|Year : 2015 | Volume
| Issue : 2 | Page : 44-48
Comparison between photostimulable phosphor plates using one or two angulations and cone beam computed tomography scans in detecting root fracture in endodontically treated teeth
Boulos Bechara1, Sabika El Muraikhi2, Alex McMahan3, Ibrahim Nasseh4, Maria Moarbes4, Sayde Sokhn4, Marcel Noujeim1
1 Department of Comprehensive Dentistry, Postgraduate Oral and Maxillofacial Radiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
2 Dental Department, Hamad Medical Corporation, Doha, Qatar
3 Department of Pathology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
4 Department of Oral and Maxillofacial Radiology, Lebanese University, Beirut, Lebanon
|Date of Web Publication||22-May-2015|
Dr. Boulos Bechara
7703 Floyd Curl Dr., Department of Comprehensive Dentistry, Postgraduate Oral and Maxillofacial Radiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900
Source of Support: None, Conflict of Interest: None
Objectives: Artifacts due to the Gutta-percha may result in an incorrect diagnosis when using cone-beam computed tomography (CBCT) only. Compare CBCT scans with photostimulable phosphor (PSP) plates using one angulation and PSP plates using two different angulations in detecting root fractures (RFs) in endodontically treated teeth. Materials and Methods: Sixty-six roots were collected and treated endodontically using gutta-percha. One-half of the roots were randomly selected and fractured. 8 cm × 8 cm fields of view (FOV) were acquired with a CBCT machine. Periapical radiographs (using intra-oral PSP plates) were also acquired using one and two angulations. Results: The area under the receiver operating characteristic curve and sensitivity were significantly greater using CBCT than using one or two PSP plate angulations. There were no significant differences between one or two PSP plate angulations. Conclusion: The accuracy of RF depiction in endodontically treated teeth using 8 cm × 8 cm FOV CBCT was greater than that obtained using one or two PSP plate angulations.
Keywords: Dental trauma, diagnosis, root fracture
|How to cite this article:|
Bechara B, Muraikhi SE, McMahan A, Nasseh I, Moarbes M, Sokhn S, Noujeim M. Comparison between photostimulable phosphor plates using one or two angulations and cone beam computed tomography scans in detecting root fracture in endodontically treated teeth. J Oral Maxillofac Radiol 2015;3:44-8
|How to cite this URL:|
Bechara B, Muraikhi SE, McMahan A, Nasseh I, Moarbes M, Sokhn S, Noujeim M. Comparison between photostimulable phosphor plates using one or two angulations and cone beam computed tomography scans in detecting root fracture in endodontically treated teeth. J Oral Maxillofac Radiol [serial online] 2015 [cited 2019 Nov 15];3:44-8. Available from: http://www.joomr.org/text.asp?2015/3/2/44/157522
| Introduction|| |
Root fracture (RF) is a complication that often leads to teeth extraction. , Endodontically treated and uncrowned posterior teeth have the highest risk for RF.  The diagnostic tools that are used most commonly in dental practices for RF depiction are conventional digital two-dimensional (2D) intraoral radiography. In order to be able to detect a RF, the X-ray beam should pass directly along the fracture line, or else the RF may not be diagnosed. 
Cone beam computed tomography (CBCT) imaging adds a significant augmentation to 2D intraoral imaging in endodontic applications.  Limited CBCT volumes have been shown to be more reliable in diagnosing RFs in studies when the teeth were not treated endodontically.  In both in vivo and in vitro studies, computerized tomography (CT) was found to perform better than intraoral techniques in RF detection. The common advantages of CBCT imaging in clinical practice are accurate images, easy image acquisition, and lower radiation doses compared with medical CT. 
It is well established that high density structures cause artifacts on the radiographic image which interfere with the diagnostic quality of CT and CBCT images.  The presence of high density bodies within the maxillofacial complex of the patient causes beam hardening and streak artifacts,  and ultimately will lead to a limited diagnostic field of the images by obscuring anatomical structure, reducing the contrast between adjacent objects, and impairing the detection of areas of interest. ,, A beam hardening artifact due to gutta-percha, which is a high density root canal filling material, is often noted on CBCT and may decrease the ability to detect RF using CBCT images. 
The Promax 3D ® (Plameca-Finland) CBCT machine captures an 8 cm × 8 cm field of view (FOV) and the dose delivered to the patient is higher than the one received from a periapical image. Bechara et al. found that when an 8 cm × 8 cm FOV was captured using the Promax 3D ® , RF detection in endodontically treated teeth was more accurate compared to photostimulable phosphor (PSP) plate images when only one angulation was used. 
