Abstract
Background: Environmental tobacco smoke (ETS) has been associated with a number of negative health outcomes for children, including sudden infant death syndrome, upper and lower respiratory illnesses, middle ear diseases, asthma and also non-respiratory illnesses such as attention deficit/hyperactivity and irritable bowel syndrome. Recently, there has been increasing interest in the potential impact of ETS on dental caries. However the findings have not been conclusive enough to confirm that passive smoking exposure contributes to dental caries, especially in children. Exposure to ETS also has been associated with other oral diseases in children including dental hard tissue anomalies, periodontal disease, and melanin pigmentation of the gingiva.
Objective: The aims of this study were firstly to determine the association between exposure to ETS and the prevalence of oral diseases (including dental caries, dental hard tissue anomalies, periodontal disease and gingival melanin pigmentation) in preschool aged children with and without exposure to ETS. The second aim was to compare the levels of known cariogenic bacteria and Candida albicans in supragingival plaque and saliva and the levels of total salivary immunoglobulin A (SIgA) in children who had been exposed to ETS and those who had never been exposed to ETS.
Methods: A structured questionnaire was used to collect data on the child’s current and previous illnesses, oral health behaviours, dietary habits, parental smoking behaviours and parents’ dental history. Supragingival plaque samples were collected prior to an intraoral examination, using an interproximal tooth brush (Colgate®). The intraoral examination involved examination of teeth present in the mouth, dental caries, enamel defects, gingival health, melanin pigmentation and other intraoral soft tissues. Stimulated saliva was collected using a cylinder saliva collector (Salivette™, Sarstedt, Inc.). Supragingival plaque and saliva were cultured on Mutans Selective Agar (MSA), Rogosa Agar (RA) and CHROMagar to determine the levels of Streptococcus mutans, Lactobacillus and Candida albicans. Total SIgA levels were quantified using indirect competitive ELISA with a Salimetrics™ kit.
Results: Forty-four children (aged 15 to 69 months) were included in this study. They were divided into two groups: ETS and non-ETS (control) based on their exposure to ETS. There were 22 children in each group. Sixteen children who had been exposed to ETS throughout pregnancy and after they were born were identified in an ETSB subgroup. More males than females were found to have had upper respiratory tract and middle ear infections during the neonatal period. Exposure to ETS was a risk factor of having these illnesses during this period. After six months, although the children who had been exposed to ETS reported more medical conditions than the non-exposed children, the difference was not statistically significant. It was found that mothers who smoked either never breastfed their children or breastfed their children for less than the recommended period of six months. Children exposed to ETS were shown to be at risk of having dental caries because they showed poorer dietary habits even though more children in this ETS group used the recommended 1000 ppm fluoride toothpaste than children in the control group. Children exposed to ETS were also found to have higher mean dmft, mean dmfs, mean percent of surfaces with demarcated opacities and higher mean Gingival Index (GI) than the non-exposed children. The children exposed to ETS before and after birth had the highest occurrence of enamel opacities. Children in the ETS group also had higher levels of Streptococcus mutans (both in plaque and saliva) and Candida albicans (in saliva) than the children in the control group. Children exposed to ETS were shown to have higher mean total SIgA (µg/ml) than the children in the control group.
Conclusion: Findings from this study show associations between exposure to ETS and oral diseases, especially dental caries. The present study did not find sufficient statistically significant evidence to determine the exact role of maternal smoking during pregnancy in contributing to oral diseases in children. Therefore, further studies, especially prospective studies with larger numbers of participants, with a focus on maternal smoking during pregnancy and afterwards should be conducted to investigate the impact of ETS (especially during pregnancy and after) on the occurrence of tooth enamel defects and other oral diseases in children.