The effect of slurry preparation methods on biaxial flexural strength of dental porcelain

Abstract

Statement of problem. One-step and incremental mixing procedures are currently used to produce dental ceramic pastes. In the ceramic industry, high quality is obtained using one-step mixing, but in dentistry, the best method has not been yet determined.Purpose. The purpose of this study is to evaluate the effects of 2 mixing techniques on the biaxial flexural strength and microstructure of dental porcelain. Material and methods.Feldspathic porcelain discs (2 x 15 mm in diameter) were produced and divided according to the ceramic paste preparation method, powder-liquid incremental mixing group (n=50) or one-step mixing, as a control group (n=50). Specimens were tested for biaxial flexural strength and characterized using porosimetry, relative humidity, SEM/EDS, XRD, and F T-IR analyses. Statistical analysis was conducted using Weibull statistics. The Weibull modulus, characteristic strength and relative humidity were compared between groups, using Student's t-test and Mann-Whitney U test (α=.05).Results. The powder-liquid incremental mixing group showed significantly higher values (SD) of Weibull modulus (6.74 (0.70), P<.001) and characteristic strength (79.87 (2.01) MPa, P<.001) when compared to the one-step mixing group (4.94 (0.94) and 75.95 (2.61) MPa). Significantly lower mean (SD) relative humidity values (P=.009) were found for powder-liquid incremental mixing group (20% (0.5%)) compared to one-step mixing group (22% (1%)). XRD spectra showed that the one-step mixing group produced higher amounts of the amorphous phase. Conclusions.Specimens produced by the incremental mixing technique showed higher biaxial flexural strength than one-step mixing. (J Prosthet Dent 2011;105:308-314)

An Assessment of the Influence of Dental Porcelain Slurry Preparation on Flexural Strength of Different Feldspathic Porcelains

“…Furthermore, the effect of porcelain powder-liquid mixing technique on bi-flexural strength was investigated. The results showed that when porcelain powder was incrementally mixed into liquid, a higher bi-flexural strength was achieved [8]. For proper porcelain condensation, porcelain powder has its particles distributed in a characterized size to yield a maximum density of particles.…”

“…However, porcelain fracture or chipping were among the most reported complications [5]. Fabrication of dental porcelain, especially feldspathic veneering, is technique-sensitive, in addition to the material's brittle nature and low strength [5,6]; therefore, thorough and precise adherence to technical fabrication protocol is crucial to clinical performance [7][8][9]. Moreover, several manufacturing factors can influence the final porcelain product, such as ceramic powder particle size, distribution, and chemical composition [9,10].…”

“…During the fabrication of porcelain prostheses, a mix of porcelain powder and liquid is made to produce the working ceramic slurry, paste for layering, and veneering to the full counter of the restoration. Ceramic slurry paste preparation conditions, ratios, and characteristics can affect the physicomechanical properties, and therefore clinical outcomes [7][8][9][10]. As dental ceramic manufacturers and technicians have different recommendations and techniques on handling ceramics, it is not necessarily proven if slurry paste preparation is clinically advantageous to the sintered porcelain quality.…”

Translucency of a Dental Porcelain Mixed by Two Ceramic Slurry Methods: A Bayesian Comparison

“…The method of mixing distilled water with the porcelain powder to reduce the presence of agglomerates during the consolidation of dry powers has already been explained for industrial scales. The second method, being an empirical approach, has been used in dental laboratories to achieve a good paste consistency that may result in intra- and interoperator variability [ 3 , 31 , 32 ].…”

Assessment of thicknesses and color properties of opaque porcelain layers applied by different dental technicians

“…Besides the thicknesses of the different porcelain layers, countless variables such as the type of dental alloy, application method, slurry preparation method, powder/likit ratio of the porcelain slurry, condensation technique, and number of firings may affect the physical properties or the final color of MCRs (1,5,8,(13)(14)(15)(16). The influences of various application techniques or materials types on the color properties of MCRs have been extensively investigated.…”