Dental Implant Design and Biological Effects on Bone-Implant Interface

Although dental implants have become a predictable aspect of tooth replacement in prosthodontic treatment [1, 2, 3, 4, 5, 6], failures of up to 10% are still encountered. Furthermore these failures have been more associated with “soft” bone quality [7], 1985) such as encountered in the maxillary posterior area [8, 9, 10, 11, 12]. In a review article by Esposito et al [13], bone quality and volume were cited as major determinants for both early and late implant failures. Primary implant stability is considered to play a fundamental role in obtaining successful osseointegration [14, 15]. Friberg et al [15] reported an implant failure rate of 32% for those implants which showed inadequate initial stability. Major contributors to initial implant stability have been suggested to be implant length, diameter, surface texture, and thread configuration. Primary implant stability in dense mandibular bone, measured with resonance frequency analysis, was similar to the implant stability measured after 3-4 months [16, 17]. However, initial stability can be significantly less in bones of low density increasing the risk of failure [18]. Although bone density and quantity are local factors and cannot be controlled, the implant design and surgical technique may be adapted to the specific bone situation to improve the initial implant stability [19]. While different implant designs have shown similar initial stabilities in dense bone [20], implant stability in soft low density bone may be influenced by the implant design [21, 22]. It has been suggested that a combination of microscopic surface topography and macroscopic levels of implant design (e.g., screw thread profiles) may be essential to create a stable bone-implant interface in a low density bone [23]. This article reviews the literature on aspects of implant design on the initial implant stability and bone responses to these factors. PubMed search was conducted using various keywords and the ‘related article’ feature. All articles up to June 2003 were reviewed; and weighted according to their scientific basis.