External root resorption is a progressive and destructive loss of tooth structure initiated by a mineralized or denuded area of root surface1,2 and is considered as a major resorptive condition without symptoms.3 The process involves interplay of inflammatory cells and hard tissue structures.
It is known to be initiated and maintained by many factors,1,4,5 but pulpal necrosis, trauma, periodontal treatment, endodontic treatment, and tooth whitening agents are the most commonly described stimulants.6 Apart from local causes, systemic factors are involved in the etiology of external root resorption.7 Hyperparathyroidism, hypertension, and genetic disorder mainly contribute for the same.
Resorptive lesions can be most simply classified as external or internal. There have been many attempts at classification, of which the system proposed by Andreasen8 is widely acknowledged (Flow Chart 1).
Of the several types of external root resorption, the most common is the external inflammatory root resorption.9,10 If the resorptive defect is progressive and lead to communication between the oral cavity and root canal, surgical intervention11-14 will be necessary to remove the granulation tissue, to debride and repair the defect, and even to enable endodontic therapy.
A 13-year-old male patient reported to the Department of Conservative Dentistry and Endodontics, with a chief complaint of broken upper front teeth. The tooth had suffered previously from a traumatic injury 2 years back. His medical history was noncontributory.
On examination, Ellis class II fracture was noted in relation to 21 along with deep periodontal pocket of 13 mm with respect to mesiobuccal aspect of 21. Other findings included grade I mobility of 21 and pain on vertical percussion for both 11 and 21. Vitality tests revealed nonvital 11 and 21.
PREOPERATIVE RADIOGRAPHIC FINDINGS
Intraoral periapical Radiograph
The intraoral periapical radiograph revealed several resorptive bowl-shaped lesions on the external root surface of 21 combined with a radiolucent lesion around root apex of the involved tooth. Lesions were visible along entire root length of 21 extending along both mesial and distal root outlines, more marked with respect to mesial aspect. Apical periodontal widening was noted with respect to root of 11 (Fig. 1A).
Cone Beam Computed Tomography
Cone beam computed tomography (CBCT) has found vast application in the field of endodontics, particularly in resorption where it acts as an invaluable diagnostic aid in assessing the three-dimensional (3D) orientation and extent of resorptive lesion.15-18 The 3D extent of the lesion was precisely determined using the various sections of CBCT (3D, Planmeca, Proface). Coronal section revealed resorption involving mesial and distal root outlines along the entire root length and with irregular borders. The lesion communicates through and through at the junction of middle and apical third. Sagittal section shows bowl-shaped resorptive lesions along buccal and palatal root borders. This lesion communicates with root canal at apical third. Periapical radiolucency is evident in sagittal section. Buccal cortical plate discontinuity was observed in axial section (Fig. 1B).
Possible therapeutic procedures were discussed with and explained to the patient and it was decided to proceed with a combined endodontic, surgical, and restorative therapy. The treatment goals pertaining to the case included retaining the tooth, endodontic treatment and restoration of the radicular defect, regeneration of osseous deformity, and improved stability and esthetics.
Conventional root canal therapy was the choice of treatment for 11. The root canal of 21 was negotiated with No. 10 K file and was debrided under rubber dam isolation. The canal was cleaned and shaped in a crown-down approach. Chlorhexidine being relatively nontoxic was used as irrigant. Calcium hydroxide (Metapex, METABIOMED Co. Ltd) was placed in the canal for 1 month.
Preliminary hematological investigations were done followed by thorough oral prophylaxis. Surgical site was anesthetized using 2% lignocaine and 1:80,000 adrenaline (Lignox 2% A, Warren, Indoco Remedies).
Crevicular incision was placed extending from distal aspect of 11 to distal aspect of 22. Vertical-releasing incisions were placed at the ends of crevicular incision. Full-thickness mucoperiosteal flap was reflected. Curettage of granulation tissue replacing the buccal cortical plate and occupying the resorption lacunae was performed. Resection of apical 5 mm of root segment was done to eliminate the lateral canals as well as resorptive lesion extending palatally, which were deemed unrestorable. The resected radicular margins were smoothed with a round bur while constantly irrigating with saline.
The resorptive site was sealed and the entire root canal was obturated using Biodentine™ (Septodont, Saint-Maur-des-Fosse's, France) which was mixed according to the manufacturer's instructions.
Freeze-dried demineralized xenograft (Osseograft, Advanced Biotech, India) was placed for osseous regeneration. Over this, bioresorbable collagen barrier membrane (Healguide, Advanced Biotech, India) was placed. Platelet-rich fibrin (PRF) which was prepared according to Choukroun's protocol further covered the membrane. The gingival tissue was stabilized using simple interrupted sutures and periodontal pack was placed (Coe Pack).
Patient was prescribed analgesics, antibiotics (Amoxicillin 500 mg thrice daily for 5 days), 0.2% chlorhexidine mouthwash, and was advised soft diet. He was reviewed after 24 hours to evaluate presence of bleeding and intactness of sutures and pack (Fig. 2).
Even though a wide variety of factors are deemed to be causative for external root resorption, the most common is trauma, particularly in cases where injury results in pulpal necrosis and damage to root surface. Bacteria, bacterial by-products, and tissue breakdown products from within the root canal system stimulate inflammation in the adjacent periodontal tissue and lead to aggressive and progressive resorption of defect leading to external inflammatory root resorption.6
The diagnosis of external inflammatory root resorption has always been a dilemma in the field of endodontics. Newer diagnostic modalities like CBCT have added precision in determining the 3D orientation and exact extent of resorptive lesions.
Since its introduction, calcium hydroxide has been widely used in the treatment of external root resorption.19 It is a strong alkaline substance with a pH of 11 to 13. It also has antimicrobial activity and tissue-dissolving ability,20 inhibits resorption,1 and induces repair by hard tissue formation.21,22
Biodentine is a novel tricalcium silicate-based material with setting time of less than 12 minutes, high mechanical strength, and excellent sealing ability. The calcium hydroxide ions stimulate the release of pyrophosphatase, alkaline phosphatase, and bone morphogenetic protein 2, which enhances mineralization.23
This biointeractive material is a fast-setting alternative to conventional calcium silicate mineral trioxide aggregate (MTA)-like cement and does not require a two-step obturation unlike MTA. It also has a better consistency after mixing and offers ease of placement.23 Zhou et al24 have stated that this material can be safely used in procedures requiring close approximation with the periodontal tissue.
Two percent chlorhexidine was used as irrigant as it is placed to be more effective against Enterococcus faecalis than sodium hypochlorite.25 Use of osseograft which is osteoconductive along with collagen membrane and PRF enhances the regenerative potential.26
External root resorption jeopardizes the longevity of a tooth, causing its early loss. Therefore, early diagnosis is extremely crucial in the management. Sooner the treatment is done, less severe will be the long-term consequences of resorption. This defect demands intervention irrespective of etiology.