Case Report
CBCT-assisted diagnosis of transient apical breakdown and buccal cortical fracture following lateral luxation: A 24-month case report
Mario M. Betancourt, DDS 1
Marino V. Carcaño, DDS, MS 1
Jorge Vera, DDS, MS 2
https://doi.org/10.71347/afv594htw
1 Endodontics faculty, Posgrado de Endodoncia, Universidad Autonoma de Tlaxcala.
2 Director, Advanced Education Program in Endodontics, Department of Periodontics and Endodontics, University at Buffalo School of Dental Medicine.
Corresponding author:
Jorge Vera DDS, MS, Director of the Advanced Education Program in Endodontics, Department of Periodontics and Endodontics, University at Buffalo School of Dental Medicine Squire Hall - University at Buffalo, State University at Buffalo South Campus, 3435 Main St, Buffalo, NY 14215
e-mail: jveraro@yahoo.com.mx
Key words: Transient apical breakdown (TAB), Lateral luxation, CBCT, Dental trauma, Pulpal necrosis, Conservative management.
Acknowledgements: The authors deny any conflicts of interest.
Abstract
Introduction: Transient apical breakdown (TAB) is a rare, reversible condition following lateral luxation. It presents as resorption in the apical root and periapical area, often seen radiographically as a periapical radiolucency. Crown discoloration may be noted clinically but typically resolves. Although self-limiting, TAB can mimic apical periodontitis or pulp necrosis, risking misdiagnosis and unnecessary intervention. CBCT imaging plays a critical role in achieving diagnostic clarity.
Objective: To report a case of TAB associated with a buccal cortical fracture, initially missed on periapical radiographs, and highlight the diagnostic value of CBCT in avoiding overtreatment.
Case Report: A 38-year-old Hispanic female experienced trauma with lateral luxation of tooth #21. Initial radiographs were inconclusive, and endodontic treatment was suggested. A second opinion and CBCT imaging revealed TAB and a buccal cortical fracture. Conservative monitoring was adopted. After 24 months, the tooth showed clinical and radiographic resolution without intervention.
Conclusion: TAB should be recognized as a possible healing response following luxation in mature teeth. CBCT significantly enhances diagnostic precision and supports conservative treatment decisions.
Introduction
Lateral luxation is a traumatic dental injury involving displacement of a tooth in a direction other than its long axis, often accompanied by alveolar socket fracture. These injuries commonly affect the anterior maxillary teeth and are usually caused by direct frontal impact. Immediate concerns include structural damage, neurovascular disruption, and pulp vitality compromise.
Correct diagnosis after dental trauma is often difficult. Pulp sensitivity tests such as thermal and electric testing may show false-negative results in the early post-trauma period due to transient neurovascular impairment. Consequently, clinicians may prematurely diagnose pulp necrosis and initiate endodontic therapy, which may not be necessary.
Transient apical breakdown (TAB) is a rare, self- limiting condition characterized by temporary radiographic periapical changes and clinical signs resembling apical periodontitis or necrosis. However, TAB is part of the healing process and generally resolves without intervention. Crown discoloration, another clinical sign of TAB, is also reversible in many cases.
Recent literature has raised concerns about overtreatment in endodontics, especially in trauma cases. Gluskin et al. (2021) emphasized the need for careful diagnostic protocols, warning against immediate intervention based solely on transient signs. Moreover, CBCT has become increasingly valuable for trauma diagnosis, offering superior sensitivity in detecting cortical fractures and subtle pathologies compared to conventional periapical radiographs (Patel et al., 2021).
This case report presents a clinical scenario in which CBCT imaging identified TAB and a buccal cortical fracture in a luxated tooth, leading to successful non-invasive management over a 24-month follow-up period.
Case Presentation
A 38-year-old Hispanic female presented for a second opinion after sustaining dental trauma while ice skating. The impact resulted in a lip laceration (Fig. 1a) and displacement of tooth #21, which she described as “moved backward.” The initial treatment, performed within three hours, consisted of repositioning the tooth and suturing the lip laceration (Fig. 1b). A periapical radiograph taken the next day showed no significant findings (Fig. 1c). Nonetheless, another provider recommended endodontic treatment.
Five weeks post-trauma, the patient reported noticeable discoloration of tooth #21 (Fig. 2a). Clinical examination revealed grade II mobility, probing depths within normal limits, and tenderness to percussion and palpation. The tooth was non- responsive to cold testing. A fixed orthodontic retainer was present (Fig. 2b), in place since completion of orthodontic treatment two years earlier.
