Pulp development, repair, and regeneration: challenges of the transition from traditional dentistry to biologically based therapies.

The traditional concept of replacing diseased tooth/pulp tissues by inert materials (restoration) is being challenged by recent advances in pulp biology leading to regenerative strategies aiming at the generation of new vital tissue. New tissue formation in the pulp chamber can be observed after adequate infection control and the formation of a blood clot. However, differentiation of true odontoblasts is still more speculative, and the approach is largely limited to immature teeth with open apices. A more systematic approach may be provided by the adoption of the tissue engineering concepts of using matrices, suitable (stem) cells, and signaling molecules to direct tissue events. With these tools, pulplike constructs have already been generated in experimental animals. However, a number of challenges still remain for clinical translation of pulp regeneration (eg, the cell source [resident vs nonresident stem cells, the latter associated with cell-free approaches], mechanisms of odontoblast differentiation, the pulp environment, the role of infection and inflammation, dentin pretreatment to release fossilized signaling molecules from dentin, and the provision of suitable matrices). Transition as a process, defined by moving from one form of "normal" to another, is based not only on the progress of science but also on achieving change to established treatment concepts in daily practice. However, it is clear that the significant recent achievements in pulp biology are providing an exciting platform from which clinical translation of dental pulp regeneration can advance.