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The core–shell chlorhexidine/amorphous calcium phosphate (CHX/ACP) nanoparticles were synthesized and used to modify the dental resin composite, aiming to improve its remineralized and antibacterial properties. The core–shell CHX/ACP nanoparticles were synthesized by vesicle-templating technology and characterized, and their sustained release and antibacterial properties were also evaluated. Subsequently, the synthesized nanoparticles were incorporated into the dental resin composite at 1 wt.%, 5 wt.% or 10 wt.% to obtain different experimental groups. The physical properties, including curing depth, double bond conversion rate, water absorption and solubility, the sustained-release effects, and mechanical properties of the modified resin composite were evaluated. The remineralization ability was also measured by SEM. The antibacterial experiment of the modified resin composite with fresh preparation or aging in water for 28 days was carried out by a plate count method. The physical and chemical characterizations showed that the synthesized nanoparticles presented a core–shell structure, and their diameter was about 98.5 nm. The shell was composed of ACP with the core full of CHX. These nanoparticles had a release effect on calcium, phosphate ions, and CHX. The nanoparticles could effectively inhibit the growth of S. mutan at a lower concentration (≥50 μg/mL). The curing depth, the double bond conversion, the water absorption, the solubility, the flexural strength, the flexural modulus, and the compressive strength of the modified resin composite were 3.86–4.88 mm, 62.32–73.61%, 1.47–2.84%, 0.21−0.48%, 45.83–109.46 MPa, 2.57–4.91 GPa, and 66.43–160.38 MPa, respectively. The modified resin composite containing 5 wt.% and above CHX/ACP nanoparticles could effectively inhibit the growth of S. mutans regardless of aging in water, with immediate and aging antibacterial rate of more than 92%. In addition, the modified resin composite had a certain remineralization property in the SBF solution verified by SEM. The core–shell CHX/ACP nanoparticles were successfully prepared and used to modify the resin composite. The modified dental resin composite with 5 wt.% CHX/ACP nanoparticles had excellent mechanical, antibacterial, and remineralization properties. It is expected to be an ideal restorative filling material for clinical application. [ABSTRACT FROM AUTHOR]

Background: The objective of this study was to investigate the influence of Er,Cr:YSGG laser irradiated at different powers on the micromorphology and the bonding property of non-carious sclerotic dentin to resin composites. Methods: Two hundred bovine incisors characterized by non-carious sclerotic dentin were selected, and the seventy-two teeth of which for surface morphological analysis were divided into nine groups according to various treatments (A: the control group, B: only treated with the adhesive Adper Easy One, C: diamond bur polishing followed by Adper Easy One, D-I: Er,Cr:YSGG laser irradiating at 1W, 2W, 3W, 4W, 5W, 6W output power, respectively, followed by Adper Easy One). The surface roughness values were measured by the non-contact three-dimensional morphology scanner, then the surface micromorphologies of surfaces in all groups were assessed by scanning electron microscopy (SEM); meanwhile, Image Pro-Plus 6.0 software was used to measure the relative percentage of open tubules on SEM images. The rest, one hundred twenty-eight teeth for bond strength test, were divided into eight groups according to the different treatments (A: only treated with the adhesive Adper Easy One, B: diamond bur polishing followed by the above adhesive, C-H: Er,Cr:YSGG laser irradiating at 1 W, 2 W, 3 W, 4 W, 5 W, 6 W output power, respectively, followed by the above adhesive), and each group was subsequently divided into two subgroups according to whether aging is performed (immediately tested and after thermocycling). Micro-shear bond strength test was used to evaluate the bond strength. Results: The 4W laser group showed the highest roughness value (30.84±1.93μm), which was statistically higher than the control group and the diamond bur groups (p<0.05). The mean percentages ((27.8±1.8)%, (28.0±2.2)%, (30.0±1.9)%) of open tubules area in the 4W, 5W, 6W group were higher than other groups (p<0.05). The 4W laser group showed the highest micro-shear bond strength not only in immediately tested (17.60±2.55 PMa) but after thermocycling (14.35±2.08MPa). Conclusion: The Er,Cr:YSGG laser at 4W power can effectively improve the bonding property between non-carious sclerotic dentin and resin composites by increasing the roughness and mean percentage area of open tubules. [ABSTRACT FROM AUTHOR]

