Pulp revascularization of immature maxillary first premolar.

An immature maxillary first premolar in an 8-year-old female was treated using a regenerative approach. The root canal was gently irrigated with 5.25% sodium hypochlorite without instrumentation under aseptic conditions and then medicated with calcium hydroxide (Ca[OH]2) for 3 weeks. The Ca(OH)2 was removed, and bleeding was initiated mechanically using a hand file to form an intracanal blood clot. Mineral trioxide aggregate was placed over the blood clot, and the access cavity was sealed with a double filling. Increases in root length and width were radiographically evident, at the 6-month follow-up exam. The case was followed for 3 years. The development of 3 roots with complete apical closure was confirmed using cone beam computed tomography.

INTRODUCTION

Conventional root canal treatment of necrotic pulp in immature teeth is challenging clinically due to incomplete root development.[1] Several methods have been used to manage the open apex of immature teeth, including apexification with calcium hydroxide (Ca[OH]2) or mineral trioxide aggregate (MTA).[2345] Although this technique induces successful apical closure with healing of the apical pathosis, the root length and thickness do not usually increase. In addition, the likelihood of root fracture may be increased.[67]

As an alternative to traditional methods, the use of a regenerative endodontic procedure has been advocated as it may reinforce the root dentinal walls through the deposition of hard tissue and promote the development of a normal apical morphology.[8910] Regenerative endodontic (revascularization/pulpal regeneration) treatment has been recently recognized by the American Association of Endodontics (AAE) as a legitimate endodontic procedure[11] and may be employed for the treatment of infected root canals in immature teeth. As defined by the AAE, this procedure is designed to physiologically replace damaged tooth structures, including dentin and dentin and root structures, as well as cells of the pulp-dentin complex. If performed properly, this treatment results in the re-establishment of biological function which is unrelated to complete regeneration of damaged tissue.[12]

Complete pulp tissue regeneration is unlikely in immature necrotic teeth when periapical tissues are infected, but removal of the infected tissue by a decontamination process may create a favorable environment for undifferentiated periodontal cells within the invagination to repair damaged tissue.[1314] The difference between root canal revascularization and endodontic regeneration of necrotic immature teeth which are accompanied by periapical pathosis is the best described by Garcia-Godoy and Murray:[14] While the infected root canal is decontaminated with medicaments and stirred to cause bleeding, in regeneration, the root canal is instrumented to remove the necrotic tissue, and a scaffold is placed in the wound after bleeding is established.

While there have been many reports on central incisors, mandibular premolars, and molars, the revascularization of maxillary premolars has not been reported. This report presents a case of successful continuous root development with a revascularization protocol for an immature permanent maxillary first premolar with necrotic pulp.

CASE REPORT

An 8-year-old female was referred to the dental clinic at King Fahad Hospital, Jeddah, Saudi Arabia, for root canal treatment. She had severe, continuous pain in the right maxillary first premolar (number 14), which had been treated with caries excavation and a pulpectomy. Otherwise, her medical history was unremarkable. Since she was asymptomatic, when she attended her appointment, cold and electric pulp testing was not applied. The tooth was not tender on percussion or palpation. Periodontal probing was within normal limits. A radiograph of the tooth revealed an immature root with an open apex, wide pulp canal, and no apical radiolucency [Figure 1]. The pulp was diagnosed as necrotic with normal apical tissues. A pulp regeneration procedure was chosen.

Figure 1

A preoperative periapical radiograph showing tooth number 14 with previously initiated endodontic treatment

The treatment plan was discussed with the patient's parents, and informed consent was obtained.

Topical anesthesia was applied to the area, and then one carpule of 2% lidocaine with 1: 100,000 epinephrine was administered via buccal and palatal infiltration. The temporary filling was removed, and the crown was built up with a glass ionomer (GI) [Figure 2a]. A rubber dam was placed, and the pulp chamber was accessed and irrigated with 10 mL of 5.25% sodium hypochlorite using a side vent needle. No instrumentation was done. The canal was dried gently with paper points, and Ca(OH)2 (Vitapex; Neo Dental Chemical Products, Tokyo, Japan) was applied as intracanal medication. A cotton pellet was placed in the pulp chamber, and the access cavity was sealed with GI filling [Figure 2b]. The patient was asked to return in 3 weeks.

Figure 2

(a) The crown built up with glass ionomer restoration and the access opening. (b) Ca(OH)2 was administered as an intracanal medication. (c) Mineral trioxide aggregate filling was applied after blood clot formation

The tooth was asymptomatic at the second appointment. One carpule of 2% lidocaine without a vasoconstrictor was administered. A rubber dam was placed, and the tooth was re-accessed. The Ca(OH)2 was removed using 10 mL of sterile saline, as the final irrigation. The canal was dried with paper points, and apical bleeding was induced with a sterile number 15 K-file. A blood clot was allowed to form 2 mm below the cement-enamel junction, and then ProRoot MTA (Dentsply Maillefer, Ballaigues, Switzerland) was gently condensed over the blood clot. A wet cotton pellet was placed on top of this, and the access cavity was sealed with GI filling [Figure 2c].

