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Abstract: Internal inflammatory root resorption (IIRR) is a rare, but significant consequence of dental trauma. Previous cases often focus on two-dimensional imaging. More widespread use of cone beam computed tomography (CBCT) has seen improved diagnostic accuracy of these defects leading to more appropriate management. In this case report, an adolescent male patient complained of a missing front tooth (UR1). Dental history revealed intrusive trauma to the predecessor as a child. The UR1 was impacted with a dilacerated root. CBCT imaging revealed severe internal root resorption, and due to its extensive nature, extraction was advised.
CPD/Clinical Relevance: Readers should be aware of the consequences of internal inflammatory root resorption and understand the importance of early detection with appropriate special investigations.
Article
Georgina Kane
Inflammatory root resorption (IRR) is a common sequela of dental trauma. IRR can occur on the external or internal surfaces of the affected teeth, with the latter being less common.1 IRR can be classified as apical or intra-radicular depending on the location of the anatomical defect, with apical internal resorption occurring frequently in teeth with peri-apical pathology, often in combination with external inflammatory apical resorption.2 Internal IRR is caused by accelerated osteoclastic activity, resorbing the intra-radicular dentine layer within the root canal, and can lead to critical damage to the tooth.3 Initially, the pulp complex has some level of vitality, although it may have been contaminated with bacterial ingress at the coronal level and subsequently suffer from chronic pulp inflammation. Internal IRR can present transiently whereby the odontoblast layer and predentin are affected before spontaneous resolution, although this is rare.4 However, as the internal IRR is often asymptomatic, it can also continue undiagnosed, to the extent that perforation of the canal can occur. Careful monitoring of all previously traumatized teeth is therefore advised. Management of internal resorption requires prompt endodontic treatment, including removal of the entire pulp tissue, canal irrigation and creation of an aseptic environment. This is most commonly achieved with sodium hypochlorite, followed by placement of calcium hydroxide until there is evidence the process has ceased, and the canal can be definitively restored.5 More recently, MTA (mineral trioxide aggregate) has demonstrated to be the material of choice for restoring perforated lesions, due to its biocompatibility and superior sealing properties.2 Treatment may be combined with a surgical approach to gain direct access to the defect. Unfortunately, in severely affected cases, the extent of resorption can be such that extraction is considered the preferred option.2,6
Internal IRR occurs most frequently in the maxillary incisors, which may relate to the increased incidence of trauma to these teeth, and has been shown to be more common in males than females.7 Treatment success appears to depend on the extent of resorption. One study that assessed internal IRR in 27 patients found that 43% had suffered previous trauma, and all teeth with non-perforating lesions demonstrated clinical and radiographic signs of healing following conventional endodontic therapy using calcium hydroxide as the intermediate medicament, before gutta percha obturation. Those with perforation defects had a very poor prognosis and endodontic surgical procedures were prone to failure.1
Internal IRR was reported in the literature as early as 1830,8 but owing to its low incidence, there is a relatively low-quality evidence base. Previous research has mainly centred on retrospective studies and case reports, with few in vivo prospective trials in circulation. Prospective trials would encounter great difficulty in recruitment owing to the silent nature of symptoms in the early stages. Historically, authors on the subject have mostly reported on the extent of resorption in two-dimensions using conventional radiography, potentially failing to identify the extent of resorption that could be visualized using three-dimensional imaging. More recently there has been a paradigm shift towards cone beam computed tomography (CBCT) for analysing resorptive lesions. Several studies have demonstrated improved diagnostic accuracy when using CBCT compared with intra-oral radiographs, which significantly improved the likelihood of selecting the correct treatment approach.9,10
Case report
A 14-year-old medically fit and well male (Patient A) attended the orthodontic new patient clinic, complaining of a missing upper front tooth (UR1). The patient's social history revealed he had moved to the UK from Brazil 3 years earlier. When the patient was 2 years old, he suffered dental trauma during a fall, leading to intrusion of the upper right deciduous central incisor (URA). The deciduous tooth then slowly re-erupted, with some transient grey discolouration that improved after a couple of months, and the tooth exfoliated at a similar time to the contralateral deciduous tooth. The permanent successor, however, never erupted. On clinical examination, the patient presented with a Class I incisor relationship on a skeletal I base, with fairly well-aligned arches and the presence of all teeth excluding the third molars and the upper right central incisor (UR1). There appeared to be localized atrophy of the alveolar crest in the UR1 region, and the adjacent crowns had tipped into the edentulous space (Figure 1).
