Light-activation of resin cement through ceramic: relationship between irradiance intensity and bond strength to dentin.
This study investigated the relationship between the irradiance transmitted through ceramic and the bond strength of a resin cement to dentin. After application of an adhesive system, elastomer molds with cylindrical orifices (1.2 mm in diameter) were placed onto bovine dentin surfaces and filled with a photoactivated luting agent (Enforce; Dentsply Caulk). Light-activation was performed through a 0.6-mm-thick ceramic disc using different intensities: 250, 400, 550, 700, or 850 mW/cm(2). Control specimens were irradiated without ceramic (1050 mW/cm(2)). The radiant exposure was kept at 30 J/cm(2). Light spectral distribution was analyzed with a spectrometer. Microshear test was conducted and modes of failure were classified under SEM. Bond strength data were analyzed with ANOVA and Student-Newman-Keuls' test (alpha < or = 0.05), and failure scores with the Kruskal-Wallis test (alpha < or = 0.05). A linear regression model assessed the relationship between irradiance and bond strength. Groups light-cured at 250 and 400 mW/cm(2) presented lower bond strengths than groups activated at 850 and 1050 mW/cm(2). The linear regression showed that a decrease in light irradiance predicts a decrease in bond strength (r(2) = 0.955; p = 0.004). A predominance of mixed failures was observed. No significant alteration in the spectral wavelengths was observed. Despite the constant energy dose, the bond strength was dependent upon the irradiance level.
Moraes
Rafael R
RR
Department of Restorative Dentistry, Dental Materials Area, Piracicaba School of Dentistry, State University of Campinas, SP, Brazil.
Correr-Sobrinho
Lourenço
L
Sinhoreti
Mário A C
MA
Puppin-Rontani
Regina M
RM
Ogliari
Fabrício A
FA
Piva
Evandro
E
D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry; D002417:Cattle; D002516:Ceramics / Q000737:chemistry*; D001840:Dental Bonding / Q000295:instrumentation / Q000379:methods; D003799:Dental Stress Analysis; D003804:Dentin / Q000737:chemistry*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D008027:Light; D008422:Materials Testing; D019279:Resin Cements / Q000737:chemistry*; D033081:Shear Strength