| Soft lining materials play an important role in clinical removable prosthodontics, which relieves the pressure transmitted by denture on mucosa. However, there is an increased probability of yeast colonization on soft lining materials, which is a causative factor in denture associated chronic atrophic candidosis (denture stomatitis). This study aimed to determine and compare the extent of Candida adherence to four commercial available soft denture lining materials.Material and methods:Four commercial available soft lining materials were investigated together with Candida albicans (ATCC 10261) in vitro adhesion assays. Soft lining materials include Softliner (Promedica, Germany),COE SOFT (GC America INC,USA),Nissin soft reverse(Nissin Dental products INC, Japan), Shanghai cold-curing softliner (Shanghai) The effectiveness of surface finishes and pH of artificial saliva to the yeast adherence to materials were studied. In addition, this in vitro study incorporated antifungal agents into soft lining materials to investigate the effectiveness of this method of drug delivery. Results:1. The surface roughness of soft lining material affects the adherence of Candida albicans significantly. Increased adherence was observed on the rough surface compared to smooth surface.2. Among four soft lining materials, the lowest adherence was seen on Softliner, the highest adherence was seen on Shanghai cold curing soft denture lining.3. After soaking into artificial saliva with different pH value (6.0,6.7,7.9), the adherence of Candida albicans on the surface increased with the soaking time. There was no significantly difference between the yeast adherence of on the COE SOFT soaked in different pH artificial saliva. Increased adherence wasobserved on the surface of acid artificial saliva soaked Nissin soft lining material, which indicated that acid circumstance was beneficial to the adherence of both materials. The adherence were similar for shanghai in acid and alkali condition, and less adherence in neutral solution. In a whole, lowest adherence on Softliner, compared to most adherence on Shanghai cold-curing soft lining material.4. Trough measuring the pH value of culture medium, it was found that the pH value decreased with the time. The first 24 hours was the early growth period, the curve kept almost in line with X axis. Since 24 hours, it was the rapid growth period , the curve declines. Till 72 hours, the growth were stable for Softliner, heat -curing and cold-curing resin, however, Shanghai cold-curing soft lining material, Nissin and COE SOFT reached the stable period till 96 hours, and pH value of culture medium drops to a minimum, which indicates the maximum number of Candida albican in culture medium.5. Itraconazole was added into soft lining materials by 3%, 6%, 9% w/w. Results showed: the antifungal ability were similar between material with 6% and 9%, both were significantly stronger than that of material with 3%. The antifungal ability of all materials with itraconazole was significantly better than only soft liner materials itself. The effective period lasts around 8 days.Conclusion:1. The adherence of Candida albicans is positively correlated with the surface roughness of soft lining materials.2. Acid saliva is beneficial to the Candida albicans adherence on the surface of soft lining materials.3. The antifungal ability of soft lining material was different. The application of antifungal drugs into soft lining materials was helpful to the antifungal function. For itraconazole, stable and effective function can be achieved by 6% w/w concentration; the effective period lasts 8 days. |
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