Endodontic management of a mandibular second premolar with perforating internal resorption by using MTA and cone beam computed tomography as a diagnostic aid.

This case report demonstrates the benefits of utilizing Cone Beam Computed tomography (CBCT) in the assessment and mineral trioxide aggregate (MTA) in the management of perforating internal resorption in a 54-year-old woman. The advent of CBCT has enhanced the clinician's ability to make a confirmatory diagnosis and determining the treatment plan before undertaking the actual treatment. Thorough cleaning and shaping of the root canal space and the resorptive defect was achieved by mechanical instrumentation, irrigation, and interim calcium hydroxide dressing. Following this obturation of the canal below, the resorptive defect was done with gutta percha using lateral and warm vertical condensation. The resorptive defect was filled with mineral trioxide aggregate. Follow-up intraoral periapical radiographs and CBCT scans at 6 months showed adequate repair of the resorption and periapical rarefaction and the tooth remained asymptomatic.

INTRODUCTION

Internal root resorption is the progressive destruction of intraradicular dentin and dentinal tubules along the middle and apical thirds of the canal walls as a result of clastic activities.[1] It might occur as a physiologic or pathologic phenomenon. In the permanent dentition, it is a pathologic event of rare type. Although the exact cause is unknown, chronic pulpal inflammation from bacterial invasion, trauma, and orthodontic treatment have been suggested as a cause in most cases.[234] Clinically, internal root resorption is usually asymptomatic, detected coincidentally through routine radiographs. Pain or discomfort may be the chief complaint if the granulation tissue has been exposed to oral fluids.[2] Radiographic examination usually reveals a fairly uniform radiolucent area with disrupted outline of the root canal.

Diagnostic accuracy based on conventional and digital radiographic examination is limited by the fact that the images produced by these techniques only provide a two-dimensional (2D) representation of three-dimensional (3D) objects.[5] This might lead to misdiagnosis and incorrect treatment in the management of internal root resorption. The advent of cone beam computed tomography (CBCT) has enhanced radiographic diagnosis providing greater 3D appreciation of the tooth, the resorption lesion, and the adjacent anatomy.[67] The true nature of the lesion might be assessed, including root perforations and whether the lesion is amendable to surgical or non-surgical treatment. Andearson has stated that an untreated internal resorption leads to premature loss of the tooth.[8] If untreated, this might result in the premature loss of the affected teeth. Therefore, nonsurgical root canal therapy is the treatment of choice to arrest the destructive process in the absence of concomitant external resorption.[9] However, the irregular confines of the resorptive cavity pose technical difficulties for thorough debridement and obturation of the pulp space. And if the internal resorption has extended to the point that it reaches the external root surface, root integrity is lost and there may be destruction of the adjacent periodontal tissues which also has to be treated.[10]

Mineral trioxide aggregate (MTA) has several clinical applications due to its superior sealing properties, bacteriostatic effects, biocompatibility, and ability to set in presence of blood.[1112] MTA has suggested indications i.e., root-end filling, pulp capping, apical filling of teeth with open apices, apexification therapy, and repair of root perforations.[13] MTA is a suitable material for the treatment of root perforations with the goal of regenerating a periodontal attachment and inducing osteogenesis and cementogenesis.[1415]

This paper reports a case of MTA repair of mandibular right premolar with an inflammatory, perforating resorptive defect in the coronal third of the root canal with use of CBCT to enhance radiographic diagnosis of internal resorption.

CASE REPORT

A 54-year-old woman reported to the dental office with pain and swelling in the right mandibular posterior region. The medical history was non-contributory. She had no history of traumatic injury or orthodontic treatment. Clinical examination showed small intraoral swelling with relation to 45. The tooth was slightly tender to percussion and served as an abutment to a long span bridge extending upto 48. The probing depths were within normal limits.

