ARC Journal of Radiology and Medical Imaging

AUTHOR DETAILS

¹ Ruy Paschoal Ramos-Junior, DDS , ² Evaldo Almeida Rodrigues, DDS,MSc, ³ IedaCrusoe-Rebello, DDS, MSc, PhD,⁴ Gabriella Lopes Rezende Barbosa, DDS, MSc , ⁵ Frederico Sampaio Neves, DDS, MSc, PhD, ^*Emmanuel Joao Nogueira Leal Silva,DDS, MSc, PhD

1Private Practice, Feira de Santana, Bahia, Brazil.
2 Department of Health, School of Dentistry, Feira de Santana State University, Feira de Santana, Bahia, Brazil
3 Department of Oral Radiology, School of Dentistry, Federal University of Bahia, Salvador, Bahia,Brazil
4 Department of Oral Diagnosis, Division of Oral Radiology, University of Campinas, Piracicaba, São Paulo, Brazil 5Department of Oral Radiology, School of Dentistry, Federal University of Bahia, Salvador, Bahia,Brazil
*Department of Endodontics, School of Dentistry, Grande Rio University (UNIGRANRIO) and Rio de Janeiro State University(UERJ), Rio de Janeiro, Brazil

*[email protected].

KEYWORDS

Cone Beam Computed Tomography; Root Fracture; Beam Hardening Artifact

INTRODUCTION

One of the challenges in Oral Radiology and Endodontics is the correct identification of root fractures. In most of the cases, the correct diagnosis of the fracture is only possible when clinical (e.g. pain, local swelling and dental mobility) and radiographic (e.g. widening of the periodontal space and periapical lesion) findings are correlated [1-3]. However, in specific cases, the root fracture diagnosis is only confirmed under periodontal surgical procedure or after extraction of the tooth [2, 4].

Cone beam computed tomography (CBCT) is an imaging modality that shows the dental structures in a three-dimensional view, as well as it offers clear structural images with high contrast. CBCT is increasingly replacing the medical computed tomography (CT) use in dentistry because it provides an adequate image quality associated with a lower exposure dose. Other advantages of CBCT are low cost, shorter scanning time and lower production of beam hardening artifacts when compared to CT [5, 6].

The presence of artifacts in CT and CBCT images due to the presence of filling materials as gutta-percha and metal posts might influence the endodontic diagnosis, especially in cases of root fractures [7-11]. Moreover, beam hardening artifacts represented by hypodense lines (dark lines) can be misdiagnosed as root fractures due to a similar radiographic appearance, leading to an incorrect management and, in some cases, culminating in unnecessary tooth extractions [4].

To the best of our knowledge, there is only one clinical report in the literature report the effects of CBCT and CT artifacts in the diagnosis of root fractures [4]. Therefore, the present article aimed to describe a case of CBCT artifact mimicking root fracture in a tooth without intracanal material.

CASE REPORT

A 27-year-old woman was referred to a private clinic after local trauma during physical activity. The patient did not have pain or other complains, and her medical history was not contributory. The dental status was satisfactory, being noted on the right lateral incisor, the presence of a dental piercing: a piece of jewelry applied on the vestibular surface of the crown. Clinical examination revealed oblique crown fracture in the middle third of the left maxillary central incisor involving enamel and dentin without exposure of the pulp. The treatment was reattachment of the tooth fragment. However, after one month, the patient returned to the clinic complaining about severe pain. The vitality pulp test was performed and the tooth had a positive response. In the periapical radiograph, no signs of root fracture or periapical pathology were observed (Figure. 1).

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Figure1. Periapical radiography showing no signs of root fracture

The patient underwent CBCT examination (Eagle 3D CBCT unit; Dabi Atlante, São Paulo, Brazil) in order to evaluate the possible presence of periapical lesion or root fracture. During the image observation, it was detected in the sagittal view, a hypodense line in the middle third of the root, buccal-palatal oriented, suggesting the presence of root fracture (Figure. 2).

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Figure2. Sagittal CBCT slice showing the possible fracture in the middle third of the root (white arrows).

