Resistência à compressão de revestimentos fosfatados para fundição de titânio em diferentes temperaturas
Compressive strength of phosphate investment for casting of the titanium in different temperatures
Nogueira, F.; Adabo, G.L.; Ferreira, A.; Rocha, S.S.; Fonseca, R.G.
Rev. odontol. UNESP, vol.35, n3, p.171-175, 2006
Resumo
O titânio apresenta características favoráveis que o torna uma excelente alternativa ao uso de ligas áureas, porém seu elevado ponto de fusão e a baixa densidade exigem máquinas especiais de fundição e revestimento resistente para suportar o processo. Esse estudo avaliou a resistência à compressão de três revestimentos fosfatados, sendo um deles específico para titânio Rematitan Plus (RP) e dois alternativos, Rema Exakt (RE) e Castorit Super C (CA), variando-se a temperatura final do ciclo (600, 515 e 430 °C). Para o ensaio de resistência à compressão, os corpos-de-prova cilíndricos (n = 10) com 20 mm de diâmetro e 40 mm de altura foram obtidos em uma matriz metálica bipartida. Após 12 horas, foram submetidos à queima em forno (EDG) conforme instruções do fabricante. Ao atingir a temperatura final programada, foi realizado o teste, em máquina de ensaios mecânicos MTS 810, à velocidade de 2 mm.min-1 até a fratura do corpo-de-prova. Após os testes, os valores de resistência em MPa foram analisados por meio do software SPSS 11.0. Aplicou – se análise de variância e teste de Tukey para comparação dos grupos (P = 0,05). Em cada temperatura, o RE apresentou maior resistência que o RP, que, por sua vez, foi superior ao CA. Analisou-se, também, a influência das temperaturas para cada material. Em geral, os materiais na temperatura final de 600 °C foram mais resistentes do que em 515 e 430 °C, que mostraram comportamento variável. Concluiu-se que o revestimento alternativo RE apresentou resistência à compressão superior à do específico para titânio e que a variação na temperatura final influenciou diferentemente cada material.
Palavras-chave
Titânio, revestimento para fundição odontológica, prótese dentária
Abstract
The titanium has favorable characteristics that become an excellent alternative to the use of golden alloys. However, his high point of fusion and the low density require special machines of casting and resistant dental investments for this process.This study evaluated the strength to the compression of three phosphate-bonded investments, one of them specific for titanium - Rematitan Plus (RP), and two alternative Rema Exakt (RE) and Castorit Super C (CA), in different end temperatures of the cycle (600, 515 and 430 °C). For the strength to the compression, cylindrical specimens with 20 mm of diameter and 40 mm of height were obtained in a bipartite metallic matrix (n = 10), after 12 hours were submitted to the burns in oven (EDG), in according to the instructions of the manufacturer. Upon reaching the end programmed temperature, was done the test in machine of mechanical test MTS 810 (MTS System Corporation, Minnesota, EUA), in speed of 2 mm.min_1 up to fracture of the specimens. After the tests the values of resistance in MPa were analyzed utilizing the software SPSS 11.0. It applied – itself ANOVA and test of Tukey for comparison of the groups (P = 0.05) and compared the material in each temperature, the RE presented bigger resistance than to of the RP, that by his time was a superior to of the CA. Analyzed itself the influence of the temperatures for each material. The materials in the end temperature of 600 °C were more resistant than in 515 and 430 °C. It was possible to conclude that the dental investments RE showed highest strength than the specific investment and the final temperature influenced differently this property of the materials.
Keywords
Titanium, dental casting investments, dental prosthesis
References
1. Lautenschlager E, Monaghan P. Titanium and titanium alloys as dental materials. Int Dent J. 1993;43:245-53.
2. Ohkubo C, Watanabe I, Ford JP, Nakajima H, Hosoi T, Okabe T. The machinability of cast titanium and Ti-6Al-4V. Biomaterials. 2000;21:421-8.
3. Syverud M, Okabe T, Hero H. Casting of Ti-6Al-4V alloy compared with pure Ti in an Ar-arc casting machine. Eur J Oral Sci.1995;103:327-30.
4. Wang RR, Fenton A. Titanium for prosthodontic applications: a review of the literature. Quintessence Int. 1996;27:401-8.
5. Zinelis S. Effect of pressure of helium argon krypton and xenon on the porosity microstructure and mechanical properties of commercially pure titanium castings. J Prosthet Dent. 2000;84:575–82.
6. Hung C-C, Hou G-L, Tsai C–C, Huang C–C. Pure titanium casting into zirconia-modified magnesia-based investment molds. Dent Mater. 2004;20:846–51.
7. Ida K, Togaya T, Tsutsumi S, Takeuchi M. Effect of magnesia investment in the dental casting of pure titanium or titanium alloys. Dent Mater J. 1982;1:8-21.
8. Oda Y, Kudoh Y, Kawada M Y, Hasegawa K. Surface reaction between titanium castings and investments. Bull Tokyo Dent Coll. 1996;37:129-36.
9. Takahashi J, Zhang JZ, Okazaki M. Castability and surface hardness of titanium cast plates obtained from experimental phosphate-bonded silica investment molds. Dent Mater J. 1993;12:238-44.
10. Hsu HK, Kikuchi H, Yen SK, Nishiyama M. Evaluation of different bonded investments for dental titanium casting. J Mater Sci Mater Med. 2005;16:821-5.
11. Hung C-C, Hou GL, Tsai CC, Huang CC. Pure titanium casting into zirconia – modified magnesia – based investment molds. Dent Mater. 2004;20:846–51.
12. Luo XP, Guo TW, OU YG, Liu Q. Titanium casting into phosphate bonded investment with zirconite. Dent Mater. 2002;18:512-5.
13. Wang RR, Welsch GE, Castro-Cedeno M. Interfacial reactions of cast titanium with mold materials. Int J Prosthodont. 1998;11:33-43.
14. Sôo S, Palmer R, Curtis RV. Measurement of the setting and thermal expansion of dental investments used for the superplastic forming of dental implant superstructures. Dent Mater. 2001;17:247-52.
15. Contreras EFR, Henriques GE, Giolo SR, Nobilo MA. Fit of cast commercially pure titanium and Ti6Al4V alloy crowns before and after marginal refinement by electrical discharge machining. J Prosthet Dent. 2002;88:467- 72.
16. Stoll R, Fischer C, Springer M, Stachniss V. Marginal adaptation of partial crowns cast in pure titanium and in a gold alloy – an in vitro study. J Oral Rehabil. 2002;29:1- 6.
17. Takahashi J, Kimura H, Lautenschlager EP, Cherner Lin JH, Moser JB, Greener EH. Casting pure titanium into commercial phosphate bonded SiO2 investment molds. J Dent Res. 1990;69:1800-5.
18. Chew CL, Land MF, Thomas CC, Norman RD. Investment strength as a function of time and temperature. J Dent. 1999;27:297-302.
19. Hero H, Syverud M, Waarli M. Mold filling and porosity in casting of titanium. Dent Mater. 1993;9:15-8.
20. Luk HWK, Darvell BW. Effect of burnout temperature on strength of phosphate bonded investments. J Dent. 1997;25:153-60.
21. Luk HWK, Darvell BW. Effect of burnout temperature on strength of phosphate bonded investments – part II – effect of metal temperature. J Dent. 1997;25:423-30. 22 Low D, Mori T. Titanium full crown casting: thermal expansion of investments and crown accuracy. Dent Mater.1999;15:185-90.
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