Dental tissue engineering is one of the most advanced areas in the broader field, as illustrated by work on growing teeth from stem cells. Several groups over the past five years have successfully implanted stem cells that led to the growth of replacement teeth in mice, and other forms of procedure such as the reattachment of teeth via engineered ligaments have also been demonstrated in laboratory animals.

In a more recent project, researchers grew mouse teeth outside the body, implanted them, and produced a very satisfactory end result as the teeth grew in and became functional:

In this proof of concept study [a] bioengineered tooth unit comprising mature tooth, periodontal ligament and alveolar bone, was successfully transplanted into a properly-sized bony hole in the alveolar bone ... Partial bone integration was observed at 14 days after transplantation, and full bone integration around a bioengineered tooth root was seen at 30 days after transplantation ... [The] engrafted bioengineered tooth displayed physiological tooth functions such as mastication, periodontal ligament function for bone remodeling and responsiveness to noxious stimulations.

...

These findings indicate that whole tooth regenerative therapy is feasible through the transplantation of a bioengineered mature tooth unit. This study also provides the first reported evidence of entire organ regeneration through the transplantation of a bioengineered tooth.

The age of bad teeth, old teeth, and artificial teeth will soon enough be coming to a close, I think. For my money, the most interesting parts of the paper relate to the challenges inherent in coaxing suitable dental stem cells into growing into teeth that have the right shape. The methodology that the researchers found worked was as follows:

To generate the shape- and length-controlled bioengineered tooth unit so that a suitable size was obtained, [the] tooth germ was inserted into a ring-shaped size-control device and then transplanted into a subrenal capsule.

Width was controlled by placing a barrier around the growing material, and the length controlled by how long the tooth was grown for - though the researchers also touched on other potential means of fine-tuning tooth shape and size. I look forward to seeing how well this methodology works when they move on to human teeth.