The Effect of Ti/Ta Ratio and Processing Routes on the Hardness and Elastic Modulus of Porous TiNbZrTa Alloys.

TiNbZrTa alloys are promising for multidisciplinary applications, such as refractory and biomedical purposes, due to their high thermal stability and non-toxicity. Hardness and elastic modulus are among the key features for their adequate industrial applications. The influence of porosity and Ti/Ta ratio were investigated on TiNbZrTa alloys produced by three different processing routes, i.e., (i) blend element and posterior press and sintering (BE + P&S); (ii) mechanical alloying with press and sintering (MA + P&S); and (iii) arc melting and casting. Porosity decreased in the following order: casting < MA + P&S < BE + P&S. The total porosity of alloys increased with increasing Ta contents, i.e., by lowering the Ti/Ta ratio. However, the Ti/Ta ratio did not considerably affect the bonding energy or the elastic modulus. Hardness was increased significantly in dense alloys compared to porous ones. However, porosity and Ti/Ta ratio did not show a clear trend in hardness among the porous alloys.

Influence of ß-phase stability in elemental blended Ti-Mo and Ti-Mo-Zr alloys.

This paper investigated the improvement of mechanical properties for one of the most used biomaterials, titanium-based alloy. To improve its mechanical properties, molybdenum was chosen to be added to Ti and Ti-Zr alloys through a mechanical blending process. After homogenization of Ti (12, 15) Mo and Ti (12, 15) Mo-6 Zr, the compaction pressure and sintering temperature were varied to create pellets. Characterization has been done using scanning electron microscopy (SEM), X-ray diffraction (XRD), Vickers's hardness, Archimedes test and ultrasonic method, and 3-point bending test. Micrograph of each pellet revealed the influence of Mo content that plays a prominent role in the variation of microstructure in the alloys Ti-Mo and Ti-Zr-Mo. The porosity and density were also influenced by changing the ß-phase. EBSD analysis shows the increase in ß-phase with the addition of Zr. The overall results indicated that the percentage of ß-phase greatly affects the mechanical properties for the specimens.

Fractographic Study of the Interface Between Zirconia Y-TZP and Its Veneering Ceramic After Shear Strength Testing.

This study analyzed the shear strength and fracture characteristics of the interface between zirconia samples and their veneering ceramic compared with a metal-ceramic and a lithium disilicate glass-ceramic control group together with an assessment of the possible relationship between the fracture characteristics and the recorded shear strength. The greatest shear strengths corresponded to the lithium disilicate glass-ceramic control group followed by the metal-ceramic control group, with lesser strengths in the zirconia groups. Since the fractographic study showed cohesive-type failure to predominate in the zirconia samples, it is concluded that improvements are needed in the veneering ceramic and liner used in zirconia restorations.

Accuracy combining different brands of implants and abutments

Objective: To evaluate the vertical misfit between different brands of dental implants and prosthetic abutments, with or without mechanical torque, and to study their possible combination. Study design: Five different brands of implant were used in the study: Biofit (Castemaggiore, Italy), Bioner S.A.(Barcelona, Spain), 3i Biomet (Palm Beach, U.S.A.), BTI (Alava, Spain) and Nobel Biocare (Göteborg, Sweden), with standard 4.1 mm heads and external hexagons, and their respective machined prosthetic abutments. The implant-toabutmentfit/misfit was evaluated at four points (vestibular, lingual/palatine, mesial and distal) between implants and abutments of the same brand and different brands, with or without mechanical torque, using SEM micrographs at5000X. Image analysis was performed using NIS-Elements software (Nikon Instruments Europe B.V.).Results: Before applying torque, vertical misfit (microgaps) of the different combinations tested varied between1.6 and 5.4 microns and after applying torque, between 0.9 and 5.9 microns, an overall average of 3.46±2.96microns. For manual assembly without the use of mechanical torque, the best results were obtained with the combination of the 3i implant and the BTI abutment. The Nobel implant and Nobel abutment, 3i-3i and BTI-BTI and the combination of 3i implant with BTI or Nobel abutment provided the best vertical fit when mechanical torque was applied. Conclusions: The vertical fits obtained were within the limits considered clinically acceptable. The application of mechanical torque improved outcomes. There is compatibility between implants and abutments of different brand and so their combination is a clinical possibility (AU)

Bond strength of selected composite resin-cements to zirconium-oxide ceramic.

