The effect of desalivation on coronal and root surface caries in rats

Although the presence of coronal caries is declining in much of the Western Hemisphere, the prevalence of root surface caries is likely to increase as teeth are retained longer than heretofore. At the same time, an increasing number of the population suffer from dry mouth as a result of taking prescription drugs, with an apparent concomitant increased susceptibility to root surface caries. This study attempted to develop an animal model which would aid in the exploration of the effects of desalivation and the development of root surface caries. Animals were desalivated, infected with Actinomyces viscosus and Streptococcus mutans (sobrinus) 6715, and fed a cariogenic diet. Coronal caries developed rapidly in the animals; sufficient disease was present after two weeks to permit evaluation of potential therapeutic agents. Alveolar bone loss and root surface lesions developed in three to four weeks. S. mutans (sobrinus) and A. viscosus established readily in all animals; however, as the investigation progressed, populations of the latter declined, possibly because of the highly acidogenic environment. This model will facilitate investigation of the influence of hyposalivation and help in the exploration of agents to alleviate the adverse effects of salivary gland dysfunction.