Management of External Root Resorption Associated with a Replanted Maxillary Central Incisor in an 11-Year-Old Patient: A Rare Case Report

Introduction

Avulsion contributes to 0.5%-16% of all dental injuries in permanent teeth and it is one of the serious injuries that require immediate attention.¹ The prognosis of the replanted tooth mainly depends on extraoral dry time, viable periodontal ligament cells, and the medium in which the avulsed tooth was stored.² Immediate replantation is the treatment of choice and is the most significant factor in periodontal ligament (PDL) healing^.3 Replantation of avulsed tooth improves aesthetics, occlusion and function.⁴ When immediate replantation of the tooth with viable periodontal ligament cells is advocated, the repair may occur with periodontal ligament fiber reattachment. However, if the extraoral dry time is prolonged, death of PDL cells will take place and result in the pathological resorption of roots.⁵ Most common complication of a replanted tooth is inflammatory external root resorption which is seen in 89% of replanted teeth. Replacement resorption/ ankylosis is also frequently associated with the replanted teeth. External inflammatory root resorption following dental trauma is due to a rise in pH from 3 to 4.5 and increased osteoclastic activity.⁶

Mineral trioxide aggregate (MTA) is a mixture of Portland cement (75%), bismuth oxide (20%), and gypsum (5%).⁷ It also contains trace amounts of CaO, SiO2 , K2 SO4, MgO, and Na2 SO4. The major ingredient Portland cement contains a mixture of dicalcium silicate, tricalcium aluminate, tricalcium silicate, and tetracalcium aluminoferrite. The powder is mixed with water to form a slurry that gradually hardens in the oral environment.7 Soluble-fraction of MTA mainly consists of calcium hydroxide and water. MTA maintains high alkaline pH (11-12) for a long period of time that establishes a favourable environment for cell division and matrix formation. MTA has a potent antimicrobial activity due to the presence of calcium hydroxide, which aids in the initial disinfection of the root canal.⁸ The purpose of this article is to report the successful management of inflammatory external root resorption associated with a replanted maxillary incisor using MTA with one year follow-up in an 11-year-old girl.

Case Presentation

An 11-year-old girl reported to the Department of Pediatric dentistry with avulsion of right maxillary central incisor due to self-fall. The patient gave a history of trauma two hours before and the parents brought the tooth wrapped in paper as they were not aware of any storage media. The tooth was immediately cleaned with a stream of saline to remove debris and was kept in milk until replantation.¹ The medical history revealed no associated concomitant systemic diseases. On intraoral examination, an empty alveolar socket was noted in relation to tooth 11 and Elli’s class III fracture with pinpoint pulp exposure and grade-II mobility in relation to 21 (Figure 1). Minor laceration injuries were observed on the lower lip. Parents were informed about the possible consequences of delayed replantation, the procedure was explained and consent was obtained. An extra-oral endodontic treatment was planned before the replantation of the tooth.⁹ After access opening and biomechanical preparation, the tooth was obturated with gutta-percha points. Local anesthesia without a vasoconstrictor was administered and the socket was rinsed gently with sterile saline. Tooth #11 was replanted in position and stabilized with a passive flexible wire and composite resin splinting (Figure 2). Direct pulp capping treatment using calcium hydroxide was performed with respect to tooth #21. Amoxicillin antibiotics and analgesics were prescribed and 0.2% chlorhexidine gluconate mouthwash was advised to maintain good oral hygiene. A tetanus booster dose was advised for the patient. The patient was asked to take soft diet for two weeks.^1,9

At the two-week recall visit, the patient was asymptomatic and the splint was removed during this visit. Inflammatory external root resorption was noticed with respect to both the central incisors 11 and 21 as seen in the panoramic radiograph (Figure 3). Vitality test and test cavity with 21 showed non-vitality of the tooth. Hence, retreatment was planned for both 11 and 21 teeth to stop further external root resorption. Guttapercha points were removed from tooth #11 followed by thorough irrigation of root canal system. Access opening, pulp extirpation and root canal irrigation were done in relation to tooth #21. The root canals were dried with absorbent paper points and a double antibiotic paste made from ciprofloxacin 500 mg and metronidazole 400 mg (1:1) was placed in the root canals of 11 and 21 up to the working length.¹⁰ The access cavity was sealed with a temporary restorative material (Cavit-G, 3M ESPE, St Paul, MN, USA). After ten days, the intracanal medicament was flushed with saline irrigation. The root canals were dried using absorbent paper points. The root canals were completely obturated with mineral trioxide aggregate (Pro Root, Dentsply/Tulsa Dental, USA) which was mixed according to the manufacturer’s instructions and placed in the canals using MTA carrier. A moist cotton pellet was placed at the root canal orifice followed by sealing with temporary restoration (Figure 4). The patient was recalled after 24 hours and the cotton pellet was removed and the access cavity was restored with glass ionomer cement. The fractured segment of teeth #11 and #21 was restored with composite resin in subsequent visits (Figure 5). The patient was followed up periodically at 3, 6, and 12 months. Periapical radiographs were taken during the follow-up visits and complete arrest of external root resorption was observed at a 6-month follow-up visit (Figure 6). The patient was asymptomatic and on percussion, the teeth showed no ankylotic tone. Intra-oral periapical radiograph and cone-beam computed tomography (CBCT) were done at 12 months follow-up visit which showed good periapical healing along with new bone formation (Figure 6). Thus, the replantation was successful and inflammatory external root resorption was arrested. The patient will be followed up periodically for the next four years.

