dental materials 27S (2011) e1–e84 e55 126 Silica film deposition on Y-TZP by plasma technique improves bonding M. Cardoso 1,∗ , J.R.C. Queiroz 1 , L. Nogueira 1 , Junior 1 , M.A. Bottino 1 , M. Ozcan 2 , A.S. Sobrinho 3 , M. Massi 3 1 São Paulo State University, Brazil 2 Zentrum fur Zahn Mund und Kieferheilkunde, Switzerland 3 Technological Institute of Aeronautics, Brazil Objectives: To evaluate the effect of different Si-based coat- ing deposited on Y-TZP by magnetron sputtering on bond strength to resin cement. Materials and methods: Eighty blocks (6 mm × 6 mm × 3 mm) of Y-TZP (Cercon) were divided into 10 groups according to surface treatment (n = 8): (Gp) pol- ished surface; (Gpr) polished surface + primer (Metalzirconia primer); (Gs) Sandblasted surface + primer; (Gps) Sandblasted surface prior to firing process of ceramic + primer; (Grf) Film deposition using radio frequency (RF), silica target and Argon plasma on polished surface + silane (Monobond S); (Gsio 2 ) Film deposition using direct current (DC), silicon target, and argon/oxygen plasma (8:1 in flux) on polished surface + silane; (Gsio) Film deposition using DC, silicon target, and argon/oxygen plasma (20:1 in flux) on polished surface + silane; (Grfps), (Gsio 2 ps) and (Gsiops) Film used in (Grf), (Gsio 2 ) and (Gsio) respectively, deposited on sand- blasted surface prior firing of ceramic + silane. Interference microscopy evaluated the roughness surface. Resin cement (Multilink) cylinders were confectioned on the Y-TZP surfaces and stored in distilled water (37 ◦ C ± 1 ◦ ; 48 h) before shear bond strength test. Fractured surfaces were analyzed by opti- cal microscopy and SEM and named in adhesive, cohesive and mixed failure. The data obtained were statistically evaluated by 1-way ANOVA and Tukey’s test (5%). Results: Groups Bond strength (MPa) Ra Gn 0 g 0.12 (<0.1) Gp 2.42 (0.3) fg 0.12 (<0.1) Gs 14.62 (3.2) b 0.51 (0.1) Gps 8.29 (1.2) cd 0.62 (0.2) Grf 6.85 (2.2) cde 0.11 (0.1) Gsio 2 10.51 (1.5) c 0.10 (0.1) Gsio 2.77 (0.7) fg 0.12 (0.1) Grfps 5.08 (2.2) def 0.61 (0.2) Gsio 2 ps 22.78 (5.2) a 0.61 (0.2) Gsiops 4.40 (1.1) ef 0.67 (0.2) The surface treatment had influence in the initial SBS results, showing that Gsio 2 r was statistically better than other groups. Roughness surface pattern did not change after film deposition. The increase of roughness surface and the film used in Gsio 2 r increased mixed failure frequency. Conclusions: Roughness surface had partial influence in initial SBS strength results when a film was used. Initial SBS results using Si-based coatings are dependent on film deposi- tion parameters. doi:10.1016/j.dental.2011.08.529 127 Effect of heat-pressing on the properties of a dental porcelain P.F. Cesar 1,∗ , M.D. Araújo 1 , R.B.P. Miranda 1 , C. Fredericci 2 , H.N. Yoshimura 3 1 University of São Paulo, Brazil 2 Institute of Technological Research, Brazil 3 Federal University of ABC, Brazil Objectives: The objective of this work was to test the hypothesis that processing a dental porcelain with the heat- pressing technique (HP) improves its mechanical properties compared to the conventional sintering (S) method. Materials and methods: Disk specimens (n = 10, ∅ 12 mm × 1 mm) were produced with feldspathic porce- lain (Vintage Halo, Shofu) using both the S (control) and HP processing methods. For the S method, green specimens were prepared by applying the porcelain slurry to a stain- less steel mold (condensation method) and sintering in a conventional dental porcelain furnace following the firing schedules recommended by the manufacturer (peak sintering temperature of 915 ◦ C). In the HP technique, refractory molds of the disks were produced by the lost wax technique. To produce pressable porcelain ingots, the porcelain slurry was dry-pressed (3 ton for 30 s) in the form of a cylinder with 12 mm in diameter and 20 mm in height. The ingot was pre- sintered at 500 ◦ C for 30 min and placed within the refractory mold that was taken into a pressing furnace and heated to 915 ◦ C, when heat-pressing occurred for 5 min at 3.5 bar. Flexural strength was determined by the biaxial test (1 MPa/s), hardness and fracture toughness were measured in a Vickers hardness tester (load of 19.6 N). Density was determined by the Archimedean principle and elastic modulus was obtained by the pulse-echo technique. Optical properties were deter- mined in a spectrophotometer in the diffuse reflectance mode (range of  between 400 and 700 nm at intervals of 10 nm). Results: Student’s “t” tests showed that HP resulted in sig- nificantly higher flexural strength and density. The elastic modulus significantly decreased after HP and there was no effect of the processing method on hardness and fracture toughness. Therefore, the hypothesis was partially accepted. The optical properties of the porcelain were significantly affected by the processing method, as HP resulted in sta- tistically lower contrast ratio and opalescence and higher translucency parameter. Property Sintering (S) Heat-pressing (HP) Flexural strength (MPa) 51.3 ± 5.6 b 67.1 ± 7.9 a Hardness (GPa) 5.9 ± 0.4 a 5.9 ± 0.3 a Fracture toughness (MPa .m 1/2 ) 1.1 ± 0.2 a 1.2 ± 0.1 a Density (g/cm 3 ) 2.42 ± 0.01 b 2.45 ± 0.02 a Elastic modulus (GPa) 66.3 ± 0.9 a 63.8 ± 2.8 b Contrast ratio 0.67 ± 0.05 a 0.44 ± 0.02 b Translucency parameter 17.6 ± 2.4 b 28.8 ± 1.2 a Opalescence index 7.8 ± 0.8 a 5.1 ± 0.3 b Conclusions: In comparison to the conventional sinter- ing processing method, heat-pressing resulted in a porcelain