Wettability and bond strength between leucite-reinforced dental porcelains and Co-Cr alloy

A series of methods has been used to evaluate metal ceramic bond strength. However, little attention has been paid to the wettability and interfacial reactions of dental porcelain/alloy systems, which may affect the bond strength of metal ceramic restorations.

The purpose of this study was to understand the wetting and spreading behaviors, the interfacial reactions, and the bonding mechanism of ceramic to metal with TiO2 and MoO3 added to the dental porcelain.

Two leucite-reinforced dental porcelains were used in the study. Twelve Co-Cr alloy sheets (15 × 10 × 2 mm) divided into 2 groups were used to evaluate the wetting process, and 12 Co-Cr alloy sheets (25 × 3 × 0.5 mm) (Bego) divided into 2 groups were used for the 3-point bond strength test. The wetting process of the porcelain/alloy systems was observed in situ with a Tommi optical dimension measurement system using a modified sessile drop method. The reaction products of the interfacial region were determined by Raman spectra analyses. Metal ceramic specimens were tested in 3-point bending at a crosshead speed of 1.5 mm/min according to ISO 9693 requirements, and the results were statistically analyzed with 1-way ANOVA (α=.05).

The addition of TiO2 and MoO3 in the dental porcelain improved the wettability of the dental porcelain/Co-Cr alloy system. The bond strength of the porcelain modified with TiO2 and MoO3 was 43 ±2 MPa and that of the unmodified porcelain was 38 ±3 MPa. The fracture of the 2 metal ceramic systems occurred near the porcelain layer.

The application of TiO2 and MoO3 to the leucite-reinforced porcelain can improve the wettability of porcelain on alloy. Porcelain/alloy wettability can be used as a guide to improve the bonding property between dental porcelain and alloys.