RestorativeDentistryZaid Al-Momani Peter J Nixon Internal and External Root Resorption: Aetiology, Diagnosis and Treatment Options Abstract: Root resorption is a pathological process that may occur after surgical, mechanical, chemical or thermal insult. Generally, it can be classified as internal and external root resorption. Depending on the diagnosis, an orthograde, surgical or a combined approach is used in management of these cases. Clinical Relevance: General dental practitioners can face difficulties in diagnosis and treatment planning for cases with root resorption. An understanding of the aetiology and pathogenesis of root resorption is critical for diagnosis, effective management and improves outcome. Dent Update 2013; 40: 102–112 Root resorption is a pathological process that is not uncommon after injuries or irritation of periodontal ligament or pulp.1 Such injuries may result from surgical, physical, chemical or thermal insult. Resorption may also occur due to mechanical stimulation, infection or neoplastic disease. Osteoclast activating factor; Macrophage chemotactic factor; Prostaglandins, heparin and bacterial products. Preventive factors acting on dentinoclasts include: anti-invasion factor and the intermediate cementum layer.2 Injuries and irritations may stimulate activating factors or reduce preventive factors, hence dentinoclasts may become activated and subsequent root resorption may occur. Root resorption continues as long as the simulating factor is present. The stimulating factor could be mechanical stimulation, pressure, infection, neoplastic process or a combination of any of these factors.3,4 Once the stimulating factors are removed, root resorption may be arrested. Cementum and dentine may form again, depending on the severity of the damaged surface area. type of resorption, the following issues need to be addressed to reach a treatment plan: Will the resorptive process be self limiting or does it require further intervention?; If the resorptive process is progressive (as observed from assessment over time), what treatment options can we provide?; If treated, what are the short- and longterm prognoses?; When is extraction and prosthetic therapy indicated? The following section will discuss the signs and symptoms, clinical and radiographic presentations of each type of root resorption. This will be followed by clinical examples on the management of root resorption. Pathogenesis The result of this process is loss of hard dental tissues (ie cementum and dentine) by dentinoclastic cell action. The function of dentinoclasts is controlled by various activating and preventing resorption factors. Activating factors include: Zaid Al-Momani, BDS, MFDS RCSEd, MDentSci(Rest Dent), Specialist Registrar in Restorative Dentistry and Peter J Nixon, BChD(Hons), MFDS RCSEd, MDentSc, FDS(Rest Dent) RCSEd, Consultant in Restorative Dentistry, Restorative Department, Level 5, Leeds Dental Institute, Clarendon Way, Leeds LS2 9JT, UK. Internal resorption The process of internal resorption occurs in chronic pulpal inflammation and less commonly after dental trauma or due to dystrophic idiopathic changes.5 In this process the pulp tissues coronal to the lesion become necrotic. In order for the internal resorption to progress, both dentinoclastMarch 2013 Classification Classification of root resorption has an important role in the process of diagnosis and treatment planning (Figure 1). In addition to classifying the 102 DentalUpdate RestorativeDentistry Figure 1. oval or elongated within the root or crown and continuous with the image of the pulp chamber or canal.5 Clinical presentation External inflammatory resorption usually occurs when infection is superimposed on a traumatic injury. External resorption External inflammatory resorption Figure 2. This activates the dentinoclast cells which results in resorption of both tooth and bone.6 If internal resorption is in the mid/apical third of the root. round. teeth that are actively continuing to resorb internally must be connected to the blood supply of the apical vital tissues. In most cases of internal root resorption the tooth is asymptomatic. Classification of root resorption. this type of resorption appears as an irregular area of resorption involving loss of both tooth structure and adjacent alveolar bone (Figure 3). External cervical root resorption: irregular area of resorption involving loss of tooth structure on UL2. it is for the most part clinically silent and would normally be diagnosed radiographically. Signs and symptoms Clinically.10 Radiographic features Figure 3. activating factors and the cells viable to keep the resorptive process going must be present.7 Radiographic features Teeth could be asymptomatic or have signs of irreversible pulpitis or necrotic pulp. Damage of the cementum layer will initiate this resorption. Hence. Signs and symptoms as a result of an irregular widening of the canal of the pulp8 (Figure 2). however. a history of pulpal symptoms may be a feature as the pulp is involved first. if the internal resorption is in the cervical/coronal part of the tooth. If the pulp succumbs completely and periradicular tissues become inflamed. exposing the underlying dentine to the passage of bacteria or their metabolites to the external root surface. Internal resorption on UL1. tooth mobility or periodontal defects. it may present as a pinkish hue because of the prolific capillaries in the pulpal inflammatory tissue resorbing the coronal dentine and enamel.9 Clinical features Radiographs reveal the lesions as radiolucent. The irregular area may appear superimposed over the root canal and could be DentalUpdate 103 . however. The outline is usually sharply defined and smooth or slightly scalloped March 2013 Clinical findings may include tooth discoloration. it can also be induced in some cases of endodontic pathosis. symptoms of periapical periodontitis may be evident. Radiographically. Careful evaluation of the periodontal condition is recommended because inflammatory resorption can be sustained by bacterial infection involving gingival tissues. tenderness to percussion. 