Pulpal Regeneration of Two Necrotic Premolars with Dens Evaginatus: A Case Series

Methods

Two 12-year-old patients were diagnosed with pulp necrosis and chronic apical abscess (sinus tract present). Both teeth—one per patient—had dens evaginatus (DE) and incomplete root formation. Pulpal regeneration (also called regenerative endodontics, revitalization, or revascularization) was performed for both patients according to the ‘AAE Clinical Considerations for a Regenerative Procedure’. Biodentine was used as the capping material over the induced blood clot in both cases. Follow-ups were conducted for both patients and demonstrated a successful outcome—radiographs demonstrate resolution of apical periodontitis and continued root development.

Discussion

Treatment of teeth with immature roots, pulp necrosis, and apical periodontitis (including chronic apical abscess) presents a dilemma for dentists. Pulpal regeneration—with Biodentine as the capping material—successfully treated endodontic disease and supported continued root formation of the premolar teeth in this case series.

Conclusion

A major goal of modern endodontics is the preservation of dentin. Biocompatible and bioactive capping materials, such as Biodentine, may enable continued root formation in immature teeth. Regenerative endodontic procedures (REPs) can allow immature roots to continue forming and may improve fracture resistance.

INTRODUCTION

Patients with atypical dental anatomy are at risk of underdiagnosis, misdiagnosis, or over-treatment if their dentist is unfamiliar with their condition. An example of one such anatomical variation is dens evaginatus (DE). DE is most commonly seen in patients of Asian descent, although it may be present in patients of other backgrounds (1).  The overall prevalence of DE in Asian populations is estimated to be less than 5% and when present, affected teeth have an extra tubercle which may also be called a talon cusp or supernumerary cusp (1). The DE tubercle typically contains a pulpal extension on the occlusal surface of posterior teeth (premolars are most common) or the lingual surface of anterior teeth (maxillary lateral incisors are most common) (1).

When teeth with DE come into occlusion with the opposing dentition, the tubercle may fracture, and the pulp is exposed. Pulp necrosis and apical infection typically follow tubercle fracture. Since root development continues for 2-3 years after the eruption, teeth with DE and pulp necrosis may have short roots and thin dentinal walls. These teeth may be fracture-prone if treated with traditional methods, such as apexification (with calcium hydroxide) or root canal treatment (with gutta-percha obturation).

Regenerative endodontic procedures (REPs) involve revascularizing necrotic teeth/roots. Clinically, vascularity is desirable and may lead to continued root development. Multiple protocols exist for REPs and successful treatment may induce the formation of a dentin bridge between the capping material and vascular tissue. Materials such as MTA and calcium silicate cements (such as Biodentine) are used as capping materials for REPs due to their biocompatibility and ability to form dentin bridges.

REPs are advocated for necrotic teeth with incomplete root development (2). REPs may increase root length, root wall thickness, and minimize the occurrence of root fractures (2).

Modern dentistry focuses on conservative treatments and the preservation of natural tooth structure. Since REPs may increase root length and thickness, REPs are in line with modern dental philosophies. The success of REPs hinges on proper diagnosis, clinical procedures, disinfection of the root canal system, and biocompatibility of capping materials.

CLINICAL SIGNS + SYMPTOMS AND DIAGNOSIS

Two cases of REPs—Patient A and Patient B—with DE are described in this case series.

Patient A was a 12-year-old female of Asian descent who presented with localized swelling and a sinus tract buccal to tooth #20. The sinus tract had been present for two months. The patient was previously evaluated by another endodontist, who referred the patient to the author in June 2021 for pulpal regeneration.

Patient B was a 12-year-old male of Asian descent. The patient had been previously evaluated by both his dentist and orthodontist, due to discomfort and swelling in the maxillary right premolar region. The patient presented in June 2022 for endodontic evaluation with the author, who observed localized swelling and a draining sinus tract associated with tooth #4. For both patients, an examination was performed, and treatment recommendations were reviewed. Pre-operative radiographs from the consultation appointments are presented in Figures 1a and 1b. Clinically, DE was present on all premolar teeth of both patients. The affected teeth (#20 and #4, respectively) had recently come into occlusion with the opposing dentition, causing dens evaginatus tubercle fracture. This led to a small pulp exposure for both patients, due to the pulpal extension into each tubercle. The result was pulp necrosis and chronic apical abscess of both teeth. Both patients’ parents chose to proceed with a REP because of the potential to increase root fracture resistance. The parents declined apexification as the first-line treatment. Each patient’s parents were informed that if the REP was not successful, an apical plug of Biodentine would be recommended to obturate the root canal system. 

Diagnosis for Patient A: Tooth #20 Pulp Necrosis with Chronic Apical Abscess; Dens Evaginatus Anatomy; Mobility 1+

Diagnosis for Patient B: Tooth #4 Pulp Necrosis with Chronic Apical Abscess; Dens Evaginatus Anatomy; Mobility unknown (due to orthodontic brackets and wires).

