The AAE describes regenerative endodontics as a Biologically based procedure designed to physiologically replace damaged tooth structures including dentin and root structures as well as cells of the pulp-dentin complex.
The problems with immature permanent teeth that become infected are they have thin dentinal walls and a lack of innervation and vasculature. The thin walls make them prone to fracture in adulthood and the lack of innervation prevent the tooth from having an immune defense against the infection.
Treatment of necrotic permanent teeth with an immature apex included either apexification or regenerative endodontics. Both these procedures have a high success rate when treating the infection in the tooth. However, when apexification procedures were used the roots were prone to fracture due to thin root walls. Regenerative endodontics allows for the continued thickening and elongation of the root, and therefore protection against fracture in adulthood.
Contemporary regenerative endodontic procedures involve at least 2 appointments. At the first appointment the tooth is disinfected with a rinse of 1.5% NaOCl and 17% EDTA, the canal is then dried and a medicament is placed. The medicament used is either a triple antibiotic paste, double antibiotic paste or calcium hydroxide. This medicament allows for further disinfection of the canal system. At the second appointment if the tooth is fully disinfected the canal is irrigated with just EDTA and then bleeding is evoked to allow growth factors and stem cells to infiltrate the canal and a blood clot is formed. Then a biocompatible barrier called Mineral Trioxide Aggregate (MTA) is placed on top of the blood clot. Then a permanent restoration is placed above the MTA. If at the beginning of the second appointment the tooth is still not fully disinfected the first appointment is repeated.
The essentials to regenerative endodontics include disinfection of the root canal system (irrigation and the intracanal medicaments), a scaffold (blood clot), growth factors, and a restoration (MTA, composite).
For a regenerative procedure to be successful the following things need to occur.
1) The infection must heal
2) Continued development of the root
3) Increased thickness of the root
4) Regain vascularity and innervation
Regenerative endodontics has a high success rate and is quickly becoming the endodontists choice of treatment for immature necrotic teeth.
Fig1: Shows an immature tooth with an infection, this infection has stopped the tooth from progressing in development and left the tooth with thin walls and prone to fracture.
Fig 2: 6 months after a pulp regenerative procedure was completed; shows increase in root length, increase in root thickness and healing of the infection.