Whole Tooth Regeneration Using a Bioengineered Tooth - New Trends in Tissue Engineering and Regenerative Medicine - page 114

4.1. Transplantation of bioengineered tooth germ or a bioengineered mature tooth unit as
a tooth replacement therapy
The critical issue dictating the success of tooth regenerative therapy via the transplantation of
bioengineered tooth germ tissue into the lost tooth region is whether the germ can erupt and
occlude properly with the opposing tooth in an adult oral environment. It has previously been
demonstrated that transplanted natural tooth germ erupts in a murine toothless diastema
region (Ohazama et al., 2004). We have also reported that a bioengineered tooth germ can
develop the correct tooth structure in an oral cavity and successfully erupt 37 days after
transplantation (Ikeda et al., 2009). The bioengineered tooth subsequently reached the occlusal
plane and achieved occlusion with the opposing tooth from 49 days onwards (Fig. 4A, B). In
the case of a transplanted bioengineered mature tooth unit comprising mature tooth, perio‐
dontal ligament and alveolar bone, the most critical consideration is whether that unit can be
engrafted into the tooth loss region through bone integration, which involves natural bone
remodelling in the recipient. A bioengineered tooth unit transplanted at a position reaching
the occlusal plane with the opposing upper first molar was successfully engrafted after 40 days
and thereafter maintained the periodontal ligament originating from the bioengineered tooth
unit through successful bone integration (Fig. 4C) (Oshima et al., 2011). The enamel and dentin
hardness of the bioengineered tooth components were in the normal range when analysed by
the Knoop hardness test (Ikeda et al., 2009; Oshima et al., 2011). These approaches demonstrate
the potential to successfully recover masticatory performance and natural tooth tissue through
state-of-the-art bioengineering technology.
Figure 4. Regeneration of a bioengineered tooth in an adult oral environment A) A transplanted bioengineered tooth
germ erupted and reached the occlusal plane with the opposing lower first molar 49 days after transplantation. B)
GFP-labelled bioengineered tooth (right panel) erupted in the oral environment of adult mice. C) A bioengineered
tooth unit was engrafted by bone integration and reached the occlusal plane with the opposing upper first molar at
40 days post transplantation.