Prospective randomized controlled clinical study comparing two types of two-piece dental implants supporting fixed reconstructions-Results at 5 years of loading

OBJECTIVES Compare clinical outcomes of two types of dental implants with non-matching implant-abutment junctions loaded with fixed implant-borne reconstructions at 5 years of loading. MATERIALS AND METHODS In 64 patients, one of two implant systems (S1, S2) was randomly used to support fixed dental prostheses (FDP). At loading (T$_{L}$ ), after 1 (T$_{1}$ ), 3 (T$_{3}$ ) and 5 years (T$_{5}$ ), the implant and reconstruction survival, biological and technical complications, radiographic marginal bone levels, clinical outcomes were recorded. The implants of the groups S1 and S2 contained of two-piece titanium implants with a non-matching implant-abutment junction. Data were analyzed on the patient level (1 implant/patient) using the non-parametric Wilcoxon-Mann-Whitney test. RESULTS Ninety-seven implants were placed and loaded with fixed reconstructions in 64 patients. At T$_{5}$ , 29 S1 and 28 S2 implants were available for the patient-level analysis. Two implants in group S1 had to be removed in the same patient due to severe peri-implantitis, resulting in a survival rate of 96.1% on the implant level and 96.6% on the patient level. No implant in group S2 was lost. The technical complication rate on patient-level amounted of 24.2% (S1) and of 6.5% (S2) (p > .05). Biological complications on patient-level were observed in 15.2% (S1) and 16.1% (S2) (p > .05). From TL to T5, the medians of the mean marginal bone level changes wer a gain of 0.15 mm in group S1 and a loss of 0.14 mm in group S2 (p > .05). CONCLUSIONS AND CLINICAL IMPLICATIONS Both implant systems revealed high survival rates and minimal changes of the marginal bone levels during 5 years. Few biological complications occurred in both groups. S1 revealed a high rate of technical complications. Therefore, both implant systems can be recommended for fixed reconstructions