Endodontic management of double dens invaginatus in maxillary central incisor.

This case report deals with the successful endodontic treatment of double dens invaginatus in maxillary left central incisor. Dens invaginatus is a rare developmental anomaly that is challenging to diagnose and treat. A patient reported with unesthetic appearance and previously attempted endodontic treatment of tooth #21. Cone beam computed tomography revealed the presence of a complex invagination communicating with the periodontium. A combination of techniques enhanced the debridement of the complex invagination. Obturation was performed using warm vertical compaction. The patient was asymptomatic during the follow-up period of 12 months.

INTRODUCTION

Dens invaginatus is a developmental anomaly characterized by invagination or deepening of enamel organ into the dental papilla of developing tooth before calcification. Subsequently, during calcification, the invaginated enamel organ develops into a small tooth within the future pulp chamber. “Socrates” (1856) was the first to described Dens invagination in a human tooth.[1]

The etiology of Dens invaginatus remains inconclusive. Various authors have suggested, localized foci of accelerated or retarded growth within the inner enamel epithelium, fusion of tooth germs, trauma, infection, the abnormal pressure to the dental arch during development, to be few of the plausible mechanism for its development.[2] The clinical and radiographic presentation of dens invaginatus is highly variable. Clinically in most of the cases, the affected tooth may present an unusual crown morphology (barrel or peg shaped) often associated with a deep lingual pit (foramen cecum).[2] Dens invaginatus is more prevalent in maxillary lateral incisors followed by the maxillary central incisors, premolars, canines, and less often in the molars.[2] The bilateral occurrence is not uncommon, and in few cases, it may be associated with other dental anomalies and syndromes such as Rubinstein-Taybi syndrome, and Sturge Weber syndrome.[3] Radiographically, the enamel invaginating into the root canal appear as a radiopaque rim, extending from the cingulum into the root canal.[4] The invagination manifest in different forms, from a less complex loop-like or pear-shaped to a more complex tooth within a tooth.[5] The invagination may serve as a portal for easy and rapid entry of microbes toward pulp. Early diagnosis of Dens invaginatus is essential to provide preventive treatment.

Double dens invaginatus is an extremely rare condition involving two enamel lined invaginations in the crown and/or roots of a tooth. This case report describes the nonsurgical endodontic management of a Double Dens invaginatus in a maxillary central incisor.

CASE REPORT

A 24-year-old female patient reported to our department with a chief complaint of occasional dull pain in relation to maxillary left central incisor, i.e., #21. The patient presented with a history of dental trauma few years back for which endodontic treatment was initiated 1 year ago.

On clinical examination, the tooth appeared to be discolored, slightly larger than its counterpart. The palatal aspect showed fracture of the entrance filling and secondary caries. The tooth was tender on percussion. There were no signs of swelling or sinus opening [Figure 1a]. Intraoral periapical radiograph revealed a radiopaque material within the root canal with a diffuse periapical radiolucency. The root appeared to be short, anomalous with poorly defined canal anatomy [Figure 1b]. Based on the clinical and radiographic findings, a provisional diagnosis of previously attempted endodontic treatment with symptomatic apical periodontitis was given. Patient was planned for endodontic treatment and consent was obtained for the same.

Figure 1

Preoperative presentation of tooth #21, (a) Clinical presentation. (b) Intra oral periapical radiograph. (c) Sagittal cone beam computed tomography section. (d) Axial cone beam computed tomography section, at cementoenamel junction. (e) Axial cone beam computed tomography section, middle third. (f) Axial cone beam computed tomography section, apical third. (g) Schematic representation of root canal morphology

Considering the complex canal morphology, cone beam computed tomographic imaging (CBCT) with a limited field of view was suggested. Sagittal CBCT section of the involved tooth revealed a slender canal on the labial aspect, and a spindle-shaped palatal invagination (PI) that was flared in the middle third but constricted at an apical and coronal third of the root [Figure 1c]. The axial CBCT section at the cementoenamel junction (CEJ) presented with three distinct root canal orifices; mesio labial invagination (MLI), distolabial canal (DLC), and PI, [Figure 1d]. Furthermore, the axial CBCT section also revealed a communication between the MLI and DLC at the middle third following which, the outline of the MLI fades off ending as a blind sac. At this level, palatally, the invagination showed an asymmetrical increase in diameter [Figure 1e]. At the apical third, the DLC terminated with a separate portal of exit. In addition, the PI faded off with a shallower groove on the external root surface that communicated with the periodontium [Figure 1f]. Schematic representation of the root canal morphology is illustrated [Figure 1g]. Based on the CBCT images, the involved tooth can be described to have a distinct DLC and two invaginations on the palatal and mesiolabial aspect. Hence, this aberrant canal morphology was identified as a Double Dens invaginatus– type 3 a, according to Oehler's classification.

