| 0380 Structural effects of mixture techniques during the ceramic paste preparation | ||
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A. PELAEZ-VARGAS, INEB - Instituto de Engenharia Biomédica, Laboratorio de Biomateriais, Porto, Portugal, Portugal, J. DUSSAN, Instituto de Ciencias de la Salud, Medellín, Colombia, L.F. RESTREPO, CES - LPH Research Group, Instituto de Ciencias de la Salud, Medellín, Colombia, and F.J. MONTEIRO, INEB - Instituto de Engenharia Biomédica, Laboratorio de Biomateriais, Porto, Portugal Introduction: Ceramic paste preparation is a fundamental phase in building up dental restorations. Usually the dental laboratory techniques include either an incremental or a “one step” mixture of powder and liquid, but the industry uses the second method with the purpose of obtaining minor micro-defects in the final material. Objective: The aim of this work was to study flexural strength and microstructure of feldspathic porcelain discs produced using two different preparation methods as a measure of their structural reliability. Methods: 100 Vita-Omega 900 porcelain discs were produced and divided according to ceramic paste preparation method, in a powder-liquid mixture group and “one-step” mixture group. Specimens were fractured in bold on ring test to measure their biaxial strength. Samples were observed in SEM and XRD was used to identify the crystalline phases of both groups. Chemical and phase analysis was conducted by EDS, XRD and FTIR spectroscopy to detect differences between the two groups. Statistical analysis include Weibull distribution and extreme values analysis. Results: The mean average values were (74.61± 16.35, m= 6.74) and (69.72 ± 12.71, m= 4.949) for powder-liquid and one-step mixture group respectively. No significant statistical differences were found between both groups. The percentiles evaluation for biaxial flexural strength has shown differences between both groups, this is more evident for lower values of strength. XRD comparison showed that more amorphous phase is present in the one-step group. SEM, EDS and FTIR evaluations did not show significant differences. Conclusions: The one-step mixture technique showed lower structural reliability meaning that there is an increase in the heterogeneity of microdefects that may be associated with increasing amounts of amorphous phase being present and increased porosity. Acknowledgement: The work was carried out under a PhD grant from Alban Program. European Union (Scholarship E05D050652CO), which is acknowledged. | ||
| Seq #72 - Ceramics: Mechanical Properties and Fracture Behavior 2:00 PM-3:15 PM, Thursday, March 22, 2007 Ernest N. Morial Convention Center Exhibit Hall I2-J | ||
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