A Case Series on Regenerative Endodontic Treatment: Clinical Applications and Outcomes

Abstract

Regenerative endodontic treatment (RET) promotes tissue regeneration and root development in immature necrotic teeth. This case series examines RET outcomes in varied cases, including immature and mature teeth with periapical pathology, failed root canal treatments, large cyst-like lesions, and internal inflammatory root resorption. Five cases were treated using standardized RET protocols, including sodium hypochlorite and ethylenediaminetetraacetic acid irrigation, intracanal medicaments, and biological scaffolds (blood clot, platelet-rich plasma, and platelet-rich fibrin). Canals were sealed with biocompatible materials, followed by clinical and radiographic monitoring. All patients remained asymptomatic, with radiographic evidence of periapical healing. Some teeth showed canal narrowing due to calcific tissue deposition. Despite the absence of pulp sensibility responses, all cases demonstrated successful healing. RET is a promising, versatile approach for managing complex endodontic conditions. Success depends on effective disinfection, scaffold selection, and individualized planning. Continued research and protocol refinement are essential for broader clinical application.

Introduction

Regenerative endodontic treatment (RET) was initially developed for immature necrotic teeth and has proven effective in promoting root development, dentinal wall thickening, and healing periapical pathology. Its application in mature necrotic teeth offers a biological alternative to traditional fillings by enabling vital tissue regeneration and resolving apical periodontitis. RET also fosters immune-mediated healing in persistent periapical lesions following failed treatments[1] and may arrest internal inflammatory root resorption through tissue regeneration.[2] Even in large cyst-like lesions with bone loss, RET supports lesion resolution by harnessing the body’s natural healing.[3] This case series highlights varied clinical scenarios demonstrating RET’s role in modern endodontics.

Case Series

Case 1: Necrotic immature tooth with periapical radiolucency

A 17-year-old male presented with discoloration of tooth 11, with a history of trauma at age 10. Clinically, the tooth was discolored, nonresponsive to pulp sensibility tests, and nontender. Preoperative intraoral periapical radiographs (IOPARs) showed periapical radiolucency and an open apex, confirmed by cone-beam computed tomography (CBCT) (SkyView 3D, MyRay, Italy) [Figure 1]. The diagnosis was pulpal necrosis with asymptomatic apical periodontitis. Treatment options were discussed, and informed consent was obtained.

Figure 1.

(a) Preoperative periapical radiograph shows periapical radiolucent lesion with relation to tooth 11 and open apex. (b) Postoperative periapical radiograph after completion of regenerative endodontic procedure. (c) 3-month follow-up radiograph. (d) 6-month follow-up radiograph. (e) 12-month follow-up radiograph. (f) 18-month follow-up radiograph. (g-i) Preoperative cone-beam computed tomography (CBCT) image. (j-l) 18-month follow-up CBCT image. Healing of periapical lesion, decrease in apical foramen diameter, and dentin wall thickening were observed

Following the American Association of Endodontists (AAE) 2021 guidelines,[4] access was made under rubber dam isolation with local anesthesia (2% lidocaine, 1:80,000 epinephrine). Working length was radiographically determined; minimal instrumentation was done. The canal was irrigated with 20 mL 1.5% NaOCl (Prime Dental Products, Mumbai, India) over 5 min, followed by saline rinse, dried, and medicated with calcium hydroxide (CH) (Ultracal, Ultradent Products, Inc., South Jordan, UT, USA). The cavity was sealed with cotton and intermediate restorative material (IRM; Dentsply DeTrey, Konstanz, Germany). A follow-up was scheduled after 4 weeks.

At the second visit, the patient was asymptomatic. After removing the intermediate restorative material (IRM) and cotton, the canal was irrigated with saline, then with 20 mL of 17% ethylenediaminetetraaceticacid (EDTA) (Desmear) for 5 minutes, and finally again with saline. Platelet-rich fibrin (PRF), prepared according to Dohan et al.[5] using Remi R 8C Centrifuge (Remi Laboratories, Mumbai, India), was placed as a scaffold, 2–3 mm below the cementoenamel junction (CEJ). Biodentine (Septodont) was placed, allowed to set for 12 min, and the tooth was restored with composite. An immediate IOPAR was taken.

Case 2: Necrotic mature teeth with periapical radiolucency

A 20-year-old male presented with purulent discharge in the upper right front region and a trauma history at age 15. A sinus tract was noted between teeth 11 and 12, with radiographs showing periapical radiolucency [Figure 2]. Tracing pointed to the apex of tooth 11. Both teeth were diagnosed with pulpal necrosis and chronic apical abscess.

Figure 2.

