Effects of surface roughness and dimorphism on the adhesion of Candida albicans to the surface of resins: scanning electron microscope analyses of mode and number of adhesions.

AIM: Candida albicans is a common oral fungus but can cause serious conditions such as Candida stomatitis. We investigated C. albicans adhesion to the surface of denture-base resins at two growth phases. METHODS: Fungal suspensions of logarithmic (9 h) and stationary phase (24 h) C. albicans (JCM2085) were used. Scanning electron microscopy (SEM) confirmed that yeast and mycelial forms were predominant in 9-h and 24-h cultures, respectively. Resin strips were polished to three surface roughness levels (Ra 3.2 µm, Ra 0.48 µm and Ra 0.06 µm) and were then immersed in C. albicans suspensions for both phases. The SEM images were taken at five sites on each strip. RESULTS: Adhesion of mycelial-form C. albicans on rough surfaces (Ra = 3.2) was 2.2 times higher than on smooth surfaces (Ra = 0.06; 7030 vs 3580 adhesions/mm(2), P < 0.01). The hyphae of these mycelial forms fully penetrated the surface cracks. Fewer adhesions occurred for yeast-form C. albicans, regardless of surface type (440-620 adhesions/mm(2), P = n.s.). CONCLUSION: Adhesion of yeast-form C. albicans was indifferent to surface roughness. In contrast, mycelial adhesion increased with surface roughness of the resin because mycelia infiltrated the minute protuberances on rough surfaces.