Intraoral periapical radiographic examination revealed a well-circumscribed, fairly round radiolucency in the cervical third of the root with diffuse periapical rarefaction [Figure 1]. Clinical symptoms and radiographic examination suggested a diagnosis of internal resorption and pulp necrosis. The Bridge was cut and removed to preserve the integrity of tooth with resorption and endodontic treatment was scheduled. It was decided not to include 44 as the patient was reluctant to sacrifice a healthy tooth and was ready to wear a partial denture in case of future loss of tooth. Implant was not considered due to financial constraint of the patient. As the conventional intraoral radiographs do not indicate the true size and spread of the lesion, the patient was sent for CBCT to evaluate the true size and nature of the lesion. Informed consent was obtained from the patient and a CBCT imaging of the mandible was performed by using the CBCT scanner (CS 9300 3D Digital Imaging System, Hatfield, PA). The involved tooth was focused, and the morphology was obtained in axial sections of 90 μm thickness with 300 μm spacing. The CBCT images revealed well-circumscribed radiolucent area with relation to 45 below the level of cemento-enamel junction, involving the distal wall of the root and extend apically upto the middle of the root length suggestive of perforating internal resorption [Figures 2].

Figure 1

Preoperative periapical radiograph showing well defined internal resorption with prosthesis

Figure 2

Preoperative 3D images showing axial plane

Based on above finding, root canal therapy was initiated. The tooth was isolated under rubber dam (Hygienic Dental Dam, Coltene Whaledent, Germany) and accessed without anesthesia. The necrosed pulp tissue was removed. Presence of hemorrhagic fluid in the canal suggested of a small communication between the resorptive defect and the lateral periodontium. Working length determination was established using apex locator (Root ZX II; Morita, Tokyo, Japan) and radiography [Figure 3]. The canal was prepared using crown down technique with ProTaper files (Dentsply, Tulsa dental specialities, Ballaigues, Swizterland) accompanied by copious irrigation with 2.5% sodium hypochlorite (Dentpro, Chandigarh, India). A calcium hydroxide paste dressing (Metapex; Meta Biomed Ltd, Choenju city, Chungbuk, Korea) was placed to alkalinize the environment and control bleeding at the perforation. The calcium hydroxide dressing was changed twice every 15 days. Master cone radiograph was taken [Figure 4] and the canal below the resorptive defect was obturated with gutta percha (Dentsply, Maillefer) and AH Plus sealer (Dentsply, Maillefer, Konstanz, Germany) using a combination of cold lateral condensation and vertical compaction with heated pluggers and condensers. The resorptive defect and the remaining canal were then condensed with MTA (Proroot MTA, Maillefer, Dentsply, Swizterland), using MTA carrier and root canal pluggers [Figure 5] (Dentsply, Maillefer). Since the perforation was very small it was decided not to place a matrix. A wet cotton pellet was placed on this and the access was temporarily sealed with MD Temp (Meta Biomed Ltd, Choenju city, Chungbuk, Korea). An immediate postoperative radiograph was taken to confirm a satisfactory filling of the resorptive defect [Figure 6]. Fourty-eight hrs later after checking the set of MTA the access cavity was finally sealed with light cure composite resin (Tetric Ceram, Ivoclare, and Vivadent). Finally, porcelain fused to metal fixed partial denture was placed after 4 weeks.

Figure 3

Intraoral periapical radiograph working length

Figure 4

Intraoral periapical radiograph master cone

Figure 5

Intraoral periapical radiograph immediately after MTA filling in the resorptive defect

Figure 6

Follow up intraoral periapical radiograph after 1 month

The patient was recalled after 3 months and 6 months and the tooth was found to be symptom-free with healthy gingiva. The periapical radiographs also showed satisfactory healing of the apical rarefaction and also formation of a calcific barrier between the perforation and lateral periodontium [Figure 7]. This was further confirmed with 6 month follow up CBCT scan [Figure 8].

