Nonsurgical endodontic management of dens invaginatus with open apex: A case report.

Dens invaginatus is a rare malformation with a widely varied morphology. It typically affects permanent maxillary lateral incisors, central incisors, and premolars. This article demonstrates rapid management of type II dens invagination with open apex and large periradicular lesion using calcium hydroxide as intracanal medicament for 1-week followed by apical plug formation with mineral trioxide aggregate Plus and lateral condensation of Gutta-percha. At 24-month follow-up, the patient was asymptomatic and lesion was entirely resolved.

INTRODUCTION

Dens invaginatus is a rare malformation of teeth, showing a broad spectrum of morphological variations. This type of developmental anomaly results from the invagination of the enamel organ into the dental papilla during the soft tissue stage of development. It ranges from small lingual pits in the cingulums of otherwise normal teeth to broad frank tracts visually or radiographically apparent in dilated teeth. It has also been referred to as in dens in dente, invaginated odontoma, dilated gestant odontoma, dilated composite odontoma, tooth inclusion, and dentoid in dente.

This kind of tooth malformation was described first by Ploquet in 1794,[1] who discovered this anomaly in a whale's tooth. Dens invaginatus in a human tooth was first described by a dentist named Socrates in 1856.[2] The incidence of dens invaginatus has been reported to be in a range of 0.04% and 10%, with the upper lateral incisors the teeth most commonly involved and followed by maxillary central incisors, premolars, canines and molars. Males are more affected by a ratio 3:1. In most cases, a dens invaginatus is detected by chance on the radiograph. Clinically, an unusual crown morphology (“dilated,” “peg-shaped,” “barrel-shaped”) or a deep foramen caecum may be an important hint, but affected teeth also may show no clinical signs of the malformation. The dentine below the invagination may be intact without irregularities but also may contain strains of vital connective tissue or even fine canals with communication to the dental pulp.[34567810] Some authors reported hypomineralized or irregularly structured dentine.[1112]

The first classification of invaginated teeth was published by Hallett in 1953.[13] However, commonly used classification proposed by Oehlers in 1957 includes the following 3 types according to the depth of the invagination and the degree of communication with the periodontal ligament or the periradicular tissue.

Type I: Invagination confined inside the crown, not extending beyond the cemento-enamel junction (CEJ).

Type II: Invagination extending beyond the CEJ; it may or may not communicate with the pulp and not reach the periradicular tissue.

Type III: Invagination extending beyond the CEJ penetrating the root and exhibiting second foramina in the apical third within the periradicular tissue.

Several theories have illustrated the etiology of dens invaginatus; however, at the present time, they remain unclear. Kronfeld[7] speculated that dens invaginatus is caused by a failure in growth of the internal dental epithelium, while at the same time there is also a proliferation of the surrounding normal epithelium, producing a static area of engulfing. Oehlers[8] considered that the distortion of the enamel organ during tooth development and the subsequent protrusion of a part of this can lead to a formation of a linear enamel canal that ends at the cingulum and in some cases at the incisal border, producing an irregular crown shape.

Different treatment modalities have been described for these teeth, and all of them related to the degree of complexity of its anatomy. They include nonsurgical endodontic treatment, endodontic surgery, intentional replantation, and finally extraction. In cases in which there is an immature apex, the use of calcium hydroxide inside the root canal has been proposed to stimulate apexification. Witherspoon and Ham[9] have described an apical closure technique in a single appointment using mineral trioxide aggregate (MTA) in teeth with pulp necrosis and immature apex, reporting it as an alternative to the traditional apexification technique with calcium hydroxide.

This article presents successful treatment in the case of dens invaginatus by doing root canal treatment w.r.t. 11 and using MTA Plus plug formation with root canal treatment w.r.t. 12, and preventive restoration using composite w.r.t. 21 and 22.

CASE REPORT

A 15-year-old male patient reported to the Department of Conservative Dentistry and Endodontics in Punjab Government Dental College and Hospital, Amritsar, with the chief complaint of pain and fluctuant swelling in the palatal region of the maxillary right incisor since 1-month. Clinical examination revealed maxillary teeth without any restorations or obvious caries, but with a lingual pit. Tooth was tender on percussion. The intraoral periapical radiographic examination demonstrated the presence of radio opaque invagination equal in density to enamel extending beyond the CEJ in both right and left maxillary central and lateral incisor. In addition, tooth 12 showed open apex with large periapical radiolucency approximately 20 mm in size [Figure 1a]. Teeth 11 and 12 did not respond to the pulp vitality tests. For further confirmation, DentaScan was advised to the patient to know the extent and depth of lesion and tooth abnormality.

Figure 1

(a) Preoperative radiograph, (b) occlusal view of DentaScan showing bilateral dens invagination, (c) three-dimensional view of incisor showing type II dens invagination, (d) access cavity showing two openings of canal, (e) immediate postoperative radiograph after mineral trioxide aggregate plug placement with lateral condensation Gutta-percha obturation and restoration, (f) 12-month follow-up radiograph showing almost complete resolution of the lesion, and (g) 24-month follow-up radiograph showing complete periapical healing along with root apex formation

