AZ 43/09), CAPES (grant selleck screening library no. BEX1319/05) and CNPq (305574/2008-6). We also thank the Special Laboratory of Lasers in Dentistry (LELO) of the Dental School of the University of São Paulo (USP). Competing interests: None. Ethical approval: Teeth donators signed an informed consent form and the experiments followed the principles of the Helsinki Declaration. “
“Tobacco use has become a habit in

the Western world, including the American continent. The tobacco, especially cigarette smoking, is the leading cause of preventable death. Although evidence indicates a decline in the number of smokers over the last 30 years, this addiction continues to be an important public health problem.1, 2 and 3 More than 4000 substances can be isolated from cigarettes, with nicotine being responsible for the dependence-forming properties of smoking,

amongst other harmful effects.4, 5 and 6 The effects of active smoking on the oral cavity and associated structures predispose Selleck Sirolimus to the occurrence of precancerous and cancerous lesions.7, 8, 9, 10, 11, 12, 13 and 14 The salivary glands are one of the most important associated structures. These glands consist of a secretory epithelium and a glandular stroma. The stroma forms a microenvironment of extracellular matrix that is fundamental for the homeostasis of this organ.15 and 16 The salivary glands are also targets of the effects of cigarette smoking. For example, the observation of cellular DNA damage demonstrates the potential carcinogenic action of nicotine, one of the components of tobacco smoke.17 Other organs are also affected by active smoking, which destructures the epithelium and adjacent connective tissue, consequently impairing the interaction between 4-Aminobutyrate aminotransferase these tissue compartments.

Some investigators have demonstrated that cigarette agents induce extracellular matrix alterations.18 and 19 In addition to the systemic and local effects of active smoking described in the literature, passive smoking has shown a possible relationship with dental problems, decreases in salivary pH, alterations in salivary flow rate, buffering capacity and protein levels, harmful effects during pregnancy, amongst others.20, 21 and 22 Chatzimichael et al. studying 240 children with bronchitis aged 6 months to 2 years, found that 50.8% of the infants presented severe symptoms of the disease when exposed to tobacco smoke.23 Similarly, an association was observed between respiratory tract infections and tobacco exposure in 87.3% of children aged 2–12 years.24 However, the mechanisms underlying this damage remain unclear. One possible cause is the production of reactive oxygen species as a result of the accumulation of nicotine and heavy metals in the cells, causing genetic alterations, amongst others.25 and 26 In contrast to these findings, Hassan et al.