Odontogenesis - a Masterful Orchestration of Functional Redundancy or What Makes Tooth Bioengineering an Intrinsically Difficult Concept

Rapid increase of knowledge in stem cell research, bioengineering technology and molecular basis of odontogenesis has finally lead us to the point where it is possible to develop approaches for treatment of tooth loss with bioengineered teeth, which one day might completely replace conventional prosthodontics and dental implants. By holding onto the premise that in order to bioengineer teeth, full understanding of how teeth develop is required, it must be acknowledged that there are certain features of odontogenesis which create obstacles in gaining that understanding. One such feature is the functional redundancy in genetic networks responsible for molecular control of odontogenesis. Abundant data imply that having functional redundancy of various elements in regulatory genetic networks is more than just a failsafe built into the odontogenic sequence in order to secure unhindered development of teeth. This phenomenon plays important roles in determination of tooth numbers and positioning, and is increasingly recognized as important for enabling sufficient plasticity of regulatory genetic networks through which the appearance of tooth-type specific and species-specific diversity of mammalian tooth morphology can be explained. Unfortunately, most of what we know about molecular basis of odontogenesis, comes from studies of mouse molars. Novel insights from developmental biology, stem cell research, and bioengineering technology are still needed, if we want to make de novo tooth bioengineering a clinically viable method for treatment of tooth loss.