METAL - CERAMIC BOND STRENGTH ANALYSIS OF COBALT-CHROMIUM DENTAL ALLOY FABRICATED BY THREE DIFFERENT TECHNIQUES (IN-VITRO STUDY)

Objectives: was to compare the bond strength of porcelain to cobalt-chromium metal alloy fabricated by three different techniques and investigation of the failure mode by scanning electron microscope
Methods: Forty-two Co-Cr specimens (25mmx3mmx0.5mm) were prepared according to ISO 9693:1999 standards using three different techniques: selective laser sintering (group1, n=14), CAD-CAM milling (group2, n=14) and lost wax technique (group3, n=14). The metal bars were veneered by firing a porcelain layer on the center of each specimen (8mm length x3mm width x1.1mm thickness), metal ceramic bond strength was evaluated by a three-point bending test then each specimen was examined by Scanning electron microscope to evaluate the failure mode.
Results: The statistical analysis of the results showed highest bond strength values associated with laser sintering group 1 with Mean ± SD of 61.79 ± 9.40 which was statistically highly significant at P < 0.001. For CAD-CAM milled group 2, moderate bond strength values with Mean ± SD of 31.21 ± 3.40 which was statistically significant at P < 0.05. The specimens that were manufactured by casting technology group 3 showed the lowest bond strength values with Mean ± SD of 24.71 ± 3.43 which was statistically non-significant at p> 0.05.
Conclusions: The alloy fabricated by the Selective laser sintering technique can provide an acceptable metal– ceramic bond strength for clinical applications, comparable to CAD-CAM milling and traditional lost wax techniques.