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Introduction. The aim of this study was to determine the effect on the flexural strength of the self-cured acrylic resin by incorporating short E-glass fiber (SEGF) and ultra-high-molecular-weight polyethylene (UHMW-PE) filler in the acrylic resin. Methods. Fifty-six rectangular (64 × 10 × 3.3 mm3) (ISO standard 20795–1:2013) self-cured acrylic resin specimens were fabricated and divided into seven groups per test, according to the percent by weight of SEGF and UHMW-PE filler (n = 8). Each testing group entails a control group and an addition of 1% and 2% SEGF, 1% and 2% UHMW-PE, 0.5% SEGF/UHMW-PE, and 1% SEGF/UHMW-PE. A three-point bending test was conducted to obtain the flexural strength of each specimen. The fractured surfaces of the specimens were evaluated, and a scanning electron microscope view was taken. Test results were statistically analyzed with one-way ANOVA and Tukey HSD tests ( p value<0.05). Results. The flexural strength of self-cured acrylic resin with the addition of 1% SEGF and 1% SEGF/UHMW-PE (50.93, 46.13 MPa) was significantly higher than that of the control group (41.72 MPa) ( p < 0.05 ). Nonetheless, the addition of 1% UHMW-PE (39.34 MPa) showed the lowest flexural strength, significantly lower than other experimental groups, except the control group. Conclusion. The addition of 1% SEGF significantly improves the flexural strength of the self-cured acrylic resin denture base.

Objectives The aim of this study was to evaluate and compare penetration ability and tensile strength among vinylsiloxanether (VSE), polyether (PE), and polyvinylsiloxane (PVS) elastomeric dental impression materials. Materials and Methods The models were constructed for penetration ability test by simulated gingival sulcus width and moist environment. The 0.05, 0.1, and 0.2 mm of simulated gingival sulcus widths were used. Each simulated gingival sulcus width was impressed 10 repeats per one elastomeric impression material. All extension of elastomeric dental impression materials was scaled by Measuring Microscope (MM-11; Nikon, Tokyo, Japan). On the issue of the tensile strength study, the models were constructed following type 1 of the ISO 37:2017 specifications and/or type C of ASTM.D412 specifications. The two-way analysis of variance (ANOVA) and Tukey's honest significant difference test were performed in the penetration ability test. The one-way ANOVA and Dunnett's T3 test were performed in the tensile strength test. The significance level was set at 0.05. Results PE showed the best extension into all widths of simulated sulcus followed by VSE and PVS, respectively. PVS was significantly higher in tensile strength than VSE and PE, while VSE was significantly higher than PE. Conclusion Penetration ability of elastomeric dental impression materials was depended on gingival sulcus width. The wider the sulcular width, the better the penetration ability of elastomeric dental impression materials. PE presented the best penetration ability, while the novel PVS showed highest tensile strength.

The aim of this study was to analyze the effect of applying short E-glass fiber (SEG) and ultrahigh molecular weight polyethylene (UWPE) filler on the shear bond strength between the repaired surface of the rapid heat-cured and the reinforced autopolymerized acrylic resin. Fifty-six circular (15 × 3.3 mm2) rapid heat-cured resins were made and assigned equally to seven different groups. These were later bonded to fifty-six circular-reinforced autopolymerized acrylic resin specimens. Every test group included a control group, along with applying 1% and 2% SEG, 0.5% SEG/UWPE, 1% SEG/UWPE, and 1% and 2% UWPE. The universal testing machine was utilized to conduct the shear bond strength test. The repaired surface of these samples was assessed. Besides, the mode of failure was visualized under stereo microscope. The shear bond strength of all experimental groups was significantly higher than that of the control group. Group 3 with the addition of 1% SEG demonstrated the highest significance (12.86 MPa). The mode of failure for most of specimens was a mixed failure. Thus, it is indicated that enhancing the resin with 1% short E-glass fiber significantly improves the shear bond strength between repaired surface of the rapid heat-cured acrylic resin denture base and the reinforced autopolymerized acrylic resin.

Objective The aim of this study was to determine the effect of finish lines on the penetration ability of polyether and polyvinyl siloxane impression material into the simulated gingival sulcus. Materials and Methods Three types of finish line (chamfer, deep chamfer, and radial shoulder) were impressed with two types of elastomeric impression material (polyether and polyvinyl siloxane) using a two-step impression technique. Ten samples of each finish line were prepared and then separated into two groups of impression material: polyether and polyvinyl siloxane. The model of the simulated gingival sulcus had a width of 0.1 mm and a depth of 3.5 mm with a subgingival finish line of 0.5 mm. The effect of the finish lines on the penetration ability of these impression materials was analyzed using a two-way analysis of variance (ANOVA) and Tukey's multiple comparison tests at a statistically significant level of 0.05. Results A two-way ANOVA revealed a significant difference among finish lines, impression materials, and their interaction. The deep chamfer and radial shoulder finish lines displayed significantly higher penetration ability than the chamfer finish line. Moreover, polyether revealed significantly higher penetration ability than polyvinyl siloxane. Conclusion The finish lines affected the penetration ability of the impression materials. Therefore, the simulated gingival sulcus model demonstrates that it is an effective way of examining impression materials' penetration abilities.