Background: Vital pulp preservation in the treatment of deep caries is challenging due to bacterial infection. The objectives of this study were to synthesize a novel, light-cured composite material containing bioactive calcium-silicate (Portland cement, PC) and the antimicrobial quaternary ammonium salt monomer 2-methacryloxylethyl dodecyl methyl ammonium bromide (MAE-DB) and to evaluate its effects on Streptococcus mutans growth in vitro. Methods: The experimental material was prepared from a 2∶1 ratio of PC mixed with a resin of 2-hydroxyethylmethacrylate, bisphenol glycerolate dimethacrylate, and triethylene glycol dimethacrylate (4∶3∶1) containing 5 wt% MAE-DB. Cured resin containing 5% MAE-DB without PC served as the positive control material, and resin without MAE-DB or PC served as the negative control material. Mineral trioxide aggregate (MTA) and calcium hydroxide (Dycal) served as commercial controls. S. mutans biofilm formation on material surfaces and growth in the culture medium were tested according to colony-forming units (CFUs) and metabolic activity after 24 h incubation over freshly prepared samples or samples aged in water for 6 months. Biofilm formation was also assessed by Live/Dead staining and scanning electron microscopy. Results: S. mutans biofilm formation on the experimental material was significantly inhibited, with CFU counts, metabolic activity, viability staining, and morphology similar to those of biofilms on the positive control material. None of the materials affected bacterial growth in solution. Contact-inhibition of biofilm formation was retained by the aged experimental material. Significant biofilm formation was observed on MTA and Dycal. Conclusion: The synthesized material containing HEMA-BisGMA-TEGDMA resin with MAE-DB as the antimicrobial agent and PC to support mineralized tissue formation inhibited S. mutans biofilm formation even after aging in water for 6 months, but had no inhibitory effect on bacteria in solution. Therefore, this material shows promise as a pulp capping material for vital pulp preservation in the treatment of deep caries. [ABSTRACT FROM AUTHOR]

The purpose of this study was to synthesize boron nitride nanosheets modified with zinc oxide nanoparticles (BNNSs/ZnO) and incorporate them as a novel inorganic filler to get an antibacterial dental resin composite. The BNNSs/ZnO nanocomposites were synthesized via the hydrothermal method and characterized by Field Emission Scanning Electron Microscope (FESEM), Transmission Electron Microscopy (TEM), Energy Dispersive Spectrometer (EDS), X-ray Diffraction (XRD) and Fourier Transform-Infrared (FTIR) Spectroscopy. The BNNSs/ZnO or BNNSs were added into the experimental dental composite with different proportions, respectively. The mechanical and physical properties of the modified dental composite were evaluated. Their antibacterial activities were also assessed by quantitative analysis using Streptococcus mutans (S. mutans). The BNNSs/ZnO nanocomposites were successfully synthesized, and the growth of ZnO nanoparticles (ZnO NPs) on boron nitride nanosheets was confirmed. The flexural strength (FS), flexural modulus (FM) and the compressive strength (CS) of all modified resin composites showed no change compared to the control group. The curing depth, degree of conversion, water absorption and solubility of the modified composites were still within the clinical requirement. The antibacterial rates of the modified composites were significantly increased compared to the control group, which can reach 98 % when 0.5 % BNNSs/ZnO was added. The modified dental resin composite with novel BNNSs or BNNSs/ZnO fillers shows significantly high antibacterial activity with suitable physicochemical and mechanical properties. [ABSTRACT FROM AUTHOR]