The maintenance of pulp vitality is critical in young patients with incomplete root formation. Prevention of bacterial infection and subsequent degeneration of pulpal tissue in children and adolescents is critical for the longterm retention of teeth. A study by Galler from University Hospital Regensburg, Germany, focused on preservation or regeneration of dental pulp in immature teeth.

As root formation progresses, epithelial cells of the Hertwig epithelial root sheath (HERS) instruct the underlying mesenchymal cells in the dental papilla to form root dentin and pulp tissue by differentiation of cells from a specific stem cell niche, the apical papilla. Both the apical papilla and the HERS are present only until root formation is complete; epithelial rests of HERS remain as cells of Malassez and may contribute to repair and maintenance of cementurn. The presence of the HERS and apical papilla may be necessary for true regeneration to take place.

After root formation, the dental pulp harbors a small percentage of stem cells. These are localized around blood vessels in the perivascular niche. They are capable of differentiation into various cell types and are involved in regular tissue turnover as well as in regeneration and repair after tissue damage. It has been shown that stem cells from inflamed pulp retain their regeneration potential.

Clinical procedures inside the root canal, such as the use of irrigants and intracanal medicaments, should be considered under the premise of creating the best possible environment for these cells to exert their regenerative potential. The implementation of regenerative procedures requires an understanding of the biological basis, and how therapeutic intervenetion will influence

  •  cell survival
  •  migration
  •  angiogenesis
  •  proliferation
  •  differentiation

Thus, the steps of a regenerative procedure will be a compromise that allows for sufficient disinfection with minimum damage to cellular structures. To date, recommendations tend toward the use of calcium hydroxide, which does not exhibit cytotoxicity in tests with stem cells from the apical papilla.

As soon as inflammation has subsided, the core element of the regenerative procedure is carried out, namely the induction of bleeding into the root canal. Ideally, the blood clot inside the root canal should reach 3 mm
below the cementoenamel junction and be covered with a biocompatible material capable of the induction of mineral formation. The access cavity is then permanently sealed.

Conclusion

Regenerative endodontic procedures have become part of the endodontic treatment spectrum. The implementation of regenerative endodontic procedures should be considered by the patient’s individual case. A growing body of evidence has demonstrated the clinical feasibility of this approach, making it likely that regenerative endodontic therapies will find their way as established procedures in endodontic practice.

Galler KM. Clinical procedures for revitalization: current knowledge and considerations. Int Endod J 2016;49:9261936.