The purpose of this study was to investigate whether RF detection using PSP plates intraoral radiographs using two different capture angulations for each root, is as accurate as an 8 cm × 8 cm FOV CBCT volume when the roots have been treated with a high density material such as gutta-percha which will cause artifact on CBCT images and decrease its accuracy in detecting the fractures. If this is the situation, use of PSP plates with two different angulations save the patient a radiation dose, time, and expense and the dental practitioner time.
| Materials and Methods|| |
Sixty-six human teeth were collected and decoronated. Single roots were prepared and filled with gutta-percha by the same operator using the same technique. Thirty-three roots, chosen randomly, were fractured with a tapered pin inserted vertically in the root canal and tapped gently with a hammer. The two root fragments were glued together with one layer of methyl methacrylate. The remainders of the roots (33) were kept intact. Eight bovine rib fragments were prepared to receive the roots [Figure 1]. Two rib fragments contained nine roots and the remainder contained eight each. The roots were distributed randomly to the eight bovine ribs fragments. The fragments were numbered from 1 to 8. Roots were placed randomly within the assigned fragment. Wax was added around the roots placed in the bone sockets to fill the gap and keep them stable. The ribs were wrapped with three layers of wax to simulate soft tissues. The rib fragments were scanned by groups : f0 ragments 1 and 2 (group 1), 3 and 4 (group 2), 5 and 6 (group 3), 7 and 8 (group 4). Each group was scanned once using the Promax 3D ® . The settings using the CBCT machine were 84 kV, 12 mA, and the voxel size was 0.2 mm; an 8 cm × 8 cm FOV was used. Two periapical radiographs were taken for each bone fragment to cover all inserted roots and depict the fractured roots. A polyvinyl siloxane putty matrix was prepared to hold the PSP plates in place. Then, the matrix was deviated with a 20° angle and both images were recaptured. In total, 32 images were captured for 8 bone fragments. The CBCT scans were exported with the viewer and each of five observers classified the presence of RFs using a five-point scale:
|Figure 1: One of the eight bone fragments containing endodontically treated roots|
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- Definitely absent,
- Probably absent,
- Probably present and
- Definitely present. PSP plates images were exported as tagged image file format files and placed on within two Microsoft Power Point ® documents; one contained only one angulation and the second contained both angulations.
Due to the fact that observers were not located in the same geographical area, they were calibrated using a document that explained how a RF appears on the screen by using descriptive terms and cropped photos of RFs. It was stated that the fracture can be at any level of the root. Reviewers were instructed in the same document to review the images under an indirect dimmed light and to calibrate the monitor using the same online tool. The observers were asked to modify their monitor contrast and brightness until they could see all the gray shades. After calibration, observers independently classified each of the images twice during two distinct viewing sessions separated by at least 14 days.
The kappa statistic  was used to assess agreement within the reader and among readers. Area under the receiver operating characteristic (ROC) curve was used to assess the accuracy of assessment of presence or absence of a RF. Sensitivity and specificity were calculated using a two-category classification constructed by considering a score of 4 or greater as positive for a RF. Area under ROC curves, sensitivity, and specificity by modality (3 modalities), readers (4 readers) and readings (2 readings for each reader) were analyzed using analysis of variance. 
| Results|| |
Agreement among and within readers
Agreement among readers using the five-category classification, by modality, is given in [Table 1]. All the kappa values indicate greater agreement than that due to chance. The agreement among readers was significantly greater for the Promax than for either the PSP 1 view or PSP 2 views. There was no difference in agreement among readers between the PSP 1 view and PSP 2 views.
Agreement among readers using the two-category classification also is given in [Table 1]. Kappa values for all three modalities indicate greater agreement than that due to chance. The agreement among readers was significantly greater for the Promax than for either the PSP 1 view or PSP 2 views.
Agreements within reader using the five- and two-category scales are given in [Table 1]. Kappa values for all three modalities indicate greater agreement than that due to chance. For the two-category scale the within-reader agreement for the Promax was significantly higher than for the PSP 1 view.
