Evaluation of the effect of adhesion resistance of porcelain material on the different surface treatments

SUMMARY Ceramics as excellent biocompatible materials are widely used to achieve highly esthetic characteristics in restorations like metal-ceramics. Although these restorations usually provide a high restorative service over the years, sometimes fracture within the esthetic material can occur. Complex nature of this prosthesis makes it an uneconomic and unpractical solution for the dentist and patient to replace failed restoration with a new one. In situations like these intraoral repairing of the restoration would be the more appropriate solution of choice. This in-vitro study investigated the bond strength resistance against shear strength of failed-porcelam-fused4o-metal-restoration-imitating examples treated with three different surface preparation methods and repaired with an adhesive bonding agent and resin material. The first group involved examples imitating failed restoration with ceramic surfaces exposed only. Nearly all the examples in this group showed cohesive failure. The highest bond strength resistance was found in the subgroup treated with sandblasting + acid etching with mean of 12.3 MPa. The second group consisted of examples imitating failed restorations with all metal surfaces exposed. In this group most of the failures were of adhesive type. The subgroup treated with sandblasting showed the highest resistance in this group with mean of 15 MPa. The third group contained examples imitating failed restorations with exposed both porcelain and metal surfaces. In this group failures of mixed (adhesive + cohesive) type were witnessed. The fracture occurred on surfaces with exposed porcelain was of cohesive and on metal surfaces was of adhesive type. The highest mean result in this group was obtained in the subgroup treated with sandblasting + acid etching and that was 12.2 MPa. There was no statistical difference found between the subgroups within any of the groups studied.