OBJECTIVES: The aim of this study was to evaluate bond strengths of zirconium-oxide (zirconia) ceramic and a selection of different composite resin cements. STUDY DESIGN: 130 Lava TM cylinders were fabricated. The cylinders were sandblasted with 80 µm aluminium oxide or silica coated with CoJet Sand. Silane, and bonding agent and/or Clearfil Ceramic Primer were applied. One hundred thirty composite cement cylinders, comprising two dual-polymerizing (Variolink II and Panavia F) and two autopolymerizing (Rely X and Multilink) resins were bonded to the ceramic samples. A shear test was conducted, followed by an optical microscopy study to identify the location and type of failure, an electron microscopy study (SEM and TEM) and statistical analysis using the Kruskal-Wallis test for more than two independent samples and Mann-Whitney for two independent samples. Given the large number of combinations, Bonferroni correction was applied (α=0.001). RESULTS: Dual-polymerizing cements provided better adhesion values (11.7 MPa) than the autopolymerizing (7.47 MPa) (p-value M-W<0.001). The worst techniques were Lava TM + sandblasting + Silane + Rely X; Lava TM + sandblasting + Silane + Multilink and Lava TM + CoJet + silane + Multilink. Adhesive failure (separation of cement and ceramic) was produced at a lesser force than cohesive failure (fracture of cement) (p-value M-W<0.001). Electron microscopy confirmed that the surface treatments modified the zirconium-oxide ceramic, creating a more rough and retentive surface, thus providing an improved micromechanical interlocking between the cement and the ceramic. CONCLUSIONS: Best results were provided by dual-polymerizing cements associated with sandblasting or silica coating and a bonding agent containing MDP.

Accuracy combining different brands of implants and abutments.

OBJECTIVE: To evaluate the vertical misfit between different brands of dental implants and prosthetic abutments, with or without mechanical torque, and to study their possible combination. STUDY DESIGN: Five different brands of implant were used in the study: Biofit (Castemaggiore, Italy), Bioner S.A. (Barcelona, Spain), 3i Biomet (Palm Beach, U.S.A.), BTI (Alava, Spain) and Nobel Biocare (Göteborg, Sweden), with standard 4.1 mm heads and external hexagons, and their respective machined prosthetic abutments. The implant-to-abutment fit/misfit was evaluated at four points (vestibular, lingual/palatine, mesial and distal) between implants and abutments of the same brand and different brands, with or without mechanical torque, using SEM micrographs at 5000X. Image analysis was performed using NIS-Elements software (Nikon Instruments Europe B.V.). RESULTS: Before applying torque, vertical misfit (microgaps) of the different combinations tested varied between 1.6 and 5.4 microns and after applying torque, between 0.9 and 5.9 microns, an overall average of 3.46 ± 2.96 microns. For manual assembly without the use of mechanical torque, the best results were obtained with the combination of the 3i implant and the BTI abutment. The Nobel implant and Nobel abutment, 3i-3i and BTI-BTI and the combination of 3i implant with BTI or Nobel abutment provided the best vertical fit when mechanical torque was applied. CONCLUSIONS: The vertical fits obtained were within the limits considered clinically acceptable. The application of mechanical torque improved outcomes. There is compatibility between implants and abutments of different brand and so their combination is a clinical possibility.

Bond strength evaluation of the veneering-core Ceramics bonds

Objective: The purpose of this study was to determine whether the bond of veneering porcelain to a ceramic corein bilayered ceramics was similar to that of the metal ceramic control of well known behaviour.Study design: Six groups of nine specimens each were fabricated, whose dimensions were 15 mm long and 8 mm in diameter at the core, and 2 mm long and 8 mm in diameter for the veneer. The groups were GR. 1 (controlgroup): CrNi alloy/d.SIGN (Ivoclar), GR. 2: IPS e.maxPress/IPS e.maxCeram (Ivoclar), GR. 3: IPS e.maxZirCad/IPS e.maxZirPress (Ivoclar), GR. 4: IPS e.maxZirCad/IPS e.maxCeram (Ivoclar), GR. 5: Lava Frame (3M ESPE)/Lava Ceram (3M ESPE) and GR. 6: Lava Frame (3M ESPE)/IPS e.maxCeram (Ivoclar).A shear strength test was used in all samples with a universal testing machine. The chosen crosshead speed wasof 0.50 mm/min. The obtained results were analyzed using a one way analysis of variance test (ANOVA) to determine whether significant differences existed between the groups (p<0.05). A Student Newman-Keuls multiple comparisons test was used. Results: GR. 1: 13.45 MPa, GR. 2: 24.20 MPa, GR. 3: 12.70 MPa, GR. 4: 7.86 MPa, GR. 5: 10.20 Mpa and GR. 6:4.62 Mpa.Conclusions: The bond strength of group 1 (control) was similar to groups 3 and 5. Group 2, whose core and venee rare both porcelains with a similar chemical composition, with silica as their main component, achieved thebest adhesive results between both porcelains. The technique on zirconia cores that showed the higher results was the pressed technique. The lowest results were for the group using porcelains from different manufacturers (AU)

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Bond strength evaluation of the veneering-core ceramics bonds.

