Robert J. Hanlon, Jr. DMD
Charles E. Jerome, DDS
Promising Techniques for Pulp Revascularization

            Recent endodontic research has demonstrated the possibility of regenerating vital tissue within the canals spaces of teeth with necrotic pulps and open apices. Teeth with vital pulps and open apices that have been replanted after avulsion from trauma have been known to revascularize. In growth of tissue in areas of apical pathosis and pulpal necrosis, however, has remained a challenge.
                Several conditions are necessary for the regeneration of intracanal tissue: (1) Resolution of apical pathosis, (2) Absence of intracanal bacterial infection, (3) Infusion of blood and tissue to provide cellular growth, (4) Stem cells to trigger growth of tissue that normally occupies the area.
                An important aspect of this process is the availability of stem cells. Stem cell research is a hot topic. While most of the controversial discussion involves importing stem cells from other sources,  the tissues in our body already contain stem cells programmed to make the specific tissue found in that area. Getting the stem cells to express that tissue is the key to regenerating tissue in the root canal space.
                Resolution of apical pathosis is routinely accomplished with non-surgical endodontic treatment. Removal of a source of bacterial inflammation, from within the canal space, allows our immune system to repair the area of pathosis in the more vascular apical osseous area. Calcium hydroxide has long been used as an inter-appointment treatment for canal disinfection, however, calcium hydroxide has been shown to destroy stem cells that are found in dentin and connective tissue. The challenge becomes disinfecting the canal space without detriment to regenerating tissue.
                Recent research has identified a “triple antibiotic paste” (TAP) that disinfects the dentin without destroying remnant stem cells. The paste consists of Ciprofloxicin, Metronidazole, and Minicycline antibiotics.  Complete canal space debridement with 5.25% sodium hypochlorite is necessary. Care to prevent extrusion of sodium hypochlorite in open apex cases is critical. The TAP is placed in the space for approximately four weeks and is placed no more coronal that the cervical area because it stains the dentin. After the TAP is removed, the space is etched with 17% ethylenediaminetetraacetic acid (EDTA) to make growth factors from the dentin available. The space is the filled to the cervical area with platelet rich fibrin (PRP). PRP is obtained from the patient by taking a blood sample and spinning it down in a centrifuge to harvest the plasma only. The plasma not only acts as a scaffold for tissue growth but it also has growth factors and stem cells to generate new tissue. An alternate technique involves stimulating apical hemorrhage into the canal space without using PRP.Anesthetics without vasoconstrictors have to be used for this technique so that normal apical blood flow can permeate the fibrin clot. The clot at the apical area has to be covered with a CollaPlug type of material and then a complete coronal seal placed to prevent orthograde bacterial penetration. The endodontic “obturation” is now normal healthy tissue replacing once irreversibly inflamed or necrotic tissue. Nothing is more biocompatible than the patient’s own tissue.
Torabinejad M, Turman M. Revitalization of tooth with necrotic pulp and open apex by using platelet- rich plasma. J Endodon 2011;37:265-268.

Lovelace et al. Evaluation of the delivery of mesenchymal stem cells into the root canal space of necrotic immature teeth after clinical regenerative endodontic procedure. J Endodon 2011;37:133-138.

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