[Physiological and pathological effects of nitric oxide and nitric oxide synthase in oral cavity].

Nitric oxide (NO) is a short-lived free radical which is not only involved in regulating many physiological processes of the body, but also closely related to many diseases. Nitric oxide synthase (NOS) is the key enzyme for NO production. NOS exists as three distinct isoforms, the endothelial NOS (eNOS), neuronal NOS (nNOS) and inducible NOS (iNOS). It has been found that nNOS and eNOS were expressed in normal pulp tissues, periodontal tissues and salivary glands, and the NO produced from nNOS and eNOS was involved in their physiological functions. NO and iNOS are involved in the occurrence and development of pulpitis, periodontitis, salivary gland disease and oral cancer. This review focuses on the physiological and pathological effects of NO and different subtypes of NOS in oral cavity.