Shear bond strength of ceramic brackets bonded with different composites and irradiated with CO2 laser

• Grant number: 11/17069-8
• Support Opportunities: Regular Research Grants
• Start date: December 01, 2011
• End date: November 30, 2012
• Field of knowledge: Health Sciences - Dentistry - Orthodontics
• Principal Investigator: Fábio Lourenço Romano
• Grantee: Fábio Lourenço Romano
• Host Institution: Faculdade de Odontologia de Ribeirão Preto (FORP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Associated researchers: Denise de Souza Matos

Abstract

This study will evaluate the shear resistance of ceramic brackets with chemical retention and mechanics, bonded with different composites and irradiated with CO2 laser. Will be used 150 healthy human premolars, their crowns will be included in acrylic resin and the buccal surfaces are planed and polished with sandpaper until expose 5mm enamel. Subsequently, the roots of the teeth will be included in PVC also with acrylic resin so that the buccal surface is perpendicular to the base of the tube. The 150 specimens will be divided into 10 groups (n = 15), 2 controls and 8 experimental. In groups1 and 2 (controls) the composite used for bonding will be the Transbond XT, and in group 1 will be glued ceramic brackets Allure (mechanical retention) and in group 2, the ceramic brackets Fascination (chemical retention). In the experimental groups 3, 4, 5 and 6 will be glued Allure bracket with composites Transbond XT, Concise, Enlight and Z250, respectively. In groups 7, 8, 9 and 10, will be glued Fascination bracket with the same composite of groups 3, 4, 5 and 6. In the experimental groups, after bonding the brackets to be irradiated with CO2 laser with 10W of potency for 3 seconds. Immediately after irradiation will be performed to test the shear strength of bonding in mechanical universal testing machine (Emic DL 500). The values of test the shear strength will be obtained in MPa and submitted to statistic analysis, using the appropriate test. The significance level adopted will be 5%. In the end, 3 specimens of each group will be evaluated in scanning electron microscopy to investigate the occurrence of damage to tooth enamel. (AU)