING IN PREGNANT WOMEN
AND TIME OF THE FIRST TOOTH ERUPTION
DIEN HOA ANH VUPhD Student – Faculty of Dentistry
Khon Kaen University
CONTENT
• INTRODUCTION
• OBJECTIVE
•METHODS
• RESULTS
• DISCUSSION
• CONCLUSION
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ABBREVIATION
• BW Birth Weight
• DTE Delayed first Tooth Eruption
• PCTC Prospective Cohort study of Thai Children
• SHS Secondhand Smoking
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INTRODUCTION
• DTE: problems / dental development
• hold space
• align into correct position
• chew and speak
• Influence factors
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INTRODUCTION
• Secondhand smoking (SHS)
• Negative effect
• Common in Thai males
• High prevalence (29.8%) of SHS
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OBJECTIVE
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To determine whether SHS during pregnancy period delayed
the time of first tooth eruption in Thai infants
METHODS – Study Design
• Part of PCTC
• Large birth cohort study: 4,300 infants, 5 sites in Thailand
• October 15, 2000 and September 14, 2002
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• Inclusion criteria:
• accessible year-round
• 800 to 900 newborns on average each year
• intend to live 5 years
• long-term commitment with the project
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METHODS – Study Design
• Family members
• In-person interview, diary records, medical records
• Secondary data – community and demographic variables
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METHODS – Study Design
• Informed consent
• The National Ethics Committee of the Ministry of Public Health of Thailand
• Khon Kaen University Ethics Committee for Human Research
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METHODS – Study Design
Independent variables
•SHS during pregnancy: Yes/No•Number of cigarettes: • 0• 0 < CIG < 50th percentile• 50th percentile +
Outcomes
•DTE: Yes/No
•Time to eruption of the first tooth
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METHODS – Independent variables and outcomes
METHODS – Potential bias
• Parents’ education level
•Mother’s age
• Child’s gender
• Birth weight
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METHODS – Statistical Analysis
• Description analysis
• Pearson regression
• Cox proportional regression
• Generalized estimating equation
• Stata SE 12.0
• p-value < .05
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RESULTS – Study sites
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Figure 1. Number of study members and location of PCTC sites in Thailand
RESULTS – Demographic Characteristics
Characteristics Total Sites
North(n=xxx)
Northeast(n=xxx)
Central(n=xxx)
South(n=xxx)
Bangkok(n=xxx)
Mother’s age (years)Mother’s highest education Father’s age (years)Father’s highest education Child’s genderBirth weight
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Table 1. Demographic characteristics in five study sites
RESULTS
Table 2. Odds ratio of having DTE among five study sites04/21/23 16
Area Number % DTE Crude OR 95%CI p-value
North xxx xx.x 1.00 Reference 0.xxx
Northeast xxx xx.x x.xx x.xx – x.xx
Central xxx xx.x x.xx x.xx – x.xx
South xxx xx.x x.xx x.xx – x.xx
Bangkok xxx xx.x x.xx x.xx – x.xx
RESULTS
n % Crude HR (95% CI) Adjusted HR* (95% CI)
Non-SHS xxxx xx.xx 1 Reference 1 Reference
SHS < 50th percentile xxxx xx.xx x.xx x.xx – x.xx x.xx x.xx – x.xx
SHS ≥ 50th percentile xxxxx xx.xx x.xx x.xx – x.xx x.xx x.xx – x.xx
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Table 3. Crude and adjusted hazard ratio of DTE between levels of smoking groups and non-smoking group
* Hazard ratio adjusted for child’s gender, maternal age, parents’ highest education level, birth weight, and alcohol drinking and caffeine consumption during pregnancy
RESULTS
Figure 2. Positive association between the number of cigarettes smoked by the fathers and the time of first tooth eruption
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RESULTS
Figure 3. Difference in the probability of DTE between SHS group and non-SHS group
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DISCUSSION
• The time of first tooth eruption was delayed in SHS women
• Biological plausible
• Consistent with other previous studies
• Similar with the study of Adler et al.
• Lawoyin et al. – Opposite relationship between BW and time of first tooth eruption.
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DISCUSSION – Strength
• Strongest observational design
•Multiple risk factors
• Large birth cohort study
• National representative
•Minimal loss to follow-up
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DISCUSSION – Limitation
• Information bias – trained and calibrated the interviewers
• Potential confounding factors – adjusting
• Causal inferences – suspect
• Change of association over time?
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CONCLUSION
• SHS in Thai pregnant women was associated with delayed time of the first tooth eruption in infants up
•Many problems in the dental and nutritional development of infants
• Further studies
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REFERENCES