The International Journal of Oral & Maxillofacial Implants, Supplement/2011

The Academy of Osseointegration (AO) is a multidisciplinary, international dental implant organization that exists to bring together individuals of different backgrounds in order to share experience and knowledge regarding dental implants. Academy members share the common goal of moving the field of osseointegrated implants forward through clinical and evidence-based research and education. The AO mission is to enhance oral health globally by advancing the science, practice, and ethics of implant dentistry and tissue engineering. The mission is achieved, in part, through annual meetings, publication of The International Journal of Oral & Maxillofacial Implants, and periodic workshops and conferences. 2010 marked the 25-year silver anniversary of the formation of the AO. As a way to recognize this milestone and to honor the AO's dedication to research and education, the AO Board organized and convened the AO Silver Anniversary Summit: Impact of Biological and Technological Advances on Implant Dentistry. The Summit was almost 2 years in the making and involved extensive planning and resources to accomplish. This could not have been achieved without the dedication of the AO Summit Planning Committee.

Cartilage failure in diarthrodial joints results in pain and a reduction in quality of life. The goal of cartilage tissue engineering is to replace or regenerate these mechanically loaded tissues to restore function to the joint. Recent advances in the authors' laboratory have resulted in the production of cartilage and fibrocartilage with clinically relevant properties. A review of salient results will constitute the bulk of this manuscript. After providing a brief background of the clinical problem, this review will highlight several specific tissue engineering tools. The approaches used to produce mechanically functional cartilage through tissue engineering have several parallels to the problems faced in osseointegration, eg, the need for mechanically appropriate tissues at the implantation site. The discussion that follows will focus on how approaches developed in identifying alternative cell sources and various exogenous stimuli for producing new cartilage may be applicable to osseointegration. Keywords: articular cartilage, regenerative medicine, self-assembly, stem cells, tissue engineering

The requirements imposed by the enormous scale and overall complexity of designing new implants or complete organ regeneration are well beyond the reach of present technology in many dimensions, including nanoscale, as researchers do not yet have the basic knowledge required to achieve these goals. The need for a synthetic implant to address multiple physical and biologic factors imposes tremendous constraints on the choice of suitable materials. There is a strong belief that nanoscale materials will produce a new generation of implant materials with high efficiency, low cost, and high volume. The nanoscale in materials processing is truly a new frontier. Metallic dental implants have been used successfully for decades, but they have serious shortcomings related to their osseointegration and the fact that their mechanical properties do not match those of bone. This paper reviews recent advances in the fabrication of novel coatings and nanopatterning of dental implants. It also provides a general summary of the state of the art in dental implant science and describes possible advantages of nanotechnology for future improvements. The ultimate goal is to produce materials and therapies that will bring state-of-the-art technology to the bedside and improve quality of life and current standards of care. Keywords: coatings, dental implants, mechanical properties, nanotechnology, osseointegration, surface engineering

The long-term stability of prosthetic implants is ultimately a function of the integrity of the biologic interaction between the resident tissues and cells and the biomaterial. Connective tissues of the skeleton undergo constant remodeling and turnover, and the interface with the implant biomaterial is therefore a dynamic structure that results from ongoing differentiation of progenitor cells into functional cellular phenotypes. An understanding of the regulation of the mechanisms by which progenitor cells initiate and maintain their interactions with the biomaterial surface while undergoing the necessary differentiation processes is thus essential to optimizing the long-term stability of prosthetic implants. This review presents evidence that the interactions between adult mesenchymal stem cells, as the principal progenitor cell type of skeletal connective tissues, and the biomaterial surfaces are influenced by surface chemistry and topography and regulated by the extracellular matrix and growth factors. Mesenchymal stem cells are also the targets of the wear debris particles that are a by-product of implant biomaterials, resulting in direct and microenvironmental effects, including apoptosis, suppression of proliferation and osteogenic differentiation, and the production of proinflammatory cytokines, that compromise the long-term stability of the bone-implant interface. These effects are initiated by endocytosis of the submicron particles by the mesenchymal stem cells. These observations strongly suggest that optimization of the stability of implant osseointegration must address factors that enhance and promote the biologic activities of the stem/progenitor cells of skeletal connective tissues.

The use of soluble signals for modulation of bone formation has become a significant area of clinical research in recent years. Improvements in implant site preparation and osseointegration have already been achieved with the use of recombinant platelet-derived growth factor and bone morphogenetic proteins on osteogenic scaffolds. Other states of insufficient bone such as osteoporosis are frequently treated with inhibitors of osteoclast function or osteoblast anabolic agents. However, despite the existence of promising therapies targeting osteoblasts and osteoclasts directly, therapies utilizing indirect regulation through secondary cellular nodes of control (NOC) are just beginning to emerge. This article will review current strategies for regulation of bone formation by targeting two primary NOCs, the osteoblast and osteoclast, as well as four secondary NOCs, the vascular, hematopoietic, mesenchymal, and neural. Keywords: bone, cell signaling, dental implant, differentiation, growth factors, regeneration, tissue engineering

Findings from the Academy of Osseointegration State of the Science on Implant Dentistry Conference clearly demonstrate that data are lacking regarding both quality of design and adequate outcome measures (standardization, validity, and relevance to patient) to support an evidence-based systematic evaluation of implant efficacy. Despite the dearth of controlled trials and the variability in defining implant survival/success, the preponderance of evidence is viewed as lending support for consideration of dental implant therapy as a safe and predictable alternative to conventional restorations for many applications. However, this minimal conclusion undermines the best intentions of the dental profession, which is striving to substantiate to the patient, third-party providers, and the government the relative benefits and risks of various prosthetic treatment alternatives. The conclusions of multiple consensus conferences have repeatedly stressed that additional research with good strength of evidence following a broad spectrum of outcomes is vital to extend the breadth of conclusions regarding dental implant treatment efficacy. However, without a set of consensusbased core outcome measures addressing pertinent clinical and patient-centered factors, future expensive, time-consuming, and technically complex clinical studies may suffer the same critical flaws seen in the current body of research. It may be possible and useful to establish a core set of well-defined, discriminatory, and feasible outcome measures for common utilization and a hierarchy of additional recommended outcome measures for specific benefit categories. Such a standardized group of outcome measures would be likely to significantly enhance the potential for future research. In addition, with the formation of consensus guidelines, there would be an opportunity for scientific journals to promote the quality of implant dentistry research by suggesting the inclusion of these core outcome measures in studies submitted for publication. Keywords: clinical trials, consensus, dental implant, outcome measure

Health-care costs are rising at an alarmingly fast rate worldwide, particularly in developed countries such as the United States. This is predominantly a result of the development of new, high-cost health technologies intended for improved diagnosis and treatment. The purpose of health technology assessment is to systematically determine the true benefits of new technologies, taking into account clinical efficacy/effectiveness and cost as well as societal preference and ethical issues. In this report, the purpose of health technology assessment is explained in light of new developments in oral health technology, particularly intraoral implants. This information is intended to educate and to challenge oral health opinion leaders to consider all of the issues involved in the development and diffusion of new oral health technologies. Keywords: decision making, health-care costs, health technology assessment, oral health technology