Regenration Potential of the Young Permanent Tooth

Resident: Swan
Article Title: Regeneration Potential of the Young Permanent Tooth: What Does the Future Hold?
Authors: Hargreaves, M. et al. (Endodontists)
Journal: Pediatric Dentistry May/June 2008 V 30 No 3
Type of Article: Conference Paper
Main Purpose: Discuss the current therapies for necrotic teeth with incompletely developed roots, along with need for continued development of biologically-based treatments that offer potential for hard tissue regeneration.
Points of Discussion:

1. Discussion of the best current therapies (apexification with long-term CaOH or MTA) that achieve good clinical results

2. Discussion of recent case reports offering offering biologically based alternative treatments
Estbalished precepts:
-revascularization occurs more predictably in teeth with open apices
-Instrumentation with NaOCl irrigation is not sufficient to reliably create needed conditions for revascularization of necrotic tooth (antibiotic paste also necessary to clear infection)
-use of "3 mix-MP" triple antibiotic paste (Cipro, Metronidazole, minocycline) is effective for disinfection of necrotic tooth canal space, setting conditions for revascularization (deliver with Lentulo spiral)
-Placement of CaOH in canal prevents revascularization coronal to location of CaOH paste

3. Key features of published cases:

a. immature permanent with wide apical opening is conducive to tissue ingrowth
b. younger patients (8-13) have greater healing capacity or stem cell regenerative potential
c. no case used instrumentation of the root canal walls; all used NaOCl as an irrigant
d. CaOH paste and combinations of multiple antibiotics were used in these patients (many of the CaOH-treated patients displayed intracanal calcifications that appear to impede dentinal wall thickening
e. formation of a blood clot might serve as a protein scaffold, permitting ingrowth of tissue.
f. nearly every study reported continued thickening of dentinal walls and subsequent apical closure

Main Concepts of Tissue Engineering:

1. Cell source
-odontoblasts can come from dental pulp, apical papilla
-apical papilla=dental papilla at apex of developing tooth. It's loosely attached to the apex,
can be detached with tweezers. Has collateral circulation, unlike pulp, so possibly can
better survive necrosis.
-it's unclear where the root development described in the cases above comes from
-could be from residual vital pulp cells, cells from apical papilla that proliferated, or
bleeding-induced angiogenesis that recruited stem cells from the apical tissues.

2. Physical scaffold
-extracellular matrices needed to promote cell growth and differentiation
-Platelet Rich Plasma (PRP) may be the best available option

3. Signaling molecules
-EDTA effectively releases growth factors from human dentin

Assessment: Interesting article discussing the concept of dentin/pulp regeneration and what's on the horizon there. Me likey.