Figure 7

Follow up intraoral periapical radiograph after 6 months

Figure 8

Follow-up 3D images showing axial plane

DISCUSSION

Internal resorption is undoubtedly an endodontic challenge, especially, if the resorptive area is extensive and perforating. When diagnosed, immediate removal of the causative agent must be considered, aiming to arrest the cellular activity responsible for the resorptive activity.[16] However, the complex irregularities of the root canal system and the inaccessibility of internal resorption defect provide technical difficulties for thorough cleaning and obturation of the root canal. The persistence of organic debris and bacteria in these areas may jeopardize the long-term success of the endodontic treatment.[17] Therefore, a detailed exploration of the interior of the root canal is necessary for a successful treatment outcome.

Although periapical and panoramic radiography produce acceptable details in the mesio-distal direction, the observation of details in the bucco-lingual direction is inadequate. The severity of internal root resorption cannot be accurately judged from 2D radiographs alone. Recently, CBCT systems (high-resolution 3D images) have attracted considerable attention as a new diagnostic imaging technique in endodontics. The advantage is that CBCT offers a noninvasive reproducible technique for 3D assessment of root canal systems and aids the clinician to visualize the internal anatomy precisely. Several case reports and studies have confirmed the usefulness of CBCT in diagnosing and managing resorptive lesions.[518] Computed tomography is a technique of image acquisition that combines the use of x-rays and computer technology, directing the X-ray beams from different angles to achieve axial section images of the object analysed. The CS 9300 3D Digital Imaging System used in this case gave series of cross sectional views to clearly observe the size and location of the defect. With the axial view the perforation site was detected at the distal wall of the root canal. This is valuable information to decide the treatment plan.[19]

A combined approach involving both hand instrumentation and antibacterial irrigation was performed on the involved tooth. Sodium hypochlorite is the most commonly use irrigant during root canal treatment due to its tissue dissolving and broad antimicrobial properties. Ultrasonic activation of irrigants should be viewed as an essential step in the disinfection of the internal resorption defect.[5] However, even with the use of ultrasonic instruments, bacteria might still remain in confined areas.[7] Chemo mechanical debridement of the root canal space fails to consistently render the root canal system bacteria-free. Thus, an intracanal, antibacterial medicament should be used to improve disinfection of the inaccessible root resorption defects. Calcium hydroxide is antibacterial and has been shown to effectively eradicate bacteria that persist after chemo mechanical instrumentation.[20] Calcium hydroxide has also been shown to have a synergistic effect when used in conjunction with sodium hypochlorite to remove organic debris from the root canal.[21]

Different approaches exist in the treatment of a perforating internal resorption. Root canal therapy combined with surgical correction may be the only option in some cases.[2223] Remineralization therapy with calcium hydroxide to form a hard tissue matrix, against which the root-filling material is condensed, has been advocated by others.[2425] Application of MTA at the perforation site precluded, in this case, the need for surgical intervention or prolonged treatment with calcium hydroxide. MTA provided good sealing of the defect. More importantly, the biologic response to this material was excellent, and complete resolution of the alveolar bone lesion had occurred by the time of a follow-up visit 3 months after the procedure. Indeed, it has been shown that MTA stimulates the propagation of human osteoblasts by offering a biologically active substrate for the cells.[14]

Management of the restoration for an endodontically treated tooth is critical. Furthermore, the longevity of an endodontic treatment is significantly increased by selecting an appropriate restoration that considers saving the tooth structure and preventing reinfection. Adhesive composite resin filling was used for post endodontic restoration. Porcelain fused to metal bridge was then given extending from 45 to 48 to restore function and esthetics.

CONCLUSION

This case report emphasizes on how conventional intraoral radiography provides clinicians with an accessible, cost-effective, high-resolution imaging modality that continues to be of value in endodontic therapy. There are, however, specific situations, both pre- and postoperatively, where the understanding of spatial relationships afforded by CBCT facilitates diagnosis and influences treatment. The usefulness of CBCT imaging can no longer be disputed-CBCT is a useful task specific imaging modality and an important technology in comprehensive endodontic evaluation.