Marginal ridge strength of tunnel-prepared teeth restored with various adhesive filling materials

This study evaluated the load required to fracture the marginal ridge of tu nnel-filled teeth restored with various adhesive filling materials. Five te st groups, each consisting of 20 extracted maxillary premolars, were filled with either composite resin or a conventional, a cermet, or two brands of resin-modified glass ionomer (polyalkenoat) cements. The tunnels were prepa red with the occlusal access placed in the mesial fossa, leaving a relative ly thin approximal wall. The teeth were subjected to incremental dynamic fo rces. A maximum absorbed energy index, quantifying the fracture resistance of the teeth, showed no statistically significant differences between the t est group with regard to marginal ridge strength, even though the elastic m oduli of the materials varied. None of the adhesive materials restored the teeth to the strength of sound teeth. (C) 1999 Elsevier Science Ltd. All ri ghts reserved.