Wear resistance of experimental titanium alloys with different antagonists

Wear resistance of experimental titanium alloys with different antagonists

d e n t a l m a t e r i a l s 2 7 S ( 2 0 1 1 ) e1–e84 group patients received a prosthetic treatment executed with the Cresco system. Control group ...

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d e n t a l m a t e r i a l s 2 7 S ( 2 0 1 1 ) e1–e84

group patients received a prosthetic treatment executed with the Cresco system. Control group patients received a screw retained fixed prosthetic manufacture made with traditional lab procedure. On the day of the surgery implants were submerged and reopened after 3 months. Randomization was made after implant reopening. Implant survival and success rate were monitored during a 3-year time. Standardized radiographs were taken on the day of the surgery, during 1st, 2nd and 3rd year follow up. The survival and success of the prosthetic rehabilitation was also considered. Results: The success rate was 100% for Cresco implants and 94.28% for screwed implants. No statistically significant difference in success rate was found between Cresco and screwed implants. Success was reported in 78.57% of the patients restored with Cresco implants and 64.70% of patients restored with screwed implants. No statistically significant difference emerged among the frequencies of success, surgical complications and prosthodontic complications in patients restored with Cresco implants and screwed implants. Conclusions: This clinical trial did not show differences in survival and success rates of implants and prosthesis randomly realized using Cresco system or traditional lab procedures. doi:10.1016/j.dental.2011.08.537 135 Effect of surface treatment of yttria-stabilized zirconia C.F. Carvalho 1 , R.X. Freitas 2,∗ , C.L. Melo-Silva 1 , T.C.F. MeloSilva 1 , L. Machado-Santos 3 , J.F.C. Lins 1 1

Universidade Federal Fluminense, Brazil Fundac¸ão Oswaldo Aranha, Brazil 3 Universidade de Taubaté, Brazil 2

Objectives: Hydrofluoric acid etching combined with silanization have not shown sufficient efficacy in providing reliable adhesion of low-silica content alumina ceramic, because of their inability to degrade the microstructure of high-alumina content ceramics. The objective of this study was to analyze the effect of surface sandblasting of a zirconiabased ceramic stabilized by yttria (Y-TPZ) as used in dental prostheses. Materials and methods: Fifty ceramics specimens were prepared (10 mm × 10 mm × 2 mm) and divided into different groups (n = 10) G1: control, no surface treatment; G2: Al2 O3 sandblasting, 40 psi; G3: Al2 O3 sandblasting, 60 psi; G4: Al2 O3 sandblasting and Al2 O3 + 110 ␮m average sized SIC particles (RocatecTM 3M ESPE) 40 psi; G5: Al2 O3 sandblasting and Al2 O3 + 110 ␮m average sized SIC particles (RocatecTM 3M ESPE) 60 psi. SEM was used to evaluate the surface characterization of the specimens. Results: All groups showed increased roughness compared with the control group and G4 showed better results compared to the other groups due to the silica tribochemical deposition on the samples surface. Conclusions: Al2 O3 sandblasting and treatment with Al2 O3 + SIC particles was more efficient in surface treatment of ceramics, and may lead to a more reliable adhesion.

136 Inorganic composition and filler particles morphology of resin cements T.R. Aguiar 1 , M. D.I. Francescantonio 1 , A.K. Bedran-Russo 2 , M. Giannini 1,∗ 1 2

State University of Campinas, Piracicaba, Brazil University of Chicago, IL, USA

Objectives: The purpose of this study was to characterize the inorganic components and morphology of filler particles of two conventional and two self-adhesive dual-curing resin luting cements. Materials and methods: The main components were identified by energy dispersive X-ray spectroscopy microanalysis (EDX) and filler particles were morphologically analyzed by scanning electron microscopy (SEM). Four resin cements were used in this study: two conventional resin cements (RelyX ARC/3M ESPE and Clearfil Esthetic Cement/Kuraray Medical Inc.) and two self-adhesive resin cements (RelyX Unicem/3M ESPE and Clearfil SA Luting/Kuraray Medical Inc.). The materials (n = 5) were manipulated according to manufacturers’ instructions, immersed in organic solvents to eliminate the organic phase and observed under SEM/EDX. Results: Although EDX measurements showed high amount of silicon for all cements, differences in elemental composition of materials tested were identified. RelyX ARC contains spherical and irregular particles, whereas other cements showed predominantly irregular fillers. In general, self-adhesive cements contained higher filler size than conventional resin luting cements. Conclusions: The differences in inorganic components and morphology of filler particles were observed between categories of luting materials. All resin cements contain silicon, however, other components varied among them. Support by grants from FAPESP, Brazil (09/51281-4 and 09/51674-6). doi:10.1016/j.dental.2011.08.539 137 Wear resistance of experimental titanium alloys with different antagonists C.D.A. Fortunato 1 , A.C.L. Faria 1 , E.A. Gomes 1,∗ , A.P.R. Alves 1 , Claro 2 , R.C.S. Rodrigues 1 1 2

University of São Paulo, Rib. Preto, Brazil São Paulo State University, Guaratinguetá, Brazil

Objectives: The aim of this study was to evaluate the wear resistance of experimental titanium alloys. Materials and methods: Eighteen hemispherical samples with a radius of 5 mm were cast in commercially pure titanium1 (CP Ti), titanium–zirconium (Ti–5Zr) alloy and titanium–tantalum–zirconium (Ti–5Ta–5Zr) alloy (n = 6). Additionally, 18 discs with a diameter of 13 mm were cast in nickel–chromium2 (Ni–Cr) and cobalt–chromium3 (Co–Cr)

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doi:10.1016/j.dental.2011.08.538

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Tritan, Dentaurum. Vera Bond II. ModellguB, Degudent.

