Effect of Pressure on Cement-Ceramic Adhesion in Microtensile Bond Tests

Objectives: Dental materials literature in the field of ceramic-cement adhesion consists of many microtensile bond strength (MBS) studies conducted under different parameters. This study tested the hypothesis that the composite blocks typically adhered to the conditioned ceramic surfaces under different loads would result in variations in MBS. Methods: Ceramic blocks (5x5x4mm) of In-Ceram Alumina (VITA Zahnfabrik) were fabricated (N=35) according to the manufacturer's instructions and duplicated in resin composite. Ceramic surfaces were ground finished to 1200-grit silicone-carbide abrasive and cleaned for 10 min in an ultrasonic bath. They were then randomly assigned to 5 groups and one surface of each ceramic block was conditioned using silica-coating utilizing laboratory type of air-abrasion device (Rocatector Delta, 3MESPE) and silanized (ESPE-Sil). Composite blocks were cemented to each conditioned ceramic block under 5 loads of pressure (10g, 50g, 100g, 500g and 750g) using a resin-cement system (Panavia F). The ceramic-cement-composite assemblies were cut under coolant water to obtain bar specimens with a bonding area of approximately 1x0.8 mm (n= 9 per group). The MBS tests were performed in a universal testing machine (1mm/min). The mean bond strengths were statistically analyzed using ANOVA (alpha=0.05). Results: Different seating forces, resulted in no significant difference in the MBS results ranging between 13.1±4.7 and 18.8±2.1 MPa (p=0.13). Conclusions: Cementation pressures at the loads tested seem not to affect the MBS results. The tested hypothesis was rejected.