The effect of dual-cured resin cement layer thickness on microtensile bond strength of simulated indirect restorations to dentin.

• Grant number: 09/07222-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2009
• End date: July 31, 2010
• Field of knowledge: Health Sciences - Dentistry - Dental Clinics
• Principal Investigator: César Augusto Galvão Arrais
• Grantee: Alline Rachid Abreu dos Santos
• Host Institution: Universidade de Guarulhos (UNG). Campus Guarulhos-Centro. Guarulhos , SP, Brazil

Abstract

This study aims to evaluate the effect of the thickness of dual-cured resin cement layer on the microtensile bond strength of simulated indirect restorations to dentin surfaces. The dual-cured cementing system (bonding agent/resin cement) XP Bond Dual-Cure/Calibra (Dentsply Caulk)and the self-adhesive Rely X Unicem will be evaluated. The occlusal dentin surface of forty human third molars will be exposed and the products will be applied to the dentin surface according to the manufacturers' instructions. Forty pre-cured 2-mm thick resin composites discs (A2 shade, TPH Spectrum, Dentsply Caulk) will be created to simulate the indirect restoration. The resin composite surface to be cemented will have either 50- or 150 µm spacers at the borders to ensure the proposed thicknesses for the resin cement layers. The resin composite discs will be cemented on the dentin surfaces and will be either light-activated for 40 s fotoativados (Optilux 501, Kerr/Demetron, Orange, CA, USA) or allowed to self-cure for 5 min under 500-g load. The restored teeth will be stored in relative humidity for 7 days at 37oC and will be serially sectioned in buco-lingual and mesio-distal directions to create sticks with cross sectional area of approximately 1 mm2. The specimens will be tested in tension using a universal testing machine (Ez-test - Shimadzu) at a cross head speed of 1.0 mm/min. The results will be analyzed using 3-way ANOVA and post-hoc Tukey's test (pre-set alpha of 5%).