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Year : 2013  |  Volume : 2  |  Issue : 4  |  Page : 235-238

Root canal revascularization via blood clotting in regenerative endodontics: Essentials and expectations

1 Department of Conservative Dentistry and Endodontics, St. Joseph's Dental College, Duggirala, Eluru, India
2 Department of Pedodontics and Preventive Dentistry, Drs. Sudha and Nageswara Rao Siddhartha Institute of Dental Sciences, Chinnaoutpalli, Gannavaram, Andhra Pradesh, India

Date of Web Publication26-Nov-2013

Correspondence Address:
Ravichandra Sekhar Kotha
Department of Pedodontics and Preventive Dentistry, Drs. Sudha and Nageswara Rao Siddartha Institute of Dental Sciences, Chinaoutpalli, Gannavaram - 521 286, Andhra Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2277-8632.122156

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Regenerating lost pulp tissue as a result of trauma or disease is very interesting and an exciting concept and revascularization via blood clotting is considered to be a feasible and practical approach in this direction. This method has been practiced since long with promising results reported by studies but so far consensus on treatment protocols as well as the nature of tissues formed inside the root canal space is lacking. The objective of this review is to appraise root canal revascularization via blood clotting procedures strived in endodontic practice and the contemporary recommendations for their successful outcome.

Keywords: Endodontics, regeneration, revascularization

How to cite this article:
Vemuri S, Kotha RS, Raghunath RG, Kandregula CR. Root canal revascularization via blood clotting in regenerative endodontics: Essentials and expectations. J NTR Univ Health Sci 2013;2:235-8

How to cite this URL:
Vemuri S, Kotha RS, Raghunath RG, Kandregula CR. Root canal revascularization via blood clotting in regenerative endodontics: Essentials and expectations. J NTR Univ Health Sci [serial online] 2013 [cited 2022 Nov 29];2:235-8. Available from: https://www.jdrntruhs.org/text.asp?2013/2/4/235/122156

  Introduction Top

Lack of homogeneity on treatment protocols and most of the materials or procedures under experimental stages has made regeneration of injured or lost tissues and organs still a riddle in modern medicine. The origin of biologically compatible regenerative endodontic procedures that allow revival of damaged dentin and root structures including the cells of pulp-dentin complex dates back to around 1952, when Dr. B. W. Hermann first reported the application of Ca(OH) 2 in vital pulp amputation. [1] Many materials like platelet-rich plasma (PRP), Emdogain, recombinant human bone morphogenic protein (rhBMP), fibroblast growth factor 2 (FGF2), as well as procedures like guided-tissue or guided-bone regeneration (GTR, GBR) and distraction osteogenesis have been tried since then to regenerate various dental tissues. [2],[3],[4],[5],[6] Off late, the focus of research in regenerative endodontics is on using a combination of stem cells, scaffolds, growth factors engaged in tissue engineering and the future looks promising. [7] However, none of these procedures could be actually transformed into realistic endodontic practice with predictable success rates.

Though root canal revascularization via blood clotting has become a new norm in regenerative endodontic practice with successful clinical results reported, conventional techniques like partial pulpotomy, apexification, and apexogenesis are not yet obsolete. [8] The notion that root canal revascularization as one stop solution to regenerate compromised pulp tissue is a misnomer due to lack of long-term follow-up studies and consensus on treatment protocols. This contemplates the difficulty in standardizing the procedure and further debate is warranted. This paper attempts to demystify various hypotheses, misconceptions, as well as the clinico-histological outcomes achieved so far.