PROCEDURE AND TREATMENT

Treatment for both patients followed the same protocol and was based on recommendations from the American Association of Endodontists (3).

Treatment at 1st Appointment:

Local anesthesia was placed and an incision and drainage were performed, to help obtain additional drainage for the apical infections. A dental dam was placed prior to accessing the root canal system. A file shot radiograph was exposed (passive placement) for length determination. Each canal was irrigated to full length with 20 ml of diluted (1.5%) NaOCl using a side-vented 30-gauge irrigation needle. A combination of EndoActivator and XP-3D finisher (passive instrumentation) was used to activate the irrigant for both teeth. After cleaning, each canal was irrigated with saline, and dried with paper points, and calcium hydroxide was placed to the junction of the middle and apical 1/3 of each root. A durable temporary restoration was placed (cotton and RMGI) and each patient was recommended to return in 4-6 weeks. Figures 2a and 2b were exposed at the end of the 1^st appointment for each patient to confirm the placement of calcium hydroxide and temporary restorative material.

Treatment at 2nd Appointment:

Both patients were asymptomatic and both patients’ sinus tracts had resolved. Patient A no longer had mobility of tooth #20, while Patient B still had orthodontic brackets and wires in place. Both patients’ treatment followed the same steps: Local anesthesia (without vasoconstrictor) was placed, followed by rubber dam placement and removal of the temporary restoration. The canal was irrigated to full length with 20 ml of 17% EDTA. The apical 2 mm of a sterile size 25 k-file was bent; the file was placed 2 mm beyond working length and rotated clockwise until apical bleeding started to fill the canal. Time was allowed for bleeding to occur, and the process was repeated 2-3x gently until the canal was visibly filled to the junction of the coronal and middle 1/3 of the root. Clotting time was permitted and a small collagen plug was placed over the blood clot, followed by increments of Biodentine as a capping material. Radiographs were exposed mid-operatively (see Figures 3a and 3b) to ensure appropriate length and density of Biodentine.

Next, a layer of resin-modified glass ionomer was placed, and light cured, followed by a permanent composite restoration and occlusal contouring. Figures 4a and 4b document the completion of the 2^nd appointment for each patient and represent the completion of “treatment” for pulpal regeneration.

FOLLOW-UP

Each patient was seen for multiple follow-up evaluations (approximately 2, 6, and 12 months). Patient A also returned for a 24-month follow-up. The most recent follow-up PA radiographs are presented in Figure 5a for Patient A (24-month follow-up) and Figure 5b for Patient B (12-month follow-up).  At all follow-up appointments, both patients were asymptomatic. Figures 5a and 5b demonstrate that apical periodontitis (infection) had resolved. In addition, the root structure of both teeth was increasing in length, and thickness, and had closed apically. Finally, a dentin bridge had formed at the mid-root level of both teeth.

DISCUSSION

Regenerative endodontic procedures (REPs) can give a second chance to permanent teeth with pulp necrosis and open apices. Teeth with incomplete root formation were previously treated with traditional apexification (with calcium hydroxide), root canal treatment, or extraction—REPs, however, may increase root length and dentin wall thickness.

Biocompatible and bioactive capping materials, such as Biodentine, are a key factor in REP success. The main reason for endodontic procedure failure is bacterial contamination. It is well-known that Biodentine can induce dentin bridge formation; this may block future bacterial access to the regenerated pulpal tissues. In addition, Biodentine does not induce inflammation of the pulpal tissues, which may improve the success of REPs.

CONCLUSION

Dens evaginatus (DE) can lead to pulp necrosis in immature permanent teeth. Regenerative endodontic procedures (REPs) performed with Biodentine may give a second chance to necrotic permanent teeth with open apices.

BIOGRAPHY

Lauren Kuhn Nuth, DMD MSD

• Adjunct Assistant Professor – University of Minnesota School of Dentistry– Minneapolis, MN
• Endodontist – Metropolitan Endodontics—Inver Grove Heights, MN
• Diplomate of the American Board of Endodontics

Dr. Lauren Kuhn Nuth is a board-certified endodontist and graduate of the Harvard School of Dental Medicine (DMD) and Medical University of South Carolina (MSD in Endodontics). She has been an Adjunct Assistant Professor at the University of Minnesota School of Dentistry since January 2020. She has published case-based research in the Southeast Case Research Journal and co-authored publications in Dental Materials, The Journal of Advanced Prosthodontics, and Decisions in Dentistry. Dr. Kuhn Nuth is passionate about education, specifically the identification and implementation of strategies to improve the efficiency and predictability of clinical outcomes and patient experiences. Dr. Kuhn Nuth has been serving patients and referring dentists in private practice in Minnesota since 2019.