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Table of Contents
Year : 2014  |  Volume : 4  |  Issue : 2  |  Page : 89-92

Pulp regeneration using nanohydroxyapatite as scaffold in an immature central incisor: A 10-month follow-up

Department of Paedodontics and Preventive Dentistry, Manipal College of Dental Sciences, Manipal University, Mangalore, Karnataka, India

Date of Web Publication15-Oct-2014

Correspondence Address:
Arathi Rao
Department of Paedodontics and Preventive Dentistry, Manipal College of Dental Sciences, Manipal University, Mangalore, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2229-5194.142945

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Tissue engineering has emerged as the fastest new concept in endodontics especially in immature teeth. In the present case report, pulp regeneration technique was done on a nonvital immature central incisor using nanohydroxyapatite. The case was followed-up to 10 months, and the final result was a completely resolved resorption of both the root and adjacent bone and also with thickening of dentinal wall. Capping the blood clot with mineral trioxide aggregate have been recognized as the protocol for successful regeneration. However, the main concern is that the clot may tend to disintegrate thus weakening the scaffold. Nanohydroxyapatite helped to support the clot and thus prevented it from collapse. Nanohydroxyapatite also underwent almost complete dissolution by the end of 10 months.
Clinical Relevance To Interdisciplinary Dentistry

  • Pulp regeneration is one of the latest techniques that have provided excellent success in an immature nonvital tooth.
  • One of the reasons for failure of this technique is the disintegration and collapse of the clot that is formed.
  • Scaffolds are used to support the clot and in the present technique, nanohydroxyapatite is used.
  • Nanohydroxyapatite also underwent almost complete dissolution by the end of 10 months.

Keywords: Immature tooth, nanohydroxyapatite, pulp regeneration

How to cite this article:
Swarup S, Rao A, Suprabha B S. Pulp regeneration using nanohydroxyapatite as scaffold in an immature central incisor: A 10-month follow-up. J Interdiscip Dentistry 2014;4:89-92

How to cite this URL:
Swarup S, Rao A, Suprabha B S. Pulp regeneration using nanohydroxyapatite as scaffold in an immature central incisor: A 10-month follow-up. J Interdiscip Dentistry [serial online] 2014 [cited 2023 Mar 27];4:89-92. Available from: https://www.jidonline.com/text.asp?2014/4/2/89/142945

   Introduction Top

Ayoung permanent tooth with a necrotic root canal system, presenting with periapical pathology and an immature root possess a challenge and is spiked with difficulties. Recent treatment strategies include one-step creation of an artificial apical barrier by using mineral trioxide aggregate (MTA) with or without an apical matrix followed by compaction of obturating material and placement of a coronal restoration. MTA has been shown to produce good sealing effects under these conditions. However, this procedure might not result incomplete root formation and might not completely reduce the chances for root fracture. [1]

Contemporary concept of medicine places much emphasizes on prevention and reversal of the diseases. This has led to the emergence of innovative and interesting field, the regenerative endodontics which is the zenith of two major disciplines; stem cell biology and tissue engineering. Regeneration is a biologically based treatment regimen that offers the potential for continued hard tissue formation in young permanent tooth with a necrotic pulp and an incompletely developed root. [2]

Numerous case reports have been published describing regenerative endodontic procedures applied to cases of necrotic immature permanent

teeth. Hargreaves et al.[3] have identified three components contributing to the success of this procedure. They include stem cells that are capable of hard tissue formation, signaling molecules for cellular stimulation, proliferation, and differentiation, and finally, a three-dimensional physical scaffold that can support cell growth and differentiation.

It would be appropriate to consider the material that could act as a scaffold and compensate for the loss of the fibrin scaffold if it occurs. The present case report is an attempt where nanohydroxyapatite has been used as scaffold aiding pulp dentin regeneration in an immature necrosed permanent central incisor.