The treatment was carried out under the dental operating microscope (Labomed, Prima DNT, United States). The secondary caries and residual temporary restoration were removed. The access opening was refined under ×2.5 [Figure 2a], and the 3-distinct orifices were located using an endodontic explorer DG16 and canals (MLI, DLC, PI) were negotiated [Figure 2b]. The orifices were enlarged using Gates Glidden Drills (Mani Inc, Japan) and working length was determined using an electronic apex locator and confirmed with radiograph. For the DLC and MLI, shaping and cleaning were carried out manually with ISO K-files using step back technique with apical enlargement up to size 40 (K files, Maillefer, Dentsply, USA). The canals were irrigated with 5.25% sodium hypochlorite solution and 17% ethylenediaminetetraacetic acid (EDTA) (reading comprehension Prep, prime dental products, India) followed by using saline as a final rinse. The final irrigation was carried out using passive ultrasonic irrigation to clean the communication between the MLI and DLC. The PI was instrumented using hand K files up to size 40 then the self-adjusting file (SAF) (ReDent Nova Ltd.) was used for further debridement [Figure 2c]. The PI was irrigated with 5.25% of sodium hypochlorite and saline using the endovac system [Figure 2d] (Discus Dental, Culver City, CA, USA). The DLC and the invagination (MLI and PI) were dried with adsorbent paper points (Dentsply Ballaigues, Switzerland). Obturation was performed using Gutta-percha and AH Plus sealer (Dentsply Ballaigues, Switzerland) by warm vertical compaction technique. The PI was obturated initially with a 3 mm of the apical plug of Biodentin (Septodont, USA) using hand plugger that snugly fit 3 mm short of the working length. This was followed by backfilling with Gutta-percha and AH Plus sealer (Dentsply Ballaigues, Switzerland) using warm vertical compaction [Figure 2e] (Elements Obturation Unit™ SybronEndo, Orange, Calif.). The access cavity was sealed with resin composite (3M Dental Products, St Paul, MN, USA). The patient was asymptomatic at the end of 12 months recall intraoral periapical radiograph revealed a significant decrease in the size of the periapical radiolucency [Figure 2f].

Figure 2

Clinical steps. (a) Access opening under Dental operating microscope (2.5× magnification). (b) Negotiation of Mesiolabial invagination (MLI) , Distolabial canal (DLC), and Palatal invagination (PI). (c) Debridement of the PI using Self Adjusting file. (d) Use of EndoVac for the PI. (e) Immediate post-operative radiograph. (f) Radiograph at 12th- month follow up

DISCUSSION

Several authors have investigated the occurrence of dens invaginatus and found maxillary lateral incisors are the most commonly involved teeth with a prevalence of 38.5%–75%.[56] Among Indians, the prevalence of dens invaginatus is as low as 0.4%.[7] The invagination of the inner enamel epithelium may occur in more than one point within the tooth resulting in double or even triple dens invaginatus.[8] Usually, the invagination originates as a pit on the coronal aspect that predisposes to caries and is separated from the pulpal tissue by only a thin layer of enamel and dentine. The invagination may occur within the root canal system or may exist separate. They may also present with intercommunications with the main canal which explains the rapid onset of pulpal necrosis.[9] The number and morphology of root canals in an invaginated tooth are highly unpredictable and variable.

In the present case, the main DLC communicated with the blind sac on the mesiolabial aspect which was considered to be a part of the invagination. Further, the PI that started with a bottleneck constriction had an abruptly dilated middle third portion that further communicated with the periodontium through an open apex [Figure 1]. Proper debridement and sealing of this intricate canal system were challenging.

