Resistance to condensation of 'condensable' resin composites as evaluated by a mechanical test

This study compared the resistance-to-condensation forces of recently intro duced condensable resin composites to that of amalgams and conventional res in composites. Using the flat platens of a servohydraulic testing machine, cylindrical specimens of each material 2.8 mm in diameter and 5.5 mm in len gth were compressed diametrally over two seconds to a thickness of 0.75 mm. Peak forces generated during compression were recorded. This method ranked the various classes of restorative material for resistan ce to condensation in the same order as most clinicians subjectively report ed, with the highest forces observed with admired dental amalgams, followed in order by spherical amalgams, condensable resin composites and conventio nal resin composites. Although peak forces observed with the condensable re sin composites were generally higher than those observed with conventional resin composites, these were significantly lower than the peak forces obser ved with amalgams.