Management of external cervical resorption with internal approach: 18 months of follow-up

Introduction: External cervical resorption (ECR) in advance stages may have a probable pulp involvement. In some of these cases, the accessibility of the resorptive process can be performed by an intraradicular approach. Aim: To report the management of an ECR, classified as Class 2cp according to Patel classification, with an internal approach. Case report: A 22-year-old male patient presented a complaint of dentin hypersensitivity related to left maxillary lateral incisor and reported a history of previous dental trauma. Based on the clinical, radiographic and tomographic findings, the left maxillary lateral incisor was diagnosed as symptomatic irreversible pulpitis with ECR class 2cp of Patel classification. The patient was scheduled for endodontic treatment, with an internal approach, and repair of the resorbed area. Intracanal dressing of calcium hydroxide paste was used in the root canal and resorption gaps. The root canal filling was performed in two steps: obturation of the apical and middle third with gutta-percha by lateral condensation technique and obturation of the cervical third and filling the resorbed area with MTA. After 18 months signs and symptoms compatible with success were observed, and the tomographic and radiographic images suggested a successful endodontic treatment and evolutionary process of repair of bone and mineralized dental tissues. Conclusion: Patel class 2cp ECR treatment through an internal approach, including conventional endodontic treatment and recovery of the reabsorbed area with calcium hydroxide and MTA is a viable treatment option, but may cause tooth discoloration.


Introduction
According to the American Association of Endodontic (2020) resorption is a condition associated with either a physiologic or a pathologic process resulting in a loss of dentin, cementum and/or bone (AAE, 2020). External cervical resorption (ECR) is a type of pathological resorption which initiated on the external aspect of the root, below the epithelial attachment (Heithersay, 2004;Patel & Beddis, 2019). The etiology of ECR remains unclear and several potential predisposing factors have been identified, such as trauma, intracoronal bleaching, orthodontics, orthognathic and other dentoalveolar surgery (Heithersay, 1999;Mavridou et al., 2017;Irinakis et al., 2020).
The clinical presentation of ECR varies considerably depending on the extent of the resorptive process (Heithersay, 2004). In early stage, the affected tooth is commonly asymptomatic, and ECR may be an incidental radiographic finding as a radiolucency in the cervical region of a tooth. In advanced stage, cervical cavitation, localized gingival inflammation and bleeding, contour and/or pinkish discoloration of the overlying enamel may be present (Patel & Beddis, 2019;Heithersay, 1999;Mavridou et al., 2017;Consolaro, 2016;Algedairi, 2019). At this stage, the patient may present with pulpal and/or periapical symptoms (Patel et al., 2009).
The radiographic appearance of ECR is variable and influenced by the size and nature of the lesion (Patel et al., 2018).
If the lesion is proximally located, radiographic assessment shows an irregular mottled, or 'moth-eaten' image in the main lesion area and radiopaque line of demarcation between the resorptive lesion and that of an apparently intact dental pulp (Heithersay, 2004;Consolaro, 2016). However, according to European Society of Endodontology there is no classical radiographic appearance of ECR lesion, and the limitations of periapical radiographs can result in misdiagnosis and/or poor management (ESE, 2018). Authors suggest that cone beam computed tomography (CBCT) is more suitable for diagnosis, treatment planning, to determine the location and extent of the defect, the restorability of the tooth and the proximity of the lesion relative to the pulp canal (Patel & Beddis, 2019;Irinakis et al., 2020;Patel et al., 2018a;ESE, 2018;Aljarbou, 2029;Rodrigues Mazón et al., 2022).
The objectives of treatment of ECR lesion are the elimination of the resorptive tissue, sealing of the resultant defect and prevention of recurrence, being significantly influenced by its location, nature, stage of progression, and accessibility of resorptive process (Heithersay, 2004;Patel & Beddis, 2019). Internal repair associated with root canal treatment is one of the treatment options for ECR proposed by ESE (2018), indicated when there is pulp involvement and the accessibility of the resorptive process is performed by an internal approach (Patel et al., 2018b). This case report presents the nonsurgical management of a tooth with ECR Patel class 2Cp lesion (Patel et al., 2018a), including conventional endodontic treatment and sealing of the resultant defect with Mineral Trioxide Aggregate (MTA) by an internal approach.

Methodology
The present study is a case report with a single patient retrospective description, focused in a fenomen that was described in maximum detail as possible (Pereira et al., 2018;Alpi, 2019). The evaluated tooth was diagnosed with a ECR treated with an internal approach. Follow-up was carried out between June 13, 2018, and November 25, 2019. The case report nature is qualitative and descriptive.
A written informed consent was obtained from the patient before the treatment. This case report was approved by the Ethics Committee of the University (protocol number 98743318.6.0000.5060) and follows the ethical principles of the Declaration of Helsinki.

