Effect of Storage in Distilled Water for Three Months on the Antimicrobial Properties of Poly(methyl methacrylate) Denture Base Material Doped with Inorganic Filler

Abstract

The colonization of poly(methyl methacrylate) (PMMA) denture base materials by pathogenic microorganisms is a major problem associated with the use of prostheses, and the incorporation of antimicrobial fillers is a method of improving the antimicrobial properties of these materials. Numerous studies have demonstrated the initial in vitro antimicrobial effectiveness of this type of material; however, reports demonstrating the stability of these fillers over longer periods are not available. In this study, silver sodium hydrogen zirconium phosphate was introduced into the powder component of a PMMA denture base material at concentrations of 0.25%, 0.5%, 1%, 2%, 4%, and 8% (w/w). The survival rates of the gram-positive bacterium Staphylococcus aureus, gram-negative bacterium Escherichia coli and yeast-type fungus Candida albicans were established after fungal or bacterial suspensions were incubated with samples that had been previously stored in distilled water. Storage over a three-month period led to the progressive reduction of the initial antimicrobial properties. The results of this study suggest that additional microbiological tests should be conducted for materials that are treated with antimicrobial fillers and intended for long-term use. Future long-term studies of the migration of silver ions from the polymer matrix and the influence of different media on this ion emission are required.

Effect of Antibacterial Silver-Releasing Filler on the Physicochemical Properties of Poly(Methyl Methacrylate) Denture Base Material

“…The paper presents the results of the second stage of research on the influence of S-P introduction as an antimicrobial filler on the properties of PMMA denture base material. In the previously published part [37], the antimicrobial properties were confirmed via three-month in vitro experiments; thus, further tests were needed to investigate the other properties of the obtained composites related to their application. Additionally, S-P has also been investigated in our other works as an additive into silicone soft lining material [53] and direct restorative photopolymerizable resin-based composites [54], where only a slight influence of the filler on some physicochemical properties was noted.…”

“…Additionally, S-P has also been investigated in our other works as an additive into silicone soft lining material [53] and direct restorative photopolymerizable resin-based composites [54], where only a slight influence of the filler on some physicochemical properties was noted. However, for the currently tested composites, the matrix and the method of introducing the filler into it were different which determined the inhomogeneous morphology of polymerized composites related with the used components (PMMA pre-polymerized particles) [37]. This could affect the physicochemical properties, thus investigations were conducted.…”

“…The method of the composites' preparation was described in a previously published work [37]. The PMMA heat-cured denture base resin, Meliodent Heat Cure (Heraeus Kulzer, Hanau, Germany), was used as a matrix and silver sodium hydrogen zirconium phosphate (Milliken Chemical, Spartanburg, SC, USA) as filler.…”

“…Silver nanoparticles have particularly strong antimicrobial properties; however, studies have simultaneously shown that the introduction of this type of additive to prosthetic materials causes an intense brown color of PMMA resin due to the plasmon effect [35] which is unacceptable for aesthetic reasons. Despite these problems, materials containing silver are still considered an attractive antimicrobial additive; therefore, in the previously presented research, it was proposed to introduce submicron inorganic particles of silver sodium hydrogen zirconium phosphate (S-P) as an antimicrobial additive to PMMA [37]. This white filler does not cause the initial dark coloring of modified materials.…”

“…In the published first part of our investigations, the morphology and antimicrobial properties of the developed composites were investigated [37]. Most of the experimental materials presented efficacy against C. albicans, even when samples were stored in distilled water for a three-month period.…”