Aim:This work evaluated the mechanical and surface behavior of different die materials. The studied materials are polyurethane resin Exakto-Form (Bredent), Gypsum type IV, Fuji Rock EP (Gc), and Durone (Dentsply).Materials and Methods:Two metallic matrices molded in polyvinyl siloxane provided 30 cylindrical test specimens for the diametral compression test and 30 hemispherical test specimens for the surface rugosity test. The cylindrical test specimens were submitted to tests of diametral compression strength using a DL2000 universal assay machine, with a load cell of 2000 Kgf and constant speed of 1 mm/min connected to the software. Kruskal–Wallis and Dunn's nonparametric tests were used to analyze the results. The hemispheres were submitted to the surface rugosity assay using a SJ201-P rugosimeter with a sensitivity of 300 μm, speed of 0.5 mm/s, and cut-off of 0.8 mm, and the readings were taken on the convex surface of the test specimens and metallic matrix. Results were analyzed using with Fisher's least significant differences test (LSD) and Dunnett's test.Results:Kruskal–Wallis test showed significant difference between die materials for diametral compression strength (P = 0.002). Dunn's test showed significantly higher values for modified polyurethane resin (Exakto-Form). The gypsum type IV, which did not significantly differ regarding diametral compression strength, showed 34.0% (Durone) and 42.7% (Fuji Rock) lower values in comparison to Exakto-Form.Conclusion:Within the parameters adopted in this study, it is possible to conclude that Exakto-Form polyurethane resin showed higher resistance to compression and was closer to the metallic matrix rugosity, and, along with the gypsum type IV Durone, showed better reproducibility of details relative to the Fuji Rock.
The aim of this study is to assess the shear strength between gingival compound resin Amarilis Gingiva (Voco, Germany) and a feldspar ceramic Creation (Willi Geller International, Austria) at the bond surface. To this end, the test considers two adhesive systems: Adper ScotchbondMulti-Purpose Plus, (3M ESPE, USA) and Adper Single BondPlus (3M ESPES, USA), and two surface treatments: with and without aluminum oxide 50 μm blasting. The specimens were distributed among four groups: G1 (blasting and Scotch Bond Multipurpose); G2 (without blasting and scotch Bond Multipurpose); G3 (blasting and Adper Single bond); G4 (without blasting and Adper Single Bond). The blocks with the ceramic were primed with hydrofluoric acid at 10% and the compound resin was applied. The test specimens were subjected to thermal cycling for 5,000 cycles at 5°C, 37.5°C and 55°C, and then tested for shear strength. Data were organized in a spreadsheet and analyzed with one-way ANOVA and Tukey's test. Here, treatment of the ceramic surface with blasting results in significant higher shear strength, regardless of adhesive type. Among the specimens submitted to blasting, the association of the adhesive 3M ESPE Adper ScotchbondMulti-Purpose Plus resulted in significantly higher shear strength.
Various further studies are still required to make polyurethane resin loaded with diatomite feasible for clinical use in making models, but when the results expressed in the study are analyzed, one verifies a high potential for this material. Conclusion: Conducting this study enabled the following conclusions to be drawn: 1-The diatomite load in the percentage of 30% increases the surface hardness, resistance to compression, traction resistance to diametral compression, resistance to fracture by impact, resistance to 3 point bending flexure and the resistance to wear by abrasion of the polyurethane resin. 2-In the comparison between the polyurethane resin modified with 30% diatomite and Type IV Plaster, the resin was superior in the tests of resistance to compression, traction resistance to diametral compression, resistance to fracture by impact, resistance to 3 point bending flexure and the resistance to wear by abrasion. 3-In view of the results found with the modification of polyurethane resin with 30% diatomite, it is feasible to use this material in dental modeling.
Objective: The aesthetics of dental materials is extremely important for the success of oral rehabilitation. Thus, in the present study we evaluated the color stability and the surface degradation of three micro hybrid composite resins after accelerated artificial aging process (AAA). Methods: Were prepared 24 specimens (n=8) for each material: Solidex, Artglass and Cesead, dimensions of Ø 15 mm by 2 mm in thickness. The samples were subjected to color analysis, before and after AAA, in a spectrophotometer according to the CIE L*a*b* parameters, and a sample of each material, was selected for morphological evaluation under scanning electron microscopy (SEM). The data were submitted to one-way ANOVA and Tukey test (α=0.05). Results: Artglass showed higher stability regarding the presence of red and yellow (p<0.05) when subjected to the AAA and fewer of these pigments (p<0.05) when compared to the Cesead and Solidex, which showed the highest luminance stability (p<0.05). ΔE Cesead was the most unstable (p<0.05). All resins analyzed by SEM showed superficial degradation when submitted to the AAA, mainly in resin Cesead. Conclusion: All materials analyzed demonstrate color change and surface degradation, Cesead resin showed the worse results.
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