Operative Dentistry

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Operative Dentistry, 2006, 31-6, 633-642

Buonocore Lecture

Buonocore Memorial Lecture

Tooth Regeneration in Operative Dentistry
JE Nör
Michael Buonocore

ABSTRACT For many years, operative dentistry has been using regenerative approaches to treat dental disease. The use of calcium hydroxide to stimulate reparative or reactionary dentin is clearly an example of such a therapeuticstrategy. The advent of tissue engineering is allowing Jacques E Nör dentistry to move forward in the use of regeneration as an underlying principle for the treatment of dental disease. Tissue engineering is a multi-disciplinary science that brings together biology, engineering and clinical sciences with developing new tissues and organs. It is based on fundamental principles that involve theidentification of appropriate cells, the development of conducive scaffolds and an understanding of the morphogenic signals required to induce cells to regenerate the tissues that were lost. This review is focused on the presentation and discussion of
*Jacques E Nör, DDS, MS, PhD, professor of dentistry, Dept of Cariology, Restorative Sciences, Endodontics and professor of Biomedical Engineering,College of Engineering, University of Michigan, Ann Arbor, MI, USA *Reprint request: 1011 N University, Rm 2309, Ann Arbor, MI 48109-1078, USA; e-mail: jenor@umich.edu DOI: 10.2341/06-000

existing literature that covers the engineering of enamel, dentin and pulp, as well on the engineering of entire teeth. There are clearly major roadblocks to overcome before such strategies move to the clinicand are used regularly to treat patients. However, existing evidence strongly suggests that the engineering of new dental structures to replace tissues lost during the process of caries or trauma will have a place in the future of operative dentistry. INTRODUCTION In the late 1980s, a polymer chemist (Robert Langer) and an organ transplant surgeon (Joseph Vacanti), proposed that it might be possibleto generate a tissue or organ by seeding the cells that make this tissue into a biodegradable scaffold.1 This approach to regenerative medicine was named tissue engineering, which is defined as an interdisciplinary field that applies the principles of engineering and the life sciences toward biological substitutes that restore, maintain or improve tissue function.2 A seminal publication in theearly 1990s describing the fundamentals of tissue engineering3 and the successful engineering of cartilage in the shape of a human ear in the dorsum of mice4 brought much attention and visibility to this emerging field. Since then, medical practitioners have increasingly used tissue engineering to treat a variety of conditions. Skin replacements for severely burned pediatric patients5 and theconstruction of new bone for patients with severe bone loss6 are examples of tissue engineering-based strategies that have been used in humans. Over the last few years, dental researchers started to explore the potential of tissue engineering to repair lost

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tooth structures and, perhaps, even for complete replacement of an entire tooth. It is projected that strategies involving the use oftissue engineering, nanotechnology and stem cells will have an increasing participation in clinical dentistry over the next 5-20 years.7 This review aims to provide a broad update on the field of tissue engineering as it applies to the regeneration of tooth structure. It is important to emphasize the fact that most of these technologies are in development and do not currently have approval by the FDAfor use in patients. Therefore, this review is written with an eye on the future, exploring the potential impact that tissue engineering may have in the future of clinical dentistry. Lessons from Molecular Signaling Events During Odontogenesis The field of tooth tissue engineering uses concepts that originate from early studies on molecular signaling during odontogenesis and also from the study...