Element Release From Light Cured Glass-ionomers at Different pH

Objectives: To evaluate leakage of elements from different glass ionomer (GI) cements in solutions with pH-values varying from 2.3 to 7.3.
Methods: The element releases from different light cure GI cement specimens were investigated based on a method for corrosion of metallic materials (ISO 22674:2006). The GI cements were mixed at room temperature (23 °C), placed in a cylindrical plastic mold (diameter 6.9 mm, hight 2.1 mm), covered with plastic strips and pressed between two glass plates. The specimens were immediately light-cured for 20 seconds. The specimens were thereafter placed in Pyrex glass tubes containing either lactic acid or Tris-buffered solutions (1 ml/cm²) for up to 7 days. The element release into the different solutions was determined by ICP-OES.

Results: The corrosion tests showed up to approximately 2000 µg/cm² of released elements. The release increased with time and acidity of the solutions, but the amount of released elements exceeded the 200 µg/cm² limit also at higher pH values than described in the standard. The most prominent elements released were Sr, Al and Si.
Conclusions: The elemental release from GIC exceeded the limit given in ISO 22674:2006, and was considerably increased at low pH. The biological and clinical consequences of elemental release should be considered.