Application of cone-beam computed tomography in the management of dilacerated maxillary central incisor associated with radicular cyst and external root resorption - A case report.

The maxillary anterior region is the most common site for the occurrence of radicular cyst in permanent dentition, because of a high frequency of trauma in this region. As radicular cyst is categorized as an inflammatory cyst, endodontic treatment of the tooth associated with the cyst becomes a part of the treatment regimen. Management of radicular cyst becomes challenging when it involves tooth with complex root morphology. This report presents the diagnosis and successful management of a dilacerated maxillary central incisor associated with a radicular cyst and external root resorption. Cone-beam computed tomography was used to view the extent of the cyst and understand the aberrant root canal morphology of the dilacerated tooth. Root canal therapy was followed by cyst enucleation, apicoectomy, and placement of platelet-rich fibrin. At 1-year recall, appreciable healing as evidenced by a decrease in the size of the radiolucency on the radiographic examination was seen. Copyright:

INTRODUCTION

In children, traumatic injuries in the anterior region are common. Trauma to deciduous teeth can cause secondary injuries to the developing permanent teeth, as the germs of the permanent incisors lie close to the roots of their predecessors.[1] Dilaceration constitutes about 3% of the total injuries to the developing teeth.[2] The term “dilaceration” was first coined by Tomes in 1848.[3] It is defined as an angulation or sharp bend or curve in the linear relationship of the crown of a tooth to its root.[4] It can result when an already formed calcified part of the germ is displaced in relation to the uncalcified part.[5] This disturbance in the root formation usually occurs in children who sustain the injury over 4 years of age (Nolla's Stage 6).[6]

The use of cone-beam computed tomography (CBCT) in the management of anatomically complex cases as in root dilacerations, facilitates accurate assessment of aberrant root canal configuration, degree of calcification, root resorption, and provides the details of associated periapical lesion.

The presence of a large periapical lesion as a radicular cyst in such complex cases necessitated the use of platelet-rich fibrin (PRF), as it facilitates wound healing and tissue regeneration. It initially acts as a biodegradable scaffold that favors the development of microvascularization, guides epithelial cell migration, and serves as a vehicle for carrying cells that are involved in both soft- and hard-tissue regeneration. PRF poses a major advantage through its gradual release of cytokines and growth factors creating a perpetual process of healing.[7]

In this case report, we present the management of a lateral incisor and a dilacerated maxillary central incisor associated with a radicular cyst and external root resorption using CBCT.

CASE REPORT

A 17-year-old boy reported with a chief complaint of pain and swelling in the upper front tooth region, a month after an automobile accident. The pain was dull and intermittent in nature. The patient did not have any contributory medical history. His parents revealed a history of trauma in the same tooth region as a result of a fall at the age of 5 years, following which he had lost his left upper front teeth. The latter trauma history coincides with the root formation stage of permanent maxillary central incisors.

On clinical examination, a unilateral solitary swelling was seen in relation to the upper left front teeth region. The swelling was present on the labial aspect, extending mesiodistally from the mesial aspect of the attached gingiva of tooth #21 to the mesial aspect of the attached gingiva of tooth 23. Superoinferiorly it extended from the mucobuccal fold region to the attached gingiva. The size of the swelling appeared to be around 0.75 cm × 1.5 cm in length and width. The swelling was ovoid, with consistency being soft and fluctuant [Figure 1a]. On percussion, there was tenderness, and Grade 1 mobility in #21, 22. Thermal and electric pulp sensibility testing of #21, 22 showed no response. Although there seemed to be periapical rarefaction present with the mesial aspect of 23, the assessment of percussion, mobility, thermal, and electric pulp sensibility assessment of 23 were found to be normal in all regards. A provisional diagnosis of a periapical abscess was made in #21, 22.

Figure 1

(a) Preoperative clinical picture of an intraoral swelling. (b) Intraoperative picture showing the extent of bony defect after cyst enucleation. (c) Bony defect filled with platelet-rich fibrin. (d and e) Intraoperative picture showing collagen membrane and suture in place. (f) Postoperative picture taken after a week showing uneventful healing. (g) Histopathological section of radicular cyst showing lining of stratified squamous epithelium with connective tissue entrapped within it (arcading pattern)

