The development of a posterior tooth composite system, in-vitro investigation

Adaptation and marginal seal of conventional MOD composite restorations was investigated in vitro with the scanning electron microscope and a dye penetration test. An optimal adaptation i.e. with over 90% "perfect margin" was achieved in conventional MOD cavity preparations without using the enamel-etch technique. After applying a composite sealer the proximal boxes were filled with a condensable composite to the level of the occlusal floor. Only after the proximal portions had hardened was the occlusal portion of the restoration completed. The proximal margin of an MOD composite restoration made in this manner is, in comparison to amalgam, about four times better adapted, however, because of the conventional cavity form with sharp line angles there is some percolation. With the presently available composite materials a clinically acceptable posterior resoration comosite system can be constructed: For the initial proximal portion a sufficiently radiopaque, condensable, not necessarily wear resistant composite would be used, and for the occlusal portion a proven wear-resistant, not necessarily radiopaque composite. On the basis of experiments measuring roughness it could be shown in test samples and in MOD composite restoration, in vitro and in vivo, that ultrafine diamond burs were well suited for the finishing of conventional and microfill composites. For the finishing of MOD microfill composites burs with fine and ultrafine diamond particles and specially developed forms are necessary.