Evaluation of the effect of different surface treatments on the bond strength of non-precious alloy‒ceramic interface: An SEM study

Abstract

Background. Dental porcelain has excellent esthetics in combination with biocompatibility and is one of the most commonly used restorative materials. Its low tensile strength remains a major drawback. The porcelain-fused-to-metal restorations have been introduced to increase the fracture resistance of dental porcelain. The aim of this study was to evaluate the effect of different surface treatments on the bond strength of a non-precious alloy to ceramic. Methods. The present cross-sectional observational study was conducted with forty samples of cobalt‒chromium that were fabricated with porcelain interposed between the two metal test pieces. The metal was subjected to combinations of different surface treatments. The samples group A (n=10) were not subjected to any surface treatments. Group B samples underwent sandblasting and surface grinding. Group C samples were subjected to sandblasting, surface grinding and degassing; and group D samples underwent sandblasting, surface grinding, ultrasonic cleaning and degassing. The tensile bond strength was measured in a universal testing machine, and a scanning electron microscope (SEM) was used to obtain images of the samples after surface treatment to determine the surface irregularities and after the debonding of the samples for the type of the bond failure. ANOVA was used for the statistical analysis. Results. The results showed significant variations in the tensile bond strength between the four groups (F=251.05, P=0.000). The SEM images of group A showed no surface irregularities; group C samples exhibited surface irregularities more than those in group B. Group D had the highest surface irregularities. SEM evaluations showed a statistically significant difference in the type of bond failure (P<0.001). Conclusion. Based on the results of this study, it can be concluded that the surface treatments on the metal increased the bond strength of the metal‒ceramic interface significantly. A combination of sandblasting, surface grinding and ultrasonic cleaning, followed by degassing, resulted in the highest tensile bond strength.

An In Vitro Study on the Shear Bond Strength of Feldspathic Porcelain to Nickel Chromium Alloy and Cobalt Chromium Alloy after Various Surface Treatments

“…Other treatment alternatives that can be used to improve the bonding between the metal alloy and the porcelain are irradiation of alloy by the Nd : YAG laser, using milled sintered base metal alloy, oxidation of the alloy surface, using alloy primer, surface grinding of alloy, degassing, ultrasonic cleaning, and by means of the thermocycling procedure [ 13 , 28 – 30 ]. Further research involving these options would provide a more complete understanding of the effect of alloy surface modifications on metal-ceramic bond strength.…”

Dental ceramic damage associated with incorrect laboratory procedures

“…The impurities remaining in the metal layer are decomposed during firing, creating gas bubbles at the metal-ceramic interface, which reduces the strength of the porcelain. 70 In addition, before applying the first layer of porcelain, it is recommended to clean the metal surface with a steam jet. As indicated by Lahori et al, regular inspection of the steam generator is important, as impurities in the steam can cause a reduction in the bond strength between metal and ceramics.…”

“…67 The most important mechanism affecting the ceramicmetal bond is the chemical bond between the ceramic and the oxide layer on the surface of the metal substructure. 70 An oxide layer is formed on the metal surface by heat treatment before firing the first ceramic layer (opaquer). The oxidation process initiates the formation of oxides, but also removes impurities from the metal framework.…”

Insightful Understanding of the Role of the Mechanical Properties in Defining the Reliability of All-Ceramic Dental Restorations: A Review

“…Despite the fact that metal ceramic restorations have been the norm for either single or multiple tooth prostheses [7], certain variables have been highlighted as conceivable limitations of these restorations. For instance, poor aesthetics that resulted from difficulty in producing the required translucency, and unfavorable metal margin visibility, particularly in the anterior teeth and poor biocompatibility, were the most common drawbacks of these restorations [8] [9] [10]. A source of failure of such restorations is delamination that takes place between the porcelain veneer and the underlying metal coping.…”