The technical details of a connection play an essential role with regard to various clinical outcomes. General statements about a connection type without knowledge of the manufacturer’s technical details should be treated with caution.
As any dental practitioner knows, there are many dental implant types available on the market, differing in features such as material, shape, size, and surface properties. Information such as survival and complication rates play a vital role in decision-making, yet well-collected data are only available for a few implant systems. A group from the University of Zurich worked to fill this knowledge gap by comparing the clinical outcomes of two dental implants with non-matching, conical implant–abutment junctions. The authors report their findings in two papers, at 5 and 8 years after loading.
Dr. med. dent. Konrad Meyenberg
In this study conducted at the Center for Reconstructive Dentistry in Zurich, the authors compared the clinical performance of two different implant systems with a conical connection. The results of the same patient population were published in two studies after 5 and after 8 years.
The authors randomized 64 patients requiring dental implant therapy to receive two-piece dental implants from one of two systems, called S1 (Osseo Speed implant TX 3.0 – 5.0 S, TX 4.5; Astra Tech Implant System, Dentsply Sirona) and S2 (Straumann Bone Level implants 3.3, 4.1, 4.8 mm, SLActive; Straumann AG) in the study. The authors did not perform a sample size calculation. Surgery was performed according to standard protocols and the manufacturers’ recommendations, and patients were followed up at various time points. Analyses were performed at both the patient and implant level. The number of implants received were 98 reported by Walter et al.
At 8 years post-implantation, 49 patients attended the follow-up visit. At this time point, the S1 group gained a median of 0.21 mm of marginal bone, while the S2 group lost a median of 0.24 mm on patient-level analysis, reported as a significant between-group difference (P<0.001). The papers also report differences in favor of S1 in the rates of peri-implant mucositis (21.4% vs 55.6%, P=0.038) and peri-implantitis (0% vs 8.3%) between the S1 and S2 implants, respectively.
Implant survival rate was not different between the groups, with Walter et al. reporting only one implant lost in each group for a mean survival rate of 97.4% on implant level.
Additionally, the technical complication rate was not significantly different between the groups at either time point, although there were notable numerical differences. At 5 years, eight S1 implants had 14 technical complications (technical complication rate, 24.1%). Regarding S2 implants, two implants had two minor chippings (technical complication rate, 6.5%). At the 8-year follow-up, the technical complication rate had increased to 35.7% (15/42 implants) for the S1 group and 16.7% (6/36 implants) for S2. Screw loosening was the predominantly observed complication, followed by chipping and fractures of screws or abutments. The authors state that the rate of technical complications for the S1 group was higher than reported in other comparable studies in the literature.
Dr. med. dent. Konrad Meyenberg
In this study conducted at the Center for Reconstructive Dentistry in Zurich, the authors compared the clinical performance of two different implant systems with a conical connection. The results of the same patient population were published in two studies after 5 and after 8 years.
Overall, this comparison of two implants with non-matching conical implant–abutment junctions provides important long-term information such as survival and complication rates. However, the lack of a sample size calculation limits the conclusions that can be drawn; it is possible that the statistically significant differences are not clinically relevant, while the insignificant results, like the technical complication rate, may be more important for the dental practitioner selecting an implant.