(a) Preoperative periapical radiograph shows periapical radiolucency with relation to teeth 11 and 12. (b) Postoperative periapical radiograph after completion of regenerative endodontic procedure. (c) 3-month follow-up radiograph. (d) 6-month follow-up radiograph. (e) 18-month follow-up radiograph. (f) 24-month follow-up radiograph shows (g-i) preoperative cone-beam computed tomography (CBCT) image. (j-l) 24-month follow-up CBCT image. The healing of periapical lesion and narrowing of root canals were evident

Treatment followed the case 1 protocol with modifications. Working length was determined using an apex locator (Root ZX II, J. Morita Mfg. Corp., Kyoto, Japan) and confirmed radiographically. The canal was sequentially instrumented with K-files(Mani Inc., Japan), and apical third of the canal was enlarged by two to four file sizes larger than the master apical file. The irrigants were activated using the EndoActivator system (Dentsply Sirona).

At the second visit, platelet-rich plasma (PRP) (prepared per Amable et al.[6]) was injected below the CEJ and allowed to clot for 10 min. Biodentine and composite restoration were completed as previously described.

Case 3: Teeth with persistent apical periodontitis after primary root canal treatment (retreatment case)

A 35-year-old male reported pain in the left upper front region. Tooth 21 was discolored and restored; tooth 22 also had a restoration. The patient had a history of trauma at age 11 and root canal treatment 7 years ago. Both teeth were tender to percussion. Radiographs showed radiopaque material in the canals and periapical radiolucency [Figure 3]. The diagnosis was previously initiated treatment with symptomatic apical periodontitis.

Figure 3.

(a) Preoperative periapical radiograph shows previously treated teeth 21 and 22 with periapical radiolucency. (b) Postoperative periapical radiograph after completion of regenerative endodontic procedure. (c) 3-month follow-up radiograph. (d) 12-month follow-up radiograph. (e-g) Preoperative cone-beam computed tomography (CBCT) image. (h-j) 12-month follow-up CBCT image shows healing of periapical lesion and calcific deposits within the canal

Treatment followed the case 2 protocol, with gutta-percha removed using Hedstrom files (Dentsply Maillefer, Ballaigues, Switzerland) without solvents.

At the second visit, a blood clot (BC) scaffold was used. After anesthesia (2% lidocaine without vasoconstrictor), a precurved #20 K-file (Mani Inc., Japan) was passed 2 mm beyond the apex to induce bleeding. A cotton pellet was placed 3–4 mm below the CEJ to allow clot formation. A gelatin sponge (Gelatamp; Coltene Whaledent) was placed over the clot, followed by Biodentine and composite restoration.

Case 4: Tooth with internal inflammatory root resorption

A 14-year-old male presented with a fractured, discolored tooth 11 in the upper right front region, following trauma 4 years ago. Tooth 11 had an Ellis Class II fracture, was nonresponsive to pulp sensibility tests, nontender, and showed internal resorption with periapical radiolucency on radiographs [Figure 4]. A diagnosis of pulpal necrosis with internal inflammatory root resorption and asymptomatic apical periodontitis was made.

Figure 4.

(a) Preoperative periapical radiograph shows tooth 11 with internal inflammatory root resorption. (b) Postoperative periapical radiograph after completion of regenerative endodontic procedure. (c) 3-month follow-up radiograph. (d) 6-month follow-up radiograph. (e) 18-month follow-up radiograph. (f-h) Preoperative cone-beam computed tomography (CBCT) image. (i-k) 18-month follow-up CBCT image shows arresting of resorption process and dentinal wall thickening

Treatment followed the case 2 protocol. Cleaning and shaping with K-files (Mani Inc., Japan) removed granulomatous tissue. Irrigants were sonically activated using the EndoActivator system (Dentsply Sirona, New York, USA) for 1 min. A BC served as the scaffold.

Case 5: Teeth with large periapical lesion

A 28-year-old male presented with swelling and pain in the upper right front region. A palatal swelling was noted near teeth 11, 12, and 13. Tooth 11 had an Ellis Class II fracture and was discolored, and radiographs showed periapical radiolucency around teeth 11–13 [Figure 5]. These teeth were diagnosed with pulpal necrosis and acute periapical abscess.

Figure 5.

(a) Preoperative periapical radiograph shows a large periapical radiolucency with relation to teeth 11, 12, and 13. (b) Postoperative periapical radiograph after completion of regenerative endodontic procedure. (c) 3-month follow-up radiograph. (d) 6-month follow-up radiograph. (e) 18-month follow-up radiograph. (f-h) Preoperative cone-beam computed tomography (CBCT) image. (i-k) 18-month follow-up CBCT image shows healing of periapical lesion, repair of cortical plate, and narrowing of the root canals. Arrow indicates cortical perforation

During access opening, straw-colored fluid was observed draining through the cavity. The procedure followed that of case 2, with platelet-rich plasma (PRP) used as the scaffold.

