Effect of phosphate-bonded investments on titanium reaction layer and crown fit

This study analyzed the reaction layer and measured the marginal crown fit of cast titanium applied to different phosphate-bonded investments, prepared under the following conditions (liquid concentration/casting temperature): Rema Exakt (RE) - 100%/237°C, 75%/287°C, Castorit Super C (CS)-100%/70°C, 75%/141°C and Rematitan Plus (RP)- 100%/430°C (special to titanium cast, as the control group). The reaction layer was studied using the Vickers hardness test, and analyzed by two way ANOVA and Tukey's HSD tests (α = 0.05). Digital photographs were taken of the crowns seated on the die, the misfit was measured using an image analysis system and One-way ANOVA, and Tukey's test was applied (α = 0.05). The hardness decreased from the surface (601.17 VHN) to 150 μm (204.03 VHN). The group CS 75%/141°C presented higher hardness than the other groups, revealing higher surface contamination, but there were no differences among the groups at measurements deeper than 150 μm. The castings made with CS - 100%/70°C presented the lowest levels of marginal misfit, followed by RE -100%/237°C. The conventional investments CS (100%) and RE (100%) showed better marginal fit than RP, but the CS (75%) had higher surface contamination.(FAPESP) São Paulo Research Foundatio

O efeito da técnica de inclusão para fundição de titânio CP na fluidez, rusogidade, camada de reação e desajuste marginal

Esse estudo avaliou o efeito da tecnica de inclusao de revestimentos fosfatados nafluidez, rugosidade de superficie, camada de reacao (α-case) e adaptacao marginal de copings fundidos em Ti cp. Os padroes foram incluidos de forma convencional ou pela tecnica de inclusao experimental, na qual os padroes foram cobertos comRematitan Ultra – RU previamente a inclusao. Os revestimentos fosfatados estudados foram: Rematitan Plus (RP), Rema Exakt (RE), Castorit Super C (CA) e o revestimento a base de espinelio Rematitan Ultra (RU) foi o grupo controle. Sete grupos experimentais foram constituidos: G1: RU (controle); G2: RP; G3: RP e RU; G4: RE; G5: RE e RU; G6: CA; G7: CA e RU. Para fluidez foram feitos corpos-de-prova quadrados (15 mm X 15 mm X 0.3 mm) e a area (mm2) foi medida por um sistema analisador de imagens (n=8). Para a rugosidade de superficie as medidas (Ra) foram feitas em rugosimetro Mitutoyo (Mitutoyo SJ 400, Kanagawa, Japan) em corpos-de-prova quadrados (12 mm x 12 mm x 2 mm) n =8. A camada de reacao foi analisada por dureza Vickers, micro-analise por energia dispersiva (EDX), microscopia optica e a composicao dos revestimentos. Para dureza Vickers as medidas foram feitas em corpos-de-prova cilindricos (obtidos a partir dos sprues fundidos nos copos-de-prova para o teste de fluidez) em profundidades de 25, 50, 100, 150, 200 e 300Wm da superficie para o centro, em durometro Micromet 2100 (Buehler, Lake Bluff, Illinois, EUA) n= 8. Para a micro-analise por energia dispersiva (EDX) um equipamento EDX LINK ANALYTICAL, modelo QX 2000, com microscopio eletronico LEO (Zeiss - Germany) e detector OXFORD (Oxford Instrumentos de nano-analises Halifax Alta Rotacao WycombeBucks-HP12 3SE, UK) foram feitas em tres areas da camada de reacao (25 Wm, 75Wm e 150 Wm). Para a microscopia optica, as amostras foram polidas e limpas com solucao acida de Kroll por 20 segundos e observadas em Microscopio...This study evaluated the effect investing technique with phosphate-bonded investment on the castability, surface of roughness, reaction layer (α-case) and marginal coping fit of CP titanium. For all analysis the specimen were coated with Rematitan Ultra - RU (experimental technique), previously to the inclusion (conventional technique) and invested into the phosphate-bonded investments: Rematitan Plus (RP), Rema Exakt (RE), Castorit Super C (CA). The seven groups studied were: G1: RU (control), G2: RP; G3: RP and RU; G4: RE; G5: RE and RU; G6: CA; G7: CA and RU. For castability, square patterns (15 mm X 15 mm X 0.3 mm) were made. The castability area (mm2) was measured by an image analysis system (n=8). The surface roughness was measured (Ra) with a rugosimeter Mitutoyo (Mitutoyo SJ 400, Kanagawa, Japan) in square resin patterns (12 mm x 12 mm x 2 mm) n =8. The reaction layer was analyzed by Vicker’s hardness, Energy Dispersive X-ray microanalysis (EDX), optical microscopy and the investments composition were studied by X ray diffraction (XRD). The Vicker’s hardness measurements were made sprue of castability test in cross – section at depths of 25, 50, 100, 150, 200 and 300Wm from the surface to the interior, using a durometer Micromet 2100 (Buehler, Lake Bluff, Illinois, EUA) n= 8. For Energy Dispersive X-ray microanalysis (EDX) was used an equipment EDX Link Analytical, model QX 2000, with Microscopy Electronic LEO (Zeiss - Germany) with detector Oxford (Oxford Instruments-Nano Analysis Halifax Road High WycombeBucks-HP12 3SE, UK) in three areas of reaction layer (25 Wm, 75Wm e 150 Wm). For the optical microscopy the samples were polished, cleaned and acid etched with the Kroll solution for 20 seconds and observed in an optical microscope Quimis (200 X) attached to an image analyzer Leika Qwin. For the study of the investments composition, samples with... (Complete abstract click electronic access below)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

