The study compared the flexural strength of In-Ceram alumina and In-Ceram zirconia systems. The probability of failure of the two glass-infiltrated ceramic core materials was analyzed with and without lamination with Vitadur-alpha porcelain.
Ten uniform beams of core materials as well as 10 beams of laminated core materials were fabricated for In-Ceram alumina and In-Ceram zirconia. The samples were subjected to three-point bending tests. Flexural strength for both ceramic core materials was determined with and without their porcelain laminations. The strength data were analyzed using the Weibull method. Modes of failure for both systems were determined using scanning electron micrography.
The strength of the In-Ceram zirconia system was significantly higher than In-Ceram alumina when comparing their core materials with and without porcelain lamination. The failure mode for both systems was predominantly transgranular fracture of alumina platelets.
In-Ceram zirconia demonstrated higher flexural strength than In-Ceram alumina.
"Authors agreed that Y-TZP can withstand physiologic functional loading forces and are comparable to metal-ceramic FPDs  . Strength and marginal fit of zirconia ceramic has been confirmed by extensive laboratory testing  . Still 5 to 10 year clinical studies are needed to determine primary mode of failure and success rate  "
[Show abstract][Hide abstract] ABSTRACT: Metal ceramic restorations were considered the gold standard as reliable materials. Increasing demand for esthetics
supported the commercialization of new metal free restorations. A growing demand is rising for zirconia prostheses.
Peer-reviewed articles published till July 2013 were identified through a Medline (Pubmed and Elsevier). Emphasizing
was made on zirconia properties and applications. Zirconia materials are able to withstand posterior physiologic loads.
Although zirconia cores are considered as reliable materials, these restorations are not problem free.
The Open Dentistry Journal 04/2014; 8(1):33-42. DOI:10.2174/1874210601408010033
"To date sufficient data is lacking on changes in the strength that occur during aging of the material. Given the flexural strength values of yttrium-stabilized zirconia, the manufacturers anticipate that the materials will comply with the flexural strength requirements of ISO 6872 even after a decrease in strength (Ryge and Cvar, 1971; Chong et al., 2002). The zirconia cores are supplied in colour and therefore have a good balance between translucency and opacity, which means that the core is not excessively transparent despite transmitting light, yet manages to mask dark coloured substrates. "
[Show abstract][Hide abstract] ABSTRACT: The objective of the study was to evaluate the clinical outcomes of all-ceramic crowns three years after placement of the restoration in the oral cavity. The aim of the present clinical study were surveyed the Procera®, Cercon® and LAVA™ systems. In total, 121 crowns were followed in 33 patients (7 men and 26 women) with an average age of 53.5 years. The eighty crowns were placed in anterior and forty one crowns in posterior teeth. The crowns were fabricated in two dental laboratories and delivered in two private dental practices. The clinical trial was conducted according to American Dental Association guidelines. The patients were requested to provide their consent to the regular clinical examination including radiographic and photographic records. A total of 102 crowns were made of zirconium oxide ceramic cores - 58 Cercon®; 43 LAVA™, while 19 crowns were made of aluminum oxide cores Procera®. The veneering ceramic LAVA™ Ceram was used. The success rate was analyzed using Kaplan-Meier statistics and, in our case, the overall three-year success rate reached 96.7%. All-ceramic crowns with polycrystalline ceramic cores have low susceptibility to fracture, in this study just 3.3%.
Prague medical report 04/2013; 114(1):22-34. DOI:10.14712/23362936.2014.35
"McCabe and Carrick  suggested that less emphasis should be placed on the mean values and standard deviations of the strength when evaluating mechanical properties . Data of mechanical tests of materials may be analyzed by a Weibull distribution in which failure probability can be predicted at any level of stress, providing information about the variability of the results and reflecting the structural precision of the materials or bonded assemblies      . Threeor two-parameter Weibull distributions can be considered. "
[Show abstract][Hide abstract] ABSTRACT: This study evaluated and compared Weibull parameters of resin bond strength values using six different general-purpose statistical software packages for two-parameter Weibull distribution.
Two-hundred human teeth were randomly divided into 4 groups (n=50), prepared and bonded on dentin according to the manufacturers' instructions using the following resin cements: (i) Variolink (VAN, conventional resin cement), (ii) Panavia21 (PAN, conventional resin cement), (iii) RelyX Unicem (RXU, self-adhesive resin cement) and (iv) G-Cem (GCM, self-adhesive resin cement). Subsequently, all specimens were stored in water for 24h at 37°C. Shear bond strength was measured and the data were analyzed using Anderson-Darling goodness-of-fit (MINITAB 16) and two-parameter Weibull statistics with the following statistical software packages: Excel 2011, SPSS 19, MINITAB 16, R 2.12.1, SAS 9.1.3. and STATA 11.2 (p≤0.05). Additionally, the three-parameter Weibull was fitted using MNITAB 16.
Two-parameter Weibull calculated with MINITAB and STATA can be compared using an omnibus test and using 95% CI. In SAS only 95% CI were directly obtained from the output. R provided no estimates of 95% CI. In both SAS and R the global comparison of the characteristic bond strength among groups is provided by means of the Weibull regression. EXCEL and SPSS provided no default information about 95% CI and no significance test for the comparison of Weibull parameters among the groups. In summary, conventional resin cement VAN showed the highest Weibull modulus and characteristic bond strength.
There are discrepancies in the Weibull statistics depending on the software package and the estimation method. The information content in the default output provided by the software packages differs to very high extent.
Dental materials: official publication of the Academy of Dental Materials 05/2012; 28(7):e76-88. DOI:10.1016/j.dental.2012.04.013 · 3.77 Impact Factor
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