Table 1 lists all the cases. Standard patient follow-up included appointments at 3, 6, 12, 18, and 24 months; some of them missed a few follow-up appointments, only case 2 reported for 24-month follow-up. Follow-up CBCT was done at 12 months or later. All of them were completely asymptomatic. All cases showed healing of periapical lesions [Figures 1-5], and none of them responded to pulp sensibility tests. In addition, case 1 [Figure 1] showed a reduction in apical foramen diameter and dentinal wall thickening, and case 2 [Figure 2] and case 5 [Figure 5] had narrowing of the root canal lumen. However, case 3 [Figure 3] had the presence of calcific deposits within the root canals of both teeth, case 4 [Figure 4] showed arrest of the resorption process and dentinal wall thickening, and CBCT of case 5 [Figure 5] showed repair of cortical plate perforation.

Table 1.

Patients’ demographic data, preoperative diagnosis, scaffold type, and follow-up period

Tooth number	Gender	Age (years)	Pulpal diagnosis	Periapical diagnosis	Scaffold used	Follow-up period (months)
11	Male	17	Pulpal necrosis	Asymptomatic apical periodontitis	PRF	18
11, 12	Male	20	Pulpal necrosis	Chronic apical abscess	PRP	24
21, 22	Male	35	Previously treated	Symptomatic apical periodontitis	BC	12
11	Male	14	Pulpal necrosis	Asymptomatic apical periodontitis	BC	18
11, 12, 13	Male	28	Pulpal necrosis	Acute apical abscess	PRP	18

PRP: Platelet-rich plasma; PRF: Platelet-rich fibrin; BC: Blood clot

Discussion

Disinfection in RET must balance microbial control with stem cell preservation. AAE guidelines[4] recommend 1.5%–3% NaOCl for this purpose. EDTA removes the smear layer, enhances medicament penetration, promotes growth factor release, and supports stem cell viability, aiding regeneration and arresting resorption. As a final rinse, EDTA also offsets NaOCl’s adverse effects. In internal resorption, irrigant activation improves debridement and biofilm disruption.

This case series used CH as the intracanal medicament for its antimicrobial action and safety for stem cells from the apical papilla (SCAP) viability. In contrast, triple antibiotic paste shows concentration-dependent SCAP toxicity in vitro.[7] CH also helps prevent and manage resorption in avulsed, replanted teeth[8] by halting root resorption through its antibacterial and alkalizing effects, which activate alkaline phosphatase and inhibit osteoclasts.

Minimal instrumentation is advised for RET in immature teeth, but no clear guidelines exist for mature teeth. A review[9] found that all studies used mechanical instrumentation like conventional treatment. In this series, mature teeth were cleaned and shaped, and periapical healing was achieved.

In RET for failed cases, chemical solvents were avoided to reduce cytotoxic risk. An ex vivo study[10] showed that chloroform and other solvents are toxic, though their effects on stem cells and dentin remain unclear. The impact of residual toxicity on stem cells in canals is also uncertain.

In cases of internal inflammatory root resorption, RET led to arrest and visible reduction of resorptive defects, aligning with previous findings.[2] Cementum-like tissues formed post-RET may contain osteoclastogenesis inhibitors, potentially halting resorption.[11]

This case series used BC, PRF, and PRP as scaffolds. BC is cost-effective but not always feasible. PRP is growth factor-rich and injectable, ideal for mature teeth but takes longer to prepare. PRF is easier to prepare but harder to place in mature teeth. All scaffolds showed similar periapical healing, consistent with a review[12] reporting no significant outcome differences.

Biodentine was chosen over MTA for its better color stability, faster setting, and promotion of stem cell osteogenic differentiation and mineralization.[13]

Although positive pulp vitality is a tertiary goal of RET, none of the treated teeth in this series responded to sensibility tests, possibly due to capping material thickness. Follow-up showed intracanal calcification and canal narrowing, likely from cell homing processes involving the migration and differentiation of osteogenic and cementogenic cells or the osteoinductive effects of calcium silicate materials. This could be due to the use of CH as intracanal medicament in the present case series, as calcification was more common in CH-treated cases than with antibiotic pastes.[14]

Conclusion

This case series highlights the effectiveness of RET in treating various conditions, including immature necrotic teeth, mature teeth with periapical pathology, persistent apical periodontitis, internal resorption, and large periapical lesions. Clinical and radiographic results reinforce the potential of RET as an effective, biologically driven treatment option. Still, continued research and extended follow-up are crucial for confirming these results and improving treatment guidelines for wider clinical use.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.