|Year : 2012 | Volume
| Issue : 1 | Page : 22-28
Cone beam computed tomography imaging as a diagnostic tool in determining root fracture in endodontically treated teeth
Eleftherios Terry R Farmakis1, Spyridon Damaskos2, Christos Konstandinidis3
1 Department of Endodontics, Dental School, University of Athens, Athens, Greece
2 Department of Oral Diagnosis and Radiology, Dental School, University of Athens, Athens, Greece
3 Private Practice, Athens, Greece
|Date of Web Publication||10-Dec-2012|
Eleftherios Terry R Farmakis
27 D. Gedeon st., Paiania
Source of Support: None, Conflict of Interest: None
Introduction: Vertical root fractures (VRFs) of endodontically treated teeth are serious complications that are associated with a poor survival prognosis. The diagnosis of VRFs is difficult, because the clinical signs and symptoms are often obscure and periapical radiographs (PAs) provide limited diagnostic information. Recently, Cone Beam Computed Tomography (CBCT) has been used to address complicated cases of VRFs with an inconclusive diagnosis. Aim: To determine the clinical diagnostic accuracy of CBCT in detecting VRFs in complex failing cases of endodontically treated teeth, as an adjunct to PAs. Materials and Methods: Evaluating the diagnostic accuracy of CBCT in a series of clinical cases of suspected VRFs, presented via clinical photographs, PAs, and CBCT images. Results: CBCT imaging significantly aided the differential diagnosis in most cases. Conclusions: CBCT imaging provides a 3D image and information in many cases of VRF that 2-dimensional PAs fail to generate. The slice thickness and interslice interval of the CBCT image influence the perception of the normal anatomy and pathoses.
Keywords: Cone beam computed tomography, diagnosis, endodontically treated teeth, vertical root fracture
|How to cite this article:|
Farmakis ER, Damaskos S, Konstandinidis C. Cone beam computed tomography imaging as a diagnostic tool in determining root fracture in endodontically treated teeth. Saudi Endod J 2012;2:22-8
|How to cite this URL:|
Farmakis ER, Damaskos S, Konstandinidis C. Cone beam computed tomography imaging as a diagnostic tool in determining root fracture in endodontically treated teeth. Saudi Endod J [serial online] 2012 [cited 2020 Jul 6];2:22-8. Available from: http://www.saudiendodj.com/text.asp?2012/2/1/22/104418
| Introduction|| |
A vertical root fracture (VRF) is a "through-and-through" crack that connects the root canal space and the periodontal ligament.  VRFs are caused primarily by endodontic procedures, followed by amalgam build-up, composite core, cast post, or screw-in post. 
Diagnosing VRFs is often complicated. A local deep periodontal pocket, dual sinus tracts, and halo-type lateral radiolucency are among the most common findings. , These clinical signs are often difficult to detect or reproduce during an examination. The justification of the poor tooth prognosis is essential in the decision making process. ,
Panoramic and periapical radiographs (PAs) are insufficient to make a definitive diagnosis in many cases of VRF. , In the past several decades, many new imaging modalities, such as digital imaging, computed tomography (CT), magnetic resonance imaging, positron emission tomography, and cone beam computed tomography (CBCT), has increased the accuracy of the diagnosis of the maxillofacial region. ,
In particular, CBCT imaging is gaining rapid acceptance in dentistry, due to its ability to generate undistorted 3-dimensional images of the maxillofacial skeleton, the teeth, and their surrounding structures. Additionally, the information that is obtained with CBCT is exceptional, and the radiation dose and costs are lower compared with conventional CT imaging. Consequently, CBCT imaging has been touted as a valuable supplement to intraoral and panoramic radiographs when conventional radiographic findings are inconclusive. ,,
The aim of this study was to investigate the clinical diagnostic accuracy of CBCT in detecting root fractures in complex failing cases that involved endodontically treated teeth as an aid to PAs.
| Case Reports|| |
In all presented cases, VRF and/or coronal perforation were suspected. A conventional radiographic imaging by using at least three PA radiographs with different horizontal angulation according to Clark's technique  was also inconclusive; therefore, the CBCT imaging technique was utilized.
The nature of the procedure and possible discomforts and risks were fully explained to all patients involved and informed consent forms were obtained.
