Shear Bond Strength of Cerana Ceramic Inserts to Dentine

Objectives:The purpose of this in vitro study was to investigate the shear bond strength of leucite-reinforced glass ceramic inserts bonded to dentine, using a dual-cure resin cement.Methods:Twenty extracted, human third molar teeth were cleaned, and embedded into metal rings with self-curing acrylic resin. The teeth were ground wet using 600-grit silicone carbide paper to expose superficial dentine. The exposed dentine surfaces were treated with OptiBond Solo Plus according to the manufacturer's instructions. The samples were randomly divided into 2 groups (n=10). In Group 1 the pre-etched and silanated ceramic inserts were removed from their sealed packets and coated with a thin layer of the mixed bonding resin. In Group 2 the ceramic inserts were subjected to additional etching and silanization of the bonding surfaces. The surfaces were etched with 9.6% hydrofluoric acid (Ultradent) for 2 minutes, rinsed with copious amounts of water and air-dried. Two layers of Silane Primer were then applied to the etched ceramic surfaces and left to evaporate before application of a thin layer of the mixed bonding resin. Nexus cement was dispensed and mixed for 10 seconds before it was applied to the bonding surfaces of the treated ceramic inserts. The ceramic inserts were seated onto the treated dentine surfaces and light-cured under constant finger pressure. The bonded specimens were stored in 37ºC water for 24 hours. The shear test was performed in a Zwick testing machine at a crosshead speed of 0.5mm/min. The mean values were analyzed using the Student- t Test.Results: The results were as follows: Group 1 = 9.2 ± 1.6MPa and Group 2 =13.6 ±2.7MPa. There was a statistically significant difference in bond strength between the two groups. Conclusion:Additional etching and silanization of the ceramic inserts significantly improved the shear bond strength to dentine.