Biomechanical aspects of oral implants Consensus report of Working Group 1 J. A. Hobkirk H. W. A. Wiskott On behalf of Working Group 1 n Authors’ affiliations: J. A. Hobkirk, UCL Eastman Dental Institute, University College London, Division of Restorative Dental Sciences, London, UK H. W. A. Wiskott, University of Geneva, Geneva, Switzerland Correspondence to: Prof. J. A. Hobkirk UCL Eastman Dental Institute 256 Gray’s Inn Road London WC1X 8LD UK Fax: þ 44 20 79151026 e-mail: j.hobkirk@eastman.ucl.ac.uk Key words: biomechanics, bone implant interactions, clinical assessment, clinical research, clinical trials, diagnosis, finite-element analysis, prosthodontics Abstract: The method used by the working group was an iterative process based upon a structured review of the relevant literature by a group of rapporteurs. The review papers were circulated to the members of the group before the conference and formed the basis for subsequent discussions. Each paper was subject to detailed collective analysis and subsequently modified on the basis of the panel’s discussions and referenced to additional relevant literature where appropriate. The group assessed the levels of evidence for the statements made in the supporting documentation and recognized that it was necessary to adopt a compromise between acceptance of the lowest level, resulting in the largest body of material, and the highest level, which, in some cases, produced little evidence. While this approach does not represent endorsement of lower evidence levels per se, it was designed to provide conclusions of clinical utility within the existing knowledge base. The consensus statements were prepared after a detailed consideration of the papers submitted to the workshop by the working group. The papers were scrutinized, amended and approved by the group. The basis of each paper is described in the section on ‘search strategy’ and defines the parameters within which the consensus statements were prepared. Impact of implant length and diameter on survival rates (Renouard & Nisand) Short and/or wide implants are generally considered as presenting a higher failure rate. Their indications are therefore limited to a few cases. Advanced surgical proce- dures were developed in order to place a standard-length implant. The present re- view (Renouard & Nisand 2006) explores the relationship between implant length/ diameter and survival rates. The level of evidence provided by the literature is rather low, and the highest level of evidence (randomized-controlled study) has not been reached in the material reviewed for this paper. However, 53 retrospective and pro- spective studies, some with controls, were available and form the basis of this report. In the present review, a ‘short’ implant was defined as a device with a designed intra-bony length of 8 mm or less. A ‘wide’ implant was defined as one in which the stated diameter was 4.5 mm or more, and a ‘narrow’ implant one in which this was less than 3.5 mm.  The structured review has demon- strated a trend for an increased failure rate with short implants.  The structured review has demon- strated a trend for an increased failure rate with wide-diameter implants.  Covariables such as surgical technique, implant surface characteristics, bone volume and density may obscure the effect of implant length per se.  Covariables such as surgical technique, implant surface characteristics, bone volume and density may obscure the effect of implant diameter per se.  The studies published after 1997, in which the importance of the covari- ables was recognized and dealt with, reported an overall survival rate for short implants that is comparable to standard length implants. The same applies to wide-diameter implants.  The morbidity associated with advanced surgical procedures (such as bone grafting, nerve transposition and alveolar distrac- tion) must be considered when evaluat- ing the survival of short or wide implants, as the use of such implants may obviate the need for augmentation procedures. Future research should be directed at the following:  Initiating studies on the effects of im- plant length and diameter. These stu- r 2006 The Authors Journal compilation r Blackwell Munksgaard 2006 n C. Aparicio, W. Bolz, F. Isidor, N. P. Lang, E. Nkenke, F. Renouard. To cite this article: Hobkirk JA, Wiskott HWA. Biochemical aspects of oral implants. Consensus report of Working Group 1. Clin. Oral Imp. Res., 17 (Suppl. 2), 2006; 52–54 52