Colonization and penetration of denture soft lining materials by Candida albicans.

ABSTRACT

OBJECTIVES: Colonization of denture soft lining materials by Candida albicans can result in clinical problems, and deterioration of the material. This study aimed to monitor this interaction by comparing the short-term adhesion of C. albicans to six denture lining materials and to monitor any longer term penetration of material by the yeast. METHODS: Denture lining materials (Molloplast B, Flexor, Permaflex, Luci-soft, Eversoft and Ufi Gel hard C) were processed against glass slides or dental stone. Adhesion of yeast to surfaces was monitored after one hour incubation (37 degrees C) of standardized (2.8 x 10(6) cfu/ml) washed cell suspension with test materials. Attached cells stained with acridine orange were counted microscopically. Penetration of yeast into materials bonded onto acrylic after six weeks incubation (culture medium was replaced weekly) was observed through sections stained using acridine orange. Hyphal and yeast penetration was estimated (qualitatively and quantitatively, respectively) for three levels of the liner (subsurface, central section and adjacent to lining-acrylic junction). RESULTS: None of the materials produced a zone of inhibition when compared with the nystatin control. There was no significant difference (p>0.5) in cell numbers on any of the smooth surfaces. Significantly, (p<0.001) higher numbers of cells were observed on roughened surfaces. Both hyphal and yeast forms were observed when penetration was monitored. Penetration was greatest into Ufi Gel hard C (no hyphae observed), but not at the acrylic-liner junction and least into Eversoft. SIGNIFICANCE: Different denture lining materials exhibit different properties in terms of susceptibility to yeast penetration, although the initial attachment is comparable. Smoother surfaces retain fewer cells. The selection of appropriate materials for a given function, and their fabrication may affect performance.