Mechanical Retention of Low-fusing Porcelain to Cast Titanium

Abstract

Purpose : This study used a three-point bending test to measure the bond strength of porcelain to cast titanium and examined the effect on bond strength of one means of mechanical retention.Materials and Methods : Retention beads (150, 200, 600 μm) were applied on the central portion of the pattern surface. After molds prepared from the patterns were cast with commercially pure (CP) titanium, the cast surfaces were air-abraded with 50 μm alumina powder. To investigate the effect of air-particle abrasion, cast titanium plates without retention beads were prepared and air-abraded with different alumina particle sizes (50, 125, 250 μm). Cast gold alloy plates air-abraded with 50 μm alumina were also prepared as references with and without 200 μm retention beads. Porcelain was applied on an area in the center of each cast metal plate. The three-point bending test was conducted at a crosshead speed of 1.5 mm/min. Fracture forces (Ff : N) and deflections (Df : mm) at fracture were recorded. The data (n=5) were statistically analyzed.Results : There were no statistical differences (p>0.05) in the Ff and Df values of specimens air-abraded using different alumina particle sizes. Increasing the size of the retention beads significantly increased the Ff and Df values of the specimens. The calculated bond strengths of porcelain to cast titanium were significantly (p<0.05) lower than to gold alloy.Conclusion : The application of retention beads significantly improved the three-point bending strength of porcelain to cast titanium.