Clinical evaluation of subgingival open sandwich restorations: 3-year results of a randomized double-blind trial

To provide a 3-year follow-up of previously treated patients to assess and compare the periodontal responses and clinical performance of proximal subgingival open sandwich restorations.

Ninety-five adults participated in the study, with a combined total of 120 compound Class II cavities. These cavities had gingival margins located below the CEJ. Four different restorative materials were used to elevate the dentin/cementum gingival margins of the cavities: resin-modified glass ionomer, glass hybrid, flowable bulk-fill composite, or ion-releasing material, which were then completed with the same overlaying composite. Different periodontal and clinical evaluations, based on the criteria set by the World Dental Federation (FDI) criteria, were performed at different time intervals, including baseline, 6 months, 1, 2, and 3 years.

The type of base material did not affect the periodontal evaluations. There were no statistically significant differences between different time intervals or base material groups in any of the evaluated FDI parameters. However, the ion-releasing material scored significantly worse in the radiographic evaluation than any of the other groups.

All tested materials are suitable for proximal subgingival open sandwich restorations, as long as the restoration/tooth margin is at least 2-mm away from the bone crest.

Clinicians can confidently choose any of the tested materials for proximal subgingival open sandwich restorations, as they have shown good outcomes from both periodontal and clinical perspectives.