Effects of undecylenic acid released from denture liner on Candida biofilms

Denture liners (DL) are easily colonized by Candida spp. In an attempt to prevent biofilm colonization, manufacturers have incorporated undecylenic acid (UDA) into DL. In this in vitro study, the effects of UDA released from DL on Candida biofilms were investigated. The concentrations of UDA released from commercial DL were determined by gas chromatography-mass spectrometry (GC-MS). Minimum inhibitory concentration (MIC) and minimum fungistatic concentration (MFC) tests were performed for C. albicans or C. glabrata, with UDA for comparison with the concentrations released from DL. Specimens of DL with (experimental group) and without UDA (control group) were fabricated, and Candida biofilms were developed on DL surfaces. Biofilms were evaluated by cell counts, metabolic activity, structure, and secretion of proteinase or phospholipase. The concentrations of UDA released were within the MIC and MFC ranges. In the presence of UDA, C. albicans biofilms were thinner and had lower numbers of viable and active cells, although no significant enzymatic changes were observed relative to the control group (p > 0.05). In contrast, C. glabrata biofilms exhibited higher cell counts and greater metabolic activity and also increased proteinase activity in the presence of UDA relative to the control group (p < 0.05). Overall, UDA did not prevent Candida biofilm formation.