The treatment of choice was extraction of the tooth and immediate dental implant placement. After the extraction, the tooth was visually inspected and no root fracture was detected. For this reason, the tooth was replanted into the alveolus and a semi-flexible splint was used during seven days. After fifteen days, the patient was revaluated and the replanted tooth had a negative response to the vitality pulp test and the endodontic treatment was performed. Calcium-hydroxide was used as the temporary intracanal material to avoid root resorption, and it was replaced every month, during one year. After this period, the root canal was sealed with gutta-percha. A 03-year follow-up was performed and no complaints were reported. During clinical examination, the absence of the dental piercing was noticed. The patient underwent a second CBCT examination and no signs of root resorption or ankylosis were detected in the tooth (Figure. 3). Additionally, no hypodense line was observed on the images.

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Figure3. Sagittal slice of CBCT image acquired at the three-year follow-up of the replanted tooth showing no signs of root fracture or external root resorption.

DISCUSSION

The present case shows that artifacts present in CBCT exams may simulate alterations even in teeth without filling materials or intracanal posts; demonstrating a significant disadvantage of this imaging technique and highlighting the importance of further studies that attempt the artifact reduction in tomographic images. There is no doubt that CBCT is a valuable aid in endodontic practice, allowing the three-dimensional visualization of structures differently from plain radiographs. However, SEDENTEXCT guidelines [12] and the European Society of Endodontology [13] stated that CBCT exams should not be requested routinely for all patients with suspected dental fracture. In fact, the potential risks and benefits of CBCT for each patient should be fully assessed based on both conventional radiographs and clinical signs and symptoms. In the present case, CBCT was used initially for the diagnosis of a possible root fracture and for the further follow-up of the replanted tooth.

CBCT artifacts arise from the inherent polychromatic nature of X-ray projection, resulting in beam hardening artifact formation due to the increase of the average energy of the beam due to the absorption of low energy photons. This effect is generated by discrepancies between physical condition and mathematics formatting used to make the reconstruction in three dimensions [14]. Two types of artifacts are formed: distortion of metal structures due to differential absorption (cupping artifacts) and hypodense streaks and bands between two objects of high radiodensity (streaking artifacts) [15].

In some cases, false-positive diagnosis can occur in CT or CBCT images acquired for root fracture diagnosis. This may happen due to artifacts obscuring the tooth root. In the case reported, it was possible to clearly observe the hypodense line in the root on CBCT images; however, no fracture was visualized in visual inspection after the extraction of the tooth. Consequently, it was possible to conclude that the hypodense line was a beam hardening artifact, despite the fact that the tooth and adjacent teeth did not have any intracanal materials, which would justify the formation of the artifact due to the high densities of the objects.

It is hypothesized that the artifact present on the image was originated from the dental piercing placed on the right maxillary lateral incisor, which could explain the hypodense line in the image. Another point that supports this hypothesis is the second CBCT examination that was acquired when the patient no longer had the dental piercing and does not present any hypodense line, this artifact or assumed fracture was not visualized. It is worth saying that a careful interpretation of CBCT data adjusted to the diagnostic task is necessary to attain the examination goals. Moreover, the final diagnosis and decision regarding the management of the finding should be associated with clinical evidences.

The false diagnosis of root fracture in CBCT images was previously reported in the literature; however, as described by Kajan & Taromsari [4] the common condition of the involved tooth is the presence of filling material. These authors reported several clinical reports of root fracture in teeth with intracanal restorations and in one of them, as in the presented case report, the fracture was visualized on the CT image but not clinically. Nonetheless, the absence of any intracanal material in the present case makes it very uncommon, highlighting the importance of a careful evaluation of tomographic images and its artifacts even in cases of unrestored teeth.

CONCLUSION

CBCT exams aiming the diagnosis of root fracture have some pitfalls and should be assessed carefully. It is necessary to evaluate properly the presence of beam hardening artifacts, regardless the presence of filling materials, not only in the tooth with the suspicion of root fracture, but also in all adjacent teeth.