A 50-year-old male was referred for the evaluation of a localized, undetermined discomfort during mastication related to the upper left quadrant. The intraoral examination revealed slight mobility of an old 8-unit fixed partial denture (FPD), extending from teeth #15 to #23, replacing teeth #14, #13, #12, and #22. The left upper canine (#23) was sensitive to percussion; no sinus tract, periodontal pocket, or any other sign of acute inflammation were evident [Figure 1]a. The PAs showed endodontic treatment of tooth #23, estimated to be 4-5 mm short of the apex, along with an associated periapical lesion extending coronally along the mesial aspect of the root to the level of the tip of the cast post [Figure 1]b. A radiolucent area with undefined borders, distally to tooth #23, was also present, adjacent to the end of the cast post.
|Figure 1: (a) Occlusal view of tooth #23, (b) Periapical radiograph (PA), (c) Saggital CBCT imaging revealing the mid-root perforation|
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As the radiographic findings were unclear, a CBCT imaging procedure was used (Accuitomo, J. Morita, Japan. field of view [FOV]: 3 × 4 cm with image intensifier; Voxel size, 0.125 mm). The transaxial images revealed an area of low density (radiolucency) extending from the canal to the periodontal ligsment space (PDL) at the level of the post in the middle of the palatal aspect of the root of tooth #23, as well as an adjacent alveolar radiolucent region with well-defined borders, leading to an unsalvageable prognosis for the tooth [Figure 1]c.
A 32-year-old male was referred for the evaluation of dull pain on tooth #25 during mastication; the symptom lasted for at least 10 days. The intraoral examination revealed the presence of a fistula at the free gingival area of tooth #25. No periodontal pocket was detected on probing. The patient's dental records showed that the tooth #25 was treated endodontically by a specialist 5 years ago, followed by an amalgam post build-up and a porcelain-fused-to-metal restoration. The radiographic examination, performed by a set of PAs, along with the insertion of a gutta-percha cone in the sinus tract confirmed the endodontic treatment the post restoration, revealed the presence of a periapical radiolucent lesion associated with the root of tooth #25 as well as the association of the fistula with the tooth [Figure 2]a.
|Figure 2: (a) Initial PA imaging of tooth #25. Gutta-percha cone inside the sinus tract leading to the middle aspect of the root, (b) CBCT axial image of #25. Cupping artifacts can be seen associated with tooth #27, (c) PA image of #25 with periodontal PAobe in place, (d) #25, extracted|
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In order to exclude the presence of VRF and to obtain the third dimension, a CBCT examination was performed (Accuitomo, J. Morita, Japan. FOV: 3 × 4 cm with image intensifier,Voxel size 0,125 mm). The CBCT axial images [Figure 2]b revealed a line-shaped area of low density (radiolucency) extending from the canal to the PDL space line at the root of tooth #25 with an intact cortical plate, confirming a hallmark of an early stage of a VRF. The distortion caused by the radiopacity of the amalgam post was also noted. The crown was removed and a crack line was observed, no bone defect was detected on probing [Figure 2]c. Eventually, the tooth was removed and the VRF was confirmed [Figure 2]d.
A 48-year-old male complained of a periodical swelling of the upper right molar-premolar region. No other consequent symptoms were evident. The intraoral clinical examination revealed a swelling that was associated with a fistula, in the area of teeth #13 and #14. Teeth #14, #15, and #18 were part of a 5-unit FPD that replaced extracted teeth #16 and #17. No pain to percussion, sensitivity to palpation, or periodontal pocket was observed.
The obtained PA radiograph revealed endodontic treatment of teeth #13, #14, and #15 with a 3-4 mm overextended endodontic filling at tooth #13 [Figure 3]a. The radiograph also showed a radiolucent area with ill-defined borders associated with the mid-root of teeth #13 and #14 which extended apically to involve the apices of both teeth. On a second PA, a gutta-percha cone was inserted into the sinus tract and found pointing toward the apex of tooth #14 [Figure 3]b.
|Figure 3: (a) Initial PA of teeth #13, 14. Radiolucency is more evident between teeth #13 and #14 at the mid-root level, (b) PA with the gutta-percha cone leading directly to the apex of tooth #14, (c) Axial CBCT imaging revealing the discontinuation of the root dentin extending from the root filling material to the PDL on tooth #14 (arrow), (d) #14, extracted|
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Since a VRF was included in the differential diagnosis, two additional PA radiographs were performed using the Clark's technique and again provided inconclusive results. In order to reach a definitive diagnosis, CBCT images were taken, (Accuitomo, J. Morita, Japan. FOV: 3 × 4 cm with image intensifier; Voxel size, 0.125 mm) revealing a VRF on tooth 14 [Figure 3]c. Consequently, the tooth was extracted, and the root fragments are shown in [Figure 3]d.
