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Nine antibacterial di-methacrylate monomers based on bis-quaternary ammonium salts (bis-QAMs) were synthesized and structurally characterized. The biological activity of the bis-QAMs was tested in terms of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) on different bacterial strains achieving promising results and, in most cases, a complete bactericidal effect using a bis-QAM concentration lower than 1 mg/mL. Two of the structures showed comparable and superior activity against S. mutans than the commercial monomer 12-methacryloyloxydodecyl pyridinium bromide (MDBP). All the bis-QAMs here described were able to inhibit S. mutans biofilm formation at a concentration equal to the MIC value. From the analysis of the obtained data, some correlation regarding the structure and the antibacterial activity of the bis-QAMs could be drawn: a flexible alkyl C 12 spacer between the two quaternary ammonium moieties increased the monomer antibacterial effect in comparison to the aromatic ones; the equilibrium between hydrophobic and hydrophilic moieties was directly correlated to the bactericidal range of action; the increase of the steric hindrance of the ammonium side groups might be both advantageous or disadvantageous to the antibacterial efficacy depending on the whole monomer chemical structure. Even though the possible correlation between the monomer structures and their bacteriostatic or bactericidal effect is under investigation, the monomers exhibited low cytotoxicity on human dental pulp stem cells, confirming their promising potential in the dental materials' field. The use of dental resins with antibacterial monomers might prevent the formation of secondary caries at the restoration margins. For this purpose, a series of di-methacrylate bis-quaternary ammonium monomers (QAMs) was developed. Unlike antibacterial mono-methacrylate monomers already described in the literature, the synthesized di-methacrylate monomers have the potential of acting as cross-linkers stabilizing the polymeric network and bear two quaternary ammonium groups that increase their antibacterial ability. The QAMs exert bactericidal activity on both Gram(+) and Gram(−) bacterial strains maintaining at the same time good biocompatibility with the oral environment. Some structural elements of the monomers were clearly related to high antibacterial properties, and this can help design new active structures and better understand their mechanism of action. [Display omitted] [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the marginal adaptation of mixed Class V cavities restored with Clearfil Protect Bond (Kuraray), Clearfil SE Bond (Kuraray), and two experimental combinations of both marketed adhesives, after fatigue and water storage. Materials and Methods: Four groups (Clearfil Protect Bond, Clearfil SE Bond, Exp. 1 and Exp. 2) of Class V cavities were restored with a microhybrid restorative composite (Clearfil APX, Kuraray). The marginal quality of these restorations was quantified by evaluation of gold-coated epoxy replicas with scanning electron microscopy before loading, after loading, and after a 12-month period of water storage. Data from marginal adaptation along the total margin length, on enamel, and on dentin were analyzed with the Wilcoxon signed rank test for differences within a group and with Kruskal-Wallis in order to assess the differences between groups. The Bonferroni test was used for post-hoc comparisons, and the confidence level was set to 95%. Results: The mean percentages (±SD) of "continuous margin" of the total marginal length ranged from 79.5% (±13.3) to 62.2% (±10.4) and from 70% (±11) to 61% (±15.1) after loading and after storage, respectively. No significant differences could be detected among the different groups. However, the marginal adaptation of Clearfil Protect Bond remained the most stable of all materials tested, as no significant differences were detected between the percentages of continuous margins before loading, after loading, or after storage. Conclusions: The use of an antibacterial adhesive system was as effective as the conventional two-step self-etching adhesive in the marginal adaptation of Class V restorations. [ABSTRACT FROM AUTHOR]

Hydrolytic and enzymatic degradation of resin adhesives over time has been mainly attributed to secondary caries formation of methacrylate-based tooth-colored resin-based composite restorations. Ability of resin adhesive monomers to infiltrate into demineralized dentin forming stiff polymer matrix and potentially bonding to tooth structure is also a crucial property. The only commercially available antibacterial monomer, 12-methacryloyloxydodecyl pyridinium bromide (MDPB), is a quaternary ammonium methacrylate. This methacrylate monomer undergoes hydrolytic degradation, and could not bond to tooth structure. In this study, a new hydrolytic resistant monomer HMTAF was synthesized. It is methacrylamide-based monomer that, unlike methacrylate, is highly resistant to hydrolysis. Its molecular structure has particular functional groups; quaternary ammonium fluoride salt with potential antibacterial fluoride-releasing activity, hydroxyl and amide group with hydrogen bonding potential to dentin collagen. Hydroxyl group also increases monomer hydrophilicity for better penetration into water-saturated dentin and sufficient resin-dentin bond. The synthesized HMTAF and its polymer showed no hydrolytic degradation in acidic environment, while MDPB and its polymer were partially decomposed under this challenge. The conversion of monomer HMTAF to polymer was illustrated by FT-IR. The results indicated that HMTAF is highly resistant to hydrolysis, polymerizable and non-cytotoxic to Vero cell lines. It is a potential monomer to be incorporated into resin adhesives for improving hydrolytic and enzymatic resistance. [ABSTRACT FROM AUTHOR]

