Xerostomia and the oral microflora

Xerostomia is the feeling of a dry mouth usually caused by hyposalivation. It may occur after radiation therapy of the head and neck, in systemic diseases such as Sjogren’s syndrome, or as a side effect of medication. Hyposalivation changes the oral microbiome with the most dramatic changes after radiation therapy. The number of lactobacilli and Candida albicans increases. Also the number of mutans streptococci increases in hyposalivated subjects, but sugar consumption is a stronger determinant for the level of mutans streptococci. Hyposalivated subjects are more susceptible to oral infections such as caries and mucosal infections. This is both caused by changes in the oral microflora and weakening of salivary protection mechanisms such as cleansing by the salivary flow and buffering capacity.