Effect of reporcelainization on the bond strength between non-precious alloys and porcelain

Porcelain fracture over non-precious crown copings is a common clinical disaster. It occurs always during cementation procedure or short after cementation and cause a great problem for the clinician. Repairing of fractured porcelain takes place if the fracture happens after cementation in the patient mouth. If the fracture happens during check up for cementation, the clinician immediately sends the fractured crown or bridge to the laboratory for correction. The correction by the laboratory is done through reapplication of porcelain on the fractured area and firing it again [reporcelainization]. The laboratory may sandblast the bare area before reapplication of porcelain, or not, exposing the restoration to the effect of the multiple firings. This problem is of great importance since till now there is lack of literature that investigates this point, especially the relationship between reapplication of porcelain on metal surface after porcelain failure and the new bond strength between the reapplied porcelain and metal

Effect of casting of five different ratios of fresh / used two ceramo-metallic alloys on bond strength to porcelain

Two ceramo-metal non-precious alloys with one type of porcelain were used in this study. Five different ratios of fresh-used alloys were tested for their bond strength with porcelain. The ratios used by weight was as follow: 100% fresh, 75% fresh and 25% used, 50% fresh and 50% used, 25% fresh and 75% used, 100% used alloy. Five rod samples were cast for each group with a total of 50 samples. Porcelain was applied and tested for shear bond strength. Results were tabulated and statistically analyzed