Dental Implant Design and Its Relationship to Long-Term Implant Success

Dental Implant Design and Its Relationship to Long-Term Implant Success
December 2003
Steigenga, Jennifer T. DDS*; Al-Shammari, Khalaf F. DDS, MSÇƒÜ; Nociti, Francisco H. DDS, PhDÇƒ?; Misch, Carl E. DDS, MDS¨?; Wang, Hom-Lay DDS, MSD
Implant Dentistry: Volume 12(4) December 2003 pp 306-317
Lippincott Williams & Wilkins
*Graduate student, Department of Periodontics/Prevention/Geriatrics, School of Dentistry, University of Michigan, Ann Arbor, Michigan.
ÇƒÜAdjunct Assistant Professor, Department of Periodontics/Prevention/Geriatrics, School of Dentistry, University of Michigan, Ann Arbor, Michigan; and Ministry of Health, Kuwait.
Çƒ?Associate Professor, Department of Prosthodontics and Periodontics, Division of Periodontics, School of Dentistry at Piracicaba, UNICAMP, S?£o Paulo, Brazil.
¨?Adjunct Clinical Professor, Department of Periodontics/Prevention/Geriatrics, School of Dentistry, University of Michigan, Ann Arbor, Michigan.
?Professor and Director of Graduate Periodontics, Department of Periodontics/Prevention/Geriatrics, School of Dentistry, University of Michigan, Ann Arbor, Michigan.
Reprint requests and correspondence to:
Hom-Lay Wang, DDS, MSD
University of Michigan
School of Dentistry
1011 N. University Ave.
Ann Arbor, MI 48109-1078
Phone: (734) 763-3383
Fax: (734) 763-5503
E-mail: homlay@umich.edu
Abstract
The purpose of this review is to evaluate the effects of the biomechanical aspects of dental implant design on the quality and strength of osseointegration, the bone-implant interface, and their relationships to the long-term success of dental implants. The engineering design of implants is based on many interrelated factors, including the geometry of the implant, mechanical properties, and the initial and long-term stability of the implant-tissue interface. There is no one optimal design criterion. However, implants can be engineered to maximize strength, interfacial stability, and load transfer by using different materials, surfaces, and thread designs. Limited information is currently available in addressing how implant thread design influences the overall implant success. Therefore, this article reviews and discusses design elements of various dental implant systems currently in use as they affect the quality of osseointegration and their relationship to overall long-term success patterns.
A major advance in dentistry has been the successful replacement of lost natural teeth by osseointegrated implants. Years of clinical experience have fostered a consensus regarding many of the placement criteria and techniques to maximize the chance for long-term implant stability and function. 1 The use of dental implants for the oral rehabilitation of fully and partially edentulous patients has greatly broadened the scope of clinical dentistry, creating additional treatment options in complex cases in which functional rehabilitation was previously limited or inadequate. The predictability and long-term success of dental implants have been well documented, both in removable and fixed prostheses. 2-5 Most of the studies reported have shown multiyear success rates of more than 90% for implants placed in fully edentulous 6-8 or partially edentulous patients. 4,9-14
Nevertheless, success rates have been reported to vary in different areas of the mouth and in different patients. For example, lower success rates have been reported for maxillary implants than for mandibular implants. 2,15,16 Attempts have been made to understand the factors that could compromise implant success. Factors such as material biocompatibility, implant design and surface, surgical technique, host bed, and the loading conditions have all been shown to influence the implant osseointegration. 17 Available bone volume has long been considered an important factor in achieving implant predictability. 18 Studies showed higher failure rates for implants shorter than 10 mm. 3 Another important influencing factor for implant success is bone density, because higher failure rates have been reported for regions with poor quality bone, eg, the posterior maxilla. 15,19-21
Consequently, modifications in implant body design and implant surfaces have been suggested to increase the success in poor quality bone by, hypothetically, gaining better anchorage and providing more surface area of load to decrease stress to the softer bone types. 15 In a rabbit study, Carlsson 22 found a more complete bone-to-implant contact around screw-shaped implants than around double cylinders and T-shaped implants. Also demonstrated was the fact that a stronger biomechanical bond was obtained with a rough implant surface than with a similarly shaped, but polished, implant surface. Furthermore, other in vivo studies have agreed that a rough surface is more suitable for implant integration than a comparatively smoother implant surface by demonstrating a higher degree of bone integration. 23-26 Surface roughness can influence the degree of osseointegration. For example, the pattern size and distribution of peaks and valleys that compose the surface roughness can significantly influence the overall intimacy and mechanical interlocking of the bone-implant interface. However, the surface condition is not the only factor that could influence osseointegration. Implant design can affect surgical insertion (eg, stability) and the bone-implant interface after occlusal loading. Implant design and surface conditions are 2 independent conditions that can alter implant success rates. This article reviews and discusses design elements of dental implants as they affect the quality of osseointegration and their relationship to long-term success..
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