development is an intricate process. The beginning of this process
starts in the embryonic stage, when the embryonic cells grow in
a certain pattern. These will later sprout into the oral cavity,
forming your teeth. Just like animals, the vertebrate species also
develop teeth, which likely have the same tooth development as
humans. And similar to hair, these are appendages that grow out
from beneath the skin. The formation of cells and biological archetype
matches those of the hair and glands in the embroyonic stages.
During the fetal stage of development, enamel, dentin, cementum
and peridontum begin to form in certain stages. In the sixth
and eight week, primary or ‘baby’ teeth start to
sprout out. The permanent teeth will develop in the twentieth
week. However, if these do not develop within the given range,
it may never develop at all. Human teeth need a healthy oral
environment for it to grow.
Maturity of Teeth
The interaction of ectoderm and mesenchyme tissues triggers
the maturation of your tooth. Ectoderm found in the oral cavity
condenses into buds, which fold into a crown of the tooth. The
interaction of the epithelium (protective sheath) and mesenchymal
tissues is an intricate process that follows a certain pattern
making up the morphology of the teeth.
Stages in Tooth Development
There are four key stages in tooth development: Bud stage, the
cap, the bell and maturation. It is, however, hard to classify
stages considering different parts are involved in the same tooth
with varying stages of development at similar times.
Bio-Signaling in Tooth Development
According to Theslef, the maturation of tooth development is
due to the signals being sent and received from one stage to
another or from a set of cells to another set of cells. In the
exact pattern, these signals are constantly recurring which eventually
lead to the eruption of a tooth. The recurrent signals between
the masenchyme cells and the ectoderm will then lead to the development
of a tooth.
In the tooth development levels, Pracrine signals these ‘go
between’ molecules in various cells and tissue layers.
There are three categories of signal molecules: Transforming
Growth Factor or TGfb, Fibroblast Growth Factor or FGC and the
Hedgehog and Wnt group. These signal molecules communicates for
the epithelium and mesenchyme cells and will also relay signals
to tissue layers. With repetitive signals, these cells will interpret
it and then relay it the next cell in the same pattern.
The most common feature in the maturity of a tooth is the brief
signal centers in the epithelium in the first stages. Within
the three groups, there were different signals that are being
passed which are: SHH (sonic hedgehog) and numerous BMPs (Bone
Morphogenetic proteins from the TGFbeta group), FGFs and Wnts
that are passed at the same time.
The primary signals are being given off during the epithelial
budding stage. From there, the enamel knot will signal to take
over to form the cap stage. This enamel knot will modulate the
maturation of the tooth crown and then control the secondary
enamel knots where the epithelial folds form a cusp.
In the initial stages of tooth maturation, the epithelium sends
BMP and FGF to the odontogenic mesynchyme. This will in turn
send signals to furthermore relay maturation of tooth.
The structure of the enamel knot signals relays signals indicating
its position. This would also send molecular signals like FGF,
BMP, Hedgehog (Hh) and Wnt signals. The epithelium and mesenchyme
cells will then pick up these relayed signals to develop the
In humans, eruption of a tooth is a course of development wherein
the teeth sprouts out in the mouth, making it visible.