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

Abstract

Dental composites are commonly used restorative materials; however, secondary caries due to biofilm acids remains a major problem. The objectives of this study were (1) to develop a composite containing quaternary ammonium dimethacrylate (QADM), nanoparticles of silver (NAg), and nanoparticles of amorphous calcium phosphate (NACP), and (2) to conduct the first investigation of the mechanical properties, biofilm response and acid production vs water-ageing time from 1 day to 12 months. A 4 × 5 design was utilized, with four composites (NACP-QADM composite, NACP-NAg composite, NACP-QADM-NAg composite, and a commercial control composite), and five water-ageing time periods (1 day, and 3, 6, 9, and 12 months). After each water-ageing period, the mechanical properties of the resins were measured in a three-point flexure, and antibacterial properties were tested via a dental plaque biofilm model using human saliva as an inoculum. After 12 months of water-ageing, NACP-QADM-NAg had a flexural strength and elastic modulus matching those of the commercial control (P>0.1). Incorporation of QADM or NAg into the NACP composite greatly reduced biofilm viability, metabolic activity and acid production. A composite containing both QADM and NAg possessed a stronger antibacterial capability than one with QADM or NAg alone (P<0.05). The anti-biofilm activity was maintained after 12 months of water-ageing and showed no significant decrease with increasing time (P>0.1). In conclusion, the NACP-QADM-NAg composite decreased biofilm viability and lactic acid production, while matching the load-bearing capability of a commercial composite. There was no decrease in its antibacterial properties after 1 year of water-ageing. The durable antibacterial and mechanical properties indicate that NACP-QADM-NAg composites may be useful in dental restorations to combat caries.

Ex vivo investigation on internal tunnel approach/internal resin infiltration and external nanosilver-modified resin infiltration of proximal caries exceeding into dentin

“…Hence, in accordance with those previous studies [110,111], we have chosen 5.5 wt% of AgNP, to vet any possible detrimental effects of the nanoparticles on penetration ability of the infiltrant resin. It is known that, next to the long-term bactericidal activity and the decreased lactic acid production driven by the nanosilver [50,112,113], AgNP increased the surface hydrophobicity of composite resins, even with low mass fractions of down to 0.3 wt% [114]. Additionally, it is worth mentioning that with these low concentrations, mechanical characteristics (like flexural strength, or elastic modulus) of the composites matched those of commercial products [112,113], even though some reports have indicated an influence on polymerization, thus increasing the amount of elutable monomers [115].…”

“…One possible prospective filler candidate would seem silver nanoparticles (AgNP) [43], ranging from 1 to 100 nm in diameter; in recent years, AgNP have been increasingly used for a wide range of applications in (nano-)medicine, and successful dental implementations have been reported as well [44,45], including composite resins [46,47]. The desired antimicrobial effects have been revealed [48,49], and especially the long-lasting [50] and the long-distance bactericidal capability [51] should qualify AgNP as complimentary additives to infiltrant resins, thus preventing the latter from microbial re-colonization.…”

Prevention of Periodontitis by the Addition of a Bactericidal Particulate Glass/Glass-Ceramic to a Dental Resin: A Pilot Study in Dogs

“…Diverse research with different additives has been carried out to develop effective antibacterial resin-based composites. Most of these additives are organic bactericides, such as: quaternary ammonium dimethacrylate (QADM) [21], dimethylaminohexadecyl methacrylates (DMAHDM) [22], dimethyl-hexadecylmethacryloxyethyl-ammonium iodide (DHMAI) [23], quaternary ammonium polyethylenimine (PEI) nanoparticles [24], chlorhexidine [25], triclosan [26] or chitosan [27]. Inorganic coatings have emerged as an alternative approach since they present several advantages compared to traditional organic agents, which include chemical stability, thermal resistance and protracted action, and they have not yet been associated with resistant organisms [28].…”

Application of Antibiotics/Antimicrobial Agents on Dental Caries

“…Moreover, some cells on NACP-QADM nanocomposites have been shown to disintegrate [98]. In addition to QAMs, it has been shown that the antimicrobial activity of ACP (amorphous calcium phosphate) and CaF2 nanocomposites can be greatly increased when added to CHX fillers, while the ability of biofilm formation was significantly reduced [98][99][100].…”