13 This process involves the progressive replacement of tooth structure by alveolar bone and may (in severe cases) lead ultimately to tooth loss. If the tooth is deemed to be unrestorable. replacement resorption appears as total loss of periodontal ligament space followed by evidence of the progressive replacement of tooth structure by bone and.8 External replacement resorption such as compression or drying of the ligament cells in the case of delayed re-implantation of an avulsed tooth. external replacement resorption and ankylosis are the result of this process.Giant cell tumours . Aetiological factors for root resorption. they may have other clinical problems. Clinical features root is lost (Figure 4). External replacement resorption follows the death of viable periodontal ligament cells due to factors Clinically.Fibro-osseous lesions Heredity Bleaching Surgery . External replacement resorption is commonly seen during and after orthodontic treatment. Radiographically. Signs and symptoms Teeth are asymptomatic and the pulp is usually vital. signs and symptoms of necrotic pulp will be noted.10 Radiographic features Treatment Once a diagnosis has been reached there is a need to assess: If endodontic intervention (orthograde/surgical) will stabilize the root resorption or not. The tooth in question is frequently firm and immobile but not ankylosed in the dental arch. depending on patient factors.Dento-alveolar . The exact treatment plan required is specific to each case. as the tooth loses its vitality.RestorativeDentistry misdiagnosed as internal resorption.14 What has an effect on the progression of external root resorption to either external surface resorption or external replacement resorption is the severity of injury and the amount of damaged surface. and If the remaining tooth structure is restorable.2% for lateral incisors. The bone and the lamina dura follow the resorbing root and present with a normal appearance around the shortened root. If the injury is minimal and the damaged surface does not cover a large surface area. if the injury is severe and the damaged area is large. On the other hand. the tooth has to be extracted and the treatment plan should be focused on replacing the tooth with an appropriate fixed/removable March 2013 Figure 4.12 Signs and symptoms External resorption Replantation of teeth Orthodontic forces Eruption of adjacent teeth Root fracture Trauma Necrotic pulp Root planing Pathology .12 Radiographic features The apical and cervical regions are common sites for this type of resorption.5% of external replacement resorption has been reported for the maxillary central incisors and 2. resulting in blunting of the root apex. An incidence of 1.Cysts . clinical and radiographic findings. and prevention of normal mesial drift. This type of resorption is self limiting and transient and can follow some traumatic injuries or orthodontic treatment. Initially. External replacement resorption: loss of tooth structure followed by the progressive replacement of tooth structure by bone.Orthognathic Mandibulectomy/Maxillectomy Internal resorption Chronic pulp inflammation Trauma Pulpotomy Restorative procedures Cracked tooth Invaginated cingulum Orthodontic tooth movement Table 1. The main radiographic feature to differentiate between these two entities is that the outline and the integrity of the canal space remain uninterrupted in external resorption. resorption heals by forming reparative cementum.Ameloblastoma . in time. incomplete alveolar process development (if the patient was young when the trauma occurred). often with involvement of a small amount of underlying dentine. it generally causes smooth resorption of the tooth structure. When the lesion begins at the apex. the tissues will heal by forming reparative cementum and external surface resorption will occur. teeth may appear healthy but. In the absence of superimposed infection surface.11 External surface resorption External surface resorption is a shallow resorption of cementum. respectively. these are signs of ankylosis. In addition.13 Tables 1 and 2 summarize the aetiological factors and key features of root resorption. radiographically the outline of the tooth 104 DentalUpdate . teeth suffering from replacement resorption have metallic sound upon percussion and lack of mobility. bone cells will be able to attach to the root surface before the cementum-producing cells. such as infra occlusion. In cases of complex external and internal root resorption. signs of irreversible tenderness to pulpitis or necrotic percussion. both of the previously mentioned techniques could be used in an attempt to arrest root resorption process. The aim of orthograde root canal treatment is to stabilize the root resorption process and to achieve hermetic seal. The location of root resorption could be located with the use of parallax technique. For repairs that are partly supragingival. or with the use of Cone Beam Computerized Tomography (CBCT). if the tooth is