A 60-year-old female was referred for evaluation of repeated small swelling of the lower left first molar region. The intraoral clinical examination revealed a fistula at the free gingival buccal area of tooth #36, which was restored by a porcelain-fused-to-metal crown [Figure 4]a. No periodontal pocket was detected on probing. No other signs or symptoms of acute inflammation were evident.
|Figure 4: (a) Clinical view of tooth #36, (b) PA of tooth #36 with no evidence of vertical root fracture, (c) Clinical view of tooth #36 with the gutta-percha cone in place of the sinus tract, (d) PA of tooth #36 with the gutta-percha cone leading to the furcation area (the arrow indicates the end of the GP cone), (e) CBCT 3-D axial image of #36,(f) CBCT 3-D cross-sectional image of tooth #36, (g) After removal of the crown and restoration material, two perforations were revealed (arrows)|
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The obtained PA radiograph revealed endodontic treatment of tooth #36, in addition to a radiolucent area affecting the alveolar bone in the furcation area of the tooth [Figure 4]b. A second PA radiograph was performed, with a gutta-percha cone inserted into the sinus tract. The cone pointed to the mesial root of tooth #36, at the level of the bifurcation, associated with a class III bone defect [Figure 4]c and d. A VRF was suspected and additional evidence was needed; therefore, a CBCT examination was performed, (Scanora 3D, Soredex, Finland. FOV: 7.5 × 14.5 cm with high resolution; Voxel size, 0.25 mm) which easily detected the boney defect in the axial images and the absence of the buccal cortical bone in the cross-sectional images. The images were thoroughly inspected, yet no VRF was noted [Figure 4]e and f. The coronal restorations were removed, and two perforations were detected at the pulpal floor. The CBCT images failed to demonstrate these perforations clearly [Figure 4]g.
A 60-year-old female was referred with sensitivity during mastication on tooth #24 which was a supporting abutment of a porcelain-fused-to-metal-fixed prosthesis. The symptoms persisted for several weeks before seeking consultation. The patient could not recall if symptoms arose after chewing on hard food. The intraoral clinical examination revealed a 3-unit FPD on teeth #22, #23, and #24 and an implant replacing tooth #25. Tooth #24 was noted sensitive to percussion and probing was within normal limits. The patient's dental records indicated that all three supporting teeth had received endodontic treatment by a specialist one year earlier.
The PA radiograph revealed a J-shaped periapical radiolucency with well-defined borders that was associated with the apex of tooth #24 and not related to the implant [Figure 5]a. As this type of lesion in an endodontically treated tooth may be indicative for a VRF,  but no localized periodontal pocket was traceable, a CBCT examination (Scanora 3D, Soredex, Finland, FOV: 7.5 × 14.5 cm with high resolution; Voxel size, 0.25 mm) was performed. The CBCT demonstrated that the radiolucency was associated only with tooth #24 and no discontinuation of dentin was observed to set a definite diagnosis of a VRF [Figure 5]b. As a result, the failing endodontic treatment was attributed to secondary contamination of the root canal space through a leaking marginal fit of the porcelain-fused-to-metal restoration [Figure 5]c; and decided to retreat. After the crown removal and rubber dam isolation, a crack line was evident [Figure 5]d. In this case, CBCT imaging failed to detect the VRF.
|Figure 5: (a) PA of case 5 revealing the J-shaped radiolucency of tooth #24, (b) Axial and cross-sectional CBCT images. The implant is not involved in the periapical lesion of tooth #24, (c) Cross-sectional image indicating a possibly ill-fitting crown (arrow) of tooth #24, (d) Crown removal revealed a crack line (arrow)|
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A 46-year-old female was referred for the sensitivity of the maxillary left the area during mastication, which developed several months earlier after chewing hard food. The intraoral clinical examination revealed a fistula that was associated with the apices of teeth 24 and 25, both of which had FPD restorations [Figure 6]a. The PA revealed radiolucency along the lamina dura. The gutta-percha cone, which had been inserted into the sinus tract, led to the middle aspect of the root of tooth #24 [Figure 6]b. Because a VRF was suspected, two more PAs were performed to verify the diagnosis, yielding inconclusive findings. CBCT images were taken to make a definitive diagnosis (Accuitomo, J. Morita, Japan. FOV: 3 × 4 cm with image intensifier; Voxel size, 0.125 mm). As seen in [Figure 6]c and a zip was evident along the root, associated with the extruded filling material.
|Figure 6: (a) Clinical view of tooth # 24 with a gutta-percha cone inside the sinus tract, (b) PA image of tooth #24 with the gutta-percha cone leading to the middle of the root but not visualized easily due to the superimposition of the root canal filling of #24 (red arrow), (c): CBCT image of tooth #24 showing the zip along the root and filling material extruding on the outer surface of the root (white arrows)|
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| Discussion|| |
Making a definitive diagnosis for a VRF, using conventional radiographic techniques, is particularly difficult. PA radiographs are essential for successful diagnosis, because the earliest sign of periapical pathology is discontinuity or widening of the lamina dura. , As PA radiographs are 2-dimensional images of 3-dimensional anatomical structures, the superimposition of adjacent structures may obscure the visibility of VRFs, as in Cases No 1 and 4.
