Resins-based denture soft lining materials modified by chlorhexidine salt incorporation: an in vitro analysis of antifungal activity, drug release and hardness

Abstract

Objectives: To evaluate the in vitro growth inhibition of Candida albicans, the rate of chlorhexidine release and shore A hardness from resins-based denture soft lining materials modified by chlorhexidine diacetate (CDA) or chlorhexidine hydrochloride (CHC) incorporation.

Methods: Resin discs were prepared from soft denture liners based on poly (methyl methacrylate) (PMMA) or poly (ethyl methacrylate) (PEMA) containing 0.5, 1.0 and 2.0 wt.% of CDA or CHC. For antifungal activity resin discs were placed on agar plates inoculated with C. albicans, after 48 h at 37°C the diameters of inhibition zones were measured. For the chlorhexidine release, discs were immersed into distilled water at 37°C, and spectral measurements were made after 48 h. Shore A hardness was evaluated at the baseline, 2 and 7 days, using 6mm thick rectangular specimens also immersed into distilled water at 37°C. Data were statistically processed by SigmaStat software using ANOVA and all pairwise multiple comparison procedures was done using the Holm-Sidak method, with α=0.05 (p<0.001).

Results: CDA added to PMMA soft liner and PEMA soft liner had a dose-related inhibitory effect on C. albicans and on chlorhexidine release rate (p<0.001). The PMMA and PEMA hardness increased statistically by time but not for the different CDA concentrations. CHC had no inhibitory effect on C. albicans.

Significance: Chlorhexidine diacetate released from resins-based soft lining materials can be convenient to reduce the biofilm development on the material surface and treat denture stomatitis, without depending on patient compliance.

Keywords: Antifungal activity; Candida albicans; Chlorhexidine; Denture soft lining materials; Drug release; Hardness.