Oehlers classified Dens invaginatus into three types. According to this classification, Type 1 is a sac-like invagination restricted to the coronal part, which does not advance beyond the CEJ; Type 2-Invagination extends beyond the CEJ but does not reach the periodontal ligament; Type 3a-Invagination extends through the root and communicates laterally with the periodontal ligament space through a pseudo foramen; and Type 3b-Invagination extends through the root and communicates with the periodontal ligament at the apical foramen. There is usually no communication with the pulp.[10] The present case was classified as “Type 3a,” as the invagination communicated the periodontium with a separate portal of exit.

Capar et al. studied the prevalence of each type of invagination using CBCT and concluded that type 1 being the most common (65.9%) and type 2 (29.5%) and type 3 (4.6%) which is least observed and the most difficult to treat. He also recommended the use of CBCT in accurately studying the intricate anatomy of Dens invaginatus.[6]

CBCT helped in the thorough understanding of the complex root canal morphology. Initially, the palatal orifice was suspected for perforation as interpreted with an electronic apex locator. Later, the CBCT imaging confirmed the presence of irregularly shaped invagination that communicated with the periodontium. The axial sections of CBCT enabled to identify the mesiolabial blind sac that was the part of the invagination and confirmed the diagnosis as Double Den invaginatus with Type 3a configuration.

There are various treatment options for Dens invaginatus depending on its complexity and pulpal status. Prophylactic sealing of the invagination and constant monitoring are required in less complex cases (Oehlers type 1 Dens invaginatus) with healthy pulp.[11] If the invagination that is communicating with the root canal exhibit signs of pulp pathosis (Oehlers type 2, 3), endodontic treatment is required. Rarely, the invagination may not communicate with the root canal wherein sealing the invagination and preserving the pulp vitality may be considered. In a recent report, treating the invagination itself resulted in resolution of the periapical lesion.[12] In our case, nonsurgical root canal treatment was planned as the invagination communicated with the root canal system. The access was modified under dental operating microscope. The slender DLC and mesiolabial blind sac were shaped with conventional hand files (ISO 0.2% taper) using step back technique (apical enlargement up to size 40). Irrigation was performed using 5.25% sodium hypochlorite, 17% EDTA and saline. The communication between the distolabial and mesiolabial blind sac was further debrided with three cycles of passive ultrasonic irrigation using 5.25% sodium hypochlorite. The PI had a bottleneck pattern with an initial constriction at the coronal third with abrupt flaring at the middle third resulting in lesser remaining dentin. For disinfecting this portion, SAF was used. These files maintain the original canal morphology by three-dimensionally adapting to the canal irregularities with their specialized design. In addition, with its gentle vertical motion kinematics of these files preserves the residual radicular dentin.[13] It allows for combined instrumentation and debridement with a continuous flow of irrigant that would optimally disinfect the invagination.

The palatal pseudo apical foramen that exited as an open apex would cause extrusion of irrigants into the periapical tissue. This problem was negated with the use of negative apical pressure irrigation system-endovac, for delivering the irrigant. The use of apical negative pressure for irrigation will minimize extrusion when compared to conventional needle irrigation. It has been reported that the apical negative pressure irrigation was safely used even in cases of wide open apex.[14] Hence for the PI,th e macrocannula of the endovac was used for debridement.

Currently, mineral trioxide aggregate (MTA) is the choice of material as an apical barrier for apexification, owing to its superior seal and excellent biocompatibility. However, its prolonged setting time and poor handling properties led to the evolution of newer materials with similar properties of MTA. Biodentin, a derivative of MTA is one such material with improved handling properties and short setting time.[15] Apical 3 mm of the PI was initially sealed with biodentin, and the remainder of the PI was backfilled with Gutta-percha and AH plus sealer using Warm vertical compaction technique (Elements Obturation Unit™ SybronEndo, Orange, Calif).

CONCLUSION

Successful nonsurgical endodontic management of this case was possible with the appropriate use of multiple techniques. First, the CBCT allowed us to understand the aberrant canal morphology better, and the use of dental operating microscope enabled us to perform a more precise treatment

SAF and endovac proved to be beneficial in managing the PI with less procedural complications.

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.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.