The relationships among fluoride, cariogenic oral flora, and salivary flow rate during radiation therapy.

Changes in the quantity of Streptococcus mutans, Lactobacillus species, and yeast Candida species were assessed in a cancer population undergoing head and neck radiation. The purpose of this study was to evaluate the effectiveness of a custom vinyl tray-applied fluoride gel to control cariogenic bacteria in a group experiencing hyposalivation because of radiation treatment. Twenty-two subjects participated in the study and served as their own controls. Whole resting and whole stimulated saliva were collected at weekly appointments beginning 1 week before and concluding 4 weeks after radiation therapy. Colony-forming units per mL of Streptococcus mutans and Lactobacillus species and semiquantitative counts of Candida species (0 = none; 1 = light; 2 = moderate; 3 = heavy) were determined from collected saliva. All patients were provided with custom vinyl vacuform mouthguards to be used daily with neutral fluoride gel (1.1% sodium fluoride). Whole stimulated and resting saliva productions decreased by 36.67% and 47.9%, respectively, by the end of 1 week of radiation therapy, and they remained low. No significant changes in cariogenic oral flora were seen during and early after radiation therapy, despite xerostomia. However, colonization by Candida albicans increased during radiation therapy for oropharyngeal cancers. Findings from this study suggest that changes in cariogenic flora may be suppressed through the use of daily topical neutral sodium fluoride gels and that colonization by Candida albicans increase during radiation therapy.