In the western dentistry world, replacing a missing tooth or damaged teeth is increasing rapidly, where post-50 year old men have an average of twelve missing teeth. As of now, procedures such as fixed or removable dentures and dental transplants are being utilized in replacing a tooth, with certain disadvantages involved. Dental transplants require a hole drilled in the jaw bone with a titanium rod. This is then capped by a ceramic or plastic tooth. However, there has been difficulty encountered when there is not sufficient jaw bone for the titanium rod to be placed in.

Bio-tooth replacement

This procedure is a better alternative than traditional teeth replacement methods, and it involves regrowing or reconstruction of a tooth in the mouth. However, the problem with this procedure is that it needs the right tooth shape. Teeth in the lower and upper jaws have different shapes, which is primarily determined during the early teeth development. There are four ways in constructing a bio-tooth:

1. Reconstruct the mature tooth as it appears in the mouth
2. Reproduce the embryonic development in the mouth
3. Induce a third dentition
4. Create a tooth-shaped scaffold, place some cells in them and wait for the cells to grow.

Of the the options presented above, only two are being tried in the conceptual stage and the other two are still being studied.

Reconstruct the mature tooth as it appears in the mouth: The four components in a tooth – the crown, dental pulp, enamel and root – are separately constructed from the materials and right cells. The drawback of this procedure is that the process has a high level of technical difficulty. The advantages, on the other hand, include having a high level of control on the process and the possible automation and scale-up.

Inducing a third dentition: This prospect has been around for quite a while, and there is an appealing proposition for this. Primarily, it works by adding molecules with either of the two earlier dentitions in development of initiating the de novo of the tooth post tooth loss. But, there are two problems encountered: genes involved in induction of tooth initiation have a part in bone development, and other cellular process and cells found in the teeth are not present in the adult jaw, therefore the molecules have nothing to act upon.

Create a tooth-shaped scaffold, place some cells in them, and let the cells grow: This procedure is highly successful, and uses tissue engineering technique. It involves seeding of biodegradable scaffolding with cells, and generation of these tissues will mold on to the shape of the scaffolding. There are various uses of these scaffolds, and may even be able to regenerate teeth and other organs, but this theory is still under investigation.

There are experiments being done on animals which demonstrate early-stage embryonic tooth cells that have the capability to regenerate a tooth. Cells in the early stage third molar tooth germs in pigs and rats, which is seeded within a scaffolding, developed little tooth germs. Early investigation findings pointed that there is a presence of stem cells during the experiment in the early-stage embryonic tooth. An elaborate explanation is that formation of these little teeth was due to the small groups of dissociated dental cells that are reorganizing themselves from their dissociated population.

This method had established a theory that scaffolding can determine tooth shape. However, this experiment showed that these tiny teeth have not taken shape of the scaffolding and there was no formation of bones. Bones are essential in building up roots which anchors the teeth in place. These are just initial experiments and are yet to confirm regenerative capabilities of early dental cells and are still on the process of producing bio-tooth.

Reproduce the embryonic development in the mouth using stem cells: Numerous attempts are being done to replicate teeth development during the embryonic stage, such as using cultured cells when embryonic cells are not obtainable. The proposal is based on the grounds that organs produced in the embryo, for in-vitro production embryonic development, should be well understood.

Tooth development occurs with the interaction of cells between the cells in oral epithelium and neural crest-derived mesenchyme cells. During this stage, there is undifferentiated mesenchyme cells that respond to epithelium cells in various ways. It has been suggested that this simple primary stage produces in-vitro from the cultured cells. These stem cell-like neural crest cells follow different paths. The primary challenge is finding cells that can replace these neural crest cells and interact with the oral epithelium cells in production of various mesenchyme cells utilized in teeth formation.

Studies in animal embryo showed bone marrow stromal cells are stem cell-like. Another challenge is finding cells which can replace embryonic oral epithelium cells to produce bio-tooth in adults from cultured cells entirely.