Prospective randomized controlled clinical study comparing two types of two-piece dental implants supporting fixed reconstructions - results at 1 year of loading

Abstract

Objectives: To analyze clinical, esthetic, radiographic, and prosthetic outcomes of implants and implant-supported reconstructions using two types of dental implants with non-matching implant abutment junctions.

Materials and methods: A total of 64 patients in need of dental implant therapy with fixed reconstructions were consecutively enrolled. They were randomly assigned to either one of two implant systems (S1: Astra Tech Osseospeed and S2: Straumann Bone Level). Baseline (day of loading) and 1-year measurements included demographics, radiographic, clinical, biologic, prosthetic, and esthetic outcomes. All data were analyzed at the patient level and at the implant level. The nonparametric Mann-Whitney U-test was used to detect differences in continuous variables between two independent groups.

Results: Ninety-seven implants (S1 = 54, S2 = 43) were placed and loaded with fixed reconstructions in 64 patients. No implant was lost during the 1-year observation period resulting in a 100% survival rate for both implant systems. At the patient level, the mean marginal bone level at implant insertion was -1.30 mm (SD ± 1.00 mm) for S1 and -1.26 mm (±1.22 mm) for S2 (negative values indicating bone levels coronal to the implant shoulder). At the time of loading, these distances measured 0.29 mm (±0.44 mm) for S1 and 0.22 mm (±0.43 mm) for S2. At the 1-year follow-up, these distances were 0.37 mm (±0.39 mm) for S1 and 0.39 mm (±1.02 mm) for S2. Technical complications of the reconstructions only occurred in Group S1, with a rate of 12% (patient level) (P > 0.05). Biologic complications were observed at a rate of 6% (S1) and 3.2% (S2) at the patient level (P > 0.05).

Conclusions: Both implant systems revealed 100% survival rates and minimal changes of the marginal bone levels during 1 year of loading. Few technical and biologic complications occurred. Therefore, both implant systems can be recommended for fixed reconstructions.

Keywords: X-ray; dental implants; fixed, partial, denture; survival.