   Case report Top

A 9-year-old boy visited our department with the chief complaint of swelling on the gingiva in the right maxillary central incisor with no pain or discomfort. The patient was accompanied by his mother who reported that the patient had a fall 1 year back. It was accompanied with dull pain, which had lasted for a few days and had subsided on medication. Previous records confirmed that the patient had Class II Ellis and Davey fracture and was restored with composite resin. Intraoral examination revealed the presence of an abscess located distal to the root of right maxillary central incisor [Figure 1]a and b]. The tooth did not respond to cold testing, and the periodontal probing and mobility were within the normal limits. The adjacent teeth were caries free, asymptomatic, and tested vital. Radiographic evaluation of the right maxillary central incisor revealed immature open apex and periapical radiolucency. An initial external resorption was also seen on the root surface at the distal surface. Based on the history offered by a parent, clinical and radiographic evaluation a diagnosis of pulpal necrosis with suppurative chronic periapical abscess was made. The medical history of the patient was noncontributory. Extraoral examination did not reveal any abnormalities. The root resorption present was a concern, but it was decided that this would not bring the prognosis down as the tooth was immature, and it was decided to proceed with the pulp regeneration technique.
Figure 1: (a) Maxillary right central incisor associated with periapical abscess. (b) Intraoral periapical showing periapical radiolucency in relation to maxillary right central incisor. Arrow - External resorption on the distal aspect

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The management of the tooth was done with the following principles in mind: [4]

  1. Minimal or no instrumentation
  2. Irrigation with 5.25% NaOCl
  3. Intracanal medication with antimicrobial agents consisting of equal parts of metronidazole, minocycline and ciprofloxacin in a paste form at the concentration of 20 mg/ml.

In addition, we decided to use nanohydroxyapatite, which will act as a scaffold for stem cell migration.

Access opening was done followed by irrigation up to one-third of its length with 10 ml of 5.25% sodium hypochlorite. No instrumentation of the canal was done. Triple antibiotic paste containing equal proportions of ciprofloxacin, metronidazole, and minocycline in a paste form mixed with propylene glycol at a concentration of 20 mg/ml was placed on the coronal third of the canal for disinfection. The cavity was sealed with glass ionomer cement.

The patient reported 2 weeks later without any symptoms. Complete healing of the sinus tract was noticed. The tooth was nontender to percussion. Periodontal probing and mobility were within normal limits, but discoloration of the crown was seen. Triple antibiotic paste was renewed, and restoration was done with glass ionomer cement. Two weeks (4 th week) later the triple antibiotic paste was removed, and irrigation using 10 ml of saline and

5.25% sodium hypochlorite solution was done. Instrumentation was done beyond the apex to induce bleeding. Blood clot was allowed to fill the canal till the level of the cementoenamel junction. The blood clot was then capped with bioresorbable nanohydroxyapatite mixed with saline (Orthogran, TopNotch, Aluva, Kerala) [Figure 2]. The tooth was then restored with glass ionomer cement.
Figure 2: Nanohydroxyapatite seen as radiopaque in the coronal region

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Two months later, the radiographic evaluation revealed healing of periapical radiolucency and external resorption. Progressive resorption of the material was observed [Figure 3]a-c]. At the end of 6 months, it was noticed that there was complete resolution of the periapical pathology with thickening of the dentinal walls and elongation of the root. The tooth was sensitive (positive response) to cold testing at the end of 8 months and was asymptomatic. Radiographic evaluation revealed complete resolution of the external resorption with the continuity of the lamina dura being re-established. Thickening of the dentinal walls can be better appreciated with commencement of root closure. The almost complete resorption of the material can also be seen. An esthetic veneering is planned for the patient at a later stage to mask the discoloration.
Figure 3: (a) At the end of 6 months, adequate resolution of the periapical and radiolucency and external resorption seen. Nanohydroxyapatite material is also seen resorbing. (b) Intraoral periapical (IOPA) at the end of 8 months with complete resolution of the periapical radiolucency. (c) IOPA at the end of 10 months. Thickening of the dentinal walls can be seen and almost complete resorption of the nanohydroxyapatite material. There is also complete healing of the external resorption

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   Discussion Top

Regeneration of necrotic pulp in an immature root is based on the concept that vital stem cells located in the apical papilla survive pulpal necrosis even in the presence of periradicular infection. [5]

The present case report emphasizes the possibility of regeneration of pulp-dentin complex in necrotic root canals that caused continued hard tissue deposition, lengthening of the root, and closure of the apex using nanohydroxyapatite as scaffold.