Figure 1.
(a) Frontal, smiling and lateral extra-oral views. (b) Upper occlusal, frontal and lower occlusal intra-oral views. The UR1 is absent and the adjacent crowns have tipped into the space.
A dental panoramic tomogram and an upper standard occlusal radiograph were taken, which revealed that the UR1 was present and impacted with a high vertical position (Figure 2), and the root appeared dilacerated. Use of the parallax technique indicated that the UR1 crown was buccal to the line of the arch. There was significant notching noted along the UR1 incisal edge, with an associated well-defined radiopacity. The differential diagnosis comprised either the retained apex of the deciduous predecessor or a denticle. CBCT imaging was performed to obtain more detailed information to aid diagnosis (Figure 3). This demonstrated severe internal IRR affecting the UR1, which had perforated the radicular dentine and cementum wall on the mesial aspect. The pulp chamber was symmetrically enlarged with characteristic ‘ballooning’ of the pulp space. The CBCT three-dimensional reconstruction clarified that the incisal radiopacity was an artefact created by notching of the central incisor crown. This was most likely caused by a crushing injury of the ameloblasts during the intrusion, as the age at injury is in keeping with expected incisal edge calcification. The long-term prognosis of the UR1 was extremely poor due to the severity of internal IRR and surgical removal of this tooth was proposed. Fixed appliances were planned to align the teeth and recreate space for a prosthetic replacement of the UR1.
Figure 2.
(a) Panoramic dental tomogram showing that UR1 is present and impacted. (b) Upper standard occlusal radiograph. Using vertical parallax UR1 appears to be positioned buccally.Figure 3. CBCT of UR1 in three reference planes and 3D reconstruction (4 x 5 cm, 90 kV, 9.0 mA). (a) Axial; (b) sagittal; (c) coronal; (d) 3D reconstruction.
Discussion
This case highlights some essential points for practitioners. First, any patient with a history of dental trauma should have the eruption of the permanent successors carefully monitored, and investigated early if there are any delays or disruption to the expected eruption sequence. Unfortunately, when clear perforation of the root is confirmed, extraction is often then recommended as the preferred treatment option, as demonstrated in earlier case studies.11
If the failure of the UR1 eruption had been identified much earlier, the extent of the resorption may have been less and the tooth might have been viable for more conservative treatment. Clinicians should be vigilant when following up patients who have had intrusion injuries in the deciduous dentition owing to the significant risks to the permanent successor, as this case has demonstrated. A recent systematic review of trauma in the permanent dentition found that intrusive luxation was the most common injury to lead to any type of root resorption. External IRR occurred more frequently with the highest incident rate reported at 92.7%, whereas internal IRR incidence was 22.2%.12 Therefore, although a less common occurrence, internal IRR must be considered as a potential sequela in any deciduous or permanent tooth that has previously suffered dental trauma.
This case has clearly demonstrated the advantage of three-dimensional imaging over conventional radiography. If the prognosis of the UR1 had been better, the treatment plan would have been to expose and bond UR1 and apply orthodontic traction to align it into the arch. CBCT, however, demonstrated this approach would have been inappropriate owing to the extent of the internal IRR. Due to the increased radiation dose, CBCT must be reserved for clinically appropriate cases, and teeth with a history of severe trauma may warrant further investigation. CBCT can be used to assess root resorption in three planes with high specificity and sensitivity, thus enabling a timely diagnosis.13 CBCT is also the ideal tool for assessment of perforated lesions.14 If the prognosis of the tooth had also been more promising, the three-dimensional imaging could have been used for a more accurate measurement guide for later endodontic procedures if indicated.11 A multidisciplinary approach is advised in these cases for improved outcomes.15
Conclusions
IIRR is a rare consequence to dental trauma and needs early detection for best outcomes. CBCT is a vital tool for accurate evaluation of resorptive defects, and clinicians should be aware of the indications and justifications for use of this diagnostic tool.
