Influence of environmental calcium/phosphate and pH on glass ionomers.
This study investigated the effects of environmental calcium/phosphate and pH on the hardness and elastic modulus of two glass-ionomer cements (GICs) [Fuji IX Fast (FN) and KetacMolar (KM)]. Specimens were randomly subjected to storage media of pH 3, 5, and 7. The calcium and phosphate levels of the storage solutions ranged from 0 to 2.4 mM. After 4 wk of conditioning, hardness and elastic modulus were determined using a depth-sensing microindentation test. Sectioned surfaces were observed with scanning electron microscopy. For both FN and KM, no significant change in hardness, elastic modulus, or surface structure were observed at pH 7 and 5, regardless of the concentration of calcium and phosphate. FN and KM specimens conditioned at pH 3 had lower hardness and modulus in comparison to those conditioned at pH 7. An increased level of environmental phosphate led to higher hardness and elastic modulus of FN and KM at pH 3. In general, a microscopic surface reaction layer was observed in specimens conditioned at pH 3. The thickness and structure of the reaction layer varied depending on environmental phosphate levels. The results suggest that the influence of environmental calcium and phosphate on GICs was pH dependent.
Wang
Xiao Yan
XY
Department of Cariology, Endodontology and Operative Dentistry, Peking University School and Hospital of Stomatology, China. wangxiaoyanpx@gmail.com
Jin
Adrian Yap U
AY
Ngo
Hien C
HC
D002130:Calcium Phosphates / Q000494:pharmacology*; D003799:Dental Stress Analysis; D004356:Drug Storage; D004548:Elasticity; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006244:Hardness; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D010316:Particle Size; D014783:Viscosity
D002130:Calcium Phosphates; C439808:Fuji IX GP Fast; D005899:Glass Ionomer Cements; C110712:ketac-molar