1

The influence of water storage and soldering on types of failure (adhesive and cohesive) in porcelain fused to metal samples. (An invitro study) Ahmed G mehdi Background: Failure of bonding between porcelain and metal is not uncommon problem in porcelain fused to metal restorations, since the bonding process between metal and porcelain is complex, critical and need great attention to all details mentioned in the literatures according to authors. Materials and Methods: Forty cylindrical metal (Ni-Cr alloy) specimens were prepared; 8 mm in diameter and 3 mm in height. 20 of these specimens were made in such a way so that it has perforation in the center of 1mm in diameter; the later group is then soldered. All the samples were oxidized, and then sandblasted with aluminum oxide. The ceramic material (vita VMK 95) was applied, the final thickness of ceramic was about 1.5 mm, and then the samples was finished and glazed. 10 of the soldered and 10 of non soldered samples were stored in distilled water for one week, and then shear test was applied for all samples. After the testing, all samples were inspected visually and microscopically to detect the nature of failure. Results and Conclusion: The result revealed that the non soldered groups have higher percentage of cohesive failure than soldered groups which has higher percentage of adhesive failure, and there is no influence of the water storage on the nature of failure. Key words: Soldering, Porcelain fused to metal, shear bond test, cohesive and adhesiv