Abstract:The purpose of this study was to compare the effect of casting temperature and atmosphere on the castability of three Ni-Cr alloys against direct flame casting method. Vera Bond (VB), Vera Bond 2 (VB2) and Wiron 99 (W99) were cast at three temperatures: VB and VB2 (1310 °C, 1340 °C and 1370 °C); W99 (1400 °C, 1430 °C and 1460 °C) in atmosphere, vacuum and direct flame. Each alloy was cast in seven different conditions. Castability was assessed by the method that verifies the alloy poten… Show more
“…In the present study, specimens were not cast by gas-oxygen flame technique. Nevertheless, it is possible that the use of these methods might have resulted in lower MCBS values when compared to other groups, since the use of casting machines that enables closing the control of casting conditions may represent a significant contribution to improving the quality of dental restorations with base metal alloys (19). However, to the best of our knowledge, there were no studies that evaluated the effect of casting atmosphere on the MCBS of the Ni-Cr alloys.…”
Section: Discussionmentioning
confidence: 98%
“…The incorrect use of a direct gas-oxygen flame may affect the properties of Ni-Cr alloys (19), despite its ideal formulation and mold temperature, due to the possibility of over-or under-melting temperature and use of the oxidizing zone of the flame during casting. In the present study, specimens were not cast by gas-oxygen flame technique.…”
The success of metal-ceramic restorations depends on an optimal bond between metal and ceramic. This study evaluated the effect of 3 casting atmospheres on the metal-ceramic bond strength (MCBS) of 2 Ni-Cr alloys, with beryllium (Fit Cast V) and without beryllium (Fit Cast SB). Sixty acrylic resin patterns (8 mm long and 5 mm diameter) were obtained using a fluorocarbon resin matrix. Wax was used to refine the surface of acrylic resin patterns that were invested and cast in an induction casting machine under normal, vacuum, and argon atmospheres at a temperature of 1340 o C. The castings were divested manually and airborne-particle abraded with 100-mm aluminum-oxide. Ten castings were obtained for each group. The IPS Classic V ceramic was applied (2 mm high and 5 mm diameter). The shear bond strength was tested in a mechanical testing machine with a crosshead speed of 2.0 mm/min. The MCBS data (MPa) were subjected to 2-way analysis of variance (a=0.05). There was no statistically significant difference (p>0.05) between the alloys or among the casting atmospheres. Within the limitations of this study, it may be concluded that the presence of beryllium and the casting atmosphere did not interfere in the MCBS of the evaluated metal-ceramic combinations
“…In the present study, specimens were not cast by gas-oxygen flame technique. Nevertheless, it is possible that the use of these methods might have resulted in lower MCBS values when compared to other groups, since the use of casting machines that enables closing the control of casting conditions may represent a significant contribution to improving the quality of dental restorations with base metal alloys (19). However, to the best of our knowledge, there were no studies that evaluated the effect of casting atmosphere on the MCBS of the Ni-Cr alloys.…”
Section: Discussionmentioning
confidence: 98%
“…The incorrect use of a direct gas-oxygen flame may affect the properties of Ni-Cr alloys (19), despite its ideal formulation and mold temperature, due to the possibility of over-or under-melting temperature and use of the oxidizing zone of the flame during casting. In the present study, specimens were not cast by gas-oxygen flame technique.…”
The success of metal-ceramic restorations depends on an optimal bond between metal and ceramic. This study evaluated the effect of 3 casting atmospheres on the metal-ceramic bond strength (MCBS) of 2 Ni-Cr alloys, with beryllium (Fit Cast V) and without beryllium (Fit Cast SB). Sixty acrylic resin patterns (8 mm long and 5 mm diameter) were obtained using a fluorocarbon resin matrix. Wax was used to refine the surface of acrylic resin patterns that were invested and cast in an induction casting machine under normal, vacuum, and argon atmospheres at a temperature of 1340 o C. The castings were divested manually and airborne-particle abraded with 100-mm aluminum-oxide. Ten castings were obtained for each group. The IPS Classic V ceramic was applied (2 mm high and 5 mm diameter). The shear bond strength was tested in a mechanical testing machine with a crosshead speed of 2.0 mm/min. The MCBS data (MPa) were subjected to 2-way analysis of variance (a=0.05). There was no statistically significant difference (p>0.05) between the alloys or among the casting atmospheres. Within the limitations of this study, it may be concluded that the presence of beryllium and the casting atmosphere did not interfere in the MCBS of the evaluated metal-ceramic combinations
“…Many manufacturers suggest using customized cast abutments as an alternative to prefabricated abutments for prosthetic rehabilitation of unconventional angulation of implants. Use of Cr-containing alloys such as Co-Cr and Ni-Cr has greatly increased due to their cost-effectiveness [15]. Evidence shows that defects in base metal restorations are mainly due to inaccurate casting rather than the suboptimal properties of the alloys [16].…”
Background:
Implant placement with more than 25° angle and use of customized abutments are still challenging in implant dentistry. Also, casting is still the most commonly used method for fabrication of customized abutments.
Objective:
This study evaluated the effect of angulation and type of abutment (castable and cast-to) on torque loss and fracture resistance after cyclic loading.
Methods:
Two implants were mounted with 0 and 30° angle on a gypsum model. Castable and Cast-to abutments were casted by cobalt-chromium alloy on each implant (10 samples in 4 groups). Rotational freedom was measured by a video-measuring microscope. The reverse torque values before and after cyclic loading (500,000 cycles) were measured by a digital torque-meter. Abutments were subjected to fracture resistance test in a universal testing machine. Data were analyzed using the Kruskal Wallis, two-way ANOVA and repeated measures tests.
Results:
Difference between castable and cast-to abutments regarding rotational freedom was not significant. Torque loss in castable abutments was significantly greater than cast-to abutments before and after cyclic loading (P < 0.05). The effect of abutment angle on torque loss before and after cyclic loading was not significant.
Conclusion:
Irrespective of the abutment angle, torque loss was significantly higher in castable groups. Considering the high fracture resistance, abutment fractures were not clinically an issue.
The Ni-Cr-Mo-Ti alloy showed high UTS, MHV and lowest EL comparaded with the tradicional Ni-Cr-Mo-Be, that show lowest UTS, MHV and higher EL when cast on induction/argon.
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