Shear Bond Strength of Resin Cements to E.max Pressed Ceramic

Objective: The long-term survival of bonded ceramic restorations is of clinical concern. This study aimed to evaluate the effect of bonding quality on the interface failure initiation loads of E.max pressed ceramic material with two resin cements.

Method: E.max pressed ceramic was used to form discs 8mm in diameter and 4mm in thickness (n=40). The ceramic specimens were fabricated in a manner that simulated their clinical application. The ceramic specimens were fabricated using a wax pattern and attaching it to a wax spool, poured into a silicone ring and then transferred to a burnout furnace. The pressed porcelain discs were wet ground to ensure flat parallel surfaces. The pressed ceramic material was divided in two groups (n=20) that were determined by the type of resin cement used; Panavia F 2.0 (Group 1) and RelyX ARC (Group 2). All luted specimens were thermal cycled for 500 cycles between 5ºc and 55ºc with a 30-second dwell time prior to performing the shear bond strength test. The shear bond strength values of the specimens were determined using a universal testing machine at a cross-head speed of 0.5 mm/min., using a knife-edge shearing rod. The nominal bond strengths in Newton were determined by dividing the force at which bond failure occurred by the theoretical bonding area. An unpaired t-test was performed to determine the difference between groups.

Results: The characteristic fracture initiation loads ranged from 44.92 to 204.38 N. Group 2 (RelyX ARC) had the greatest mean observed load to fracture (141.937 N), SD (35.6) which was significantly greater than Group 1 (Panavia F 2.0) (P<.001).

Conclusions: These results suggest that the clinical use of the RelyX ARC with E.max pressed ceramic provides higher bond strength values than when Panavia F 2.0 is used.