Fig. 1. Images submitted by the patient from her initial consultation with the first dentist: (a) clinical photograph showing a traumatic laceration of the upper lip; (b) sutured lip laceration with repositioned tooth; (c) periapical radiograph taken the
following day, revealing no apparent abnormalities.
Radiographic evaluation with periapical imaging (GXS-700 sensor, Gendex, Hatfield, PA, USA) showed slight widening of the periodontal ligament (Fig. 3a). A limited field (5×5 cm) CBCT scan (OP3D Pro, KaVo) revealed a buccal cortical plate fracture and a well-defined periapical hypodense area in the sagittal view (Figs. 3b-d).
Based on these findings, a diagnosis of lateral luxation with buccal cortical fracture and transient apical breakdown (TAB) was made. Considering the absence of acute symptoms and the expected self-limiting course, a conservative observation- based approach was adopted. The patient was informed about the diagnosis, treatment options, and potential risks, and consented to monitoring.
At 4 months, pulp testing showed a positive response to cold and an average electric pulp test value of 46. The patient was asymptomatic. At 6 months, a periapical radiograph and a CBCT showed healing of the buccal cortical plate and considerable reduction in the apical lesion (Figs. 4a-d).
At the 24-month follow-up, clinical evaluation showed grade I mobility, no pain on palpation or percussion, positive cold response, and a significant improvement in crown color (Fig. 5). A periapical radiograph revealed a normal pulp chamber and canal, with no radiographic evidence of pulp canal obliteration (Fig. 6a).
Fig. 2. Clinical photographs taken five weeks post-trauma. (a) Tooth #21 showing marked dark discoloration compared to adjacent teeth. (b) Fixed orthodontic retainer in place since the completion of the patient’s orthodontic treatment, two years prior to the traumatic injury.
Fig. 3. Radiographic and tomographic evaluation five weeks post-trauma. (a) Periapical radiograph showing mild widening of the periodontal ligament in the periapical region of tooth #21. (b) Limited 5×5 field CBCT, coronal section, revealing a periapical hypodense area at the level of tooth #21, consistent with transient apical breakdown (TAB). (c) Sagittal section along the longitudinal axis of tooth #21, displaying a periapical hypodense area and discontinuity of the buccal cortical plate at the apical level, suggestive of a fracture. (d) CBCT view 1 mm mesial to the center of tooth #21, where the buccal cortical fracture is more evident.
Fig. 4. Radiographic and limited 5×5 field CBCT at the 6-month follow-up. (a) Periapical radiograph showing widening of the apical periodontal ligament space and flattening of the radiographic apex of tooth #21, with the fixed orthodontic retainer visible coronally. (b) Coronal section demonstrating reduction of the periapical hypodense area and evidence of root apex remodeling. (c) Sagittal view along the longitudinal axis of tooth #21 indicating healing of the buccal cortical bone. (d) Sagittal view 1 mm mesial to the center of tooth #21 confirming cortical bone healing.
Fig. 5. Clinical photograph taken at the 24-month post-trauma follow-up, demonstrating significant color restoration. At this appointment, the patient reported no pain on palpation, exhibited grade I mobility, and showed a positive response to cold testing.
CBCT confirmed complete regeneration of the cortical bone and resolution of the periapical lesion (Figs. 6b-c). The patient was discharged with no need for further treatment. Clinical Timeline:
Time point | Event / Observation |
Day 0 (Trauma) | Ice skating injury, luxation of #21, lip laceration, tooth repositioned |
Day 1 | Periapical radiograph taken – no abnormalities noted |
Week 5 | Discoloration and mobility observed; CBCT reveals TAB and buccal cortical fracture |
Month 4 | Positive cold and electric pulp tests; no symptoms reported |
Month 6 | CBCT shows cortical bone healing, reduced periapical radiolucency |
Month 24 | Full clinical and radiographic recovery confirmed; tooth remains vital |
Fig. 6. Radiographic and limited 5×5 field CBCT at the 24-month follow-up. (a) Periapical radiograph showing a normal periapical appearance with flattening of the radiographic apex of tooth #21 as part of the repair process. The fixed orthodontic retainer is visible in the coronal region. (b) Coronal section demonstrating complete healing of the periapical area of tooth #21 with root apex remodeling. (c) Sagittal slice along the longitudinal axis of tooth #21, indicating complete healing of the buccal cortical bone.