restorable. a muco-periosteal flap could be raised to identify the resorbed area. However. This may be followed by curettage and repair of the root surface area with appropriate sealing material. and it may facilitate the regeneration of March 2013 the periodontal ligament.RestorativeDentistry Resorption Type Internal resorption External inflammatory resorption Clinical Features Clinical Findings Location on Root Pulp Sensitivity Radiographic (Thermal or Electric) Features Pink spot on crown May have Anywhere May be positive in cervical 1/3. Alteration in the anatomy of root canal systems due to root resorption may make this more challenging to achieve.15 These properties also mean that MTA is ideal for surgical repair of external resorption which is not supragingival. MTA cannot be used supragingivally as its slow set (4−24 hours) means that it may be washed away by saliva. is highly biocompatible and possesses good sealing properties. prosthesis. However. MTA has an antimicrobial effect. tenderness over Mostly has no apex clinical symptoms in mid/apical 1/3 Tooth No symptoms. In these cases. The use of gutta-percha (GP) cones and thermoplastic GP is generally the method of choice to achieve complete obturation of the canals. surgical and combined (orthograde and surgical) techniques were used in the management of root resorption. Mineral Trioxide Aggregate (MTA) can be placed from an orthograde approach (Case 1) to create this apical barrier. endodontic intervention with either orthograde or surgical endodontics. may be feasible to preserve the tooth. The following section will explain cases in which orthograde. DentalUpdate 107 . when obtaining radiographs. a surgical approach may be considered in the management of these cases. or Anywhere Negative discoloration. Prior to attempting any surgical repair. Anywhere May be positive Asymmetrical Intact replacement percussion. tooth pulp mobility and periodontal defects Root Canal Symmetrical Canals expand into oval-shaped lesions enlargement of root canal Irregular radiolucent lesion of root and adjacent bone Intact External surface Healthy None Usually apical as Positive Smooth resorption Intact resorption a result of trauma resulting in or orthodontic blunting of root treatment apex and shortened root External Metallic sound on No symptoms. Thermoplastic GP is particularly useful to treat irregular canal anatomy such as that seen in internal root resorption. because it is the only material that is reported to allow apposition of cementum and the formation of bone consistently. If root resorption has resulted in an open apex. MTA is considered to be an ideal material for use against bone. a material such as composite or glass-ionomer is required. Key features of root resorption. Loss of periodontal ligament space Table 2. lack of initially signs replacement of resorption mobility of necrotic pulp as root structure with tooth loses vitality bone. it is essential to locate the position of the resorption (buccal/lingual) and assess whether its size is likely to be amenable to repair. In addition. then it may be necessary to create an apical barrier prior to the obturation stage. these cases should be appropriately selected and should be carried out by experienced clinicians. or both. If the tooth suffers from external root resorption. External root resorption is on the mesial aspect of apical third of the root. and to backfill the remainder of the canal with thermoplastized gutta-percha (Obtura II. Case 3: surgical technique Figure 7. the UL1 was not tender to percussion. The remainder of root canal space was filled with thermoplastized gutta-percha (Obtura II. Spartan. The MTA plug on the level of external root resorption. This was improved by adding a small amount of composite filling cervically. The patient was reviewed 6 months later. After root canal preparation. US). Upon clinical examination. The sensibility tests for the UL2 were positive. an MTA plug was placed at the level where the external root resorption is communicating with the root canal to achieve appropriate apical seal (Figure 7). She was referred to the restorative department regarding the unsatisfactory appearance of the crown on the UR1 due to gingival recession. Spartan. Figure 8. US). Case 2 Figure 5. Radiographic examination revealed full bony infill and apical healing with the root-treated tooth (Figure 8). the patient was still symptom-free. and there were no signs of infection.RestorativeDentistry was extirpated and a radiograph was obtained with a file in situ showing that the root resorption originates from the mesial aspect of the apical third of the root (Figure 6). Figure 6. Initial transplanted LR5. the UL2 had external cervical resorption. round-oval radiolucency on the cervical and mid apical third (Figure 2). clinically or radiographically (Figure 10). as opposed to MTA in the previous case. The treatment of choice in this case was to use the surgical approach to gain access to the cervical root resorption and to repair March 2013 108 DentalUpdate . Figure 5 shows the initially transplanted LR5 in the position of the UR1. On clinical examination. The treatment of choice in this case was an orthograde approach by chemomechanical debridement of the canal using conventional hand instruments and filling the apical two-thirds with GP (Figure 9). along with gingival overgrowth covering part of the lesion (Figure 11). No mobility or pocketing was noted. The LR5 An 18-year-old patient was seen in the restorative department regarding the pink appearance of