This study evaluated microhardness profiles and calculated depths of cure at 80% of the surface microhardness of experimental dental resin composites having different base monomer compositions and different filler fractions. Composites were prepared using four different base monomers (bisphenol A‐glycidyl methacrylate [Bis‐GMA], urethane dimethacrylate [UDMA], ethoxylated bisphenol‐A dimethacrylate [Bis‐EMA], and Fit‐852) with triethylene glycol dimethacrylate (TEGDMA) used as a co‐monomer at three filler:resin matrix weight percent fractions (50:50, 60:40, and 70:30). Uncured material was placed in 3D printed molds and light cured for 40 s from the top surface only. Knoop microhardness was measured at the top of the specimen, and at every 0.5 mm up to 4 mm in depth. Microhardness at the surface increased in all experimental composites as the filler fraction increased. When comparing base monomers, microhardness was the highest in UDMA‐based composites, while Bis‐GMA‐based composites showed the lowest values. When comparing depth of cure as a function of base monomer type, both Bis‐GMA and Bis‐EMA showed significantly lower values than UDMA or Fit‐852. Composites having 50 wt% filler showed a significantly higher depth of cure than those with 60 and 70 wt% filler. Base monomer and filler fraction significantly influence microhardness and depth of cure in these experimental composites.

Glass fiber posts (GFP) have an elastic modulus that shares structural characteristics with dentin. Ineffective removal of the smear layer (SL) in the root canal after post space preparation reduces resin tag formation, compromising an efficient hybrid layer formation leading to a subsequent debonding. In this sense, this review article focuses on the published literature related to dentin conditioning for GFP placement with the use of acidic solutions such as EDTA, citric and maleic acid or prefabricated conditioning solutions such as MTAD and QMix, both with/without activation by sonic or laser devices, analyzed by scanning electron microscopy (SEM) and/or push- out bond strength (POBS) test. The collected information suggested that the conditioning agent that showed better results for dentin conditioning increasing the bond strength of the GFP to the root canal is 17% EDTA without activation.

This study aimed to assess how different resin matrix formulations affect the fatigue resistance of resin dental composites. Model dental composites were formulated using six distinct monomer mixtures: two Bis-GMA (bisphenol A-glycidyl methacrylate):TEGDMA (triethylene glycol dimethacrylate) (60:40 and 80:20 mole%), two UDMA (urethane dimethacrylate):TEGDMA (60:40 and 80:20 mole%), one Bis-GMA:UDMA:TEGDMA (35:35:30 mole%), and one Fit852:UDMA:TEGDMA (35:35:30 mole%). Cyclic fatigue resistance (CFR) of the resin composites was measured in a biaxial test mode using staircase analysis. Additional evaluations included biaxial flexural strength (BFS), degree of conversion (DC), water sorption (WS), and viscoelastic properties of the unfilled resins, such as the storage modulus (E′), loss modulus (E″), tan δ (E″/E′), and stiffness (k′). Data were subjected to one-way ANOVA with Tukey post hoc analyses. Pearson correlation and stepwise regression analyses were conducted to examine the relationships among variables. The UT6040 model composite exhibited the highest CFR (82.61 ± 8.83 MPa), significantly outperforming other formulations. Tan δ of the resin matrix showed the strongest correlation with CFR (r = 0.974), and was also shown to be the most influential predictor for the CFR of the particulate composites. The composition of the resin matrix has a significant impact on the CFR of dental composites. Among the properties evaluated, the viscoelastic parameter tan δ emerged as a strong and reliable predictor of CFR, emphasizing the importance of targeting viscoelastic behavior in the design of dental composite formulations.