Effect of Hydrogen Peroxide On Salivary Peroxidase System

Objective: In the oral cavity hydrogen peroxide is derived from oral bacteria, leukocytes, and salivary glands and utilized in the peroxidation reaction of salivary peroxidase to form antibacterial products and water. The aim of the present study was to study in vitro and in vivo effect of hydrogen peroxide on the function of the salivary peroxidase system. Methods: Parotid saliva was treated with increasing concentrations of hydrogen peroxide and aliquots removed after 10, 60, 120, and 240 seconds and analyzed for salivary peroxidase activity, thiocyanate and hydrogen peroxide. Ten volunteers were asked to rinse with 5 ml of 4 and 40 mM of hydrogen peroxide for 30, 60, and 120 seconds and the saliva analyzed for the peroxidase system components. Results: In vitro studies indicated that the function of the peroxidase system was impaired when saliva was treated with higher concentration and for longer time, while the system was capable to handling low concentration of peroxide. In vivo studies showed that saliva in the oral cavity was effectively removed hydrogen peroxide, however when 40 mM rinse was administered, there was an accumulation of hydrogen peroxide in the saliva indicating the peroxidase system was impaired. Conclusions: We conclude that exogenous source of hydrogen peroxide have an adverse effect on the salivary peroxidase system and may result in accumulation of hydrogen peroxide in the oral cavity and may be harmful to the oral mucosa.