n 1 Eur J Oral Implantol 2012;5(2):?–? RANDOMISED CONTROLLED CLINICAL TRIAL Christoph Arnhart, DDS Senior Staff, Oral Surgery, Bernhard Gottlieb Dental School, Medical University of Vienna, Vienna, Austria Andrej M. Kielbassa, DDS, PhD Professor, Head of the Department of Operative Dentistry and Periodon- tology, Charité - Univer- sitätsmedizin Berlin, Berlin, Germany; and Head of the Centre for Operative Dentistry and Periodontology, University of Dental Medicine and Oral Health, Danube Private University (DPU), Krems, Austria Rafael Martinez-de Fuentes, DDS, PhD Associate Professor, Department of Prostho- dontics, Faculty of Dentis- try, University of Seville, Seville, Spain Moshe Goldstein, DMD Senior Staff, Department of Periodontology, The Hebrew University – Hadassah Medical Center, Jerusalem, Israel Jochen Jackowski, DDS Professor, Head of the Department of Oral Surgery, University Witten/Herdecke, Witten, Germany Martin Lorenzoni, MD, DDS, PhD Professor, Department of Prosthodontics, Medical University of Graz, Graz, Austria continuation next page Christoph Arnhart, Andrej M. Kielbassa, Rafael Martinez-de Fuentes, Moshe Goldstein, Jochen Jackowski, Martin Lorenzoni, Carlo Maiorana, Regina Mericske-Stern, Alessandro Pozzi, Eric Rompen, Mariano Sanz, Jörg R. Strub Comparison of variable-thread tapered implant designs to a standard tapered implant design after immediate loading. A 3-year multicentre randomised controlled trial Key words dental implant, peri-implant bone remodelling, soft tissue evaluation, variable- thread design Objectives: This randomised, controlled multicentre trial aimed at comparing two versions of a variable-thread dental implant design to a standard tapered dental implant design in cases of immediate functional loading for 36 months after loading. Materials and methods: 177 patients (325 implants) were included at 12 study centres and randomly allocated into one of three treatment groups: NAI (variable-thread design, NobelAc- tive internal connection), NAE (variable-thread design, NobelActive external connection) and, as control, NR (standard tapered design, NobelReplace tapered groovy). Inclusion criteria con- cerned healed bony implant sites and feasibility for immediate loading. Clinical and radiographic examinations were performed at implant placement and after 3, 6, 12, 24 and 36 months. The outcome measures were marginal bone remodelling (primary outcome), implant survival and success, papilla score, plaque accumulation, and bleeding on probing. Results: 127 patients (NAI: 45, NAE: 41, NR: 41) were followed-up and evaluated after 36 months. No signiicant differences in cumulative survival rates were seen for the groups (NAI: 95.7%; NAE: 96.3%; NR: 96.6%). In all groups, bone remodelling occurred during the irst 3 months, with stable or even increasing bone levels after the initial remodelling period. The bone remodelling from inser- tion to 36 months for the NAI group (-0.89 ± 1.65 mm) was comparable (P = 0.98) to that of the NR group (-0.85 ± 1.32 mm). The NAE group showed comparable bone remodelling during the irst year, with an increase in following years resulting in signiicantly less overall bone loss (-0.16 ± 1.06 mm) (P = 0.041). Overall improvement in papilla size was observed in all treatment groups. Conclusions: Over 36 months, the results show stable or improving bone levels for all treatment groups after the initial bone remodelling seen during the irst 3 months after placement. The vari- able-thread implants showed results comparable to those of standard tapered implants in cases of immediate function, and therefore can be considered as a treatment option for immediate loading. Conflict-of-interest statement: The present study (T-117) was supported by Nobel Biocare Services AG, Kloten, Switzerland. All authors were funded by their institutions. The authors declare that there is no affiliation or any other conflict of interest to the sponsor. The final protocol was elaborated and finalised in a consensus between all participating centres during an investigator meeting prior to the start of the study. The study was conducted independently at each centre according to the study protocol. Information on the study protocol can be found online at http://clinicaltrials.gov/ (NCT01397617).