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BioMed Research International
Volume 2017, Article ID 7376261, 9 pages
Research Article

In Vitro Evaluation of Manual Torque Values Applied to Implant-Abutment Complex by Different Clinicians and Abutment Screw Loosening

1Private Practice, Istanbul, Turkey
2Department of Prosthodontics, Faculty of Dentistry, Istanbul University, Istanbul, Turkey
3Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Istanbul University, Istanbul, Turkey
4Department of Statistics, Yıldız Technical University, Istanbul, Turkey
5Department of Mechanical Engineering, Faculty of Mechanical Engineering, Istanbul Technical University, Istanbul, Turkey
6Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Istanbul University, Istanbul, Turkey

Correspondence should be addressed to Onur Dincer Kose;

Received 2 November 2016; Revised 18 December 2016; Accepted 16 March 2017; Published 3 April 2017

Academic Editor: Konstantinos Michalakis

Copyright © 2017 Onur Dincer Kose et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Preload is applied to screws manually or using a torque wrench in dental implant systems, and the preload applied must be appropriate for the purpose. The aim of this study was to assess screw loosening and bending/torsional moments applied by clinicians of various specialties following application of manual tightening torque to combinations of implants and abutments. Ten-millimeter implants of 3.7 and 4.1 mm diameters and standard or solid abutments were used. Each group contained five implant-abutment combinations. The control and experimental groups comprised 20 and 160 specimens, respectively. Implants in the experimental group were tightened by dentists of different specialties. Torsional and bending moments during tightening were measured using a strain gauge. Control group and implants with preload values close to the ideal preload were subjected to a dynamic loading test at 150 N, 15 Hz, and 85,000 cycles. The implants that deformed in this test were examined using an optical microscope to assess deformities. Manual tightening did not yield the manufacturer-recommended preload values. Dynamic loading testing suggested early screw loosening/fracture in samples with insufficient preload.