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were pre-treated as recommended by cement manufacturers. Steel rods were cemented under pressure (20 g/mm 2 ) onto teeth and zirconia discs. After light-curing (lc) following the manufacturers’ instructions, specimens were stored for 24 h at 37 ◦ C and 100% rel. humidity. SBS was measured using a universal testing machine (Zwick Z010, crosshead speed: 0.75 mm/min). Intrinsic discoloration was tested using lc cement discs (15 mm × 1.5 mm). After storing in water for 1 month at 36 ◦ C, color of the discs was determined with a d/8 ◦ spectro-photometer (Color i7, xrite) and �E values were calculated. Degree of neutralization was determined by measuring the increase of pH of the mixed cement within 24 h (�pH) using pH indicator sticks (Fisherbrand). ACTA abrasion was measured according to ISO/TS 14569-2 (200,000 cycles, load 15 N, slip 15%). Data obtained were analyzed using Multiple Range Test (95% LSD). Results: – Values in one column with the same characters are statistically not different. Material SBS Enamel (MPa) dental materials 26S (2010) e1–e84 e63 SBS Dentin (MPa) SBS Zirconia (MPa) Discoloration (H2O) (�E) �pH within 24 h ACTA abrasion (�m) Maxcem Elite 24.3 a,b 4.6 c 24.3 b 5.2 2.5 71.4 ± 2.0 d SmartCem 2 20.5 b 5.0 c 24.7 b 1.4 4.5 51.4 ± 6.1 b G-CEM 21.6 a,b 9.8 b 28.5 a,b 2.6 5 56.6 ± 3.8 c RelyX Unicem 2 Automix 25.9 a 19.2 a 37.6 a 1.1 6.5 45.9 ± 2.5 a Conclusions: RelyX Unicem 2 Automix showed the best performance profile with excellent results in all tested material properties compared to all other cements in this study. Neutralization as indicated by a high �pH-value contributes to the longevity of the cementation. doi:10.1016/j.dental.2010.08.142 135 Measurement of the phase transformation of 3Y-TZP in depth using Raman spectroscopy C. Wulfman 1,2 , N. Dupont 2 , M. Sadoun 1 , M. Lamy De La Chapelle 2 1 URB2I-EA4462, University Paris Descartes, France 2 CSPBAT, University of Paris 13, France Objectives: Kinetics of phase transformation of partially stabilized zirconia (TZP) is usually studied through X-ray diffraction (XRD) or atomic force microscopy (AFM). Those techniques enable the observation of the surface of the sample, in a grain-size or nm depth, respectively. Furthermore, XRD permits a quantitative measurement of the transformed volume. The aim of this study is to measure the monoclinic phase amount in 3Y-TZP in relation with depth using Raman spectroscopy (RS). Materials and methods: Two XRD controlled pure tetragonal samples of 3Y-TZP (VITA ® ) were exposed to in vitro aging at 130 ◦ C in Ringer solution under a pressure of 6 bar for 0, 25 and 90 h. The monoclinic volume (Vm) was measured using XRD, following the Garvie and Nicholson relations. Deeper measurements were also performed with Raman spectroscopy, using an excitation wavelength at 632 nm with a power of 1 mW (HeNe Laser), coupled with confocal microscope. Objectives 10× and 100× are used to reach spatial resolutions at the micrometer scale (around 3 �m and 1 �m, respectively). Confocal pinhole aperture is gradually enlarged to deepen laser penetration. According to Clarke and Adar, monoclinic volume is given by: Vm = 0.97(I 145 t I178 m + I189 m + I256 t ) + I178 m + I189 m where It and Im indicate the intensities of the peaks of the tetragonal and monoclinic phases with peaks wavenumber in superscript. Results: Method Depth (�m) Vm (%) 0h 25h 90h XRD 0.1 0 70 70 RS 100× 1 0 42 64 RS 10× 2 0 12 37 RS 10× 14 0 7 24 RS 10× 70 0 2 15 In-depth measurements show a higher and deeper transformation rate after 90 h, due to water penetration, that was not detected with XRD.
