Effects of Quaternary Ammonium Chain Length on Antibacterial Bonding Agents

Abstract

The objectives of this study were to synthesize new quaternary ammonium methacrylates (QAMs) with systematically varied alkyl chain lengths (CL) and to investigate, for the first time, the CL effects on antibacterial efficacy, cytotoxicity, and dentin bond strength of bonding agents. QAMs were synthesized with CL of 3 to 18 and incorporated into Scotchbond Multi-Purpose (SBMP) bonding agent. The cured resins were inoculated with Streptococcus mutans. Bacterial early attachment was investigated at 4 hrs. Biofilm colonyforming units (CFU) were measured after 2 days. With CL increasing from 3 to 16, the minimum inhibitory concentration and minimum bactericidal concentration were decreased by 5 orders of magnitude. Incorporating QAMs into SBMP reduced bacterial early attachment, with the least colonization at CL = 16. Biofilm CFU for CL = 16 was 4 log lower than SBMP control (p < .05). All groups had similar dentin bond strengths (p > .1). The new antibacterial materials had fibroblast/ odontoblast viability similar to that of commercial controls. In conclusion, increasing the chain length of new QAMs in bonding agents greatly increased the antibacterial efficacy. A reduction in Streptococcus mutans biofilm CFU by 4 log could be achieved, without compromising bond strength and cytotoxicity. New QAM-containing bonding agents are promising for a wide range of restorations to inhibit biofilms.KEY WOrDs: antibacterial activity, Streptococcus mutans, quaternary ammonium compounds, dentin bonding, fibroblasts, odontoblasts. (Mjör and Toffeneti, 2000;Sakaguchi, 2005). Replacing failed restorations accounts for 50% to 70% of all restorations performed (Frost, 2002;Bagramian et al., 2009). Biofilm acids could lead to caries (ten Cate, 2006); hence antibacterial resins were developed to inhibit biofilms (Imazato et al., 1999;Imazato, 2003;Beyth et al., 2006;Namba et al., 2009;Cheng et al., 2012a). Indeed, previous studies investigated the copolymerization of quaternary ammonium methacrylates (QAMs) to develop antibacterial resins (Imazato, 2003;Li et al., 2009;Xie et al., 2011;Antonucci et al., 2012;Xu et al., 2012;Zhang et al., 2012).Composites are the principal materials for tooth-cavity restorations (Ferracane, 2011) which are bonded in cavities via adhesives (Ferracane et al., 2010;Spencer et al., 2010;Pashley et al., 2011). Residual bacteria could exist in the prepared cavity, and microleakage could allow bacteria to invade the tooth-restoration interfaces. Therefore, it is beneficial for primer/ adhesive to be antibacterial (Imazato et al., 1998;Imazato, 2003;Li et al., 2009;Hiraishi et al., 2010;Cheng et al., 2012b). Quaternary ammonium can cause bacteria lysis by binding to membranes (Beyth et al., 2006). A previous study revealed that long polymeric chains with positive charges and hydrophobicity effectively killed bacteria (Lin et al., 2002). When the alkyl chain length (CL) was increased, the hydrophobicity increased, thereby enhancing its propensity to penetrate the hydrophobic bacterial membrane (Tiller...

Quaternary ammonium compounds in dental restorative materials

“…It had been suggested that DMAE-CB could be incorporated into the dental adhesive stably with better biocompatibility 52) . Besides that, Li et al 5,53) and Zhou et al 54) had incorporated new quaternary ammonium methacrylates (QAMs) with systematically varied alkyl chain lengths into SBMP bonding agent. It was found that QAM with CL16, DMADDM, had the best antimicrobial effect.…”

“…The antibacterial effect against two E. faecalis strains (ATCC and an endodontic isolate) were assessed, and results had shown that addition of QPEI nanoparticles improved the killing ability of PCS against biofilms of both E. faecalis strains and the effects of AH Plus on the biomass of biofilms from the ATCC strain. Moreover, there were no relevant changes in physicochemical and 95) quaternary ammonium polyethyleneimine QPEI unpolymerizable composite resin 24) , endodontic materials [89][90][91] quaternary ammonium dimethacrylate QADM/IMQ polymerizable composite resin [25][26][27]32) , adhesive system 42) 2-methacryloxylethyl dodecyl methyl ammonium bromide MAE-DB polymerizable composite resin 28,29) 2-methacryloxylethyl hexadecyl methyl ammonium bromide MAE-HB polymerizable composite resin 28,29) 2-Dimethyl-2-dodecyl-1-methacryloxyethyl ammonium iodine DDMAI polymerizable composite resin 30) quaternary ammonium methacrylate QAM polymerizable composite resin 31) , adhesive system 5,53,54) 2-methacryloyloxyethyl phosphorylcholine MPC polymerizable composite resin 33) dimethylaminododecyl methacrylate DMADDM polymerizable adhesive system [43][44][45] quaternary ammonium methacrylate polymer QAMP unpolymerizable adhesive system [46][47][48] methacryloxylethyl cetyl ammonium chloride DMAE-CB polymerizable adhesive system [49][50][51][52] benzalkonium chloride BAC unpolymerizable adhesive system [55][56][57] , glass ionomer cement 73,74) , endodontic materials 87) poly-2-methacry...…”

“…Thereafter, studies reported 4) that methacryloyl groups and aliphatic quaternary ammonium groups were combined, then quaternary ammonium antimicrobial monomer containing different alkyl chain lengths was developed. Besides that, the antimicrobial properties of these monomers was evaluated by the authors, and methacryloxylethyl cetyl ammonium chloride (DMAE-CB) with the best antimicrobial activity was screened out, thus suggesting that the antimicrobial properties of QACs were related to the alkyl chain length of quaternary ammonium groups 5) . In addition, several studies demonstrated that MDPB and DMAE-CB were lethal to both planktonic and biofilm forms of varied cariogenic bacteria, and they could kill more than 90% of the bacteria within 60 s at high concentrations 6,7) .…”

Protein-repellent and antibacterial functions of a calcium phosphate rechargeable nanocomposite

“…A quaternary ammonium dimethacrylate (QADM) was incorporated into a composite, yielding a strong antibiofilm effect [31]. Recently, a new dimethylaminohexadecyl methacrylate (DMAHDM) was synthesized and incorporated into dental resin, which showed the strongest antibacterial effect among the antibacterial monomers tested [35]. In addition, 2-methacryloyloxyethyl phosphorylcholine (MPC) was incorporated into resins to repel protein and bacterial attachment [36].…”

“…The pH measurements were not collected from 0 h to 24 h of culture, because the planktonic bacteria in the growth medium would affect the pH values. In this way, the measured pH was only related to the biofilm adherent on the composite disk, and there was no non-adherent bacteria contribution from the medium [35,36]. The pH data were recorded once every hour from 24 h to 36 h of the incubation.…”