The conventional radiographs reveal such fractures best when the X-ray beam is parallel to the fracture line and when there is neither superimposition of other adjacent structures nor other hard tissues or radiopaque restorative materials. Under such circumstances, the diagnosis of VRF is often based on clinical or other radiological findings, such as a V-shaped pattern osseous defect , and J-shaped periradicular radiolucency. 
As the current literature suggests, CBCT imaging contributes to the detection of VRFs compared to conventional radiographic techniques.  Periapical disease may be detected sooner using CBCT vs periapical views, and the true size, extent, nature, and position of periapical and resorptive lesions can be assessed. Additionally, root fractures, root canal anatomy, and the true alveolar bone topography around the teeth may be clearly defined. 
CBCT images also have greater value in the morphological description of periodontal bone defects, while the digital PA radiographs provide more bone details.  Wang et al.  demonstrated that CBCT imaging increases the accuracy of diagnosis of root fractures, as confirmed by surgical procedures on experimental material. The same conclusions were reached by Bernades et al., who reported that CBCT is the perfect complementary tool to conventional radiographic techniques in the diagnosis of VRFs.
By definition, VRFs extend longitudinally onto the root surface. Therefore, it is logical to assume that a horizontal cross-section, which is perpendicular to the VRF, provides the best diagnostic image. Axial slices are more accurate than coronal or sagittal images in revealing VRFs.  Moreover, the orientation of a fracture line has no significant influence on the accuracy of CBCT, because it is insensitive to VRF line orientation due to its 3-dimensional nature. The same group also reported greater accuracy of CBCT scans compared with PA radiographs in detecting VRFs.  These data are consistent with our findings, whereas VRFs were not visible on the PA in four instances; only in the last case was radiolucency along the lamina dura evident.
CBCT imaging is not always superior to PA radiographs in detecting a VRF, due in part to parameters that influence the CBCT image, such as detector type and characteristics, the FoV, the scan selection, and the voxel size (which influence contrast and resolution), as well as system-specific imaging artifacts. Under these circumstances, significant differences arise between different CBCT systems in which disparate technologies are embedded.
In general, the smaller the scan volume, the higher the spatial resolution of the image is. As the earliest sign of periapical pathology is a discontinuity in the lamina dura and widening of the periodontal ligament space, it is desirable that the optimal resolution of the any CBCT imaging system used in Endodontics does not exceed 200 μm-the average width of the periodontal ligament space.  Additionally, Liedke et al., have recommended a minimal voxel resolution of 0.3 mm for the detection of external root resorption. 
Despite the provision of the third dimension, the spatial resolution of CBCT images (0.4 mm to 0.076 mm or equivalent to 1.25 to 6.5 line pairs/mm [l p./mm]) is inferior to conventional film-based (approx. 20l p./mm) or digital (ranging from 8-20l p./mm) intraoral radiography. 
Factors such as beam quality and filtration are unique to a specific machine, while other factors, such as FOV, can sometimes be operator controlled. Typically, the smaller the FOV for a given system, the lower the radiation dose applied. ,
The slice thickness and interslice intervals are also significant in viewing normal anatomy and pathoses in CBCT imaging. Statistically significant differences exist between bone heights when slice thickness or interslice interval varies by greater than 1 mm (P < 0.005).  CBCT images with 0.4-mm-thick cross-sections provide values that approximate those of the gold standard (image acquisition, with dimensions equal to the original), indicating a more accurate assessment of periodontal bone loss. 
Regarding the perforation of the pulp chamber in Case 4 and in the fractured premolar of Case 6, detection of the lesion was impossible by CBCT due to the compromised image quality.
In practice, patients with suspected root fracture fall into two broad categories. First, there are those with acute trauma to anterior teeth, often children. Second, there are patients whose teeth may have fractured due to chronic trauma during normal function, usually in endodontically treated teeth. In the second group, the weight of evidence suggests that root fillings and posts limit diagnostic accuracy due to the distortion that is related to those materials because of the differential absorption known as cupping artifacts, which create star-shaped streak artifacts, mimicking crack lines on CBCT images. Of course, in some of these cases, diagnosis can be made, and prognosis assessed, on clinical examination evidence alone, so imaging may not always be indicated. In other cases, conventional radiography may provide sufficient information for management. It is already showed that limited volume, high-resolution CBCT is indicated in the assessment of dental trauma (suspected root fracture) in selected cases, where conventional intraoral radiographs provide inadequate information for treatment planning. 
| Conclusions|| |
CBCT images provide a 3-dimensional view and information that 2-dimensional PA radiographs fail to provide in many cases of root fractures. The effects of slice thickness and interslice interval are significant in viewing normal anatomy and pathoses in CBCT images. The increasing use of CBCT in dental offices may be expected to result in improved diagnosis of VRFs, but with an increased patient dose and healthcare costs.
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