About this Research Topic
The field of tissue engineering and regenerative medicine has taken an enormous stride over the past 25 years. While earlier generations of tissue engineering essentially focused on attempting to regenerate tissue by building it from scratch, the latest generation aims to recapitulate naturally occurring developmental pathways to stimulate the body to do just that. Regenerative medicine on the other hand strives to trigger endogenous repair mechanisms to tease the body into healing itself by modulating the inflammatory response, enhancing progenitor cell recruitment, promoting angiogenesis and finally tissue repair.
Recently, regenerative dentistry applications have emerged including those to revascularize and regenerate dentin/pulp tissue after root canal therapy, engineer periodontal ligament tissue and bone, or to regenerate an entire tooth. These strategies will most likely extend not only to cell transplantation but also to approaches such as inducing endogenous cell homing as well using scaffolds and bioactive cues.
Amongst regenerative dental applications, regenerative endodontics can be considered a pioneer field in introducing actual clinical translation of tissue engineering and regenerative medicine to dental practice. It was not until a call for action was published in 2007 that both clinicians and scientists began to redirect their attention to regenerative strategies as viable treatment modalities for management of teeth with necrotic pulps. This constituted the true first steps towards endodontists entering the field of tissue engineering and regenerative medicine. Tissue engineering approaches suggested for regenerative endodontics include but are not limited to: those directed to induce revascularization, the use of stem cell therapy through injection into the root canal system, ex-vivo engineering of pulp tissue and implanting in situ, using pulp cells seeded onto three dimensional scaffolds conforming to the shape of the root canal system, 3D cell printing, the use of injectable polymerizable hydrogel scaffolds, and gene therapy.
Stemming from the recent paradigm shift in tissue engineering and regenerative medicine; namely stimulating endogenous repair rather than building from scratch, regenerative endodontic proce-dures (REPs) have finally shown their first applications in the clinic. The discovery of resident stem cells in virtually all dental as well as periapical tissues has pushed the concept even further.
Although regenerative endodontic procedures are now considered part of many daily clinical practice regimens there are still several challenges that need to be addressed to reach full clinical translation of this new science and its applications. Challenges include but are not limited to; developing appropriate antibacterial regimens that are effective yet having minimal toxicity to targeted stem cell populations, new quantitative methods of assessment following REPs, as well as establishing criteria of successful treatment outcome that are no longer compared to the goals of conventional endodontic treatment but that can encompass the biological goals associated with REPs and address the true objectives of a tissue engineering or regenerative medicine approach to tissue replacement. Addressing such challenges will also require a deeper understanding of the intricate processes of dental tissue repair and regeneration and the driving forces behind them.
Keywords: Translational endodontics, dental stem cells, stem/progenitor cell recruitment, dentin-pulp complex regeneration, dentinogenesis, endogenous tissue regeneration