Comparative study of ceramometal tensile bonding strength in two base metal alloys

Statement of Problem: One of the greatest problems in metal –ceramic restorations is debonding of porcelain from dental alloys. Production of dental alloys by Iranian companies necessitates the evaluation of physical and handling properties of these products. In this study the bond strength between porcelain and two types of base metal alloys, Supercast (with beryllium) and Minalux (without beryllium) was investigated. In this experimental study 10 cylindric bars from each base metal alloy were prepared. The bars were degassed and porcelain was applied around them in a disc form (8 mm diameter and 2 mm thickness). The bond strength of porcelain to metal bars was tested with the shear strength test by Instron. Data were analyzed with student t-test and P<0.05 was considered as the limit of significance. The mean failure load was 71.58±6.4 KgF for Supercast and 67.34±5.48 for Minalux alloy. The bond strength of Supercast and Minalux were 55.85±4.99 MPa and 52.54±4.27 MPa respectively. The difference was statistically significant (P0.001). This study showed that nickel-chromium-beryllium alloy (Supercast) produced significantly better ceramometal bonding than nickel chromium alloy without beryllium (Minalux).