Cervical gap formation in class II composite resin restorations.

In vitro, class II restorations were made in three materials, one regular, one microfilled composite and one experimental condensable composite with a porous filler. The aim was to study cervical marginal gap widths appearing in composite restorations when acid etch technique was used. The gaps were about 35 micron for the two contemporary materials and about 10 micron for the experimental one.