Background: The effectiveness of each resin composite material composition in enabling homogeneous monomer conversion and reducing polymerization shrinkage (PS) is an important issue. Thus, this study aimed to evaluate the degree of conversion (DC) and PS of low-shrinkage bulk-fill composites (BFCs) in 4-mm thickness. Materials and Methods: Four bulk fill (Tetric EvoCeram Bulk Fill, Sonic Fill, XTra Fill, and Venus Bulk Fill) and one conventional (Filtek Z350 XT) resin composites were tested in this study. Teflon molds of 4-mm depth were used to prepare resin composite specimens. All tested resin composites were packed in bulk then light cured for the recommended time by their manufacturers. DC% was determined by Fourier transform infrared spectroscopy; PS was determined using the strain gauge method. Data were subjected to one-way ANOVA/Tukey's test (α = 0.05). Results: DC% results were as follows: Venus Bulk Fill > XTra Fill > Sonic Fill > Tetric EvoCeram Bulk Fill > Filtek Z350 XT with a significant difference between each others at P ≤ 0.001. For PS %, significant difference resulted between tested groups at P ≤ 0.001. Where Venus Bulk Fill < XTra Fill = Sonic Fill < Tetric EvoCeram Bulk Fill < Filtek Z350 XT. Conclusions: Low-shrinkage resin monomers seem to be beneficial for reducing PS with enhancement in the DC. Increased filler loading in BFCs had a positive effect on reducing PS, while its effect on the DC was material dependent.

Objective Bonding to different dentin substrates influences resin composite restoration outcomes. This study investigated the influence of different adhesion protocols on the shear bond strength of universal adhesive systems to sound and artificial caries-affected dentin (CAD).Materials and Methods Occlusal enamel of 80 premolars were wet grinded to obtain flat midcoronal dentin. Specimens were equally divided according to the substrate condition: sound and CAD by subjecting to pH-cycling for 14 days. Each dentin substrate was bonded with the adhesive systems used in this study: Single Bond universal adhesive or Prime&Bond universal (applied either in etch-and-rinse or self-etch adhesion protocol). Adhesive systems were utilized according to manufacturers’ instructions, then resin composite was built up. Specimens were tested for shear bond strength. The data were analyzed by three-way analysis of variance, and failure modes were determined using stereomicroscope.Results There was no statistically significant difference between the two tested adhesive systems on artificially created CAD with different adhesion protocols. On sound dentin, Single Bond universal, either in the etch-and-rinse or self-etch adhesion protocols, revealed higher statistically significant shear bond strength mean values compared with CAD.Conclusion Single Bond universal adhesive in an etch-and-rinse adhesion protocol improved only bonding to sound dentin, while no added positive effect for the etching step with Prime&Bond universal adhesive was found when bonded to both sound and CAD substrates. The influence of CAD on the performance of the universal adhesives was material-dependent.

Background: The aim of this work was to study the influence of simulated body fluid (SBF) and Pseudomonas aeruginosa (in Mueller Hinton Broth, MHB media) on the hydration reactions, formation of strätlingite (C₂ASH₈) and morphology of a composite material based on nano-size tri-calcium silicate (C₃S) and tri-calcium aluminate (CA) phases. The two experimental phases were prepared in laboratory by firing the required molar ratios of chemically pure reactants by solid-state reactions at elevated temperatures. Investigation of setting time, micro-hardness, pH of immersion solution, X-ray diffraction analysis, infrared spectroscopy, scanning electron microscopy and cytotoxicity were also carried out. Results: The results emphasized that the hydrated compounds of C₃S phase can partly solve the problem of conversion process through the formation of the more stable and highly mechanical stratlingite hydrate (C₂ASH₈) plates that results in an increase in hardness values for samples cured in distilled water (DW) at 37 °C. The SBF solution showed more strength loss than those cured in Pseudomonas aeruginosa microbe (MHB) medium bacterial solution. SEM and EDAX analyses emphasized the formation of hydroxyapatite at 37 °C. Conclusions: The prepared cements are promising for dental application.

Background: The aim of this study was to compare the clinical performance of Nano-hydroxyapatite-modified conventional glass ionomer cement (NHA-GIC) and Nano-hydroxyapatite-modified resin-modified glass ionomer cement (NHA-RMGIC) with conventional glass ionomer (CGIC) and resin-modified glass ionomer (RMGIC) in the treatment of caries class V cavities. Sixty patients with at least two cervical caries lesions participated in this study. A total of 120 class V cavities were prepared and then restored using different restorative materials. Restorations were clinically evaluated according to modified United States Public Health Service criteria at baseline and after 3, 6 and 9 months. Results: There was no statistically significant difference in the clinical performance of the different restorative materials at any of the follow-up periods. However, throughout the study period there was a statistically significant change in the color match, surface texture and marginal integrity in NHA-GIC. A statistically significant change in the surface texture and marginal integrity was found in GIC. On the other hand, there was only a statistically significant change in surface texture in NHA-RMGIC. Conclusions: All tested restorative materials, control (CGIC and RMGIC) as well as experimental (NHA-GIC and NHA-RMGIC), exhibited comparable clinical performance after 9 months follow-up.