Methods. A total of 88 Class I and 32 Class II restorations were made using Z100 (3M Dental Products Div.), Clearfil Ray-Posterior (Kuraray Co. Ltd.) and Prisma TPH (Caulk/Dentsply). Quadrant impressions were taken using a polyvinyl siloxane impression material, and stone casts were obtained every six months for indirect evaluations of anatomical form and marginal adaptation. The restorations were evaluated directly by three clinicians using the Ryge criteria.

Results. The authors statistically evaluated parameters at each recall period, using a ² test; compared baseline scores with the recall scores, using a McNemar test; and evaluated changes in the parameters, using the Cochran Q test. Color match, cavosurface margin discoloration and secondary caries remained unchanged at the end of the 24-month recall period for all materials (P .05). A total of 11.5 percent of the Z100 restorations and 16.7 percent of the Prisma TPH restorations showed a slight crevice along the margin (P .05). The surface texture was scored as Bravo only for Clearfil Ray-Posterior restorations at the end of the study (P .05). The authors found that the indirect evaluation results were different from the direct evaluations for Z100 and Prisma TPH.

Conclusions. According to these findings, all the materials used are suitable for posterior restorations. The difference between the two evaluation methods can be attributed to the level of sensitivity.

Clinical Implications. With the improvement in materials, careful case selection and application of the restorative techniques, posterior composites placed under appropriate conditions and monitored routinely can be expected to last 10 years or longer.