FOR MANY YEARS clinicians have observed the damaging effects of cancer therapy on the oral structures. 1 Patients receiving irradiation to the head and neck region experience a marked decrease in salivary secretion. This permanent radiation-induced xerostomia (dry mouth condition) has been found to be significant in producing extreme susceptibility to caries. Although xerostomia of a lesser degree is produced by certain antidepressant or antihistamine medications, this drug-induced condition is reversible, and caries susceptibility remains high only while salivary gland function is depressed. Immunosuppressed and myelosuppressed patients undergoing chemotherapy, however, like irradiated patients and others who are physiologically debilitated, are highly subject to caries. In these patients, caries is primarily related to decreased interest, and thus decreased efficiency and regularity, in oral hygiene. The antiemetic medications frequently necessary during chemotherapy also have an antisialagogne action, which also is reversible in its depressive effect on salivary secretion.
In 1976, Dreizen et al. 2 monitored 30 patients receiving tumoricidal ionizing radiation to the head and neck area, including all the major salivary glands. Samples of stimulated whole saliva were obtained from each patient before radiation treatment and at weekly intervals during treatment. A venous blood sample was also drawn with each salivary sampling. The result of the investigation revealed a progressive decrease in salivary flow rate, pH, and buffering capacity, as evidenced by electrolyte secretion. No significant changes were observed between pretreatment and posttreatment serum electrolyte levels.
In 1977, Dreizen et alJ observed 42 patients treated with cancericidal radiation that included all major salivary glands. Careful measurement of stimulated whole salivary flow rate revealed that a tumor dose of 200 rad/day caused a decrease of 57% after five treatments (1 week), a decrease of 76% after 30 treatments (6 weeks), and a continued progressive decrease that resulted, 3 years after completion of radiation therapy, in a flow rate 5% of the pretreatment flow rate.
The investigation of Brown et al. 4 in 1978 involved microbiologic studies of 36 patients who were receiving radiation therapy that included all the major salivary glandular tissues. Comparisons of oral microflora in the patients before and periodically up