In general, stem cells are defined by having two major properties: (1) They are capable of self-renewal and

(2) when they divide, some daughter cells give rise to cells that eventually become differentiated cells. Dental stem cells belong to the multipotent category of stem cells that are capable of giving rise to multiple lineage of cells. [6]

Iwaya et al. [7] suggested that the open apex provide a good communication from pulp space to the periapical tissues, therefore in spite of periapical disease the pulp may be only partially necrotic and infected.

Until date, four types of human dental stem cells have been isolated and characterized: [2],[8],[9],[10],[11]

  • Dental pulp stem cells (DPSCs)
  • Stem cells from exfoliated deciduous teeth (SHED)
  • Stem cells from apical papilla (SCAP)
  • Periodontal ligament stem cells (PDLSCs).

Dental pulp stem cells and SHED are from the pulp and SCAP is from the pulp precursor tissue, the apical papilla. These cells can differentiate into odontoblast-like cells and produce dentin-like tissue in both in vitro and vivo study systems. SCAP together with PDLSCs are able to form a root-like structure when seeded onto the hydroxyapatite-based scaffold. These dental stem cells may thus potentially be utilized for dental tissue regeneration, that is, pulp/dentin and periodontal ligament. It is observed that SCAP may survive the infection to allow root maturation while the survived DPSCs in the remaining vital pulp rebuild the lost pulp tissue in the canal and may give rise to replacement odontoblasts to substitute for the damaged primary odontoblasts. Although radiographic evidence of hard tissue deposition was noticed, it has been theorized that this hard tissue could be due to the ingrowth of dentin, cementum, or bone. [8],[9]

Young et al. [12] generated mineralized tooth-like structures by seeding porcine tooth bud cells on poly (L-lactide-co-glycolide) scaffolds. Although the resulting structures did not conform to the shape of the implanted scaffolds, this example demonstrated that the fabrication of engineered biological tissues may be possible.

Complete disinfection of the canal space using triple antibiotic paste, formation of a blood clot inside the canal space by inducing bleeding from the apex and capping the blood clot with MTA have been recognized as the protocol for successful regeneration. The concern about the fibrin scaffold is that the erythrocytes would undergo necrosis shortly after clot formation and thereby leading to degeneration of the scaffold. [3]

Pulp tissues are three-dimensional structures, and an appropriate scaffold is needed to promote cell growth and differentiation. It is known that extracellular matrix molecules control the differentiation of stem cells contain growth factors and undergo biodegradation over time. Thus, a scaffold is far more than a simple lattice to contain cells. [13]

Hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 ) is the major mineral component of bone and enamel. It is used as a scaffold to manage bone defect problems, by aiding to seed the cells and serve as a template for tissue regeneration. [14],[15] It is a porous material that allows cells to migrate through the pores, provides good conditions for nutrient transport, tissue infiltration and ultimately, vascularization. Nanohydroxyapatite was tried in this case as the nanocrystals exhibit high levels of biomimetic properties due to their composition, structure, morphology, bulk, and surface physical-chemical properties. It also resorbs after certain time of residence in the body, demonstrating its biocompatibility as demonstrated in the present report. [16],[17],[18],[19]

In the present case, there was a complete resolution of the periapical radiolucency and external resorption. Capping the blood clot with MTA have been recognized as the protocol for successful regeneration. The concern about the clot undergoing disintegration leading to the degeneration of the scaffold is minimized with the use of nanohydroxyapatite. Nanohydroxyapatite helped to support the clot and thus prevented it from collapse, thereby acting like a perfect scaffold. Nanohydroxyapatite also underwent almost complete dissolution by the end of 10 months.

