Implant vs abutment level connection in implant supported screw‐retained fixed partial dentures with cobalt‐chrome framework : 1‐year interim results of a randomized clinical study

Background: Screw‐retained fixed partial dentures (FPD) have shown a lower incidence of biologic complications and an easier retrievability compared with cemented FPD. Purpose: To compare the marginal bone loss at conical connection implant restored with a screw retained cobalt‐chrome FPD in an implant‐level (IL) or an abutment‐level (AL) setup. Materials and Methods: Patients with at least two adjacent missing teeth were randomly allocated to be restored with IL or AL FPD. Periapical radiographs and clinical examination were taken at implant placement, prosthetic connection, 6 and 12 months to evaluate marginal bone loss (MBL), and soft tissue conditions. Complications were used to calculate prognostic indexes. Results: Fifty patients were treated with 50 FPD supported by 119 implants. The difference of MBL between the IL and AL groups was statistically significant (P = 0.003). At 1 year, MBL was 0.086 ± 0.313 mm and 0.005 ± 0.222 mm in the IL and AL groups, respectively. The presence of BoP increased with time in IL, whereas it decreased in AL group (P < 0.001). A minor complication was encounted in one FPD. Conclusions: A low grade of MBL was present after 1 year. IL showed greater amount of MBL and soft tissue inflammation indexes than AL. In FPD, AL may be a safer procedure than IL setup in order to preserve a healthy periimplant tissue