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alloys to use as antagonists. Casting was made using an electric arc in an argon atmosphere, and the alloy was injected into the mold by vacuum pressure. After casting, the samples were divested, sandblasted and polished. For the abrasion test, the roughness of the antagonists was adjusted to 0.75 ␮m and the samples were embedded into rings of polyvinyl chloride (PVC) using autopolymerizing acrylic resin.4 The samples were submitted under a load of 5 N during 40,000 cycles in the wear machine with a frequency of 4.4 Hz. Loss of vertical height was used to verify the wear resistance of the samples. The surfaces of the samples were evaluated by scanning electron microscope (SEM). Data were analyzed by 2-way repeated-measures ANOVA to compare the wear resistance of the materials (˛ = 0.05). Results: A loss of vertical height (␮m) was found for all groups, as showed by the results (mean and standard deviation): CP Ti × Ni–Cr (301.0 ± 28.0); CP Ti × Co–Cr (76.0 ± 14.0); Ti–Zr × Ni–Cr (291.0 ± 15.0) Ti–Zr × Co–Cr (80.0 ± 16.0); Ti–Ta–Zr × Ni–Cr (308.0 ± 34.0); Ti–Ta–Zr × Co–Cr (85.0 ± 8.0). No statistically significant difference was found between alloys (P = 0.448). However, there was a statistical difference between the antagonists (P < .05) and Ni–Cr alloy exhibited higher wear than Co–Cr. Conclusions: The results suggest no difference between the experimental alloys and CP Ti, and for the clinical use of these materials, the Co–Cr antagonists should be chosen. doi:10.1016/j.dental.2011.08.540 138 Change in artificial teeth position in relined dentures, when submitted to disinfection by microwave energy F.C.P. Gonc¸alves ∗ , T.J.A. Paes Jr., S.C.M. Cavalcanti, L.H. Silva, N.B. Bourg

Conclusions: The microwave disinfection method caused dimensional changes of conventional or relining complete dentures. doi:10.1016/j.dental.2011.08.541 139 Effect of thermo-mechanical cycling on the flexural strength of ceramics E.T. Kimpara ∗ , V.C. Macedo, C.C. Marinho, C.S.M. Martinelli, P.C.P. Komori UNESP – Universidade Estadual Paulista, Brazil Objectives: The purpose of this study was to evaluate the effect of thermo-mechanical cycling on the flexural strength of a feldspar ceramic subjected to surface treatment with hydrofluoric acid. Materials and methods: Twelve bars of Vita Block Mark II were fabricated with dimensions of 2 mm × 4 mm × 16 mm. The bars were etched with 10% hydrofluoric acid for 20 s and then, a layer of luting agent was applied on the surface. After, the bars were divided into two groups (n = 10): G1 – control, the bars was not aged; and G2 – the bars was submitted a thermo-mechanical cycling. The cycled group received a load of 40 N, with a frequency of 4 Hz, at 1,200,000 mechanical cycles and 1750 thermal cycles between 5 ◦ C, 37 ◦ C and 55 ◦ C, 30 s each. The three point flexural test was performed in a universal testing machine with a speed of 0.5 mm/min. The values of flexural strength was submitted a one-way ANOVA and Tukey’s test. Results: Groups

Mean (MPa) and standard deviation

G1 – Control G2 – Thermo-mechanical cycling

113.77 (± 7.73)A 104.69 (± 8.08)B

Universidade Estadual Paulista – UNESP – FOSJC, Brazil Objectives: To evaluate possible changes in the position of artificial teeth in relined complete dentures when submitted to disinfection by microwave energy. Materials and methods: A microwave-cured acrylic resin (Vipi-Wave) and a rigid charside relining material (New Truliner) were used. Four groups (n = 6) were created, according to the use or not of relining and the disinfection with microwave energy (cycle of 3 min at 650 W). Specimens in the form of maxillary dentures were relined. To analyze the change of position of artificial teeth, scanned images obtained from the occlusal plane of the prostheses were measured using the software ImageTool, comparing the distance between tooth surfaces before and after polymerization. The results were analyzed with ANOVA and Tukey’s post hoc test (5%). Results: Groups subjected to disinfection showed a statistical significant change of tooth position compared to the control group (conventional cycle), and that change was proportional when comparing the different measured areas of the arch.

4 Vipi flash, VIPI Ind., Com., Import. & Export. of Dentistry Products.

One-way ANOVA demonstrated a p-value <0.02 and the Tukey’s test, with a confidence interval of 5%, showed a statistical difference. Conclusions: It can be concluded that aging by thermomechanical cycling decreases the flexural strength of etched ceramics. doi:10.1016/j.dental.2011.08.542 140 In vivo ageing of dental zirconia ceramics: 24-Months results T. Kosmac 1,∗ , P. Jevnikar 2 , A. Kocjan 1 1 2

Jozef Stefan Institute, Slovenia University of Ljubljana, Slovenia

Objectives: Zirconia-based, all-ceramic FPDs are manufactured to serve in the aggressive environment of the oral cavity for a certain period of time. While the ageing behavior of tetragonal zirconia (Y-TZP) femoral heads in vivo is welldocumented, no systematic ageing study with dental Y-TZP ceramics under clinical conditions has been performed so far.