Use of a new assay technique for quantification of antifungal activity of nystatin incorporated in denture liners.

Denture-induced stomatitis with concurrent candidal infection is the most commonly encountered intraoral abnormality among individuals who wear dentures. The institutionalized elderly demonstrate increased susceptibility and could benefit from its management with a fungicidal denture liner. As an integral part of the prosthesis, the efficacy of the fungicidal liner would be independent of patient compliance and/or nursing involvement and would provide a predictable therapeutic modality. In this study a "slant agar assay" was developed to evaluate the in vitro antimycotic activity of Visco-gel and Lynal liners impregnated with various concentrations of nystatin over a 14-day period in nonaqueous and aqueous environments. The results were as follows: preparations incorporating higher concentrations of nystatin resulted in greater inhibition of Candida albicans growth; Visco-gel liner-nystatin preparations exhibited a greater fungicidal activity than equivalent Lynal preparations; loss of potency by all of the reline-nystatin preparations consisted of an initial rapid loss between days 0 and 2, followed by a plateau during which the preparations gradually continued to lose inhibitory activity; and 1 million units of nystatin were necessary to maintain an adequate level of antifungal activity in an aqueous environment, where the liners demonstrated decreasing antifungal activity proportional to the duration of exposure to water.