Antifungal effect of tissue conditioners containing poly(acryloyloxyethyltrimethyl ammonium chloride)-grafted chitosan on Candida albicans growth in vitro

Abstract

Background/purpose: Denture stomatitis is a pathological condition affecting the mucosa underneath ill-fitting dentures, and Candida albicans is considered its main etiologic factor. Tissue conditioners are temporary lining materials often applied to dentures to treat inflamed tissues. However, tissue conditioners do not exert antifungal activity, and the soft surface texture harbors C. albicans easily. The aim of this study was to examine the antifungal activity of tissue conditioners modified with chitosan (CS) or a quaternized chitosan (QCS), which was synthesized by grafting 2-[(acryloyloxy)ethyl] trimethyl ammonium chloride onto CS.

Materials and methods: Tissue conditioners containing varying weight percentages of CS or QCS were prepared as experimental discs 10 mm in diameter and 1 mm in thickness. Samples were co-cultured with C. albicans and the number of colony forming units was recorded. Other evaluations included cell toxicity and tensile bond strength to the resin denture base.

Results: It was found significantly fewer fungal colonies in tissue conditioners modified with CS or QCS, and none when the weight percentage of QCS exceeded 5%. CS and QCS did not affect the viability of human gingival epithelium cells or fibroblasts, and tensile bond strength did not differ between control and modified tissue conditioners.

Conclusion: This study provides a foundation for the development of QCS as a novel and safe antifungal agent applied to tissue conditioners in clinical practice.

Keywords: chitosan; denture stomatitis; quaternization; tissue conditioner.

Figure 1

Chemical structure of 2-[(acryloyloxy)ethyl] trimethyl ammonium chloride (AETMAC)-grafted chitosan.

Figure 2

Fourier transform infrared spectrophotometry (FTIR) spectrum for AETMAC, chitosan (CS) and quaternized chitosan (QCS). The FTIR spectrum of CS and QCS were largely similar, however, QCS exhibits two distinct absorption peak at 1733 cm⁻¹ and 953 cm⁻¹, these correspond with specific functional groups in AETMAC: the CO stretching vibrations of the ester groups and the C-N stretching vibration of quaternary ammonium groups. These two absorption peaks demonstrate the successful grafting of AETMAC onto chitosan.

Figure 3

Comparison of Candida albicans growth in culture media with tissue conditioners, tissue conditioners with chitosan (CS), and tissue conditioners with quaternized chitosan (QCS). Data are presented as mean ± SD; *: p < 0.05 vs. control; #: p < 0.05 for CS vs. QCS.

Figure 4

Cytotoxicity of chitosan (CS)/quaternized chitosan (QCS)-modified tissue conditioner discs to hGF and hGE cells. Cell viability after incubation with CS and QCS was calculated. (A) hGF cell viability. (B) hGE cell viability. Data are presented as mean and standard deviation.

Figure 5

Comparison of tensile bond strength to the acrylic resin denture base between control tissue conditioners and chitosan (CS)- or quaternized chitosan (QCS)-modified tissue conditioners. Data are presented as mean and standard deviation.