Streptococcus mutans, (S.mutans), is the leading cause of decay and produces acids from sugar that is consumed and dissolves hard enamel coating on teeth.
Secondhand smoke directly affects teeth and microorganisms in a number of ways, including inflammation of the oral membrane, damage to the salivary gland function and a decrease in serum vitamin C levels, as well as immune dysfunction. Children exposed to passive smoking lowers salivary IgA, (Immunoglobulin A), levels and produces higher levels of sialic acid with higher activity. Sialic acid allows S. mutans to form dental plaque and caries.
The research team analyzed data of 76,920 Japanese children born between 2004 and 2010, who attended routine health checkups at 0, 4, 9 and 18 months, and at 3 years of age at health care centers in Kobe City, Japan.
An evaluation was completed by who provided information about secondhand smoke exposure from pregnancy to 3 years of age and other lifestyle factors, such as dietary habits and oral care. Dental problems were defined as at least one decayed, missing or filled tooth assessed by qualified dentists.
The research findings identified prevalence of smoking as 55.3%, and 6.8% with children showed evidence of tobacco exposure. A total of 12,729 cases of dental caries were identified, mostly decayed teeth.
Exposure to tobacco smoke at 4 months of age was associated with an approximately twofold increase in the risk of caries. “Exposure to secondhand smoke at 4 months of age, which is experienced by half of all children of that age in Kobe City, Japan, is associated with an increased risk of caries in deciduous teeth. Although these findings cannot establish causality, they support extending public health and clinical interventions to reduce secondhand smoke,” said the lead author of the study.
Secondhand smoke and incidence of dental caries in deciduous teeth among children in Japan: population based retrospective cohort study, Shiro Tanaka et al., The BMJ, doi: 10.1136/bmj.h5397, published 21 October 2015.