the UL2. Radiograph 18 months post-operatively. The patient reported a history of extensive orthodontic treatment. The diagnosis was internal resorption. Cases 1 and 2: orthograde technique Case 1 A 24-year-old lady had her LR5 transplanted to replace the UR1 when she was 11 years of age. the tissues were healthy and no tenderness was noted. Clinically. After 18 months of carrying out the treatment. A 66-year-old patient was referred from his GDP regarding persistent infection related to his UL1. Radiographic examination revealed a well-defined. Figure 16.RestorativeDentistry Figure 15. Flap repositioned and the gingival margin contoured. A mucoperiosteal flap with a distal vertical releasing incision was raised to expose the lesion (Figure 12). Figure 10. Figure 9. The cervical root resorption was restored with composite (Figure 13). Radiograph with master cone to fill apical two-thirds with GP. Figure 13. Figure 18. The patient was reviewed and the site of surgery healed well. Pre-operative clinical view of external cervical root resorption on UL2. The enamel and dentine on UL2 was minimally prepared. The resorbed area on UL2 was restored with composite. with composite. A mucoperiosteal flap raised to identify the extent of resorbed area on UL2. Figure 12. Case 4: surgical and orthograde approach A 44-year-old patient was referred regarding persistent infection DentalUpdate 111 . A mucoperiosteal flap raised from UL1–3. Ginigival margin overgrowth covering the cervical root resorption on UL2. Radiograph 6 months post-operatively. Cervical root resorption was restored with composite. Figure 17. the March 2013 flap was repositioned and the gingival margin was contoured with inverse bevel gingivectomy (Figure 14). Figure 11. Composite was used in this case as the restoration was partly supragingival. Figure 14. Clinical endodontic and surgical management of tooth associated bone resorption. the patient was still asymptomatic and the gingivae had healed well (Figure 19). Radiographically. External root resorption: its implication in dental traumatology. Hiremath H. 36: 491−525. on occasion. D March 2013 CPD Answers 112 DentalUpdate . Gunraj M. 6. Decisions on management are made on a case by case basis. 13. Garber T. Figure 19. D 5. orthodontics and endodontics. Lin S. B. In this case. D 3. 4. Gulabivala K. Root resorption: aetiology. Root resorption − etiology. 19: 175−182. Frank A. References 1. 18: 93−108. 12. Dent Traumatol 2003. Bhagwat S. Clinical diagnosis of internal resorption: an exception to the rule. Orthograde endodontics. 88: 647−653. Heithersay G. Mauger M. 3. a mucoperiosteal flap was raised to identify the extent of the resorbed area (Figure 16). After the root canal retreatment. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999. The cavity was restored with composite (Figure 18) and the flap repositioned. the plan was to replace the root canal treatment. C 8. Clement D. Discussion The basis of this paper is to provide clinicians with an overview on root resorption with a view to increasing their understanding of this topic and to assist them in reaching a diagnosis. C 9. paedodontics. 33: 999−1003. B 10. Yakub S. D 2. Endod Dent Traumatol 1985. 5. Walker W. Eliades T. Lindskog S. a combination of the two may be able to stop further resorption successfully and preserve the affected tooth. The enamel and dentine were minimally prepared (Figure 17). Int Endod J 1995. Metgud S. B. Mineral Trioxide Aggregate: a new material for endodontics. it explains methods of root resorption management. Invasive cervical resorption: a case report. 2004: p61.RestorativeDentistry related to UL2. Kulkarni S. Athanasiou A. 2004: pp357−358. A. 18: 72−92. Searson L. St Louis. Management of tooth resorption. the repaired area was sound and the periapical area had healed well (Figure 20). 10. January/February 2013 1. classification and treatment choices based on stimulation factors. 2. 18: 109−118. C. 11. Radiographic examination revealed an appearance of external cervical root resorption and a short single point root filling (Figure 3). One year post-operative radiographic view for UL2. General morphological aspects of resorption of teeth and alveolar bone. 20: 248−250. Dent Update 1993. Tronstad L. Mo: Mosby. D 4. On a 1-year review. Dental root resorption. 7. D 7. Barclay CW. A. Root resorption − diagnosis. That is in contrast to MTA. 15. A. 52 Figure 20. Schwartz R. 1: 221−227. 14. London: Quintessence Publishing. Aust Dent J 2007. Torabinejad M. J Am Dent Assoc 1999. White S. 8. J Endod 1998. 28: 255−260. there is a periodontal pocket in the region of the repair. Int Endod J 1985. Bakland L. In addition. Tsesis I. 9. Hammarstrom L. Root resorption. Int Endod J 1985. surgical endodontics and. Diagnosis and treatment of external invasive resorption. Risk Management in Orthodontics: Experts’ Guide to Malpractice. One year post-operative clinical view of UL2. Oral Radiology: Principles and Interpretations 5th edn. (Suppl 1): S105−S121. Fuzz Z. 130: 967−975. Clinical examination revealed a cavity which was probed on the labial aspect of the tooth (Figure 15). periodontics. J Endod 2007. A 6. B. Dent Clin N Am 1992. 94: 500−504. Int Endod J 1985. Andreason JO. Heithersay G. As the periodontal ligament does not re-attach to composite. Pharoah M. terminology and clinical manifestations. to which soft tissues may attach. this to be followed up by a surgical procedure to restore the resorption area. classification and clinical management.
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