The purpose of this study is to investigate the marginal precision of CNC-milled frameworks fabricated of CP grade 4 Titanium and of Cobalt-chrome alloy through digital technology and to compare them with conventional cast frameworks. Material and Methods: A titanium model of a mandibular arch with six implant analogues has been utilized as a master. The master model has been measured with a coordinate measuring machine. Fifteen rigid anatomic frameworks have been created on the master model utilizing cast gold alloy and milled Titanium and Cobalt-chrome material. The fifteen anatomic frameworks have been measured in the same manner of the master model. While the milled frameworks have been measured once, at the end of the milling process, the cast anatomic frameworks have been measured twice, immediately after the casting and divesting procedures and also after a technical adaptation procedure. Each anatomic framework has been weighed. To compare the measurements obtained from each group of frameworks, descriptive statistics were conducted as well as one-way ANOVA, considering statistically significance at p < 0.05. Results: The mean weight for the cast frameworks was 33.41grams, 18.12grams for the Cobalt-chrome frameworks and 8.7grams for the Titanium ones. The mean tridimensional deviation of the center point position for each group of frameworks was 261 micrometers (cast frameworks before adaptation), 49 micrometers (cast frameworks after adaptation), 26 micrometers (milled frameworks in Cobalt-chrome) and 26 micrometers (milled frameworks in Titanium). Conclusions: Within the limitation of this in vitro study, absolute passive fit cannot be achieved, no matter which type of material and technique is utilized. Anatomic milled frameworks fabricated in Titanium or in Cobalt-chrome present reduced center point deviation compared to cast framework. Titanium frameworks present reduced weight compared to Cobalt-chrome frameworks and to cast frameworks.
The precision of fit of cast and milled full-arch implant-supported restorations.
STELLINI, EDOARDO;MENEGHELLO, ROBERTO;CERARDI, ANDREA;BRESSAN, ERIBERTO
2013
Abstract
The purpose of this study is to investigate the marginal precision of CNC-milled frameworks fabricated of CP grade 4 Titanium and of Cobalt-chrome alloy through digital technology and to compare them with conventional cast frameworks. Material and Methods: A titanium model of a mandibular arch with six implant analogues has been utilized as a master. The master model has been measured with a coordinate measuring machine. Fifteen rigid anatomic frameworks have been created on the master model utilizing cast gold alloy and milled Titanium and Cobalt-chrome material. The fifteen anatomic frameworks have been measured in the same manner of the master model. While the milled frameworks have been measured once, at the end of the milling process, the cast anatomic frameworks have been measured twice, immediately after the casting and divesting procedures and also after a technical adaptation procedure. Each anatomic framework has been weighed. To compare the measurements obtained from each group of frameworks, descriptive statistics were conducted as well as one-way ANOVA, considering statistically significance at p < 0.05. Results: The mean weight for the cast frameworks was 33.41grams, 18.12grams for the Cobalt-chrome frameworks and 8.7grams for the Titanium ones. The mean tridimensional deviation of the center point position for each group of frameworks was 261 micrometers (cast frameworks before adaptation), 49 micrometers (cast frameworks after adaptation), 26 micrometers (milled frameworks in Cobalt-chrome) and 26 micrometers (milled frameworks in Titanium). Conclusions: Within the limitation of this in vitro study, absolute passive fit cannot be achieved, no matter which type of material and technique is utilized. Anatomic milled frameworks fabricated in Titanium or in Cobalt-chrome present reduced center point deviation compared to cast framework. Titanium frameworks present reduced weight compared to Cobalt-chrome frameworks and to cast frameworks.
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