Habitual "psychoactive substance (PS) use" is defined as the repeated use of PS, despite the knowledge of its negative health consequences. [1] Some of the readily available PSs are alcohol, tobacco, and arecanut. [2] Tobacco, either as smoked or smokeless form, is one of the most commonly used PS. [3] Smoked tobacco forms are cigarettes, cigars, and loose tobacco in pipes or handmade beedies. [4] Smokeless form of tobacco is available as unflavored tobacco, traditional betel quid, and flavored forms, such as Khaini, Zarda, Mishri, and Datun, or is available in combination with arecanut such as Gutkha and mawa. [4,5] Whether usage of smoked or smokeless tobacco forms have systemic as well as locoregional effects. [6] In oral cavity, saliva is the first biological fluid that gets exposed to the toxic chemicals present in tobacco or arecanut. [5,7] Saliva is a complex secretion of the oral cavity, wherein 93% of volume is secreted by the major salivary glands and remaining 7% is secreted by minor glands. [8] Saliva is composed of 99% of water, 1% of organic and inorganic molecules, and various antibacterial substances. Saliva plays a significant role in maintaining homeostasis of the oral cavity. [8,9] Daily secretion of saliva ranges from 0.75 to 1.5 L/day. Unstimulated whole salivary flow rate (SFR) is about 0.3-0.5 ml/min. The normal pH of saliva ranges from 6.7 to 7.3. The buffering capacity of saliva is an important factor and it usually correlates with flow rate, decrease in the flow rate tends to decrease buffering capacity thereby decreasing the salivary pH (acidic), making the oral mucosa and dental structures more vulnerable to changes, [10] and thus the quantity and quality of saliva are important in maintaining the integrity of oral health. [11] Reduction in the quantity of saliva is known as hyposalivation or xerostomia. Xerostomia is the perceived feeling of dry mouth which may or may not be associated with salivary gland hypofunction. It is subjective and can be measured by means of questionnaires. On the other hand, hyposalivation is a demonstrable reduction in SFR that can be measured objectively by collecting saliva over a specified period of time. Assessment of
