In the head and neck anatomy course I took many
decades ago, we were taught that cranial sutures,
although fibrous in newborns, were calcified in teens
and adults, and allowed for no movement and no
further growth. Cranial sutures of infants were not
fused, allowing for growth of the cranial bones to
accommodate brain growth. The teachings back then
suggested that with age, cranial sutures would fuse so
no movement occurred and the suture would become
completely calcified. However, the age at which this
calcification occurred was the subject of much debate.
Findings based on the use of new technology analyzing
cranial bones more closely shows sutures are not
completely calcified in teens or adults as was once
thought. Researchers found a membrane in the suture
separating the cranial bones. This membrane is composed
of mesenchymal stem cells, which can differentiate
into connective tissue and bone. Therefore, the
cranial bones do continue to grow throughout life,
even though it may be minimal.
The periodontal ligament (PDL) might also be
considered a suture, as the PDL contains stem cells
which can be differentiated into fibroblasts or
osteoblasts, making new connective tissue and bone.
In periodontal disease, we see regeneration of lost
tissues, not just repair of the damage. With pressure
on a tooth in one direction, we see bone loss. On the
opposite side that has been stretched, we find new
bone formation, created by stem cell proliferation in
the PDL. Considering the extent of the PDL area
around all the teeth in an arch, the arch actually can
be considered a cranial suture.
Research has confirmed the pulp of deciduous
teeth contains stem cells and companies now offer harvesting
and preserving of these cells. Dental researchers
are working to harness these stem cells through tissue
engineering of craniofacial tissues, which would
replace restorative materials by growing new teeth.
This will certainly bring interesting changes to the
clinical setting, but not for several years.
In the meantime, triggering palatal stem cells to
grow bone is already being done. Palatal growth is
influenced by genetic coding as well as environmental
factors, such as thumb sucking and tongue position.
For example, if the tongue isn't resting in the
palate there will be no passive stretching pressure on
the palate to stimulate expansion and growth to provide
enough room for all the teeth. Instead, the environmental
effect of the thumb instead of the tongue
will create a narrow, high palate with inadequate
space for all the teeth and therefore crowded, overlapping
teeth.
When palatal growth is stopped prematurely for
environmental reasons, the mid-face doesn't reach proportional
development. Mandibular development will
also be influenced by premature interruption of palatal
growth. Knowing the palatal suture contains stem cells
that can be triggered to grow new bone, even in adults,
is exciting news. Based on biology and genetics, Singh
designed the DNA Appliance, a retainer that puts gentle
stretching pressure on the palatal suture as well as
the PDL sutures of the teeth to stimulate new bone
growth and expand the palate, no matter how old the
patient. Expanding the palate will change the mid-face
region and in some cases, open the airway. Yes, you do
have stem cells in your palatal suture and genetics is
now more of a part of dental care than ever.
|