The Antibacterial Effects of Quaternary Ammonium Salts in the Simulated Presence of Inhibitors in Root Canals: A Preliminary In-Vitro Study

Abstract

To investigate the antibacterial effects of two newly developed quaternary ammonium salts (QAMs)-dimethylaminododecyl methacrylate (DMADDM) and dimethylaminohexadecyl methacrylate (DMAHDM), in the presence of various root canal inhibitors. Streptococcus gordonii, Enterococcus faecalis, Lactobacillus acidophilus and Actinomyces naeslundii were used. Dentine, dentine matrix and dead bacteria were selected as inhibitors. The antimicrobial efficacy of monomers of DMADDM and DMAHDM was tested against suspensions formed by mixtures of four bacterial species in or without the presence of inhibitors. The inhibition results were compared with chlorhexidine (CHX) and sodium hypochlorite (NaOCl). One-way analyses of variance (ANOVA) followed by Tukey's multiple comparison test was performed to determine significant differences. The antibacterial effects of DMADDM and DMAHDM were variably inhibited dentine, dentine matrix and dead bacteria. CHX and NaOCl showed substantivity and they inhibited bacteria present in suspension. The concentration of compound decreased in the dentine block due to constant release. Bacterial colonies on the dentine surface and dentine tubules were significantly inhibited by DMADDM and DMAHDM. The antibacterial effects of DMADDM and DMAHDM could be inactivated by dentine, dentine matrix and dead bacteria, while DMADDM and DMAHDM could inhibit bacteria colonization on the dentine surface and kill bacteria present in dentinal tubules. The antibacterial effects of DMADDM and DMAHDM as free monomers in the presence of inhibitors was evaluated for the first time. They could help inhibit the residual bacteria on the dentine surface and in dentinal tubules that may cause persisting infection. Therefore the novel QAMs showed great potentials as root canal medication.

Introducing Semi-Interpenetrating Networks of Chitosan and Ammonium-Quaternary Polymers for the Effective Removal of Waterborne Pathogens from Wastewaters

“…Although the application of quaternary ammonium salts as bactericidal agents is still a challenge in this field, studies have reported its effective action against Gram-negative bacteria such as Escherichia coli [42,[49][50][51]. Considering this, the current study illustrates the bactericidal potential of a novel semi-IPN hydrogel for wastewater treatment.…”

Starvation Survival and Biofilm Formation under Subminimum Inhibitory Concentration of QAMs

“…Briefly, 1 mL of MTT dye (0.5 mg/mL in PBS) was added to each well and incubated anaerobically at 37°C for 1 h. After 1 h, the disk was transferred to a new 12-well plate and 1 mL of dimethyl sulfoxide (DMSO) was added to solubilize formazan crystals. After brief mixing, DMSO solution was then transferred into a 96-well plate and the absorbance was read at 540 nm (OD 540 ) [ 26 ]. Three replicates were tested for each group.…”