Clinically,fractures are the main cause of computer-aided design and computer-aided manufacturing(CAD/CAM)3 mol%-yttria-stabilized tetragonal zirconia polycrystal(Y-TZP)all-ceramic dental restorations failure because ...Clinically,fractures are the main cause of computer-aided design and computer-aided manufacturing(CAD/CAM)3 mol%-yttria-stabilized tetragonal zirconia polycrystal(Y-TZP)all-ceramic dental restorations failure because of repetitive occlusal loading.The goal of this work is to study the effect of test methods and specimen’s size on the flexural strength of five ceramic products.Both biaxial flexure test(BI)and uni-axial flexure tests(UNI),including three-point flexure test(3PF)and four-point flexure test(4PF),are used in this study.For all five products,the flexural strength is as follows:BI>3PF>4PF.Furthermore,specimens with smaller size(3PF-s)have higher values than the bigger ones(3PF).The difference between BI and UNI resulted from the edge flaws in ceramic specimens.The relationship between different UNI(including 3PF-s,3PF and 4PF)can be explained according to Weibull statistical fracture theory.BI is recommended to evaluate the flexural strength of CAD/CAM Y-TZP dental ceramics.展开更多
Porcelain fused to metal(PFM)has received great attention over the last few years due to its importance in the dentistry.Kalsilite(K_(2)O·Al_(2)O_(3)·SiO_(2))is a high thermal expansion porcelain,suitable fo...Porcelain fused to metal(PFM)has received great attention over the last few years due to its importance in the dentistry.Kalsilite(K_(2)O·Al_(2)O_(3)·SiO_(2))is a high thermal expansion porcelain,suitable for bonding to metals.However,kalsilite is a metastable phase which gets converted into crystalline leucite upon heating.In the current work feasibility of developing stable kalsilite phase,dispersion of MgF2 in it as an additive and using mechanochemical synthesis are studied.Micro fine dental material has been formulated by mixing prepared kalsilite with low temperature frit(LTF)in different ratio.The crystalline phases evolved in fired powders are characterized by powder X-ray diffraction(XRD)technique.Kalsilite with different ratio of LTF has been cold pressed and heat treated to examine its coefficient of thermal expansion(CTE),flexural strength,apparent porosity(AP),bulk density(BD)and microstructure.Results indicate that MgF_(2) addition and high milling duration help in kalsilite stabilization.Temperature also plays an important role in this stabilization,and at 1100℃single phase kalsilite formation is observed.Present outcomes demonstrate that it is easily possible to synthesize a stable single phase kalsilite with desirable properties.展开更多
基金This work was supported by grants from Natural Science Foundation of China(81200814)National Key Technology R&D Program of China(no.2012BAI22B03).
文摘Clinically,fractures are the main cause of computer-aided design and computer-aided manufacturing(CAD/CAM)3 mol%-yttria-stabilized tetragonal zirconia polycrystal(Y-TZP)all-ceramic dental restorations failure because of repetitive occlusal loading.The goal of this work is to study the effect of test methods and specimen’s size on the flexural strength of five ceramic products.Both biaxial flexure test(BI)and uni-axial flexure tests(UNI),including three-point flexure test(3PF)and four-point flexure test(4PF),are used in this study.For all five products,the flexural strength is as follows:BI>3PF>4PF.Furthermore,specimens with smaller size(3PF-s)have higher values than the bigger ones(3PF).The difference between BI and UNI resulted from the edge flaws in ceramic specimens.The relationship between different UNI(including 3PF-s,3PF and 4PF)can be explained according to Weibull statistical fracture theory.BI is recommended to evaluate the flexural strength of CAD/CAM Y-TZP dental ceramics.
基金The authors gratefully acknowledge the financial support of DST(TDT division,reference No.DST/SSTP/UP/197(G)2012),Ministry of Science&Technology,New Delhi,India.
文摘Porcelain fused to metal(PFM)has received great attention over the last few years due to its importance in the dentistry.Kalsilite(K_(2)O·Al_(2)O_(3)·SiO_(2))is a high thermal expansion porcelain,suitable for bonding to metals.However,kalsilite is a metastable phase which gets converted into crystalline leucite upon heating.In the current work feasibility of developing stable kalsilite phase,dispersion of MgF2 in it as an additive and using mechanochemical synthesis are studied.Micro fine dental material has been formulated by mixing prepared kalsilite with low temperature frit(LTF)in different ratio.The crystalline phases evolved in fired powders are characterized by powder X-ray diffraction(XRD)technique.Kalsilite with different ratio of LTF has been cold pressed and heat treated to examine its coefficient of thermal expansion(CTE),flexural strength,apparent porosity(AP),bulk density(BD)and microstructure.Results indicate that MgF_(2) addition and high milling duration help in kalsilite stabilization.Temperature also plays an important role in this stabilization,and at 1100℃single phase kalsilite formation is observed.Present outcomes demonstrate that it is easily possible to synthesize a stable single phase kalsilite with desirable properties.