Randomized controlled clinical study comparing two types of two-piece dental implants supporting fixed restorations—Results at 8 years of loading

Abstract

Objectives: To assess clinical, technical, biological, and radiographic outcomes of implants supporting fixed restorations using two types of dental implants with non-matching implant–abutment junctions at 8 years. Materials and methods: Sixty-four patients were randomly assigned to receive one of two implant systems (S1 or S2) and eventually fixed restorations. Patients were examined at loading (TL), one (T1), three (T3), five (T5), and eight years (T8). Outcome measures included implant and restoration survival, technical and biological complications, and radiographic bone levels. All data were analyzed on the implant and patient level. Results: Ninety-eight implants were inserted in 64 patients and loaded with fixed restorations. At 8 years, 49 patients with 42 (S1) and 36 (S2) implants (25 in group S1 and 24 in group S2 on the patient level) were re-examined. The survival rates on the patient level were 97.6% (S1) and 97.2% (S2). The marginal bone levels (the primary endpoint) amounted to a gain of 0.21 mm (Q1: −0.11 mm; Q3: 0.5 mm) (S1) (p =.007) and to a loss of 0.24 mm (Q1: −0.79 mm; Q3: 0.05 mm) (S2) (p =.001) between baseline (TL) and T8 (intergroup p