Prospective Cohort Study of Thai Children

1. Prospective Cohort Study of Thai Children SECONDHAND SMOKING IN PREGNANT WOMEN AND TIME OF THE FIRST TOOTH ERUPTION DIEN HOA ANH VU PhD Student – Faculty of Dentistry Khon Kaen University

2. CONTENT • INTRODUCTION • OBJECTIVE • METHODS • RESULTS • DISCUSSION • CONCLUSION

3. ABBREVIATION • BW Birth Weight • DTE Delayed first Tooth Eruption • PCTC Prospective Cohort study of Thai Children • SHS Secondhand Smoking

4. INTRODUCTION • DTE: problems / dental development • hold space • align into correct position • chew and speak • Influence factors

5. INTRODUCTION • Secondhand smoking (SHS) • Negative effect • Common in Thai males • High prevalence (29.8%) of SHS

6. OBJECTIVE To determine whether SHS during pregnancy period delayed the time of first tooth eruption in Thai infants

7. METHODS – Study Design • Part of PCTC • Large birth cohort study: 4,300 infants, 5 sites in Thailand • October 15, 2000 and September 14, 2002

8. METHODS – Study Design • Inclusion criteria: • accessible year-round • 800 to 900 newborns on average each year • intend to live 5 years • long-term commitment with the project

9. METHODS – Study Design • Family members • In-person interview, diary records, medical records • Secondary data – community and demographic variables

10. 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

11. METHODS – Independent variables and outcomes Outcomes • DTE: Yes/No • Time to eruption of the first tooth Independent variables • SHS during pregnancy: Yes/No • Number of cigarettes: • 0 • 0 < CIG < 50th percentile • 50th percentile +

12. METHODS – Potential bias • Parents’ education level • Mother’s age • Child’s gender • Birth weight

13. METHODS – Statistical Analysis • Description analysis • Pearson regression • Cox proportional regression • Generalized estimating equation • Stata SE 12.0 • p-value < .05

14. RESULTS – Study sites Figure 1. Number of study members and location of PCTC sites in Thailand

15. RESULTS – Demographic Characteristics Table 1. Demographic characteristics in five study sites

16. RESULTS Table 2. Odds ratio of having DTE among five study sites

17. RESULTS * Hazard ratio adjusted for child’s gender, maternal age, parents’ highest education level, birth weight, and alcohol drinking and caffeine consumption during pregnancy Table 3. Crude and adjusted hazard ratio of DTE between levels of smoking groups and non-smoking group

18. RESULTS Figure 2. Positive association between the number of cigarettes smoked by the fathers and the time of first tooth eruption

19. RESULTS Figure 3. Difference in the probability of DTE between SHS group and non-SHS group

20. 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.

21. DISCUSSION – Strength • Strongest observational design • Multiple risk factors • Large birth cohort study • National representative • Minimal loss to follow-up

22. DISCUSSION – Limitation • Information bias – trained and calibrated the interviewers • Potential confounding factors – adjusting • Causal inferences – suspect • Change of association over time?

23. 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

24. REFERENCES