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.
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
- Reconstruct the mature tooth as it appears in the mouth
- Reproduce the embryonic development in the mouth
a third dentition
- 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.