Potassium ion release from a glass ionomer cement matrix

Glass ionomer was mixed with water alone and with water containing two levels of potassium ion, added as potassium chloride. The dimensions of the specimens varied; discs, cylinders and a rectangular bar were used. Release of potassium was measured until it ceased. A little potassium was released from cement mixed with water but could be accounted for by traces present in the glass. Release took 2 months for the lower level and 1.5 years for the higher level of addition. For some specimen groups not all the potassium added was subsequently released. Potassium release tended towards the pattern found for fluoride release naturally occurring from glass ionomer cements in being proportional to t1/2 but was less certain at the lower addition. Release was not related to the dimensions of the sample as has been shown for release of intrinsic fluoride.