Passive smoking, chiefly among young children, may cause serious health problems according to a report by World Health Organization, WHO. It is estimated that almost one billion grown up people smoke worldwide and at least 700 million children live with them. Clearly, children are the most vulnerable group who are in danger of passive smoking. Many researchers have studied the deleterious effect of passive smoking on respiratory disorders, snoring or sleep fragmentation in children and infants. It is believed that the prevalence of childhood leukemia in children who live with smoker parents is a consequence of passive smoking. On the other hand, there are only a few works showing the relationship between general oral health or formation of dental caries and passive smoking in preschool, elementary school children and adolescent.
Human whole saliva is a complex mixture of components in many aspects similar to other body fluids. Saliva is secreted by three paired major salivary glands and hundreds of minor salivary glands which is located below mucosal surfaces of the mouth.