Area under receiver operating characteristic curve
Average areas under the ROC curve for each modality are shown in [Figure 2]. Areas under the ROC curves are significantly >0.5 indicating that all three modalities were able to accurately classify the presence of a fracture to a degree greater than that due to chance. The area under the ROC curves for the Promax was significantly greater than that for both the PSP 1 view and the PSP 2 views. There was no significant difference between the PSP 1 view and the PSP 2 views.
|Figure 2: Average area under receiver operating characteristic curve, by modality. Error bars represent 95% confidence intervals. Dashed reference line represents area of 0.5, that is, classification no better than chance. (a) Significantly higher than 0.5 (b) cone beam computed tomography (CBCT) significantly higher than photostimulable phosphor 1 (PSP 1) view (c) CBCT significantly higher than PSP 2 views|
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Sensitivity and specificity
Using a score of 4 or greater as indicating a positive classification, the average sensitivities are shown in [Figure 3]. The sensitivity of the Promax was significantly greater than that for both the PSP 1 view and the PSP 2 views. There was no significant difference between the PSP 1 view and the PSP 2 views.
|Figure 3: Average sensitivity, by modality. Error bars represent 95% confidence intervals. (a) Cone beam computed tomography (CBCT) significantly higher than photostimulable phosphor 1 (PSP 1) view (b) CBCT significantly higher than PSP 2 views|
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The average specificities are shown in [Figure 4]. There were no significant differences among the specificities of the three modalities.
|Figure 4: Average specificity, by modality. Error bars represent 95% confidence intervals|
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| Discussion|| |
Accuracy (area under the ROC curve) and sensitivity were significantly higher using CBCT than both one and two angulations using PSP plates. Although the specificity using CBCT was higher than PSP plates, these differences were not statistically significant. There was no statistically significant difference in accuracy, sensitivity, or specificity noted between taking one or two angulations when acquiring PSP plate images. However, when two angulations were acquired, accuracy, sensitivity, and specificity were slightly enhanced while the radiation dose required for the second angulation is minimal (2 μSv).  Thus, this study provides little support for acquiring the second view. Bernardes et al.  took three projections using periapical films for teeth on which simulated root resorption were made at different levels using two different depths: 0.6 mm and 0.3 mm. They found that when using CBCT all resorption were seen for both depths. Accuracy using periapical films was 52% and 69% for the respective depth of 0.3 mm and 0.6 mm. In the current study, both one and two angulations lead to an accuracy within the 60% range. Sogur et al.  used a combination of PSP plates and F speed films with a 10° difference in angulation to evaluate acid-induced periapical lesions and compared the accuracy with CBCT. They found that two views were better than one although not statistically significantly better, findings similar to the current project. CBCT was still the best modality to use. Molina et al.,  studying RF in children and adolescents, found that as the number of radiographic projections increased, RFs were identified more often.
Librizzi et al. found that diagnostic efficacy of CBCT scans (Hitachi CB MercuRay ® CBCT scanner) for the evaluation of erosive changes in the temporomandibular joint was highest for the 6-in FOV and lowest for the 12-in FOV.  These findings suggest that the smallest, still adequate CBCT FOV should be acquired when high spatial and contrast resolutions are needed to achieve the diagnostic task. Bechara et al. found that using a smaller FOV increases the contrast-to-noise ratio.  Although the machines were not made by the same manufacturer, the machine with the smallest FOV performed the best in all aspects. The 8 cm × 8 cm FOV used in the current study showed a significant difference in area under the ROC curves compared to both PSP plate imaging modalities.
PSP plates modalities had a comparable specificity to the one obtained with the CBCT modality. It was found when the equalization tool was used that the specificity of PSP plates images was higher than CBCT.  This finding suggests that using clinically enhancement tools with PSP plate images leads to better specificity, that is, less false positive diagnosis.
Cone beam computed tomography was more sensitive than both PSP plates images modalities because clinically, if the X-ray beam does not pass by the line of fracture, the RF will not be noted leading to an increase of false negative classifications when using PSP plates. From a clinical standpoint, in an endodontically treated root, if the fracture is noted on an enhanced PSP plate image, it strongly suggests that that the root is fractured although there are false positive diagnoses. On the other hand, if the patient is symptomatic and no fracture shows on the PSP plate image, it may be due to the presence of anatomy that may be superimposed on the fracture and a small FOV CBCT scan will be indicated. PSP plates' sensitivity noted in this current study was not significantly different from 50%. The rate of the false negative was high and in the presence of an intact root, the accuracy of detecting a fracture using PSP plate modalities is not different from guessing.
| Conclusion|| |
This study was an in vitro study which showed that the presence of high density material in the roots such as gutta-percha will decrease the accuracy of RF depiction using an 8 cm × 8 cm FOV CBCT; however, the accuracy was noted to be better than using one or two PSP plate angulations.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]