OBJECTIVE: The purpose of this study was to determine whether the bond of veneering porcelain to a ceramic core in bilayered ceramics was similar to that of the metal ceramic control of well known behaviour. STUDY DESIGN: Six groups of nine specimens each were fabricated, whose dimensions were 15 mm long and 8 mm in diameter at the core, and 2 mm long and 8 mm in diameter for the veneer. The groups were GR. 1 (control group): CrNi alloy/d.SIGN (Ivoclar), GR. 2: IPS e.maxPress/IPS e.maxCeram (Ivoclar), GR. 3: IPS e.maxZirCad/IPS e.maxZirPress (Ivoclar), GR. 4: IPS e.maxZirCad/IPS e.maxCeram (Ivoclar), GR. 5: Lava Frame (3M ESPE)/Lava Ceram (3M ESPE) and GR. 6: Lava Frame (3M ESPE)/IPS e.maxCeram (Ivoclar). A shear strength test was used in all samples with a universal testing machine. The chosen crosshead speed was of 0.50 mm/min. The obtained results were analyzed using a one way analysis of variance test (ANOVA) to determine whether significant differences existed between the groups (p<0.05). A Student Newman-Keuls multiple comparisons test was used. RESULTS: GR. 1: 13.45 MPa, GR. 2: 24.20 MPa, GR. 3: 12.70 MPa, GR. 4: 7.86 MPa, GR. 5: 10.20 Mpa and GR. 6: 4.62 Mpa. CONCLUSIONS: The bond strength of group 1 (control) was similar to groups 3 and 5. Group 2, whose core and veneer are both porcelains with a similar chemical composition, with silica as their main component, achieved the best adhesive results between both porcelains. The technique on zirconia cores that showed the higher results was the pressed technique. The lowest results were for the group using porcelains from different manufacturers.

In vitro experimental study of bonding between aluminium oxide ceramicsand resin cements

To evaluate bond strengths of different resin cements to two aluminum oxide-based ceramics. Methods: Onehundred ten ceramic cylinders were produced and given four different surface treatments. Resin cement cylinderswere then bonded to the ceramic cylinders using different resin cements and the bond strength was determinedby shear testing to the breaking point. We were thus able to obtain results for the different combinations of porcelain,surface treatments and cements. All data was analyzed using the Kruskal-Wallis test for more than twoindependent samples and the Bonferroni correction applied (a=0.01). An optical microscopy study was carriedout to analyze the type of failure, and an electronic microscopy examination was carried out in order to evaluatethe changes produced in the ceramic by the different surface treatments. Results: The best values correspondedto the control group, composed of silicate ceramics combined with Variolink II resin cement. In-Ceram Aluminashowed no significant differences with respect to the type of cement applied. Procera AllCeram obtained the bestvalues when silica coated using the CoJet System and applying Variolink II, or when sandblasted and applyingClearfil SE Bond + Porcelain Bond Activator and Panavia F cement. Significance: Surface treatment modifies theceramic surface and influences the bond strength, as does the type of cement used. Silica coating is recommendedto improve adhesion to Procera AllCeram, applying Variolink II, or sandblasting plus resin cement containingMDP (Panavia F) (AU)

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In vitro experimental study of bonding between aluminium oxide ceramics and resin cements.

UNLABELLED: To evaluate bond strengths of different resin cements to two aluminum oxide-based ceramics. METHODS: One hundred ten ceramic cylinders were produced and given four different surface treatments. Resin cement cylinders were then bonded to the ceramic cylinders using different resin cements and the bond strength was determined by shear testing to the breaking point. We were thus able to obtain results for the different combinations of porcelain, surface treatments and cements. All data was analyzed using the Kruskal-Wallis test for more than two independent samples and the Bonferroni correction applied (a=0.01). An optical microscopy study was carried out to analyze the type of failure, and an electronic microscopy examination was carried out in order to evaluate the changes produced in the ceramic by the different surface treatments. RESULTS: The best values corresponded to the control group, composed of silicate ceramics combined with Variolink II resin cement. In-Ceram Alumina showed no significant differences with respect to the type of cement applied. Procera AllCeram obtained the best values when silica coated using the CoJet System and applying Variolink II, or when sandblasted and applying Clearfil SE Bond + Porcelain Bond Activator and Panavia F cement. SIGNIFICANCE: Surface treatment modifies the ceramic surface and influences the bond strength, as does the type of cement used. Silica coating is recommended to improve adhesion to Procera AllCeram, applying Variolink II, or sandblasting plus resin cement containing MDP (Panavia F).