IMPROVEMENT TO THE MARGINAL COPING FIT OF COMMERCIALLY PURE TITANIUM CAST IN PHOSPHATE-BONDED INVESTMENT BY USING A SIMPLE PATTERN COATING TECHNIQUE

Statement of problem. Coatings of zirconite, Y2O3 or ZrO2 on wax patterns before investing in phosphate-bonded investments have been recommended to reduce the reaction layer in titanium castings, but they are not easily obtainable. Spinel-based investments are relatively stable with molten titanium and could be used as coatings to improve the quality of castings made with those investments. Purpose. The purpose of this study was to evaluate the effect of pattern coating with a commercial spinel-based investment before investing in 1 of 3 phosphate-bonded investments on the marginal coping fit and surface roughness of commercially pure titanium castings. Material and methods. Ten square acrylic resin patterns (12 x 12 x 2 mm) per group were invested in the phosphate-bonded investments Rematitan Plus (RP), Rema Exakt (RE), and Castorit Super C (CA) with or without a coating of the spinel-based investment, Rematitan Ultra (RU). After casting, the specimens were cleaned and the surface roughness was measured with a profilometer. Copings for dental implants with conical abutment were invested, eliminated, and cast as previously described. The copings were cleaned and misfit was measured with a profile projector (n=10). For both tests, the difference between the mean value of RU only and each value of the phosphate-bonded investment was calculated, and the data were analyzed by 2-way ANOVA and Tukey's HSD test (alpha=.05). In addition, the investment roughness was measured in bar specimens (30 x 10 x 10 mm), and the data (n=10) were analyzed by 1-way ANOVA and Tukey's HSD post hoc test (alpha=.05). Results. Two-way ANOVA for casting surface roughness was significant because of the investment, the coating technique, and the interaction between variables. One-way ANOVA was performed to prove the interaction term, and Tukey's post hoc test showed that RP with coating had the lowest mean, while RP had the highest. CA with coating was not different from RP with coating or CA without coating. RE with coating was similar to CA, while RE was different from all groups. For coping marginal fit, the 2-way ANOVA was significant for the investment, the coating technique, and the interaction between variables. The interaction was analyzed by1-way ANOVA and Tukey's HSD test that showed no significant difference among the coated groups, which had better marginal fit than the groups without coating. Among the groups without coating, CA had significant lower marginal misfit than RP, while RE was not different from CA and RP. For the investment surface roughness, the 1-way ANOVA was significant. CA and RU were smoother than RE and RP (P<.001). Conclusions. The coating technique improved the quality of castings fabricated with phosphate-bonded investments. (J Prosthet Dent 2012;108:51-57)State of Sao Paulo Research Foundation (FAPESP) [05/03105-1]State of Sao Paulo Research Foundation (FAPESP