  Root Canal Revascularization Via Blood Clotting Top

Conventionally, revascularization is believed to be achievable only for the root canal space of an avulsed, reimplanted tooth. [9],[10],[11],[12] However, studies prove that the same can be achieved for an immature or mature permanent tooth with periapical periodontitis or abscess by means of thoroughly disinfecting the canal followed by inducing bleeding and establishing blood clot into the root canal system via over-instrumentation supplemented by a good coronal seal. [13],[14],[15],[16] Theoretically, it was presumed that the formation of a blood clot in the sterile root canal system creates a scaffold of fibrin that entraps stem cells capable of initiating new tissue development. [7]

Revascularization of avulsed teeth

Most of the case reports demonstrated successful revascularization of the pulp space after reimplantation of avulsed teeth with immature apices. [9],[10],[11],[12] Vital apical portion of the pulp that grow coronally to replace the necrotic tissue and intact crown of the tooth which offers a good seal against bacterial permeability are the reasons implied for the same. [16] Also, the short roots and open apices create an unique environment for the ingrowth of new tissues into the root canal space. [9],[10],[11],[12]

Revascularization in infected immature teeth

Revascularization of the pulp space in infected immature teeth with apical periodontitis is impossible unless the canals are disinfected. From this, it can be interpreted that disinfection of the canals is a critical step for the success of revascularization. [13],[14],[15] Much emphasis is laid on disinfection with intracanal irrigants like sodium hypochlorite or chlorhexidine as the thin dentinal walls preclude successful biomechanical preparation as well as to protect the viability of the cells of dental pulp stem cells. [17],[18],[19],[20],[21] This is usually followed by a pack of tri-antibiotic paste (a mixture of ciprofloxacin, metronidazole, and minocycline paste) or Ca(OH) 2 for several weeks to further sterilize the canal. [18],[22],[23],[24],[25] Discoloration of the dentin had been reported with minocycline containing mixture and either cefaclor can be substituted for it or it can be left out of the combination. [26] Maintaining good coronal seal is one more imperative aspect for the success of the procedure and most of the studies sealed Mineral Trioxide Aggregate (MTA) over blood clot followed by a composite restoration. [15],[27],[28] However, at least one study had used calcium-enriched mixture (CEM) cement placed over blood clot with good results. [19]

Revascularization in infected mature teeth

Necrotic pulps with closed apices require over-instrumentation since it was demonstrated that apical diameters of 1.1 mm have greater likelihood of revascularization. [29] This is necessary to promote adequate nutrient diffusion and oxygen supply for the initial viability of the cells, as the cells that are more than 200 μm away from the point of maximum oxygen diffusion are prone for anoxia and necrosis. [30]

  Factors Influencing Revascularization Top

The type of tooth injury, fracture type, presence of necrosis or infection, periodontal status, presence of periapical lesions, stage of tooth development, vitality status, patient age, and patient health status are some of the factors influencing revascularization. [8] Thorough disinfective protocol and good quality coronal seal also influence revascularization. [13],[14],[15],[27],[28] In addition, it is the blood clot irrespective of scaffold that is very important for revascularization. [31] Some clinicians have recommended the use of an anesthetic without a vasoconstrictor when trying to induce bleeding. [28] Also, young patients have shown considerable degree of success rates when compared with older since the number of circulating stem cell concentrations in older patients might be lower. [32]

  Merits of Revascularization Top

Root canal revascularization via blood clotting is a relatively simple and practical approach which can be accomplished with presently available instruments and materials. Moreover, the possibility of immune rejection and contamination can be averted since the root canal system is filled with patient's own blood cells. [7] Case reports have revealed progressive thickening of dentinal walls, continued root development, and positive response to thermal pulp testing. [15] A 24-month follow-up comparative study between revascularization induced maturogenesis and conventional apexification found the former to be advantageous. [33]

  Drawbacks of Revascularization Top

The reliance on patient's compliance to carry out the procedure in multiple visits and the lack of long term follow-up studies makes revascularization procedure a supplement but not a substitute to the already existing treatment protocols like apexogenesis, apexification, or partial pulpotomy. [8] Also, the concentration and composition of the progenitor/stem cells entrapped in the fibrin clot is unpredictable, particularly in older patients and may lead to disparity in the results. [32]

  Histological Aspects of Revascularized Tissue Top

A successful regenerative endodontic procedure must restore the damaged coronal, cervical or apical dentin and resorbed root, in addition to the rejuvenation of pulp-like tissue; ideally, the pulp-dentin complex. Hertwig's epithelial root sheath (HERS) cells signal the progenitor or stem cells of the periodontal ligament and apical papilla to differentiate into cementoblast and root primary odontoblasts cells that contribute to cementum-like tissue and root dentine respectively. [34],[35] The survival of cells of HERS and apical papilla in apical periodontitis or abscess is vital to produce cementum-like tissue and root development after revascularization procedure. [36]

