Aluminium release from glass ionomer cements during early water exposure in vitro

Aluminium is a major constituent of glass ionomer cements. During mixing and setting aluminium is released from the glass into the polyalkeonic acid solution. Part of this aluminium may not combine with the polyalkeonic acid, but may be released from the cement. The aluminium release from auto-cured and light-cured glass ionomer cements during early water exposure was studied. The former cements released more aluminium than the latter. Scanning electron microscopy (SEM) showed extensive loss of polymer matrix for the cements with the highest aluminium release. Insufficient curing of light-cured cements also resulted in loss of matrix. It is suggested that the considerable release of aluminium from glass ionomer cements during early water exposure may explain the reported lack of mineralization of predentin in the pulp beneath glass ionomer cements. This would correspond to the inhibiting effect of aluminium on bone mineralization.