Discussion
Transient apical breakdown (TAB) is an uncommon outcome of luxation trauma, with reported prevalence around 4.2% (Andreasen 1986, Cohenca et al. 2003). Clinically, TAB may closely resemble apical periodontitis, as both can present with percussion sensitivity, tenderness to palpation, and an absence of response to thermal pulp testing. This symptomatic overlap often leads to misdiagnosis and potentially unnecessary endodontic intervention.
Trauma to the dentin–pulp complex, particularly affecting the Aδ fibers, may result in false-negative responses during pulp testing due to temporary ischemia, inflammation, and hypoxia. These fibers depend on oxygen for ATP production, essential for the sodium-potassium pump’s function (Jain & Gupta, 2013; Torebjörk & Hallin, 1973). Thus, a lack of response shortly after trauma may reflect transient dysfunction rather than irreversible pulpal necrosis (Bourguignon et al., 2020).
Early coronal discoloration - a hallmark of TAB - was documented by the patient using her smartphone, offering a visual timeline of chromatic changes (Figs. 7a–b).
Fig. 7. (a) Photograph taken by the patient with a mobile phone 10 days after the trauma, showing dark discoloration of tooth #21 compared to tooth #11; the low image quality is due to the use of a mobile device. (b) Photograph taken by the patient 3 months post-trauma, illustrating chromatic recovery of tooth #21 relative to tooth #11; image quality remains reduced due to mobile phone use.
Such discoloration typically emerges within 10–14 days post-trauma and may reverse as healing progresses. In this case, color improvement was observed within three months, supporting the notion that superficial dentin staining in vital teeth is reversible (Holand, 2019; Stangel et al., 1996).
By the 24-month follow-up, the tooth exhibited nearly complete chromatic normalization and radiographic healing. CBCT played a critical role in diagnosing the buccal cortical fracture and associated apical radiolucency, both indicative of TAB. Importantly, CBCT facilitated an observation- based treatment plan by providing diagnostic confidence and preventing unnecessary root canal therapy. Its superior sensitivity for detecting cortical bone changes - often missed by 2D radiography - is well-documented (Patel et al., 2021).
The cortical fracture in this case was detectable only through CBCT, underscoring the modality’s enhanced diagnostic power. These fractures are rarely discussed in the literature (Patel et al., 2021; Andreasen & Kahler, 2015), likely due to the limitations of intraoral radiographs in identifying cortical discontinuities at the time of trauma (Andreasen & Lauridsen, 2015).
The prevalence of pulp necrosis following luxation trauma varies widely, between 15–59% (Andreasen et al., 2019), with necrosis potentially occurring as late as two years post-injury (Andreasen & Vestergaard Pedersen, 1985). However, this variability often stems from limited diagnostic sensitivity in traditional 2D imaging. In the present case, 24 months post-trauma, the pulp chamber and canal of tooth #21 appeared normal and comparable to the contralateral incisor. No evidence of pulp canal obliteration (PCO) was noted - a condition more frequently seen in immature teeth and generally developing within the first year post- trauma in approximately 25% of cases (Andreasen et al., 2019b; McCabe & Dummer, 2012; Clark & Levin, 2019; Vera et al., 2023).
At final follow-up, tooth #21 had regained color, the periapical radiolucency had resolved, and the periodontal condition remained stable. The tooth responded normally to cold testing and electric pulp testing, with no sensitivity to palpation or percussion. A limited 5×5 cm CBCT scan confirmed complete bone regeneration and absence of periapical pathology.
It is essential to recognize TAB as a natural reparative response in mature teeth following luxation. Clinical signs such as temporary discoloration and non-responsiveness to pulp testing should not automatically trigger invasive therapy (Lozano González et al., 2014). Diagnostic evaluation should consider the presence or absence of other pathologic indicators - such as sinus tract formation, persistent swelling, spontaneous pain, or progressive radiolucency.
CBCT imaging, when used in conjunction with clinical evaluation, significantly improves diagnostic accuracy for trauma-related injuries. It aids not only in visualizing pathology but also in tracking the healing process and informing treatment planning with greater confidence.
Patient education is critical, particularly when adopting a wait-and-see approach. Clinicians must clearly communicate the uncertainty and potential for future complications, including pulp necrosis or canal obliteration. Commitment to regular follow-up is essential. If there is doubt about a patient’s ability to return for ongoing monitoring, early endodontic intervention may be the more prudent option.
Conclusion
This case report emphasizes that transient apical breakdown can mimic pathology yet often represents a self-healing process following luxation trauma. CBCT imaging was instrumental in diagnosing a cortical fracture and avoiding unnecessary treatment. Conservative observation, paired with accurate imaging and long-term follow- up, supported full recovery of both tooth structure and vitality.
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