Discussion

In the exarticulation of teeth, both the pulp and periodontal ligament (PDL) suffers severe damage and the repair of the replanted tooth depends on a combination of several factors.¹⁰ Immediate replantation is one of the most important factors that contribute to PDL healing. On prolonged extraoral dry time, all three types of resorptions have been reported, namely surface resorption (4.5%), inflammatory external root resorption (30%), replacement resorption/ankylosis (61%).³ More mature the root development, thinner the PDL cell layer on the root surface and it cannot tolerate even the short extra-oral dry period resulting in the initiation of root resorption.³ In this study, only 25% of teeth showed normal PDL healing.³ Another study reported inflammatory external root resorption to be 84.9% of the pathological resorptions and severity of trauma was the major relevant factor contributing to the initiation of root resorption. External inflammatory root resorption starts at the earliest when compared to replacement resorption.² Al Kahtani A11 reported initiation of inflammatory external root resorption at two weeks after replantation. Even in the present case report, initiation of inflammatory external root resorption was observed as early as two weeks after replantation.

In the majority of the cases, an avulsed tooth is replanted with prolonged extraoral dry time without placing in a proper storage media which results in the destruction of PDL cells. This will lead to unwanted sequelae of external root resorption, exposing the root canal filling material.³ Several management protocols have been recommended in the past based on the maturity of the apex and timeliness of initial care.^12,13 Conventional methods include immediate replantation followed by long-term placement of calcium hydroxide in the root canals,^12,13 root surface treatment with antibiotics;¹² other methods include use of enamel matrix protein14 or bisphosphonates.¹⁵ Avulsion of tooth involving immature apex with short extra-oral time can be managed by immediate replantation followed by periodic assessment of tooth vitality.^12,13 In case of prolonged extra-oral time, long-term placement of calcium hydroxide in the root canals is recommended to prevent inflammatory root resorption because of its good biological properties.^12,13 However, there are a few drawbacks associated with calcium hydroxide which include long treatment duration,¹⁶ need for frequent change of dressings,¹⁶ weakening of the dentinal structure, and crown fracture after prolonged intracanal therapy due to its strong alkalinity.¹⁷ 

Mineral trioxide aggregate is a tricalcium mineral complex and a bioactive material.¹⁸ On contact with tissue fluid, MTA releases calcium ions which react with hydroxyapatite. Hydroxyapatite precipitation takes place on the surface and continues internally into the MTA due to its porous nature and thus changes the overall composition of MTA adjacent to dentine. The apatite layer over the MTA is responsible for the chemical bonding to radicular dentine. MTA chemically bonds to dentin through a diffusion-controlled reaction that takes place between apatite crystals and dentine. MTA in contact with the biological environment stimulates the calcification process consisting of hydroxyapatite and calcium-containing materials. Biocompatibility, sealing ability and dentinogenic activity is the result of these physio-chemical reactions.⁷ MTA showed less inflammatory reactions and intense bone formation on contact with periodontal tissues.¹⁸ Epithelial attachment was noted at the cementoenamel junction in the teeth which were obturated with MTA.¹⁸ Therefore it is recommended as root canal filling material to prevent inflammatory root resorption in replanted teeth.¹⁸

In the present case, MTA was used as a root canal filling material in treating the replanted tooth with inflammatory external root resorption. At three months follow-up, the root resorption had stopped and by the end of six months, new bone formation was observed in the periapical region and interdental area. Limitations of mineral trioxide aggregate as root canal filling material are as follows.¹⁰ Physical properties make it difficult to handle during the placement of MTA into the root canals using MTA carrier. It is very difficult to remove MTA if endodontic retreatment is needed.¹⁹ Some amount of crown discoloration is observed with both white and grey MTA.¹⁰ Higher cost factors are associated with MTA compared to calcium hydroxide. The other disadvantage is the artifacts seen in the follow-up CBCT images that hinder the diagnosis in many clinical conditions. These are the streak effects that are produced through-beam hardening phenomenon when photons are diffracted from their original path after interaction with matter.²⁰ The artifacts seen in the CBCT images of the present case are also due to MTA material (Figure 6). However, periapical tissue biocompatibility makes MTA as the material of choice to prevent external root resorption in delayed tooth replantation.¹⁰ Aggarwal et al.,¹⁰ reported a similar case of successful management of a replanted tooth with severe inflammatory root resorption using MTA with four years follow-up. The high alkaline pH of MTA and the wider dentinal tubules are the advantages for the deactivation of inflammatory root resorption and odontoclastic activity.¹⁰ Another case report of an avulsed immature tooth which was successfully managed by replantation and root canal obturation with MTA with 12 months follow-up has shown successful arrest of inflammatory root resorption.¹¹

Conclusion

In the successful management of avulsed teeth where extra-oral dry time is prolonged and inflammatory root resorption is anticipated, root canal obturation with MTA is the preferred and beneficial treatment option to prevent inflammatory root resorption.