Ultrasonic Cleaning Affects Bond Strength of Sandblasted Restoration to Cement

Objectives: The purpose of this study was to evaluate the influence of ultrasonic cleaning of sandblasted surface of dental ceramic and alloy on bond strength to resin luting material. Methods: Zirconia-based ceramic (Lava, 3M ESPE, Germany) and cobalt chromium alloy (COBALTAN, Shofu Co, Japan) specimens (n=40) were randomly divided into two groups respectively; sandblasting and ultrasonic cleaning after sandblasting (n=20 for each). The surface of specimens was polished with silicon carbide abrasive paper (# 500, Striders A/S, Denmark) and sandblasting was performed using laboratory sandblaster (50 micrometer aluminum oxide, Shofu Co). The ultrasonic cleaning after sandblasting group was further applied ultrasonic cleaning for 5 minutes with distilled water, while the sandblasting group was applied no ultrasonic cleaning. These specimens were well air-dried and processed a luting material (Panavia F 2.0, Kuraray Medical, Japan) with 2mm thickness and 3.6mm in diameter. These specimens were stored in distilled water at 37degrees C for 24hours and shear bond strength values were determined at a crosshead speed of 0.5mm/min. Data was statistically analyzed using Mann-Whitney Rank Sum Test. Results: With zirconia-based ceramic, the mean shear bond strength value for sandblasting group was 13.1MPa and was significantly higher than that for ultrasonic cleaning after sandblasting group (9.7MPa, p<0.001). With cobalt chromium alloy, the mean shear bond strength value for sandblasting group was 12.9MPa and was significantly higher than that for ultrasonic cleaning after sandblasting group (8.8MPa, p=0.006). Conclusions: It seems reasonable to suppose that ultrasonic cleaning of zirconia-based ceramic and cobalt chromium alloy decrease the bond strength between the sandblasted surface of materials and resin luting material.