3-year evaluation of a new open sandwich technique in Class II cavities.

Purpose: To evaluate the durability of a new open sandwich restoration with, as shown in a previous scanning electron microscope study, improved interfacial adaptation. A polyacid-modified resin-based composite (PMRC; compomer) was placed as an intermediate layer and covered with resin composite (RC). A direct RC restoration was used as control.

Materials And Methods: Of 57 patients, each received at least one pair of Class II restorations, one PMRC/RC open sandwich and one RC control. In total, 75 pairs of Class II restorations, 68 premolars and 82 molars, all in occlusion, were placed by two dentists. Most of the cavities were surrounded by enamel. The restorations were evaluated at baseline, 6, 12, 24 and 36 months by a slightly modified USPHS criteria.

Results: Five of 148 restorations evaluated during 3 years were rated as unacceptable. Two, one in each group, because of endodontic treatment and one RC restoration was replaced because of tooth fracture. Secondary caries was observed contiguous to one restoration in each group at the 36-month recall. Except for the two patients with pulpitis, none of the others reported postoperative sensitivity. No significant differences were seen between the restoration techniques. For marginal adaptation a significant change occurred between baseline and 6 months in both groups. For marginal discoloration, a significant change was observed at 6 months in the sandwich group and at 36 months in the RC group. Color match of the resin composite material changed significantly in both groups at 36 months. It was concluded that both techniques showed good durability during the 3-year follow up.