Based on DentaScan images and clinical examination, diagnosis was made as bilateral dens invaginatus type II w.r.t. 11, 12, 21, 22; nonvital tooth 11, 12 with radicular cyst in relation to right lateral incisor [Figure 1b and c]. Hence nonsurgical endodontic treatment was recommended with respect to 11 and 12, and written consent was taken from the patient before undergoing the treatment. Local anesthesia (lidocaine 2% with epinephrine 1:80 000) was applied. The teeth were isolated with a rubber dam, and two lingual access openings (main canal and invaginated canal) were made in maxillary right central and lateral incisor to expose the invagination [Figure 1d]. Both the openings of the canal were joined. The working length of the canal was established using apex locator (iPex NSK) and confirmed radiographically. Chemo-mechanical cleaning was performed. Intracanal calcium hydroxide dressing was given for a period of 1-week. An apical barrier of 4 mm thickness was created with MTA Plus (Prevest DenPro) in tooth 12 and it was left with a cotton pellet moistened with distilled water for 24-h. At the following appointment, the cotton pellet was removed and after verifying the setting of MTA Plus, the rest of the canal was filled with Gutta-percha points (Dentsply Mailliefer) using lateral condensation technique in right maxillary lateral incisor. The root canal treatment in right maxillary central incisor was completed using lateral condensation technique. Postendodontic restoration was done with nanohybrid composite (Coltene Whaledent) in both teeth [Figure 1e].

Follow-up, including radiographic and clinical examination, was performed at 6, 12, and 24 months. Six months later, the reduction in the size of radiolucency was observed. The tooth was asymptomatic, and all clinical findings were within normal limits. After 12 months, the radiographic examination showed almost complete healing of periapical lesion with no recurrence of palatal swelling [Figure 1f]. After 24 months, complete periapical healing and along with root apex formation was found [Figure 1g].

Preventive treatment was performed using composite as restorative material on deep lingual groove in maxillary left central and lateral incisor.

DISCUSSION

Dens invaginatus requires early diagnosis and intervention, because it may quickly result in periradicular pathosis. Dens invagination is a blind sac forming a deep pit and is a site of bacterial growth. The enamel in these defects is often malformed or may have numerous fine canals connecting the invagination with the pulp space. It constitutes challenge to manage with endodontic therapy because of complexity of the root canals and type and extent of invagination. Two canal orifices, one regular and one invagination opening, were found without additional help.

Nonsurgical endodontic treatment in teeth with dens invaginatus should be the first treatment alternative before recurring to endodontic surgery, intentional replantation, or extraction of the tooth. Nonsurgical root canal treatment has excellent long-term outcomes, better than those of surgery, because it seeks to disinfect the entire root canal system, rather than just to seal the apex. Even though larger lesions are somewhat less likely to heal than smaller lesions, the size of the lesion does not influence the choice of treatment. The current case of dens invaginatus was classified as Ohelers type II because the radiographic examination showed the invagination extending beyond the CEJ and remained confined as a blind sac with no communication with the main canal. The invagination allows entry of irritants into an area which is separated from pulpal tissues by only a thin layer of enamel and dentin and presents a predisposition for the development of infection. Thus, without any history of caries, or trauma, irritants and microorganisms from the oral cavity caused inflammation.

In this case, nonsurgical root canal treatment of dens invaginatus, which was characterized by the presence of an open apex, loss of vitality with the presence of periapical cyst formation, was performed and was successful. Meghana and Thejokrishna[14] suggested that the nonsurgical root canal treatment should be attempted first irrespective of the size of lesion, and surgical intervention must be the second option and is only indicated when non-surgical root canal treatment has failed or the anatomic variations of the canals do not allow access for the biomechanical preparation of the canals. Periapical surgery is indicated in cases of unsuccessful apexification in immature teeth with dens invaginatus and nonvital pulp.

A complete disinfection of the canal is of great importance to promote healing of affected periradicular tissues. In this case, sodium hypochlorite as irrigation and calcium hydroxide as intracanal medication between appointments were used to obtain this result. Calcium hydroxide has a very high therapeutic index. The treating dentist ensured that the apical infection had resolved and that apical tissues had stopped oozing before the MTA Plus was placed. MTA Plus is a finer powder, lower-cost product that has a composition similar to tooth-colored ProRoot MTA and is proposed for treating dental pulp (pulp capping, cavity lining, and pulpotomies) and root canals (root-end filling, perforation repair, root resorption, apexification, and obturation in pulpectomy).[15] An acidic environment, produced by an infection, could adversely affect the setting of MTA. Calcium hydroxide kills most endodontic pathogens; it augments sodium hypochlorite irrigation during root canal debridement and treatment.[16] Like sodium hypochlorite, calcium hydroxide may reach inaccessible parts of the complex invaginated root canal system that may not be amenable to mechanical cleaning. One of the major problems in endodontic therapy in teeth with pulp necrosis and open apex is obtaining an adequate closure of the root canal. MTA Plus has been proposed as a material for immediate closure of the apical opening without waiting for a natural healing process. The apical closure technique using MTA Plus in one appointment has been suggested in order to avoid contamination of the canal between appointments. This will create an apical barrier in the canal preventing the extrusion of root filling material into the periapical tissues. It has been demonstrated that MTA Plus induces the formation of a calcified matrix in the periapical tissue and regeneration of new cement, possibly associated with its high sealing capacity, biocompatibility, alkaline pH, and liberation of substances activating the cemento-blasts, which in turn will deposit a matrix for the cemento-genesis. The treatment period when using calcium hydroxide to obtain a biological apical closure is long, introducing concerns about intervisit contamination of the pulp space.

CONCLUSION

Dens invaginatus is a rare malformation of the teeth, showing a broad spectrum of morphologic variations in size and form of the crowns and roots. Early detection and appropriate preventive measures are of paramount importance in managing these types of dental anomalies. This case report has shown that class II dens invaginatus with an open apex and a periapical cyst can be successfully treated nonsurgically.

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Conflicts of interest

There are no conflicts of interest.