Cuspal movement and microleakage around reinforced glass ionomer cements

The effect of restoration of mesio-occluso-distal cavities in molar teeth with reinforced glass ionomer cements on cuspal flexure in vitro is reported. Measurements of cuspal flexure using linear variable displacement transducers were carried out for 90 min after the placement of two types of reinforced glass ionomer cement. The measurements demonstrated that no movement occurred except in cases where the materials were allowed to dehydrate. Under these circumstances the opposing cusps moved toward one another. This movement was observed to be directly related to time. Microleakage was very much less than that observed for composite materials evaluated under the same test conditions.