Tissue engineering approaches for regenerative dentistry

Although teeth can withstand enormous abrasive forces, they are susceptible to damage due to trauma, acids and bacterial attack. Conventional treatment relies on synthetic materials to fill defects and replace whole teeth, but these remain substitutes and cannot restore the tissues' physiological architecture and function. With the isolation of postnatal stem cells from various sources in the oral cavity and the development of smart materials for cell and growth factor delivery, possibilities for alternative, biology-based treatments arise. Interdisciplinary approaches are needed to move from replacement to regeneration, involving clinicians as well as biologists, stem cell researchers and material scientists. First, in order to provide an appreciation for the complexity of the tooth as a whole, its components and surrounding structures will be described. Next, the basic principles of tooth development will be presented, which can be applied to recreate signaling events and utilize them to build whole teeth. For the regeneration of individual tooth structures, the classical tissue engineering triad can be utilized, using dental stem cells, scaffold materials and relevant growth and differentiation factors. Recent successful engineering initiatives on whole teeth as well as on specific tissues such as enamel, the dentin-pulp complex or periodontal ligament will be discussed. In projecting future research directions, we conclude with a brief discussion of key components necessary to develop effective strategies for dental tissue engineering, which might enable us to implement novel regenerative strategies in clinical practice in the near future.