Effect of chronic tobacco-betel-lime "quid" chewing on human salivary secretions.

Salivary flow rates by mechanical stimulation with forced spitting method and by chemical stimulation with 10% citric acid were determined in 25 healthy adult subjects with a history of chronic tobacco-betel-lime "quid" chewing and in 25 healthy control adults with no history of chewing. The chewers secreted more saliva as compared to nonchewers on chemical, but not on mechanical stimulation. The salivary amylase, potassium, and sodium levels were lower in chewers, but the reductions of the first two components only were significant. These reductions were thought to be due to increased salivary flow with its dilutional effect. There was no difference between the two groups with respect to salivary pH. The salivary flow rates by either method had significant positive correlation with the duration of chewing, but not with the amount of tobacco chewed. Salivary potassium was inversely correlated with the amount of tobacco chewed. It was concluded that chronic tobacco-betel-lime quid chewing induces excessive secretion of more watery saliva leading to a concomitant decrease in enzyme and electrolyte content. One or more of the following factors were considered to be operating in causing increased salivary flow in chewers effect of nicotine or tobacco on other constituents of the quid, chronic salivary gland hyperplasia, or chronic hypertrophy of the muscles of mastication.