Effect of hydrophobic surface treated fumed silica fillers on a one-bottle etch and rinse model dental adhesive

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.

Experimental EDX analysis of different periodontal splinting systems

Physiological/normal tooth mobility may be defined as the slight displacement of the clinical crown of a tooth, which is allowed by the resilience of an intact and healthy periodontium, under the application of a moderate force. The factors influencing the success and longevity of dental splinting are the type of material used for the splint, the type of composite resin, the number and location of the dental units included for splinting (maxillary or mandibular arch). In periodontology, the term 'splint' is defined as the joining of two or more teeth into a rigid unit through restorations or fixed or removable devices. The purpose of using periodontal splints for tooth immobilization is to provide a period of rest in the areas where the healing process has begun and to allow normal functioning there where the tissues alone would not be able to withstand occlusal forces. The aim of the present study was to evaluate comparatively, by means of energy dispersive electron spectrometry (EDX), the chemical composition in the case of in vitro samples that structurally reproduce direct periodontal immobilization systems using fiberglass strips and fluid composite resins. The differences in the chemical composition of the investigated materials can influence their physiochemical properties, but also their biological and toxicological reliability. Elements such as C, O, Al, Si and Ba were identified as common elements among the resins tested in the present study. The only difference in terms of the component elements was found in the case of the fluid composite Clearfil Majesty ES Flow, which, apart from the elements mentioned, also presented Co in its structure.

Dentin Bond Integrity of Filled and Unfilled Resin Adhesive Enhanced with Silica Nanoparticles-An SEM, EDX, Micro-Raman, FTIR and Micro-Tensile Bond Strength Study

The objective of this study was to synthesize and assess unfilled and filled (silica nanoparticles) dentin adhesive polymer. Methods encompassing scanning electron microscopy (SEM)-namely, energy dispersive X-ray spectroscopy (EDX), micro-tensile bond strength (µTBS) test, Fourier transform infrared (FTIR), and micro-Raman spectroscopy-were utilized to investigate Si particles' shape and incorporation, dentin bond toughness, degree of conversion (DC), and adhesive-dentin interaction. The Si particles were incorporated in the experimental adhesive (EA) at 0, 5, 10, and 15 wt. % to yield Si-EA-0% (negative control group), Si-EA-5%, Si-EA-10%, and Si-EA-15% groups, respectively. Teeth were set to form bonded samples using adhesives in four groups for µTBS testing, with and without aging. Si particles were spherical shaped and resin tags having standard penetrations were detected on SEM micrographs. The EDX analysis confirmed the occurrence of Si in the adhesive groups (maximum in the Si-EA-15% group). Micro-Raman spectroscopy revealed the presence of characteristic peaks at 638, 802, and 1300 cm^-1 for the Si particles. The µTBS test revealed the highest mean values for Si-EA-15% followed by Si-EA-10%. The greatest DC was appreciated for the control group trailed by the Si-EA-5% group. The addition of Si particles of 15 and 10 wt. % in dentin adhesive showed improved bond strength. The addition of 15 wt. % resulted in a bond strength that was superior to all other groups. The Si-EA-15% group demonstrated acceptable DC, suitable dentin interaction, and resin tag formation.