   References Top

1.Hachmeister DR, Schindler WG, Walker WA 3 rd , Thomas DD. The sealing ability and retention characteristics of mineral trioxide aggregate in a model of apexification. J Endod 2002;28:386-90.  Back to cited text no. 1
2.Chueh LH, Huang GT. Immature teeth with periradicular periodontitis or abscess undergoing apexogenesis: A paradigm shift. J Endod 2006;32:1205-13.  Back to cited text no. 2
3.Hargreaves KM, Giesler T, Henry M, Wang Y. Regeneration potential of the young permanent tooth: What does the future hold? J Endod 2008;34 7 Suppl: S51-6.  Back to cited text no. 3
4.Huang GT. A paradigm shift in endodontic management of immature teeth: Conservation of stem cells for regeneration. J Dent 2008;36:379-86.  Back to cited text no. 4
5.Thibodeau B, Trope M. Pulp revascularization of a necrotic infected immature permanent tooth: Case report and review of the literature. Pediatr Dent 2007;29:47-50.  Back to cited text no. 5
6.Robey PG, Bianco P. The use of adult stem cells in rebuilding the human face. J Am Dent Assoc 2006;137:961-72.  Back to cited text no. 6
7.Iwaya SI, Ikawa M, Kubota M. Revascularization of an immature permanent tooth with apical periodontitis and sinus tract. Dent Traumatol 2001;17:185-7.  Back to cited text no. 7
8.Gronthos S, Mankani M, Brahim J, Robey PG, Shi S. Postnatal human dental pulp Stem cells (DPSCs) in vitro and in vivo. Proc Natl Acad Sci U S A 2000;97:13625-30.  Back to cited text no. 8
9.Miura M, Gronthos S, Zhao M, Lu B, Fisher LW, Robey PG, et al. SHED: Stem cells from human exfoliated deciduous teeth. Proc Natl Acad Sci U S A 2003;100:5807-12.  Back to cited text no. 9
10.Seo BM, Miura M, Gronthos S, Bartold PM, Batouli S, Brahim J, et al. Investigation of multipotent postnatal stem cells from human periodontal ligament. Lancet 2004;364:149-55.  Back to cited text no. 10
11.Nakashima M, Akamine A. The application of tissue engineering to regeneration of pulp and dentin in endodontics. J Endod 2005;31:711-8.  Back to cited text no. 11
12.Young CS, Terada S, Vacanti JP, Honda M, Bartlett JD, Yelick PC. Tissue engineering of complex tooth structures on biodegradable polymer scaffolds. J Dent Res 2002;81:695-700.  Back to cited text no. 12
13.Bi Y, Ehirchiou D, Kilts TM, Inkson CA, Embree MC, Sonoyama W, et al. Identification of tendon stem/progenitor cells and the role of the extracellular matrix in their niche. Nat Med 2007;13:1219-27.  Back to cited text no. 13
14.Galler KM, D'Souza RN, Hartgerink JD, Schmalz G. Scaffolds for dental pulp tissue engineering. Adv Dent Res 2011;23:333-9.  Back to cited text no. 14
15.Zhang R, Ma PX. Poly (alpha-hydroxyl acids)/hydroxyapatite porous composites for bone-tissue engineering. I. Preparation and morphology. J Biomed Mater Res 1999;44:446-55.  Back to cited text no. 15
16.Karageorgiou V, Kaplan D. Porosity of 3D biomaterial scaffolds and osteogenesis. Biomaterials 2005;26:5474-91.  Back to cited text no. 16
17.Heise U, Osborn JF, Duwe F. Hydroxyapatite ceramic as a bone substitute. Int Orthop 1990;14:329-38.  Back to cited text no. 17
18.Kuboki Y, Takita H, Kobayashi D, Tsuruga E, Inoue M, Murata M, et al. BMP-induced osteogenesis on the surface of hydroxyapatite with geometrically feasible and nonfeasible structures: Topology of osteogenesis. J Biomed Mater Res 1998;39:190-9.  Back to cited text no. 18
19.Li L, Pan H, Tao J, Xu X, Mao C, Gub X, et al. Repair of enamel by using hydroxyapatite nanoparticles as the building blocks. J Mater Chem 2008;18:4079-84.  Back to cited text no. 19


  [Figure 1], [Figure 2], [Figure 3]

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