Dental Pulp Regenration: Current Knowledge And Future Directions

INTRODUCTION

Dental pulp regeneration is a unique sort of tissue engineering to restore the tooth structure by biologic means. Regenerative endodontics is one of the most exciting researches to rejuvenate the human cells in order to restore and establish normal functions in immature permanent teeth with pulpal necrosis. Researchers are at the forefront of this research to explore the more unexplored pages of nature. Our knowledge in the fields of regenerative endodontic treatment to the necrotic immature permanent teeth optimally results in continued root development, increased thickness in the dentinal walls, apical closure and complete restoration of pulpal functions.

The regenerative endodontics is the golden future of dentistry and this concept gives a hope of converting the non- vital tooth into vital once again. The American association of endodontics, glossary of endodontic terms 2012 has defined regenerative endodontics as “Biologically based procedures designed to replace damaged structures, including dentin and root structures, as well as cells of the pulp-dentin complex’’.

BRIEF HISTORY

In 1932,G.L. Fledman proposed the biological aseptic principle of tooth therapy, regeneration of pulp and used dentine fillings for stimulating pulp regeneration. In 1961, Nygard Ostby conceptualized the concept of regeneration endodontics through pulp. In 2001, Iwaya described a procedure revascularization for continued root development. In 2004, Banchs and trope proposed revascularization of infected immature teeth.

CURRENT APPREHENSION

Out of various regeneration approaches like root canal vascularization, stem cell therapy, pulp implant, scaffold implant 3D printing, injectable scaffolds and gene therapy, the clinically feasible approach of pulp regeneration is only available.¹  The American dental association current dental terminology (ADA CDT) recognized pulp regeneration procedure and coded it as follows:-

ADA CDT Codes for pulpal regeneration procedures

First phase of treatment:-

D3351- debridement and placement of antibacterial medication

Interim phase (repeat of medication replacement):-

D3352- interim medication replacement

Final Phase:-

D3354 –pulpal regeneration – (completion of regenerative treatment in an immature permanent tooth with necrotic pulp); does not include final restoration.

ADA Guidelines for follow up evaluation–

–Tooth should be asymptomatic and functional

-Radiographic evaluation:

6-12 months- resolution of periapical radiolucency

-may see increased wall thickness

12-24 months- increased dentinal wall thickness

– increased root length

The majority of current case reports have shown prospective clinical outcomes with absence of clinical signs and symptoms, radiographic evidence of resolution of periapical radiolucency, continued root development and increased canal wall thickness. The substantial benefit of this biological tissue engineering over other restorative procedures is, the reparative matrices becomes an integral part of the tooth and strengthens the root walls of restored tooth.

Based on the ADA guidelines, a huge number of successful cases have been reported. Torabinejad and Faras has reported the histological report showing the pulp –like vital connective tissue from tooth after regenerative endodontic treatment². Positive responses to cold and electric pulp tests have been reported in some cases.

CALL INTO QUESTION

Can intracanal antibiotics be substituted??

Bachs and Trope has reported the triple antibiotic paste to be cytotoxic to stem cells at clinically recommended concentrations³. Also an additional appointment may be required because of the vehicle of triple antibiotic paste(propylene glycol) may be difficult to remove from the dentin surface. The aim of antibiotics is to sterile the root canal for regeneration of healthy pulp. The use of EndoVac apical negative –pressure system can be used to safely deliver the irrigating agents to the full extent of root canal terminus and remove the organic tissue and microbial content effectively.

Discolouration and Permanent staining

The presence of minocycline can cause severe discolourations and permanent staining. The substitution of minocycline from triple antibiotic paste by cefaclor or clarithromycin can be an answer. Additionally presence of MTA (grey and white) might be another source of discolouration which can be substituted by calcium enriched mixture (CEM) over the blood clot.

Unpredictable outcomes

Noosrat et al reported a case report where root maturation occurred but root canals were found empty.⁴ In other reports cementum- like hard tissue was deposited on root canal walls, and bony islands were found in the entire root canals.⁵These reports put a question mark on the positive predictability of the regenerative protocol.

FUTURE OUTLOOK

The advances in the biomedical engineering have made the achievement impossible to an achievable dream. Regenerative endodontic have potential to be an effective and safe mode of saving structural integrity of an immature non vital permanent tooth. Based on the current scenario the researchers all around the world are working

on the next level advancements. Soon the dentists will be able to deliver these regenerative therapies as a part of their routine dental treatments. These developments in regeneration of a functional dentin-pulp complex will have a promising impact in retaining the natural dentition and reaching the ultimate goal of healthy oral cavity.

REFERENCES

1. Murray PE, Garcia-Godoy F, Hargreaves KM. Regenrative endodontica: Areview of current status and a call for action. J Endod 2007;33:377-90.
2. Torabinejad M,Faras H. A clinical and histological report of a tooth with an open apex treated with regenerative endodontics using platelet- rich plasma. J Endod 2012 2012; 38:864-8.
3. Bachs F, Trope M. Revascularization of immature permanent teeth with apical periodontitis: new treatment protocol? J Endod 2004;30:196-200.
4. Nosrat A, li K L, Vir K, Hicks M L, Fouad AF. Is pulp regeneration necessary for root maturation? J Endod 2013;39:1291-5.

Yamauchi N, Nagaoka H, Yamauchi S, Teixira F B, Miguez P, Yamauchi M. Immunohistological characterization of newly formed tissues after regenerative procedure in immature dog teeth. J Endod 2011;37:1636-41

Dr Sarita Bhandari

(Dental Postgraduate Student)