A longitudinal study was performed to assess the effects of radiation-induced xerostomia on the human oral microflora. Pronounced microbial population shifts were found in each of five intraoral sites tested. Cariogenic microorganisms gained prominence at the expense of noncariogenic microorganisms in concert with the saliva shutdown. These changes occurred before the onset of clinical caries irrespective of whether or not a topical fluoride gel was used as a caries preventive.
Saliva and serum electrolyte concentrations were monitored in 30 patients given a course of xerostomia-producing cancer radiotherapy. The mean flow r a t e of stimulated whole saliva decreased 83.3% during a 6-week treatment period. The striking reduction in saliva o u t p u t was accompanied by significant increases in saliva Na+, C1-, Cat+, Mg" and Prot.-concentrations and by a decrease i n saliva HCO; content. The xerostomic saliva was more concentrated and had a greater salinity t h a n t h e pretreatment saliva in each instance. In contrast, none of t h e serum electrolytes measured was significantly altered by t h e subtotal salivary shutdown.Cancer 38:273-278, 1976.
Of 42 head and neck cancer patients with radiotherapy-induced xerostomia, 36 survived to permit a postirradiation caries evaluation. Twenty-three developed an average of 17.6 caries lesions and 13 had no new lesions within 30 months postirradiation. All caries-inactive patients had been initially assigned to daily self-application of a 1% sodium fluoride gel. The preirradiation caries experience and the oral microbial profile were comparable in both groups. After tumoricidal irradiation, the mean plaque increase of Streptococcus mutans was 25 times greater in the caries-active than in the caries-inactive group. Postirradiation caries was also associated with increased plaque Lactobacillus sp, Candida sp, and Streptococcus sp, and serum IgD and IgG concentrations. Conversely, plaque Staphylococcus sp, Streptococcus salivarius, and Veillonella sp and saliva IgA concentrations were significantly higher in the caries-inactive than in the caries-active group. Both groups demonstrated decreases in plaque Streptococcus sanguis, Neisseria sp, Fusobacterium sp, and Bacteroides sp.
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