The next day, the GI filling and cotton pellet were removed, and the pulp chamber was filled first with a layer of GI and then with composite. After 3 months, the patient reported to the clinic with no symptoms and radiography showed no remarkable changes [Figure 3a]. After 6 months, the tooth was asymptomatic, and the coronal filling was intact. X-rays revealed a clear increase in root length and shape and the apical part of the root had bifurcated [Figure 3b]. The patient was referred to the periodontics clinic to have a stainless steel crown constructed.

Figure 3

(a) Periapical radiography at the 3-month follow-up exam showed no definite apical changes. (b) After 6 months, an increase in root length and signs of two developing roots were observed

After 1 year, the tooth was still asymptomatic, and radiography showed complete root development [Figure 4a]. A 3-year follow-up radiograph confirmed apical closure with a distinct intact lamina dura [Figure 4b]. Axial, coronal, and sagittal two-dimensional section cone-beam computed tomography (CBCT) images showed complete development of the tooth with one palatal and two buccal roots [Figure 5].

Figure 4

Follow-up radiographs after 1 year (a) And 3 years (b) Showing complete development of the roots with an intact lamina dura

Figure 5

Axial cone beam computed tomography of the apical third of the root (a) Revealed three roots: Mesiobuccal, distobuccal, and palatal roots. Sagittal imaging showed the two buccal roots (b) Palatal roots (c). MBR: Mesiobuccal root, DBR: Distobuccal root, PR: Palatal root, BR: Buccal root

DISCUSSION

Regenerative endodontic procedures in immature teeth involve copious irrigation without instrumenting the root canal, followed by the application of antimicrobial agents and placement of a biocompatible filling over the initiated blood clot to preserve the remaining apical vital pulp tissue. The status of the pulp tissue and size of the apical opening determine the treatment outcome.[89] In the case presented here, three completely developed roots with normal periapical tissue were observed radiographically and by CBCT over a 3-year period. Similar findings have been described in most case reports.[91015] Thickening of the root canal wall and closure of the apical foramen are achieved by growth of the periodontal ligament tissue and the deposition of cementum inside the canal space, as demonstrated by Thibodeau et al.[16] in immature dog teeth. In addition, the rich apical blood supply at the open apex in immature teeth facilitates the survival of postnatal dental pulp stem cells residing in the dental pulp tissue regardless of the status of the periapical tissue.[1718]

Blood clot, platelet rich fibrin (PRF) and platelet rich plasma (PRP), act as natural scaffolds for numerous growth factors and were recently employed by several investigators for regenerative endodontic procedures. The blood clot, which is initiated during treatment, acts as a scaffold promoting tissue regeneration and root maturation.[19] It has been hypothesized that induction of bleeding inside the root canal allows stem cells from the apical papilla to proliferate within the root canal.[20] In addition, vascular endothelial growth factors incorporated into the blood clot may contribute to cell proliferation occurring inside the root canal space of immature teeth, promoting tooth development and maturation.[21] The importance of the blood clot in the periapical healing of teeth with empty canals was reported by Ostby[22] while failure to initiate a blood clot inside the canal has a negative effect on the outcome of regenerative endodontics.[1623]

Despite the increased concentration of growth factors and cell proliferation of platelet concentrates when compared to blood clots,[24] PRF and PRP were not used in this study due to the age of the patient and the unavailability of materials. According to Hotwani and Sharma,[25] additional randomized and controlled clinical trials are needed to substantiate the long-term benefits and outcomes of PRF and PRP-associated treatments in clinical applications.

In this case, there was no periapical infection; this provided a good environment for the remaining vital apical tissue to allow the tooth to continue its normal development. Disinfection of the root canal space with an intracanal medicament plays a role in apical closure. Triple antibiotic treatment and Ca(OH)2 have been used with good results. As an alternative to triple antibiotic treatment, Ca(OH)2 was used here and provided satisfactory results similar to other reported cases.[9151619] Ca(OH)2 is an effective bactericidal agent with negligible cytotoxicity and has little impact on the diffusion of growth factors and biomolecules from dentin.[26] Due to its high pH (12.5), contact with Ca(OH)2 may cause tissue necrosis when used in revitalization procedures, resulting in destruction of vital apical tissues, which interferes with cell differentiation.[2728] To overcome these effects on cellular toxicity, we restricted use of Ca(OH)2 to the coronal third of the root canal as has been previously suggested.[1029] A triple antibiotic was not used to avoid crown discoloration and allergic reactions.[3031] In addition, antibiotic treatment increases the risk for development of bacterial resistance which might have led to treatment failure.[32]

CBCT has been applied extensively in endodontics to diagnose apical pathologies and root fractures and to evaluate root canal morphology.[3334] The morphology of the root and canal system, in this case, was viewed using CBCT, which confirmed the complete development of three roots. The presence of 3 canals in a Saudi female is rare. Elkady and Allouba[35] evaluated the root and canal morphology of maxillary premolars in a Saudi subpopulation using CBCT and reported that 0.0% had three canals while Al-Nazhan et al.[36] reported an incidence of 1% using conventional radiographs.

The coronal pulp space, in this case, was sealed with a GI base followed by a bonded resin material and stainless steel crown. This provided a bacteria-tight seal and had been reported to be an important factor in successful regenerative endodontics.[19]

CONCLUSION

The successful outcome of the present case suggested that a well-controlled revascularization technique is effective for immature teeth with necrotic pulp tissue and periapical pathosis.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.