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Single dental implant retained mandibular complete dentures – influence of the loading protocol: study protocol for a randomized controlled trial

Nicole Passia1*, Miha Brezavšček2, Elfriede Fritzer3, Stefanie Kappel4, Thomas Kern5, Ralph G Luthardt6, Nadine Frfr von Maltzahn7, Torsten Mundt8, Michael Rädel9, Axel von Stein-Lausnitz10 and Matthias Kern1

Author Affiliations

1 Department of Prosthodontics, Propaedeutics and Dental Materials, Christian-Albrechts University of Kiel, Kiel, Germany

2 Department of Prosthetic Dentistry, University Hospital Freiburg, Freiburg, Germany

3 Center for Clinical Studies, Christian-Albrechts University of Kiel, Kiel, Germany

4 Department of Prosthodontics, Heidelberg University Hospital, Heidelberg, Germany

5 Department of Prosthodontics and Biomaterials, University Hospital Aachen, Aachen, Germany

6 Center of Dentistry, Department of Prosthetic Dentistry, Ulm University Hospital, Ulm, Germany

7 Department of Prosthodontics, University Hospital Hannover, Hannover, Germany

8 Department of Prosthetic Dentistry, Ernst-Moritz-Arndt University of Greifswald, Greifswald, Germany

9 Department of Prosthetic Dentistry, Dresden University of Technology, Medical Faculty Carl Gustav Carus, Dresden, Germany

10 Center for Dental and Oral Medicine, Department of Dental Prosthetics, University Medical Center Hamburg Eppendorf, Hamburg, Germany

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Trials 2014, 15:186  doi:10.1186/1745-6215-15-186

Published: 24 May 2014



Over the years, there has been a strong consensus in dentistry that at least two implants are required to retain a complete mandibular denture. It has been shown in several clinical trials that one single median implant can retain a mandibular overdenture sufficiently well for up to 5 years without implant failures, when delayed loading was used. However, other trials have reported conflicting results with in part considerable failure rates when immediate loading was applied. Therefore it is the purpose of the current randomized clinical trial to test the hypothesis that immediate loading of a single mandibular midline implant with an overdenture will result in a comparable clinical outcome as using the standard protocol of delayed loading.


This prospective nine-center randomized controlled clinical trial is still ongoing. The final patient will complete the trial in 2016. In total, 180 edentulous patients between 60 and 89 years with sufficient complete dentures will receive one median implant in the edentulous mandible, which will retain the existing complete denture using a ball attachment. Loading of the median implant is either immediately after implant placement (experimental group) or delayed by 3 months of submerged healing at second-stage surgery (control group). Follow-up of patients will be performed for 24 months after implant loading. The primary outcome measure is non-inferiority of implant success rate of the experimental group compared to the control group. The secondary outcome measures encompass clinical, technical and subjective variables. The study was funded by the Deutsche Forschungsgemeinschaft (German research foundation, KE 477/8-1).


This multi-center clinical trial will give information on the ability of a single median implant to retain a complete mandibular denture when immediately loaded. If viable, this treatment option will strongly improve everyday dental practice.

Trial registration

The trial has been registered at Deutsches Register Klinischer Studien (German register of clinical trials) under DRKS-ID: DRKS00003730 since 23 August 2012. ( webcite).

Single midline implant; Edentulous mandible; Mandibular complete denture; Implant-supported overdenture; Implant therapy