Effect of water-aging on the antimicrobial activities of an ORMOSIL-containing orthodontic acrylic resin

Abstract

Quaternary ammonium methacryloxy silicate (QAMS), an organically modified silicate (ORMOSIL) functionalized with polymerizable methacrylate groups and an antimicrobial agent with a long lipophilic alkyl chain quaternary ammonium group, was synthesized through a silane-based sol–gel route. By dissolving QAMS in methyl methacrylate monomer, this ORMOSIL molecule was incorporated into an auto-polymerizing, powder/liquid orthodontic acrylic resin system, yielding QAMS-containing poly (methyl methacrylate). The QAMS-containing acrylic resin showed a predominant contact-killing effect on Streptococcus mutans (ATCC 35668) and Actinomyces naeslundii (ATCC 12104) biofilms, while inhibiting adhesion of Candida albicans (ATCC 90028) on the acrylic surface. The antimicrobial activities of QAMS-containing acrylic resin were maintained after a 3 month water-aging period. Bromophenol blue assay showed minimal leaching of quaternary ammonium species when an appropriate amount of QAMS (<4 wt.%) was incorporated into the acrylic resin. The results suggest that QAMS is predominantly co-polymerized with the poly(methyl methacrylate) network, and only a minuscule amount of free QAMS molecules is present within the polymer network after water-aging. Acrylic resin with persistent antimicrobial activities represents a promising method for preventing bacteria- and fungus-induced stomatitis, an infectious disease commonly associated with the wearing of removable orthodontic appliances.

Quaternary ammonium-based biomedical materials: State-of-the-art, toxicological aspects and antimicrobial resistance

“…Recently, quaternary ammonium methacryloxy silicate (QAMS) has been developed with both antibacterial and anti-fungal properties for incorporation into dental removable appliances fabricated from acrylic resin (i.e. PMMA) [288][289][290]. In those in vitro studies, acrylic resin containing 5 wt% QAMS exhibits contact-killing microbiocidal activities on S. mutans, Actinomyces naeslundii and C. albicans single species biofilms.…”

“…It was previously perceived that polymerized "contact killing" antibacterial resin polymers exhibit antimicrobial activities only via direct contact of bacteria, without antibacterial effects against planktonic (free-floating) bacteria [349]. However, recent studies of QA-containing materials conducted with confocal laser scanning microscopy and three-dimensional reconstruction of biofilms stained with live-dead fluorescent stains [350,351] indicate that those materials possess a reducing spectrum of biocidal activities from the substrate surface to the top of the biofilms [230,288,289,352,353]. That is, the presence of dead microorganisms is not limited to the bottom of the biofilms that is in contact with the antibacterial surface.…”

One-year water-ageing of calcium phosphate composite containing nano-silver and quaternary ammonium to inhibit biofilms

“…25 In addition, the antimicrobial activity of a QAM-containing acrylic resin has been shown to be maintained after 3 months of water-ageing. 44 However, whether the antibacterial effects decrease after 6 months is unclear, and longer term studies (for example, 1 year) have not been reported for antibacterial dental resins.…”

Three-dimensional biofilm properties on dental bonding agent with varying quaternary ammonium charge densities

“…In addition, image-processing techniques can be used for quantitative analysis of biofilms to obtain a detailed visualization of thick biofilm samples [37], which cannot be obtained via conventional phase contrast or fluorescence microscopy. While the 3D viability distributions in dental biofilms were studied via CLSM techniques previously [32,33,38,39], to date, there has been no report on the effect of quaternary amine charge density of dental resin on the 3D viability distribution of biofilms.…”