Objectives This study systematically review the literature to assess the effectiveness of antibacterial monomers incorporated into dental adhesive systems against major oral bacteria; as well as the research advances and the future prospects of this technology. Methods The following seven databases were screened: MedLine (PubMed), Lilacs, Ibecs, Web of Science, Scopus, Scielo , and The Cochrane Library . Furthermore, the online system Questel Orbit (Paris, France) was accessed to obtain patent data. The inclusion criteria were articles and patents that investigated the antimicrobial activity of antibacterial monomers in dental adhesive systems. Only documents written in English, Spanish or Portuguese were included. Results After screening, 33 studies and eight patents fulfiled all the criteria and were included. Antibacterial agents, such as QA, MDPB, DMAHM and DMADDM were found in patents, which claimed their incorporation into adhesive compositions, dental cements, composite resins. MDPB was the only antimicrobial monomer incorporated into a commercially available adhesive system, Clearfil Protect Bond™ (Kuraray Co. Ltd., Japan). All studies reported the inclusion of antimicrobial monomers in adhesive systems to be an effective dental treatment strategy. Significance There are potential areas to be explored with antibacterial monomers for dentistry, and their use could have important implications for future more conservative dental treatments. Although there is evidence of antibacterial activity from in vitro studies, clinical studies must be conducted to confirm the effectiveness of these materials in the prevention of dental pathologies. [ABSTRACT FROM AUTHOR]

Pretreatment of dentin using colloidal platinum nanoparticles (CPtN) can enhance the bond strength of dentin adhesives. However, the combination of CPtN, which is negatively charged, with cationic monomer-containing adhesive may reduce the antibacterial activity of the original material. Thus, the purpose of this study was to assess the effect of CPtN on the bactericidal activity of two cationic antibacterial monomers, 12-methacryloyloxydodecylpyridinium bromide (MDPB) and methacryloxylethyl cetyl dimethyl ammonium chloride (DMAE-CB). The rapid killing effects of the two monomers against planktonic or attached Streptococcus mutans in the presence or absence of CPtN were examined by viable cell counts. The measurement of minimum inhibitory and bactericidal concentrations demonstrated that CPtN up to 2.5 mM has no antibacterial activity. In the absence of CPtN, rapid killing of both planktonic and attached Streptococcus mutans were achieved by the two cationic monomers. Combination with 0.1 mM CPtN did not reduce the bactericidal effects of the two monomers, indicating that CPtN may be used as a pretreatment with antibacterial adhesives. [ABSTRACT FROM AUTHOR]

Oral biofilm accumulation at the tooth–restoration interface often leads to recurrent dental caries and restoration failure. The objectives of this study were to: (1) develop a novel bioactive crown cement containing dimethylaminohexadecyl methacrylate (DMAHDM) and nano-sized amorphous calcium phosphate (NACP), and (2) investigate the mechanical properties, anti-biofilm activity, and calcium (Ca2+) and phosphate (PO43−) ion release of the crown cement for the first time. The cement matrix consisted of pyromellitic glycerol dimethacrylate and ethoxylated bisphenol-A dimethacrylate monomers and was denoted PEHB resin matrix. The following cements were tested: (1) RelyX luting cement (commercial control); (2) 55% PEHB + 45% glass fillers (experimental control); (3) 55% PEHB + 20% glass + 25% NACP + 0% DMAHDM; (4) 52% PEHB + 20% glass + 25% NACP + 3% DMAHDM; (5) 51% PEHB + 20% glass + 25% NACP + 4% DMAHDM; (6) 50% PEHB + 20% glass + 25% NACP + 5% DMAHDM. Mechanical properties and ion release were measured. Streptococcusmutans (S. mutans) biofilms were grown on cements, and colony-forming units (CFUs) and other biofilm properties were measured. The novel bioactive cement demonstrated strong antibacterial properties and high levels of Ca2+ and PO43− ion release to remineralize tooth lesions. Adding NACP and DMAHDM into the cement did not adversely affect the mechanical properties and dentin bonding strength. In conclusion, the novel NACP + DMAHDM crown cement has excellent potential for restoration cementation to inhibit caries by suppressing oral biofilm growth and increasing remineralization via Ca2+ and PO43− ions. The NACP + DMAHDM composition may have wide applicability to other biomaterials to promote hard-tissue formation and combat bacterial infection. [ABSTRACT FROM AUTHOR]