Creep behavior of glass-ionomer restorative materials.
The creep of microspecimens of five glass-ionomer filling materials and one glass-ionomer-cermet cement was studied by means of a torsional creep apparatus. The glass-ionomer specimens were aged one week and conditioned in 37 degrees C water. Shear stress of 2.47 x 10(-4) N.m was maintained for three h, and recovery was followed for 50 h. Creep curves were obtained at 21, 37, and 50 degrees C. The effect of temperature increase was studied. All the glass ionomers exhibited linear visco-elastic behavior at low deformations. Their shear moduli and resistance to creep were similar to those of some composites measured by the same method. The increase of temperature influenced the creep behavior and moduli of the materials (i.e., increased creep and residual strains and decreased shear modulus). Although the applied torque was very small, there was permanent deformation, the result of viscous flow in all experiments which was more pronounced at 50 degrees C.
Papadogiannis
Y
Y
School of Dentistry, Aristotle University of Thessaloniki.
Helvatjoglou-Antoniadi
M
M
Lakes
R C
RC
Sapountjis
M
M
D016722:Cermet Cements; D003722:Dental Alloys; D005899:Glass Ionomer Cements / Q000737:chemistry*; D008298:Maleates; D008422:Materials Testing; D012823:Silicate Cement; D014783:Viscosity
D016722:Cermet Cements; D003722:Dental Alloys; D005899:Glass Ionomer Cements; D008298:Maleates; C054101:ChemFil II; D012823:Silicate Cement; C037885:Fuji-ionomer; C040964:Ketac-Fil