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Introduction: Radiation therapy to head and neck region may lead to decreased salivary flow with subsequent reduction in the buffering capacity and alteration of oral microflora, and eventual increased risk of radiation induced caries.

Aims & Objectives: The purpose of this longitudinal study was to investigate the alterations in a select group cariogenic microflora, and dental plaque pH in ten patients with radiation therapy and ten healthy controls, following 1M sodium bicarbonate rinses.

Materials and methods: Over a period of 14 days each, the test and the control groups were requested to rinse their mouths with either sodium bicarbonate, distilled water or they went through a rinse free period. After each period they were recalled to the clinic and plaque pH measurements were made at baseline and after 10, 30 and 60 minutes following a sucrose rinse. Microbial cultures were performed to assess levels of mutans streptococci, lactobacilli and the total bacterial count.

Results: The results showed no significant difference in the plaque pH profile after using sodium bicarbonate rinses in both the irradiated and healthy subjects. There was a significant increase in lactobacilli counts between the control and experimental groups for all the phases (p<0.05).

Conclusion: The baseline plaque pH in irradiated subjects did not show higher acidity compared to healthy individuals although a delayed period of pH recovery of to neutral levels was noted. Following sodium bicarbonate rinses, there was an increased Lactobacilli count without any sustainable effect on the plaque pH. Further research is warranted to evaluate the shifts in oral microbial ecology in head and neck irradiated patients and the effect of palliative measures such as sodium bicarbonate rinses on oral flora of these patients.

Dental Plaque, Radiation, Saliva, Oral Microflora