CAD/CAM System (cam + system)

Distribution by Scientific Domains
Medical Sciences60%

Selected Abstracts

Clinical fit of all-ceramic three-unit fixed partial dentures, generated with three different CAD/CAM systems

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2005
Sven Reich
In this study, the hypothesis was tested that the marginal and internal fit of CAD/CAM fabricated all-ceramic three-unit fixed partial dentures (FPDs) can be as good as in metal,ceramic FPDs. Twenty-four all-ceramic FPDs were fabricated and randomly subdivided into three equally sized groups. Eight frameworks were fabricated using the Digident CAD/CAM system (DIGI), another eight frameworks using the Cerec Inlab system (INLA). Vita Inceram Zirkonia blanks were used for both groups. In a third group frameworks were milled from yttrium-stabilized Zirconium blanks using the Lava system (LAVA). All frameworks were layered with ceramic veneering material. In addition, six three-unit metal-ceramic FPDs served as control group. All FPDs were evaluated using a replica technique with a light body silicone stabilized with a heavy body material. The replica samples were examined under microscope. The medians of marginal gaps were 75 µm for DIGI, 65 µm for LAVA and INLA and 54 µm for the conventional FPDs. Only the DIGI data differed significantly from those of the conventional FPDs. Within the limits of this study, the results suggest that the accuracy of CAD/CAM generated three-unit FPDs is satisfactory for clinical use. [source]

Microtensile Bond Strength and Impact Energy of Fracture of CAD-Veneered Zirconia Restorations

JOURNAL OF PROSTHODONTICS, Issue 3 2009
Moustafa N. Aboushelib DDS
Abstract Purpose: With state-of-the-art CAD/CAM technology, the fabrication of large and complex zirconia frameworks is just a click away. On the other hand, veneering of the frameworks is still operator-dependent. The aim of this work was to evaluate CAD veneering of zirconia restorations in terms of zirconia veneer bond strength and impact energy of fracture in a step towards complete automation of the fabrication process. Materials and Methods: A new CAD/CAM system was used to fabricate a resin replica of the esthetic ceramic required to veneer a zirconia framework. The replica was seated on the zirconia framework and further processed using press-on technology. The bond strength between zirconia and the CAD veneer was evaluated using microtensile bond strength test. The impact energy of fracture of the specimens was also investigated. Manually layered zirconia specimens served as a control (,= 0.05). Results: There was no significant difference in the microtensile bond strength between zirconia and either of the used veneers (39 MPa). Even though the impact energy of fracture of the CAD-veneered and manually layered specimens was almost identical (0.13 J), the former demonstrated a cohesive fracture of the veneer, while the latter failed by delamination of the veneer ceramic. Conclusion: CAD veneering is a reliable method for veneering zirconia restorations. [source]

Clinical fit of all-ceramic three-unit fixed partial dentures, generated with three different CAD/CAM systems

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2005
Sven Reich
In this study, the hypothesis was tested that the marginal and internal fit of CAD/CAM fabricated all-ceramic three-unit fixed partial dentures (FPDs) can be as good as in metal,ceramic FPDs. Twenty-four all-ceramic FPDs were fabricated and randomly subdivided into three equally sized groups. Eight frameworks were fabricated using the Digident CAD/CAM system (DIGI), another eight frameworks using the Cerec Inlab system (INLA). Vita Inceram Zirkonia blanks were used for both groups. In a third group frameworks were milled from yttrium-stabilized Zirconium blanks using the Lava system (LAVA). All frameworks were layered with ceramic veneering material. In addition, six three-unit metal-ceramic FPDs served as control group. All FPDs were evaluated using a replica technique with a light body silicone stabilized with a heavy body material. The replica samples were examined under microscope. The medians of marginal gaps were 75 µm for DIGI, 65 µm for LAVA and INLA and 54 µm for the conventional FPDs. Only the DIGI data differed significantly from those of the conventional FPDs. Within the limits of this study, the results suggest that the accuracy of CAD/CAM generated three-unit FPDs is satisfactory for clinical use. [source]

Effects of tyroserleutide on gene expression of calmodulin and PI3K in hepatocellular carcinoma,

JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2008
Lan Zhao
Abstract Tyroserleutide (YSL) is a tripeptide compound that has exhibited inhibitory effects on hepatocellular carcinoma in our previous research. The mechanism of this antitumor activity involves the second messenger, Ca2+. Ca2+ influences cell function through the Ca2+/calmodulin (CaM) pathway, and abnormality of the Ca2+/CaM system correlates closely with the occurrence of tumors. In addition, CaM associates with phosphatidylinositol 3 kinase (PI3K), thereby enhancing the activity of PI3K, which promotes cell proliferation. In order to investigate its anti-tumor mechanism, we studied the effects of YSL on CaM protein expression and mRNA level, PI3K activity, PI3K regulatory subunit p85 protein expression and mRNA level, and the mRNA level of PI3K catalytic subunits p110, and p110, in human hepatocellular carcinoma BEL-7402 xenograft tumors in nude mice. Our results showed that YSL decreased the mRNA level and protein expression of CaM, inhibited the activity of PI3K, and reduced the mRNA level and protein expression of the PI3K regulatory subunit p85 and mRNA level of PI3K catalytic subunits p110, and p110,. Accordingly, it is suggestive that the anti-tumor effects of YSL may be mediated by down regulation of CaM and PI3K subunits p85 and p110, influencing the signal transduction pathway in the tumor cells and perhaps overcoming the dysfunctional PI3K activity in tumors. J. Cell. Biochem. 103: 471,478, 2008. © 2007 Wiley-Liss, Inc. [source]

Introducing Radius of Torsure and Cylindroid of Torsure

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 8 2003
David B. Dooner
Robotic path planning can involve the specification of the position and orientation of an end-effector to achieve a desired task (e.g., deburring, welding, or surface metrology). Under such scenarios the end-effector is instantaneously rotating and translating about a unique axis; the ISA. Alternately, the performance of direct contact mechanisms (viz., cam systems and gear pairs) are dependent on the surface geometry between two surfaces in direct contact. Determination of this geometry can entail the parametrization of a family of geodesics curves embedded within each surface. This parametrization is tantamount to an end-effector rotating and translating about an ISA. In both scenarios there is a unique ISA for each geodesic embedded in a surface. Here, curvature and torsion of a spatial curve are coupled together to define an alternative definition for the radius-of-curvature of a spatial curve. This new definition is identified as radius of torsure to distinguish it from the classical definition for radius-of-curvature. Further, it is shown that the family of twists that corresponds to the pencil of geodesics coincident with a point on a surface defines a cylindroid: the cylindroid of torsure. An illustrative example is provided to demonstrate this difference. © 2003 Wiley Periodicals, Inc. [source]