By Aaron Welk, D.M.D.
One of the challenges in endodontics is the treatment and management of an immature tooth with a necrotic pulp. Traditional treatment approaches include creation of a hard barrier which root canal filling material can be obturated against. This root end closure procedure is called apexification. Calcium hydroxide apexification is a procedure that allows for the induction of a hard tissue barrier apically . One of the disadvantages of this approach is it can take a many months for the barrier to form.
The introduction of Mineral Trioxide Aggregate (MTA) in the 1990’s allowed for a similar approach  to creating apical barriers in a timelier manner . With MTA apexification, an immediate barrier could be placed. Both calcium hydroxide and mineral trioxide aggregate have been proven clinically, but with the absence of continued root development, both techniques leave the roots with thin dentin walls and short overall root length, leaving the tooth more susceptible to failure due to root fracture .
Regenerative endodontics is a contemporary approach to addressing this problem. This procedure uses tissue engineering principles in facilitating the continued growth and development of the pulp-dentin complex. In other words, when you have a case with an immature apex and necrotic pulp, regenerative endodontics allows for continued root development, thicker dentin walls, longer root length, and a closed apex, thus reducing the risk of fracture during tooth function.
Success is dependent on the activity of a newly identified population of stem cells, the so-called stem cells from apical papilla (SCAP) (Fig. 23-38) , a hidden treasure with enormous potential for tissue regeneration and bioroot engineering .
All immature teeth with open apices may be considered candidates for regenerative treatment, even if they have obvious pulp-space infection, a discharging sinus, or have been previously root canal treated .
Bioengineering has a tremendous potential in dentistry. Researchers continue to optimize scaffolds that may encourage revascularization of the pulp space, and to explore the options of seeding cell populations into the properly sterilized pulp spaces of immature teeth . Dentistry’s call for action has never been louder as we seek effective, biologically based treatments for our pediatric patients. If you have questions about pulp regenerative procedures, I encourage you to contact your local endodontist to discuss this topic.
The pulp regeneration procedure is as follows :
- Tooth with necrotic pulp and an immature apex
- Pulp space not needed for post/core, final restoration
- Compliant patient
- Two (or more) appointments
- Use of antimicrobial(s)
- Possible adverse effects: staining of crown/root, lack of response to treatment, pain/infection
- Alternatives: MTA apexification, no treatment, extraction (when deemed nonsalvageable)
- Permission to enter information into AAE database (optional)
- Local anesthesia, rubber dam isolation, access
- Copious, gentle irrigation with 20ml NaOCl using an irrigation system that minimizes the possibility of extrusion of irrigants into the periapical space (e.g., needle with closed end and side-vents, or EndoVac). To minimize potential precipitate in the canal, use sterile water or saline between NaOCl. Lower concentrations of NaOCl are advised, to minimize cytotoxicity to stem cells in the apical tissues
- Dry canals
- Place antibiotic paste or calcium hydroxide. If the triple antibiotic paste is used: 1) consider sealing pulp chamber with a dentin bonding agent [to minimize risk of staining] and 2) mix 1:1:1 ciprofloxacin:metronidazole:minocycline
- Deliver into canal system via Lentulo spiral, MAP system or Centrix syringe
- If triple antibiotic paste is used, ensure that it remains below CEJ (minimize crown staining)
- Seal with 3-4mm Cavit, followed by IRM, glass ionomer cement or another temporary material
- Dismiss patient for 3-4 weeks
- Assess response to initial treatment. If there are signs/symptoms of persistent infection, consider additional treatment time with antimicrobial or alternative antimicrobial.
- Anesthesia with 3% mepivacaine without vasoconstrictor, rubber dam, isolation
- Copious, gentle irrigation with 20ml EDTA, followed by normal saline, using a similar closed-end needle.
- Dry with paper points
- Create bleeding into canal system by over-instrumenting (endo file, endo explorer)
- Stop bleeding 3mm from CEJ
- Place CollaPlug/Collacote at the orifice, if necessary
- Place 3-4mm white MTA and reinforced glass ionomer and place permanent restoration
Clinical and Radiographic exam:
- No pain or soft tissue swelling (often observed between first and second appointments
- Resolution of apical radiolucency (often observed 6-12 months after treatments
- Increased width of root walls (this is generally observed before apparent increase in root length and often occurs 12-24 months after treatments
- Increased root length
Dr. Welk is a 1998 graduate of the OHSU School of Dentistry. He received his specialty certificate in endodontics in 2002 from OHSU. Dr. Welk is a Diplomate of the American Board of Endodontics. He is past-president of the Oregon State Association of Endodontics, past-president of the Clackamas County Dental Society, and currently serves on the board of trustees for the Oregon Dental Association. He maintains a private practice in West Linn, Oregon.
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