Author: Dr.Vijay Kumar.
G- 9/10, 2nd Floor, Malviya Nagar, New Delhi



Abstract:
Internal root resorption following trauma to permanent teeth is a rare finding. Damage to the internal protective layer and inflammatory reaction adjacent to it leads to resorptive process. Since the process is asymptomatic, it is diagnosed on routine radiographs. The internal resorption perforating the root and communicating with the periodontal tissues poses a treatment challenge to clinicians. This paper presents the management of internal root resorption with literature review and a case report.

Introduction:
Resorption of the root of a permanent tooth is a pathological process that occurs on inner (internal resorption) or the outer surface (external resorption) of the tooth and can ultimately lead to loosening of the tooth and its early loss. Alteration in the protective attachment layer (predentin internally and pre cementum externally) and the presence of inflammatory process adjacent to the altered root surface are essential for root resorption to occur.

Internal root resorption (intracanal root resorption) is a rare entity with prevalence rate of only 2%.¹ This pathologic process is generally asymptomatic and diagnosed on routine radiographic examination.² AAE defines it as “pathologic process initiated within the pulp space with loss of dentin”.³ The exact etiology of the process is not known ^2,3 Although trauma, persistent chronic pulpitis,⁴ heat produced during cavity cutting,⁵ orthodontic therapy⁶ and recently the mutation in IL-1RN gene⁷ are suggested to be associated with internal root resorption.  It is caused by transformation of normal pulp tissue into granulation tissue.^2,8 Damage to the odontoblasts lead to the compromise in the integrity of predentin and exposes the intraradicular dentin.⁹ The osteoclasts and macrophages converted from undifferentiated cells of pulp after inflammation gets activated and causes the resorption of intraradicular dentin.¹⁰

Although internal resorption can occur at any level in root canal space, it is more prevalent in cervical area of tooth^11,12 where it presents as “pink spot”.¹³ Ingrowths of granulation tissue gives the crown portion a pinkish colour, known as “pink tooth of Mummery”.¹⁴ The radiographic features include the large, round or oval defect, often symmetric with the shape of ampoule in the pulp space.^15,16 The border are in continuity with the root canal and the defect remains stationary with change in angulations of radiographs.¹⁷ Presence of vital pulp tissue is essential for internal root resorption to take place and the pulp vitality tests generally shows a positive response.¹⁸ The negative vitality response can be seen after necrosis of coronal pulp or complete necrosis of pulp after the active resorption process has took place.¹⁹ The treatment involves endodontic therapy to remove the blood supply and arrest the resorption process.18 This case report presents a case of internal root resorption with periapical pathology successfully treated with conventional endodontic therapy.

Case report:
A 55 year old woman reported to the department of conservative dentistry and endodontics with pain related to right upper front tooth from past one week. Clinical examination revealed the fractured crowns of teeth # ^11,21 involving enamel and dentin. Tooth # ¹¹ was tender to percussion and palpation with grade I mobility. Intraoral periapical radiograph showed resorptive area in cervical third of root canal of tooth ¹¹ and loss of apical lamina dura with periapical radiolucency of approximately 10 x12mm in dimensions (figure 1). The electric pulp vitality test failed to elicit any response. A diagnosis of internal inflammatory root resorption with apical periodontitis was established on the basis of clinical and radiographic findings.

Figure 1: Pre operative radiograph showing internal root resorption and periapical radiolucency in right maxillary central incisor (tooth # 11)	Figure 2: Intra operative radiograph showing apical sectional root canal filling with gutta percha in tooth # 11	Figure 3: Immediate post operative radiograph showing complete obturation of root canal and internal resorptive defect with thermo plasticized gutta percha in tooth # 11	Figure 4: Follow-up radiograph showing arrest of resorptive process with complete periapical healing in tooth # 11

After local anaesthic administration, the access opening was made using round and tapered fissure burs. Tooth was non vital with necrotic pulp. The root canal was copiously irrigated with 2% sodium hypochlorite before instrumentation. The working length was established by apex locator and confirmed by radiograph. Apical preparation was done up to ISO size 70 k-files using step back technique. The resorption defect was circumferentially filled with H-files along with NaOCl irrigation for complete removal of the necrotic tissue remnants. After preparation the root canal was dried and Ca(OH)2 paste as an intracanal medicament was placed for 15 days.

In the next appointment, patient was relieved of her pain and was asymptomatic. The Element obturation system (SybronEndo, Orange, CA, USA) and calcium hydroxide based sealer (seal apex, Sybron-Kerr, Romulus, MI, USA) was used for obturation. First the apical filling was done up to the resorption defect and backfilling was completed with thermo plasticized gutta percha using the extruder (figure 2, 3). The access opening was sealed with glass ionomer cement and aesthetic build up of the fractured teeth was done with composite.

At the 6 month follow up, patient was asymptomatic and with no clinical signs of inflammation. The follow up radiograph showed arrest of resorption process and healed periapical radiolucency with re-establishment of apical lamina Dura (figure 4).

Discussion:
Precementum and predentin are the protective layers of tooth and damage to these leads to external and internal root resorption respectively.¹² Metaplasia of cells is seen as cause of internal replacement root resorption where the resorption defect is replaced by bone and connective tissue.² Some authors suggested the role of periodontal tissues in the internal resorption defects. The polymorphism of IL-1 gene presents a significant risk factor for development of pathologic root resorption process and mutation in IL-1RN gene has been reported as cause of idiopathic internal root resorption in monozygotic twins.⁷ In our case, trauma to the maxillary right central incisor leads to the damage to predentin and continuous irritation through exposed dentinal tubules after crown fracture had initiated inflammatory internal root resorption.

Usually the patient is asymptomatic and internal resorption is often diagnosed on routine radiograph.² Symptoms develop only after the pulpal necrosis when the infection reaches the periapical area resulting into symptomatic apical periodontitis or if the resorptive process results into a communication with external tooth surface, which forced the patient to visit dentist. Sodium hypochlorite, because of its antibacterial and tissue dissolving abilities is used to remove the inflamed tissue that can’t be removed with instrumentation. Calcium hydroxide dressing was used to control the infection and for disinfection of root canal.

Large lesions cause the reduction in the resistance of the tooth to the shear forces that may lead to the tooth fracture.^17,20 Filling the resorption defect with dual cure resin was suggested to improve the sealing and to strengthen the tooth structure, ²¹ but such an approach may pose difficulty in root canal retreatment, if the endodontic therapy fails. Warm vertical condensation may cause root fracture in the weekend root structure²² hence the hybrid technique was used for root canal filling where thermo plasticized gutta percha passively filled the entire resorption defect.

In the perforating root resorption, sealing the communication is a challenge. Various material have been used but with inherent drawbacks of leakage and biocompatibility. MTA is a good option for treating the perforating resorption because of its excellent sealing, biocompatibility, bactericidal effect and ability to set in the presence of blood. ^8,23

Conclusion:
Internal root resorption can be successfully managed by thorough debridement of root canal and disinfection by sodium hypochlorite and calcium hydroxide. Thermoplasticized gutta percha provides a good option for three dimensional obturation of a non perforating internal root resorption defect.

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