Selective Inhibition of Streptococci Biofilm Growth via a Hydroxylated Azobenzene Coating

Brief Narrative Review on Commercial Dental Sealants-Comparison with Respect to Their Composition and Potential Modifications

The scope of this paper is to compare different dental sealants and flow materials indicated for sealing pits and fissures considering their chemical formula. The narrative review aims to address the following questions: What is the essence of different dental sealants' activity, how does their chemical formula affect their mechanisms of caries prevention, and what makes a dental sealant efficient mean of caries prevention? Another vital issue is whether the sealants that contain fluoride, or any other additions, have potentially increased antimicrobial properties. An electronic search of the PubMed, Cochrane, Web of Science, and Scopus databases was performed. The following keywords were used: (dental sealants) AND (chemical composition). Additionally, information about composition and indications for clinical use provided by manufacturers were utilized. All of the considered materials are indicated for use both in permanent and primary dentition for sealing fissures, pits, and foramina caeca. The selection of suitable material should be made individually and adjusted to conditions of the sealing procedure and patient's needs. Cariostatic mechanisms increasing sealants' effectiveness such as fluoride release are desired in modern dentistry appreciating preventive approach. The review aims are to find crucial elements of sealants' composition which affect their cariostatic mechanisms.

Azobenzene as Antimicrobial Molecules

Azo molecules, characterized by the presence of a -N=N- double bond, are widely used in various fields due to their sensitivity to external stimuli, ch as light. The emergence of bacterial resistance has pushed research towards designing new antimicrobial molecules that are more efficient than those currently in use. Many authors have attempted to exploit the antimicrobial activity of azobenzene and to utilize their photoisomerization for selective control of the bioactivities of antimicrobial molecules, which is necessary for antibacterial therapy. This review will provide a systematic and consequential approach to coupling azobenzene moiety with active antimicrobial molecules and drugs, including small and large organic molecules, such as peptides. A selection of significant cutting-edge articles collected in recent years has been discussed, based on the structural pattern and antimicrobial performance, focusing especially on the photoactivity of azobenzene and the design of smart materials as the most targeted and desirable application.

Synthesis, characterization and evaluation of azobenzene nanogels for their antibacterial properties in adhesive dentistry

The presence of cariogenic bacteria within the prepared tooth cavity at the adhesive resin-dentin interface is detrimental to the long-term stability and function of composite restorations. Here, we report the synthesis and incorporation of methacrylated azobenzene nanogels within bisphenol A-glycidyl methacrylate/hydroxyethyl methacrylate/ethanol (B/H/E) adhesive resins and evaluate their ability to reduce the bacterial invasion of cariogenic Streptococcus mutans biofilms while preserving the mechanical strength and structural integrity of the critical interfacial connection between the restoration and the tooth. The azobenzene nanogel, with a hydrodynamic radius of < 2 nm and a molecular weight of 12,000 Da, was polymerized within B/H/E adhesive formulations at concentrations of 0.5 wt.%, 1.5 wt.%, and 2.5 wt.%. While the double-bond conversion, cytocompatibility, water solubility, and sorption of the adhesive networks were comparable, azobenzene nanogel networks showed improved hydrophobicity with a ≥ 25° increase in water contact angle. The polymerized adhesive surfaces formulated with azobenzene nanogels showed a 66% reduction in bacterial biofilms relative to the control while maintaining the mechanical properties and micro-tensile bond strength of the adhesive networks. The increased hydrophobicity and antibacterial activity are promising indicators that azobenzene nanogel additives have the potential to increase the durability and longevity of adhesive resins.

Acrylated Hydroxyazobenzene Copolymers in Composite-Resin Matrix Inhibits Streptococcus mutans Biofilms In Vitro

Purpose: The purpose of this study was to evaluate the effect of acrylated hydroxyazobenzene (AHA) copolymers in a composite-resin matrix on Streptococcus mutans (SM) biofilms. Methods: The AHA was synthesized and polymerized within a bisphenol A-glycidyl methacrylate and triethylene glycol dimethacrylate (bisGMA:TEGDMA) matrix while bisGMA:TEGDMA discs served as controls. The cytotoxicity of AHA was determined using a cell viability assay. Sucrose-dependent SM biofilms were grown on the AHA and control substrates. At 24 hours and after mechanical toothbrushing (equivalent to six months), the number of live SM was quantified on the substrates and in the surrounding media. Microscopic images of the substrates were captured after live-dead staining. Results: The AHA substrates were as biocompatible as bisGMA: TEGDMA substrates. The microscopic images and quantification demonstrated no live SM on the AHA substrates and in the surrounding media as compared to the controls. The inhibitory efficacy of AHA substrates on SM biofilm was intact even after mechanical toothbrushing. Conclusions: Acrylated hydroxyazobenzene in a composite-resin matrix completely inhibits SM proliferation growth and demonstrates a zone of SM inhibition. The antibacterial propertyof AHA could be harnessed for caries prevention in high caries-risk children by incorporating AHA into the restorative and sealant materials.