Exposure to Secondhand Smoke and the Development of Childhood Caries: NHANES 2011-2012

According to the World Health Organization more than half of the children world-wide are exposed to tobacco smoke, with the majority of this exposure occurring at home. Recently there is growing evidence linking secondhand smoke to the development of dental caries in the pediatric population.  Children with family members who smoke are noted to have more decayed, missing or filled teeth compared to children who have no smokers in the family. 

Dental caries continue to plague young children with numerous adverse effects including pain, poor growth and development, decreased quality of life as well as the potential for the development of life threatening secondary infections.  Oral health is not only linked to a child’s quality of life but also to their general health.  Development of dental disease during childhood can also increase the risk for developing adult periodontal disease, which has been associated with cardiovascular disease, respiratory disease, diabetes and, in pregnant women, as adverse perinatal outcomes.

Factors associated with the development of childhood caries are numerous and complex as they are related to social, economic and/or cultural behaviors.  Despite previous literature linking secondary smoke to dental caries in children, the majority of parent oral health education focuses on dietary habits, oral hygiene habits, fluoride supplementation and the importance of preventive dental care.  

Purpose: The purpose of the study was to investigate the association between a child’s exposure to secondhand smoke and the development of dental caries taking into account the child’s sugar intake, dental care experiences and sociodemographic factors. 

Methods: Cross-sectional data of children age 4 to 11 from the U.S. National Health and Nutrition Examination Survey (NHANES) (2011-2012) were utilized.  Data from NHANES is collected from representative U.S. populations using a multistage, stratified, cluster sampling design. Data are obtained via personal household interviews and health examinations. The household interview collects demographic, socioeconomic, dietary, and health history information. The examination component consists of physical and dental examinations and various laboratory tests. The primary independent variables of interest were environmental tobacco smoke (ETS) exposure noted by: 1) the number of cigarette smokers living inside the house; 2) the quantity of cigarettes smoked inside the house; and 3) serum cotinine level of 0.2 ng/mL or greater.  Additional independent variables associated with dental caries included the household references person’s age, gender, race, marital status, socioeconomic status, education level of the head of household, health insurance, mother’s age when the child was born, mother’s smoking status during pregnancy, child’s birth weight, current weight status of the child, use of dental services, and sugar intake.  Dental caries status was defined as a tooth which was: 1) missing due to dental disease, 2) missing due to dental disease but replaced by a removable or fixed restoration and/or, 3) a primary or secondary tooth with surface conditions.  Bivariate analysis was completed to determine associations with dental caries status.  Variables with p<0.1 in the bivariate association were included in multivariable logistic regression analyses to determine independent associations with dental caries status.  All analyses accounted for NHANES’ complex sampling design and p<0.05 was considered statistically significant.

Results: A total of 1,551 children ages 4 to 11 years were included in the analysis with 52% (n=811) found to have at least one missing tooth or tooth with surface changes. Overall, 13% (n=199) were noted to have a smoker inside the home, while 36% of these children had two or more active smokers in their homes. Serum cotinine levels were found to be at a moderate level (0.2-1.0 ng/ml) in 12% and high level (>1 ng/ml) for 8% of the children. Children living in home where one or more cigarettes were smoked daily were 1.59 times more likely to have dental caries compared to those who had no cigarette smoked in the house (95% CI=1.02-2.47, p=0.041); however, cotinine levels were not found to be significantly associated with caries status. Income level continues to be a major factor influencing caries status. Children living in a family with an income to poverty ratio less than 1.25 were 1.79 times more likely to have dental caries compared to an income to poverty ratio 4 and above (95% CI=1.06-3.03, p=0.029). Children without any insurance were at highest risk and 2.5 times more likely to have dental caries (95% CI=1.41-4.41, p=0.002) while those with Medicare/Medicaid were 1.67 times more likely to have dental caries compared to those with private insurance (95% CI=1.08-2.58, p=0.021). Additionally, those children whose last dental visit was for preventive services were 74% less likely to have dental caries compared to those whose main reason for their dental visit was an active problem (95% CI=0.14-0.46, p<0.001). 

Conclusions: Dental caries, a preventable disease, continues to be a common chronic problem experienced by numerous children.  The results of this study provide further evidence of the vulnerability of children to environmental exposures and those from lower socioeconomic levels that place them at risk for adverse health outcomes including dental caries and possible long term health consequences associated with dental decay. Further, despite having Medicaid insurance that includes dental coverage, children living below the poverty level continue to suffer from dental disease at a higher rate than those with private insurance. Behaviors associated with tobacco use may also result in other unhealthy behaviors related to childhood caries such as poor oral hygiene practices, poor dietary habits and decrease use of preventive services.  Recognizing that the exposure to secondhand smoke can increase the risk for childhood caries and is also amenable to behaviors, it is critical to emphasize the importance of avoiding tobacco exposure in future educational information and programs aimed at improving oral and primary care health outcomes for children and families.