e64 dental materials 26S (2010) e1–e84 Table1–EM(GPa(SD)) and FS (MPa (SD)) data from the tested materials. Material EM FS G-CEM Automix (GC) 7.75 a (1.15) 114.03 e (13.55) G-CEM Capsules (GC) 7.85 a (0.71) 60.04 f (11.12) RelyX Unicem Clicker (3M ESPE) 3.58 b (0.6) 49.0 g (5.24) RelyX Unicem Maxicap (3M ESPE) 5.36 c (0.59) 41.6 g (7.9) Maxcem Elite Automix (Kerr) 4.32 d (0.19) 69.74 f (7.83) SpeedCEM Automix (Ivoclar Vivadent) 5.02 c (0.42) 79.81 h (19.83) Superscript letters indicate statistically homogenous subsets. Conclusions: Raman spectroscopy enables quantitative measurement of zirconia monoclinic phase from subsurface (1 �m) to a depth of 70 �m. This method is thus appropriate to explore diffusion of water in the thickness of the material and its clinical consequences. doi:10.1016/j.dental.2010.08.143 136 Mechanical performance of self-adhesive resin cements J.I. Zorzin, A. Petschelt, U. Lohbauer Dental Clinic 1, University of Erlangen-Nuernberg, Germany Objective: Elastic modulus (EM) and Flexural strength (FS) are main material properties characterizing the mechanical performance of self-etching resin luting cements. The aim of this study was to obtain the EM and FS from a representative spectrum of this material class. Materials and methods: Six different self-etching resin luting cements were selected for measuring EM and FS. Barshaped specimens (2 mm × 2mm× 25 mm) were produced (n = 15, self-curing mode) and stored in distilled water for 24 h at 37 ◦ C prior to measurements in a universal testing machine (Z2.5, Zwick, Germany). Statistical analysis was performed using ANOVA and Tukey’s test (p < 0.05). Results: The material G-Cem showed the highest EM and FS, at least in the automix application. Different application forms of the same material showed a significant difference in FS whereas not in EM (Table 1). Conclusions: Self-etching resin luting cements have heterogenous mechanical properties. EM and FS have a great variation depending on the brand and application form. The automix/clicker application form produced improved results compared to their capsule counterpart, probably due to less internal porosity. doi:10.1016/j.dental.2010.08.144 137 Self-etching cement–dentine interface: A macrostructural evaluation P.A. Acquaviva, F. Cerutti, M. Gagliani, A. Cerutti University of Brescia, Italy Objectives: The aim of this study was to evaluate the adhesive interface of a new self-adhesive material used for fiber post cementation, studying the macrostructural aspect of adhesive interface and how a further etching step affects the dye infiltration after thermocycling. The null-hypothesis was an absence of infiltration and voids after thermocycling. Materials and methods: 40 single-rooted teeth were endodontically treated and sectioned at CEJ, randomly split into two groups (A & B) then the same kind of post 1 was luted with an experimental cement 2 : in group A the post space was etched with H3PO4 – for 15 s prior to placement, while no additional etching was performed in group B. Each root was cut into 4 slices at increasing distance from CEJ (1-3-5-7 mm), then analyzed after thermocycling (ISO/TS11405:2003) and immersion in a 2% methylene-blue solution (24 h). After the image steromicroscope acquisition (13×), the macrostructural analysis exploited a digital automated software, 3 in order to assess the degree of infiltration, presence of guttapercha, micro or macrovoids. The data were statistically analysed using 2 and Student’s t-test (p = 0.05). Results: The etching procedure improves the compositedentin bond by reducing the rate of infiltration: we observed a significant infiltration in sections until 5 mm in group B (p < 0.05). The presence of voids was due only to operator errors or anatomical variables, since the self-mixing application system ensures no air bubbles within the material. Conclusions: A further etching step could be a reliable method to improve the cement–dentin adhesion in post luting. doi:10.1016/j.dental.2010.08.145 138 Effective fluoride recharging protocols for various orthodontic adhesives B.S. Lim 1 , S.J. Lee 1 , D.Y. Lee 2 , S.J. Ahn 1 1 Seoul National University, Seoul, South Korea 2 Korea University, Seoul, South Korea Objectives: The purpose of this study was to evaluate the fluoride recharging capacity of various orthodontic adhesives and to find the most effective fluoride recharging protocol for them. Materials and methods: Five orthodontic adhesives were used: a non-fluoride-releasing composite (Transbond XT), a fluoride-releasing composite (Lightbond), a polyacidmodified composite (compomer) (Transbond Plus), and two resin-modified glass-ionomers (RMGI) (Fuji Ortho LC and Multi-Cure). Each sample was placed into deionized water (DW) and the initial fluoride release was measured for 2 months. Each sample was then subjected to four different treatments to simulate a fluoride recharge: 1000 ppm NaF solution, acidulated phosphate fluoride gel (APF), fluoridecontaining dentifrice and DW. After topical fluoride treatment, each sample was submitted to fluoride re-release tests. Results: Amounts of fluoride re-release (ppm/g/day) of orthodontic adhesives after various topical fluoride treatments. 1 FRC Postec Plus #3, Ivoclar-Vivadent. 2 Experimental cement, Ivoclar-Vivadent. 3 Jmicrovision.
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