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Influence of environmental calcium/phosphate and pH on glass ionomers
Author(s) -
Wang Xiao Yan,
Jin Adrian Yap U.,
Ngo Hien C.
Publication year - 2007
Publication title -
european journal of oral sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.802
H-Index - 93
eISSN - 1600-0722
pISSN - 0909-8836
DOI - 10.1111/j.1600-0722.2007.00443.x
Subject(s) - phosphate , elastic modulus , calcium , scanning electron microscope , materials science , glass ionomer cement , modulus , hardness , phosphate glass , composite material , chemistry , dynamic modulus , dynamic mechanical analysis , young's modulus , mineralogy , nuclear chemistry , metallurgy , biochemistry , polymer
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.