On an intraoral periapical radiograph, root resorption and a periapical lesion were seen in #21, 22. The root dilaceration in #21, oriented in the buccolingual direction appeared as a round opaque region with a radiolucent area in its center (bull's eye appearance)[8] [Figure 2a]. Although angulated radiographs were taken, the exact anatomy of the tooth could not be appreciated. To ascertain the variations in tooth anatomy and its root canal system, dental imaging with CBCT (Carestream 9300 scanner, Rochester, NY) at a resolution of 0.09 mm × 0.09 mm × 0.09 mm for the affected region was made to view the size and extent of the lesion threedimensionally. Sectional CBCT showed a well-defined radiolucent lesion involving the periapices of #21, 22 with size 8.3 mm × 11.7 mm × 8 mm in length, width, and breadth with well-defined sclerotic borders. On the sagittal section, erosion of the labial cortical bone was seen in #21, 22. External root resorption was evident on the apical third of #21, 22 [Figure 2b and c]. Based on the clinical and radiographic findings, a final diagnosis of the radicular cyst was made, with a differential diagnosis being a dentigerous cyst. In addition, root dilaceration was noted in the buccolingual direction in #21 [Figure 2b-e].

Figure 2

(a) Preoperative intraoral periapical radiograph showing periapical lesion and external root resorption involving 21, 22. (b) Cone-beam computed tomography showing the extent of the cyst, dilacerations and resorption with 21. (c) Extent of the cyst on coronal view. (d and e) Axial view showing dilaceration in the bucco-lingual direction. (f) Sagittal view showing pulp chamber calcification with 21. (g-j) Comparative images of immediate postoperative radiograph, 3, 6 and 1 year shows depicting the progressive healing

The treatment plan was discussed with the patient, and a written consent form was obtained from both the parents and the patient. In the first appointment, the teeth were stabilized using a composite wire splint. The #21, 22 were anesthetized with an infraorbital nerve block using 2% lidocaine with 1:80,000 epinephrine (Lignox 2% A, Indoco Remedies Ltd).

Endodontic treatment of #21, 22 was performed under rubber dam (Coltene/Whaledent, OH, USA) isolation, under magnification and illumination (STAC loupes × 3.5, Analytical Medical Technologies, India). Access cavity was prepared using a no. 2 round bur. An Endo Z Bur (Dentsply Maillefer, Ballaigues, Switzerland) was used for deroofing of the pulp chamber.

The root canal of #21 was difficult to locate as the pulp chamber was calcified [Figure 2f]. An ultrasonic Start-X™ #1, #3 (Dentsply Maillefer) was introduced with a piezo ultrasonic generator (EMS MINIPIEZON) for refinement of the access cavity walls and to displace the calcified mass obstructing the canal orifice.

Pulp tissue was extirpated by a barbed broach (Dentsply Maillefer,). Root canal preparation was done using both crown-down and step-back techniques. Coronal two-third of the root was prepared with HyFlex™ Controlled Memory system (HFCM; Colte'ne/Whaledent, Allstatten, Switzerland). Working length (WL) was determined using an electronic apex locator (Dentsply Propex Pixi, Dentsply Maillefer, Ballaigues, Switzerland) and was confirmed radiographically; The WL of #21, 22 were 23 and 20 mm respectively. The root canals were cleaned and shaped with the K Flexi file (Mani Inc, Tochigi-Ken, Japan), Ni-Ti K files and HyFlex™ Controlled Memory system, up to a size of 0.04/25 for #21 and 0.06/40 for #22.

The manual dynamic activation method of irrigation was followed. Application of short gentle strokes by insertion of a well-fitting guttapercha cone to the WL of a previously shaped canal was done to hydrodynamically activate the irrigant. 2.5 ml of 2.5% NaOCl was flooded in the canal and push-pull strokes were manually performed to the WL at an approximate rate of 100 strokes/min for 30 s. For the next 30 s, the above cycle was repeated with 2.5 ml of 2.5% NaOCl, followed by 17% ethylenediaminetetraacetic acid (EDTA), thereby activating each irrigant for a minute with a total volume of 5 ml/irrigant.

Final irrigation of normal saline and chlorhexidine (2%) was followed after copious irrigation with sodium hypochlorite and EDTA. Calcium hydroxide dressing (Metapex, Meta Biomed Co., Ltd, Korea) was placed after drying the canals with paper points, and the access cavities were closed using Cavit G (3M ESPE).