It was speculated that pulp tissue regeneration might occur after revascularization procedure but there was no convincing histologic evidence indicating true pulp regeneration. [37] Several animal studies have described the tissue in the canal space as cementoid or osteoid and periodontal ligament-like fibrous connective tissue. It has been hypothesized that the periodontal ligament tissue ingresses into the root canal space and might deposit cementum on the canal walls. [31] On the other hand, one study revealed that there was about 30% possibility of the pulp tissue entering the pulp space instead of the periodontal tissue. [11] However, human studies are not available till date so as to understand the exact nature of the hard tissue formation and root development.

  Conclusions Top

Based on the present studies, it is reasonable to conclude that revascularization is a reparative process rather than regenerative process. Further studies are warranted to substantiate the regenerative potential of the revascularization process inside the root canal space. As the exact nature of the tissue formed inside the pulp canal in humans is not completely understood, it is better to consider revascularization therapy only when other conventional modalities of treatment like apexification, apexogenesis, and partial pulpotomy fail.

  References Top

1.Hermann BW. On the reaction of the dental pulp to vital amputation and calxyl capping. Dtsch Zahnarztl Z 1952;7:1446-7.  Back to cited text no. 1
2.Kassolis JD, Rosen PS, Reynolds MA. Alveolar ridge and sinus augmentation utilizing platelet-rich plasma in combination with freeze-dried bone allograft: Case series. J Periodontol 2000;71:1654-61.  Back to cited text no. 2
3.Heijl L, Heden G, Svärdström G, Ostgren A. Enamel matrix derivative (EMDOGAIN) in the treatment of intrabony periodontal defects. J Clin Periodontol 1997;24:705-14.  Back to cited text no. 3
4.Fujimura K, Bessho K, Kusumoto K, Ogawa Y, Iizuka T. Experimental studies on bone inducing activity of composites of atelopeptide type I collagen as a carrier for ectopic osteoinduction by rhBMP-2. Biochem Biophys Res Commun 1995;208:316-22.  Back to cited text no. 4
5.Takayama S, Murakami S, Shimabukuro Y, Kitamura M, Okada H. Periodontal regeneration by FGF-2 (bFGF) in primate models. J Dent Res 2001;80:2075-9.  Back to cited text no. 5
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8.Garcia-Godoy F, Murray PE. Recommendations for using regenerative endodontic procedures in permanent immature traumatized teeth. Dent Traumatol 2012;28:33-41.  Back to cited text no. 8
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10.Barrett AP, Reade PC. Revascularization of mouse tooth isografts and allografts using autoradiography and carbon-perfusion. Arch Oral Biol 1981;26:541-5.  Back to cited text no. 10
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23.Hoshino E, Kurihara-Ando N, Sato I, Uematsu H, Sato M, Kota K, et al. In-vitro antibacterial susceptibility of bacteria taken from infected root dentine to a mixture of ciprofloxacin, metronidazole and minocycline. Int Endod J 1996;29:125-30.  Back to cited text no. 23
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31.Thibodeau B, Teixeira F, Yamauchi M, Caplan DJ, Trope M. Pulp revascularization of immature dog teeth with apical periodontitis. J Endod 2007;33:680-9.  Back to cited text no. 31
32.Amler MH. The age factor in human extraction wound healing. J Oral Surg 1977;35:193-7.  Back to cited text no. 32
33.Aggarwal V, Miglani S, Singla M. Conventional apexification and revascularization induced maturogenesis of two non-vital, immature teeth in same patient: 24 months follow up of a case. J Conserv Dent 2012;15:68-72.  Back to cited text no. 33
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37.Friedlander LT, Cullinan MP, Love RM. Dental stem cells and their potential role in apexogenesis and apexification. Int Endod J 2009;42:955-62.  Back to cited text no. 37

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