Adherence of Candida species to newly polymerized and water-stored denture base polymers

The aim of this in vitro study was to examine the adherence of yeasts to newly polymerized and water-stored denture base polymers using four Candida strains with different cell surface hydrophobicities.

Thirty-two autopolymerized denture base polymer specimens were stored in distilled water at 37 degrees C for 7 days and 32 were newly polymerized. Sixteen specimens of each group were pretreated with unstimulated mixed saliva (saliva group), and 16 were pretreated with phosphate-buffered saline ([PBS] PBS group) at 37 degrees C for 1 hour. Hydrophobicity of the newly polymerized and water-stored specimen surfaces was determined by contact angle measurements. C guilliermondii, C albicans, C glabrata, and C tropicalis were grown on tryptic soy agar. They were pretreated either with saliva or PBS and suspended in PBS. Four parallel test specimens were incubated without agitation in each yeast suspension at 37 degrees C for 1 hour, washed, and allowed to dry in air. Adherent cells were fixed, gram stained, and counted from 10 high-power light-microscopy fields of each specimen.

Enhanced adherence of yeasts was observed in water-stored test specimens in comparison to newly polymerized test specimens. Salivary pellicle reduced the hydrophobicity of test specimens and the adherence of yeasts. No differences in contact angles of distilled water between newly polymerized and water-stored polymers were observed.

Yeasts seem to adhere less to newly polymerized than water-stored denture base polymer. This may be due to the release of residual monomer from the newly polymerized material.