Oxidation effects on porcelain-titanium interface reactions and bond strength

Area of Science:

• Materials Science
• Biomaterials Engineering
• Dental Materials

Background:

• Titanium offers strength, corrosion resistance, low density, and biocompatibility, making it suitable for dental restorations.
• Conventional ceramic-metal restorations are widely used due to aesthetics and mechanical properties.

Purpose of the Study:

• To investigate the effects of oxidation on porcelain-titanium interface reactions.
• To determine the impact of temperature and atmosphere on the bond strength of porcelain-titanium systems.

Main Methods:

• Pure titanium samples were heat-treated in a porcelain furnace (600-1000°C) under vacuum or air.
• X-ray diffraction (XRD) analyzed surface composition changes.
• Vickers hardness testing measured material hardness.
• Tension-shear tests evaluated bond strength.
• Metallographic microscopy examined the porcelain-titanium interface.

Main Results:

• Increasing firing temperature led to a decrease in alpha-Ti and an increase in titanium dioxide (TiO2) peak intensity.
• Vickers hardness of titanium increased with temperature, particularly above 900°C, and was higher in air than vacuum.
• Tension-shear bond strength was highest at the green stage and decreased significantly after treatment above 900°C.
• Metallography revealed a thick TiO2 layer at the interface for samples treated above 900°C, correlating with weakened bond strength.
• Standard degassing procedures for ceramic-gold were unsuitable for porcelain-pure titanium.

Conclusions:

• High-temperature treatment of titanium in porcelain furnaces promotes TiO2 formation, which detrimentally affects the bond strength.
• Excessive TiO2 layer formation weakens the porcelain-titanium interface.
• Optimal bonding in porcelain-titanium restorations necessitates precise temperature control and may require modified processing protocols compared to conventional systems.