Bond strength evaluation of two step self-etching adhesive to dentine of teeth submitted to internal bleaching activated by the LED-laser system

• Grant number: 09/09544-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2009
• End date: October 31, 2010
• Field of knowledge: Health Sciences - Dentistry - Endodontics
• Principal Investigator: Melissa Andreia Marchesan
• Grantee: João Felipe Bonatto Bruniera
• Host Institution: Universidade de Ribeirão Preto (UNAERP). Campus Ribeirão Preto. Ribeirão Preto , SP, Brazil

Abstract

The aim of this study is to evaluate ex vivo the influence of intracoronary dentin bleached with different hydrogen peroxide gels activated by a LED-laser system on the bond strength of two step self-etching adhesive system used in the restoration of endodontically-treated teeth, using shear bond strength test followed by type of failure analysis under stereoscopic magnification. Thirty intracoronary dentine fragments (25 mm2) will be embedded in acrylic resin and divided into 3 groups (n=10): G1- non-bleached; G2- bleached with 35% Whiteness HP Maxx hydrogen peroxide; G3- bleached with 38% Opalescence Xtra hydrogen peroxide. Hydrogen peroxide will be applied on the dentine surface and activated with LED-laser for 45s. This protocol will be repeated 3 times, in a single session. After 14 days, the specimens will receive the application of two-step Clearfill SE bond (Kuraray Medical INC., Kurashiki, Okayama, Japão) followed by FiltekZ100 and after 24h they will be submitted to the shear bond strength test using the Universal Testing Machine (2 kN e 0.5 mm/min) until the restoration is dislodged. The displacement values will be submitted to statistical analysis with the Instat 3 Program (±=0.05) to verify if there are statistically significant differences between the groups. The specimens will also be evaluated qualitatively under stereoscopic magnification to verify the type of failure mode that occurred: adhesive, cohesive and mixed.