Influence of powder/liquid mixing ratio on porosity and translucency of dental porcelains. 2004

Yunlong Zhang, and Jason A Griggs, and Adam W Benham
Department of Biomaterials Science, Baylor College of Dentistry, Dallas, TX 75246, USA.

BACKGROUND Dental technicians use a variety of techniques when condensing dental porcelains. It is unclear whether these techniques affect the total porosity and translucency of dental porcelains. OBJECTIVE The objective of this study was to determine whether varying the powder/liquid ratio during condensation affects porosity and translucency of porcelains. Material and methods Duceram LFC dentin, Duceram LFC incisal, IPS Eris dentin, and IPS Eris incisal porcelains were studied. For each specimen, 1.0 g of porcelain powder was mixed with 1 of 3 different volumes of deionized water to form a slurry with a thin, medium, or thick consistency. The slurries were condensed in a plastic syringe mold, fired, and polished to a 3-microm finish to form 12 groups of 4 specimens each (14-mm diameter, 1.10-mm thickness). The apparent density (g/mL) of each specimen was measured using Archimedes method, and the porosity (%) calculated. Each specimen was coupled to standard ceramic tiles using an immersion liquid, and the color shade was measured in CIE Yxy coordinates using a tristimulus colorimeter. Translucency was assessed by calculating the contrast ratio of shade value (Y) in front of black versus white backgrounds. Two-way analysis of variance and Tukey's multiple comparison tests (alpha = .05) were used to test for significant effects of factors. RESULTS Porcelain type and powder/liquid ratio had a significant interactive effect on the apparent density (P < .001) and on total porosity (P = .003); however, there was no consistent trend. The powder/liquid ratio did not significantly affect translucency (P = .28), but porcelain type had a significant effect on translucency (P < .001). CONCLUSIONS In this in vitro study, total porosity of specimens prepared using 4 porcelains was found to be sensitive to powder/liquid ratio; whereas translucency was found to be insensitive to powder/liquid ratio.

UI MeSH Term Description Entries
D008422 Materials Testing The testing of materials and devices, especially those used for PROSTHESES AND IMPLANTS; SUTURES; TISSUE ADHESIVES; etc., for hardness, strength, durability, safety, efficacy, and biocompatibility. Biocompatibility Testing,Biocompatible Materials Testing,Hemocompatibility Testing,Testing, Biocompatible Materials,Testing, Hemocompatible Materials,Hemocompatibility Testings,Hemocompatible Materials Testing,Materials Testing, Biocompatible,Materials Testing, Hemocompatible,Testing, Biocompatibility,Testing, Hemocompatibility,Testing, Materials,Testings, Biocompatibility
D011208 Powders Substances made up of an aggregation of small particles, as that obtained by grinding or trituration of a solid drug. In pharmacy it is a form in which substances are administered. (From Dorland, 28th ed) Powder
D002516 Ceramics Products made by baking or firing nonmetallic minerals (clay and similar materials). In making dental restorations or parts of restorations the material is fused porcelain. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed & Boucher's Clinical Dental Terminology, 4th ed) Ceramic
D003116 Color The visually perceived property of objects created by absorption or reflection of specific wavelengths of light. Colors
D003124 Colorimetry Any technique by which an unknown color is evaluated in terms of standard colors. The technique may be visual, photoelectric, or indirect by means of spectrophotometry. It is used in chemistry and physics. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
D003775 Dental Polishing Creation of a smooth and glossy surface finish on a denture or amalgam. Dental Burnishing,Dental Finishing,Burnishing, Dental,Finishing, Dental,Polishing, Dental
D003776 Dental Porcelain A type of porcelain used in dental restorations, either jacket crowns or inlays, artificial teeth, or metal-ceramic crowns. It is essentially a mixture of particles of feldspar and quartz, the feldspar melting first and providing a glass matrix for the quartz. Dental porcelain is produced by mixing ceramic powder (a mixture of quartz, kaolin, pigments, opacifiers, a suitable flux, and other substances) with distilled water. (From Jablonski's Dictionary of Dentistry, 1992) Porcelain,Porcelain, Dental,Dental Porcelains,Porcelains,Porcelains, Dental
D006358 Hot Temperature Presence of warmth or heat or a temperature notably higher than an accustomed norm. Heat,Hot Temperatures,Temperature, Hot,Temperatures, Hot
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000704 Analysis of Variance A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable. ANOVA,Analysis, Variance,Variance Analysis,Analyses, Variance,Variance Analyses

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