Evaluation of color stability, degree of conversion and bond strength of luting systems after artificial aging

• Grant number: 11/11937-8
• Support type: Scholarships in Brazil - Doctorate
• Effective date (Start): November 01, 2011
• Effective date (End): February 28, 2014
• Field of knowledge: Health Sciences - Dentistry - Dental Clinics
• Principal researcher: Luis Alexandre Maffei Sartini Paulillo
• Grantee: Lucia Trazzi Prieto
• Home Institution: Faculdade de Odontologia de Piracicaba (FOP). Universidade Estadual de Campinas (UNICAMP). Piracicaba , SP, Brazil

Abstract

The resin cements are vital for fixing laminates, the color stability and bond strength of these cements are important to achieve a successful clinical outcome. The aim of this study "in vitro" was to evaluate the physical properties of resin cements and flowable composite used in luting veneers enamel, through the evaluation of color stability and bond strength after artificial aging, and yet, the degree of conversion. For this, two separate studies were developed; the first study used 48 human incisors. These teeth were randomly divided into 6 groups (n = 8 ) , formed by luting systems RelyX Veneer / Single Bond 2 ( 3M ESPE ) , RelyX ARC / Single Bond 2 ( 3M ESPE ) , Filtek Flowable / Single Bond 2 ( 3M ESPE ) , Variolink Veneer / Tetric N - Bond ( Ivoclar Vivadent - ) , Variolink II / Tetric N - Bond ( Ivoclar Vivadent - ) and Tetric N -Flow / Tetric N - Bond ( Ivoclar Vivadent - ). To evaluates the color stability enamel preparations in dental crowns with 0.6 mm deep simulating preparations for veneers were performed. After 48 laminates were fabricated using ceramic IPS Empress Esthetic, which were luting according to the experimental groups. Twenty-four hours after luting the initial color was measured with spectrophotometer (Vita - Easyshade). After thermal-mechanical aging with 2,500 thermal cycles, 1,200,000 cycles mechanical load of 50 N and accelerated aging by light for 300 hours (150Kj / m) new color measurement was performed. To measure the degree of conversion of 48 specimens (n = 10 ) of each resin cement and composite resin flow were made (with dimensions of 5 mm diameter and 0.5 mm thick) and absorption spectra were obtained by the spectrometer Spectrum 100 FTIR / UATR. For the second study were selected another 48 human incisors to microshear bond strength, for this test luting two ceramic cylinders (IPS Empress Esthetic) was performed with 1 mm diameter and 2 mm height on the labial enamel planned after twenty-four hours the first cylinder was attached to the EZ -test machine for measuring the bond strength and the remaining cylinder was subjected to accelerated aging by light, and then test for the new bond strength and fracture pattern was performed was analyzed under a light microscope. Data were submitted to ANOVA and Tukey test (± = 0.05). Regarding the first study the color stability of all materials tested showed significant change in clinically perceptible color (”E > 3.3) but showed no statistical difference between them. The degree of conversion, Tetric Flow and Variolink Veneer obtained the best results, and Filtek Flow, RelyX Veneer and Variolink II showed intermediate results to differ from each other and cement RelyX ARC showed the lowest degree of conversion. The second study presented as a result of luting systems Single Bond/ RelyX ARC and Tetric N-Bond/Variolink II showed the best bond strength when compared to other systems, Tetric N-bond/Variolink Veneer and Single Bond 2/RelyX Veneer were statistically similar and higher flow composite resins, which have the lowest values. From the results it can be concluded that all luting systems suffer noticeable change in color after undergoing aging in relation to the dual materials microshear test showed better performance but when assessed in relation to the degree of conversion had the lowest conversion statistically different from the other materials tested. (AU)