How to Perform Regenerative Endodontics on an Immature Necrotic Tooth (Two-Visit Protocol)

A young tooth dies before its root finishes forming, and you have two options: wall it off, or bring the canal back to life. Regenerative endodontics (REP) is the biological option — it doesn't just fill the tooth, it lets the root keep growing. Here's why it works, and why every step protects a specific population of stem cells.

The idea: biology instead of a barrier

REP is for exactly one tooth — an immature permanent tooth with an open apex and a necrotic pulp. That precise combination is the entire reason REP exists; a mature or vital tooth is the wrong indication.

There are two answers to a dead young tooth, and the contrast is the keystone. Apexification builds an artificial barrier and fills the canal: the root stops where it was, leaving thin, fracture-prone walls and no further growth. REP instead recruits the body's own cells to keep the root developing — thicker walls, a longer root, and an apex that closes over time.

Why can a dead tooth regrow at all? Because an immature tooth still holds a reservoir of stem cells near its open apex — the stem cells of the apical papilla (SCAP). Every design choice exists to protect and recruit them: gentle disinfection that spares those cells, conditioning the dentin to release growth factors, and provoking bleeding so cells and a fibrin scaffold fill the canal. The mental model is four moves — disinfect, scaffold, seal, regrow — and once you understand SCAP, the logic of every step follows.

Set expectations honestly: healing apical periodontitis and eliminating symptoms is the primary goal, and added root length and thickness is the bonus REP uniquely offers. A tooth can succeed without dramatic growth, so never promise a longer root.

Key takeaways

• REP is for one tooth only: immature, open apex, and necrotic pulp. Miss any of the three and it's the wrong procedure.
• Barrier versus biology: apexification walls the tooth off; REP regrows a living root — thicker walls, more length, a closing apex.
• Everything protects SCAP: the stem cells near the open apex are why a dead tooth can regrow, and every step keeps them alive.

Learn the full protocol

The complete walkthrough lives in Dentalverse: the narrated video lesson, the step-by-step protocol with exact irrigation numbers, armamentarium, and the pitfalls that sink a case, plus a night-before prep sheet. Start with [the reference page](/explore/procedures/regenerative-endodontics-rep) for the structured overview, then [start free](/signup) to learn it the way you'll actually perform it.

This article is a study aid, not medical advice. Always follow your institution's protocols and current clinical guidelines.