Case Report
A 22-year-old male patient presented at the clinic of the School of Dentistry of the Federal University of Espirito Santo, Brazil. The patient reported pain related to left maxillary lateral incisor, with exacerbation when exposed to heat or cold, and with pulsation at night. The patient reported a history of dental trauma involving this tooth when he was 12 years old, and six months after dental trauma, he underwent orthodontic treatment. An intraoral clinical examination showed presence of a small localized swelling in the marginal gingival of tooth No. 22, without tenderness to percussion or palpation. The tooth was responsive to thermal pulp test, with an intense and prolonged sensitivity. On probing, a respective pocket depth of 6 mm was detected in the mesiobuccal region of left maxillary lateral incisor.
Radiographic assessment showed an irregular mottled radiolucency mesial to the pulp space of tooth No. 22 with preservation of the pulpal limits, and a breakdown of the crest of alveolar bone mesial (Figure 1 A). Research, Society and Development, v. 12, n. 6, e17912642184, 2023 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v12i6.42184 4 CBCT examination revealed a hypodense area with a circumferential spread of 180º in the cervical region of tooth No. 22, and with radicular perforation of the existing resorption defect (Figures 1 B,

C, D and E).
Based on the clinical, radiographic and tomographic findings, the tooth No. 22 was diagnosed as symptomatic irreversible pulpitis with ECR Patel class 2Cp lesion. Thus, the treatment plan included the management nonsurgical of the root canal and repair of the resorptive defect via an orthograde approach using MTA.
The root canal treatment was performed using the modified Oregon technique, with hand files and 2.5% sodium hypochlorite. After chemo-mechanical preparation, the resorptive defects and root canal system were filled with an intracanal dressing of calcium hydroxide paste. On the second appointment, apical and middle third of root canal were filling with gutapercha and AH Plus cement (Dentsply Sirona, Ballaigues, Switzerland), using the Tagger

Discussion
The etiology of ECR is not well understood, although dental trauma and orthodontics are associated with more than 35% of ECR cases (Patel & Beddis, 2019, Heithersav, 1999Mavridou et al., 2017;Irinakiset al., 2020). This case report showed the effect of a non-surgical approach in the success of treatment of a tooth with ECR Patel class 2Cp lesion, with historic of dental trauma and orthodontics.
The space of root canal is surrounded by a protective layer, resistant to the resorptive process, identified radiographically by a radiopaque line15. This layer is referred to as the pericanalar resorption-resistant sheet (PRRS), and consists primarily of predentine and dentine (Mavridou et al., 2016). The presence of this barrier explains the asymptomatic nature of ECR at initial stage and it could be postulated that pulpal symptoms only develop when the resorption ultimately penetrates through PRRS and is secondarily invaded by oral microorganisms (Heithersav, 2004). Thus, ECR represents an asymptomatic condition at early and intermediate stages, with scarcity of clinical signs. In most of cases, ECR lesion is diagnosed in advanced stages, when they are symptomatic, and show clinical signs, such as a cervical pink stain and other findings (Patel et al., 2009;Pace et al., 2018). In this case report, the diagnosis of ECR was established 10 years later dental trauma and orthodontics, when the pulpal symptoms were present.
The management of ECR lesion depends on several factors, such as its location, nature, stage of progression, and accessibility of resorptive process (Heithersav, 2004;Patel & Beddis, 2019;ESE, 2018). The ESE and American Association of Endodontists & American Academy of Oral & Maxillofacial Radiology recommends that CBCT should be considered for the assessment and/or management of root resorption (Patel et al, 2018a). Early diagnosis and appropriate management have shown to improve the likelihood of tooth retention (Heithersav, 2004), and the CBCT scan has demonstrated a significant impact on clinical decision-making in cases of ECR (Rodrigues Mazón et al., 2022). Recently, authors have classified ECR into 3-dimensions, considering the ECR lesion height, circumferential spread, and proximity to the root canal (Patel et al., 2018a). ESE used this classification for the most recent position statement of ECR which recommends internal repair and root canal treatment in cases classified as Class 2Cp, according to Patel classification based on CBCT images, like present study (ESE, 2018). The root canal treatment was required due diagnosis of symptomatic irreversible pulpitis.
The objectives of treatment of ECR lesion are the elimination of the resorptive tissue, sealing of the resultant defect and prevention of recurrence, (Heithersav, 2004;Patel & Breddis, 2019;ESE, 2018). In the present case report a CaOH-based intracanal medication was used to interrupt the resorptive process, reducing the action of osteoclasts. Besides that, CaOH has an antibacterial action, reduces the clastic activity, stimulates repair and inducts of hard tissue deposition, being indicated in cases of root resorptions (Farhad & Mohammadi, 2005).
The correct filling of the resorption defect using a material with a good sealing ability and excellent biocompatibility, cease the process and its recurrence is not detected. MTA was used to seal the resorption defect, and showed a restoration of crestal alveolar bone and good adaption (Algedairi, 2019; Pace et al., 2008;Yilmar et al., 2010). The MTA have a good sealing ability that can serve as repair material, present excellent biocompatibility, but cause tooth discoloration, as seen in the present study ( Figure 2e). More recently, new formulations of tricalcium silicate-based materials have been introduced as an alternative to MTA. These materials, such as Biodentin, presents better physical, chemical, and biological properties, and do not cause tooth discoloration, have no long setting time and have better handling properties than MTA (Algedairi, 2019;Hung et al., 2014;Kaup et al., 2015) and can be an alternative in cases of ECR (Rotondi et al., 2020;Howait et al., 2021).

Final Considerations
The nonsurgical management, with an internal approach of external cervical resorption (ECR), classified as Class 2cp according to Patel classification, including conventional endodontic treatment and reparation of the resorbed area with calcium hydroxide and Mineral Trioxide Aggregate, is a viable treatment option, however it can cause tooth discoloration.
For future research and articles, new materials based on calcium silicate should be investigated in cases of ECR treated with internal approach.