Since the publication of Spallanzani, it is known that following
surgical amputation, the tail of the urodele amphibians
Xenopus tadpole regenerates. Restoration of tails, legs
and jaws also occurs in the salamander after surgical removal. At the same period, Trembly split hydra heads and
obtained multiheaded individuals. By bisecting a hydra,
two complete animals were produced. During many years, a
gap persisted between the biological regenerative capacities
and what was requested for surgical therapies. This gap was
gradually reduced, and now nearly disappeared. Successive
steps highlight the fundaments of regenerative biodentistry.
Implantations of stem cells and surgical approaches in
dentistry are derived from epithelio-mesenchymal assembly
of embryological tissues. After reactivation of the concepts
ahead of clinical applications, new treatments guiding
organ repair and regeneration in mammals pave the way
for biodentistry improvements. Indeed, applied to the field
of human therapies the replacement of lost teeth by tissueengineered
dental recombinants appears as a fascinating
goal.
The initially aim of dental tissue engineering was to
generate a whole tooth, or within some limits took into
consideration, to concentrate on the regeneration of a
missing part. The aim of dental tissue engineering may been
limited to enamel repair, but this is still at an experimental
stage. Or a more realistic objective was to heal the dental
pulp, and consequently to provide a contribution to dentin
mineralization as a substitute to endodontic therapy.
Restorative approaches of root canal treated tooth have
relatively limited long-term survival and many failures are
associated to diverse complications such as transversal or
longitudinal fissures followed by subsequent fractures, and/or
chronic periapical inflammation. Substitutive therapies to
endodontic treatments have been suggested and innovative
strategies have been envisioned, including metallic implants
or bridges. However, during the last decades, advances in the understanding of tooth development, as well as stem
cell biology permit to consider the biological replacement
of lost dental tissues and provide the foundation of novel
opportunities in dental tissue engineering.
Developing dental substitutes appear not only as a fascinating
goal in restorative dentistry, but raises also the question of
technical feasibility. It is clear that many open questions take
origin from a series of interrogations and the answers that
are given are still confusing.
What is exactly our goal? Are we
willing to create or recreate a whole tooth? Are we willing
to regenerate only a small part of dental tissues? Our aim
may be limited to the healing and regeneration of a dental
pulp? But will it be possible to use the newly formed pulp as
a support for pulp mineralization, playing a role as a potential
substitute for endodontic treatment? Each attempt to provide
an efficient clinical answer implicates another strategy.
Alternatively, it seems sometimes mandatory to evaluate the
value of another method, another technic or to test another
biomaterial. Consequently, any improvement needs firstly the
identification of the question to be answered, and afterward
the development of adapted cellular or biological materials.
The present approaches imply stem cells, scaffolds, structural
and signaling molecules, transcription and growth factors.
In this review we concentrate exclusively on the current
knowledge related to pulp stem cells and we discuss their
potential functions and implications in regenerative dentistry.
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