A day later, in the second appointment, after the removal of the dressing, obturation was done using cold lateral compaction technique, with gutta-percha of size 0.04/25 for #21 and 0.06/40 for #22 (Colte'ne/Whaledent), and bioceramic sealer (ANGELUS BIO-C SEALER). The access cavities were temporarily sealed with Cavit G, and periapical surgery was initiated to manage the radicular cyst. To obtain a mucoperiosteal flap, a sulcular incision along the gingival margin from 11 to 23, a vertical incision distal to tooth 11, and a distal to tooth 23 were made. The buccal cortical plate was eroded in relation to 22. The cyst was completely enucleated, and the enucleated cystic lining was preserved for histopathological examination. Periradicular curettage was thoroughly performed and the apical 2–3 mm of the root was resected in both teeth using a multipurpose bur (Dentsply Maillefer). The angle of the root-end resection was kept perpendicular to the long axis of the teeth. After curettage and apicoectomy, the bony defect was copiously irrigated with betadine and saline [Figure 1b]. The root end cavity was prepared to a depth of 3 mm along the long axis of teeth with an FG34 inverted cone bur (SS White Burs, Inc, Lakewood, NJ). To attain a sound periapical seal in relation to 21 and 22, Mineral Trioxide Aggregate (ProRoot MTA; Dentsply Tulsa Dental, Tulsa, OK) was used as a retrograde filling material. Meanwhile, 10 ml of blood was drawn into a test tube and centrifuged immediately for 12 min at 3000 rpm, using a REMI centrifuge machine (Model R-8c, 12 × 15 mL swing-out head) to obtain PRF. The serum obtained was expelled, and the PRF was placed in the intrabony defect [Figure 1c]. A collagen membrane (Healiguide; Advanced Biotech, Chennai, Tamil Nadu, India) was placed on the labial window, the flap was gently repositioned and sutured with 3-0 size silk suture material [Figure 1d and e]. Postoperative instructions were given to the patient, and a course of analgesics and antibiotics was prescribed. The patient was asked to use chlorhexidine gluconate (0.12%) mouth rinses for 30 s two times a day until the sutures were removed.

After 2 weeks postoperatively [Figure 1f], splinting was removed and the access cavities were restored with a universal composite resin restorative material (3M, ESPE). The tissue sent for histological examination revealed the presence of a thin layer of nonkeratinized stratified squamous epithelium, with mixed inflammatory infiltration in both the connective tissue and epithelium. Histopathological findings confirmed the diagnosis of radicular cyst in relation to 21 and 22 [Figure 1g]. At recall visits of 3 months, 6 months, and 1-year, healing as evidenced by an appreciable decrease in the size of the periradicular radiolucency was seen [Figure 2g-j].

DISCUSSION

In the course of exarticulation, the root curvature of the primary tooth provokes a slight rotational movement to injure the bud of the successor permanent tooth.[2] The parents revealed a history of trauma to the patient at his 5 years of age, during which he had lost his upper front tooth. The trauma history coincides with the root formation stage of permanent maxillary central incisors and supports for the cause of dilaceration associated in relation to 21.

External inflammatory root resorption occurs when an inflammatory response develops immediately within the periodontal ligament and bone as a result of luxation injuries to teeth. The elicited inflammatory response activates the clastic cells to cause root resorption, as the precementum and the cementoblasts on the root surface are either damaged or removed during trauma.[9] The resorption in the present case could also be due to a long-standing infected root canal system. The existing inflammatory stimulus in the periradicular region results in the proliferation of the epithelial cell rests of malassez, thereby initiating the formation of a radicular cyst.[10]

PRF was considered to regenerate both, the hard and soft tissues. PRF was first introduced by Choukroun et al. in 2001.[11] The preparation of PRF requires neither anticoagulants nor bovine thrombin.[12] PRF is a naturally derived concentrate of white blood cells, platelets, and fibrin.[13] Leucocytes play a key role in wound healing because of their anti-infectious action as well as immune regulation via the secretion of immune cytokines such as interleukin (IL)-1β, IL 6, IL-4, and tumor necrosis factor-alpha. Platelets and macrophages in PRF secrete a large number of growth factors that include transforming growth factor-β1, platelet-derived growth factor, vascular endothelial growth factor, and insulin-like growth factor-I that are capable of promoting cell migration, proliferation, and differentiation.[14] A study done by Dar et al. to evaluate the efficacy of PRF in osseous regeneration in 20 cases of cystic lesions revealed progressive, predictable, and significant radiographic osseous regeneration within 6 months postoperatively.[15] A systematic review by Joshi et al. showed that the combination of MTA + PRF in periapical lesions resulted in a faster and definite periapical lesion healing. The use of MTA provided a good apical sealing ability because of the release of calcium and hydroxyl ions from the set matrix.[16] The osseous regeneration in the present case can be attributed to the regeneration potential of the PRF membrane [Figure 1f].

CONCLUSION

Thorough extraction of case history provides a great deal in interpreting and managing cases of trauma. The use of naturally obtained PRF in the treatment of cystic lesions promoted healing and osseous regeneration. By establishing a correct diagnosis with the aid of CBCT, and adhering to the basic principles of endodontic treatment, a complex case can be successfully managed.

Declaration of patient consent

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

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.