To compare selected anatomical and treatment-related diagnostic parameters estimated by cone-beam computed tomography and by digital periapical radiography in teeth with apical periodontitis, and to evaluate reliability of different examiners in interpretation of images obtained by both methods.
Teeth with apical periodontitis were evaluated independently by 2 endodontists and 1 radiologist based on 128 cone-beam computed tomography (CBCT) and 162 digital periapical radiography (DPR) images. Anatomical (size, relation with root, location of periapical radiolucency) and treatment-related (canal obturation length, homogeneity, coronal seal) parameters were assessed. Fleiss kappa reflected inter-observer agreement while intra-examiner agreement was estimated by Cohen’s kappa. McNemar and McNemar-Bowker tests served for evaluation of differences between CBCT- and DPR-based estimates.
Cohen’s kappa ranged from 0.62 to 1 for all examiners. Fleiss kappa values were nearly perfect for majority of parameters. Diagnostic discrepancy between methods was found for size of radiolucency that in 15 - 17% cases was larger, and in 25 - 28% smaller in DPR than in CBCT images. DPR revealed 20% of root canals scored as non-obturated while in CBCT - obturation present. Canal obturation was rated as homogenous by CBCT, while absent or non-homogenous by DPR, in 17 - 23%, and 11 - 14% of cases, respectively. Radiologist detected more root perforations in CBCT than in DPR images.
Good intra- and inter-examiner agreement for anatomical and treatment-related diagnostic parameters was achieved using cone-beam computed tomography and digital periapical radiography methods and demonstrated similar diagnostic capability, although variation regarding root perforations and canal obturation quality was observed.
Radiological examination of patients with presumed periapical pathology is an accepted diagnostic method to confirm the presence of the periapical diseases [
The digital periapical radiographic (DPR) imaging has been accepted in clinical practice for nearly thirty years, and has become a routine diagnostic procedure in endodontics. However, due to the limited ability to provide a detailed view of the three-dimensional anatomical structures, DPR is often claimed to give lack of information about the important parameters such as alveolar bone thickness, root canal anatomy, size, extension and location of periapical lesions [
An important limitation of the CBCT is the patient’s exposure to high radiation doses that vary a lot, depending on a number of factors such as field of view, the desired image resolution, X-ray beam energy, filtration, exposure time, receptor technology, even the patient’s size and age [
Despite the large number of studies focused on the comparison of the efficacy of different radiological methods in endodontic diagnosis, a comprehensive analysis of different anatomical and treatment-related parameters potentially having a prognostic value for the teeth subjected to root canal treatment has not been found in the literature. Moreover, the potential differences in diagnostic ability of DPR and of CBCT may influence the clinical decisions in treatment planning [
The aim of this study was to compare the estimates of selected anatomical and treatment-related parameters obtained from the cone-beam computed tomography and the digital periapical radiographic images in teeth with apical periodontitis, and to evaluate the reliability of different examiners in the interpretation of the images obtained by both methods.
The data were obtained from the patients participating in a large clinical trial aiming to assess the selected anatomical and treatment-related parameters in teeth with apical periodontitis (AP) based on CBCT and DPR. All patients were examined clinically and radiographically (CBCT and DPR) in the dental clinic (Vilnius Implantology Centre clinic, Vilnius, Lithuania) and were scheduled for endodontic treatment from December 2016 to December 2018. All the participants gave written informed consent to be involved in the study. The study protocol was approved by the Ethical Committee of Biomedical studies, Lithuania (Protocol No 111; edition No BE-2-27).
The study participants were adult patients aging 46 (SD 12.3) years-old (range 18 to 70 years-old) referred for the endodontic treatment with a specialist. Patients with at least one tooth with apical periodontitis (AP) (periapical changes radiographically detected associated with necrotic pulp or root filled teeth), sufficient periodontal support, primary and retreatment root canal treatment cases were included in the study. Patients had baseline CBCT images performed for general treatment planning purposes no earlier than one month prior to treatment. Both primary and retreatment cases were included. Pregnant women, immunosuppressed patients, and patients presenting with un-restorable teeth (e.g., deep root caries lesion, root fracture) or, with probing depths > 5 mm around the marginal bone were excluded.
A total of 128 CBCT and 162 DPR images of 176 teeth were obtained from 128 patients who fulfilled the above described inclusion criteria and agreed to participate.
The time interval between CBCT and DPR examinations was no more than 1 month.
The images were obtained with i-CAT scanner (Imaging Sciences International Inc., Hatfield, PA, USA); exposure parameters: 84 kV, 5 mA, 0.3 mm voxel resolution, 6 x 16 cm field of view, 18.3 sec acquisition time. All the obtained images were examined on the 27-inch flat panel display computer screen (Apple, MacBook Pro, USA) with a pixel resolution of 2,560 x 1,440, in a dimmed room without time restrictions for the evaluations. The CBCT images were evaluated using the original viewing program from i-CAT viewing software (Imaging Sciences International, Inc., Hatfield, PA, USA). The images that best confirmed presence or absence of a periapical lesion in the sagittal, coronal and/or axial planes were used. The filters were set to normal, and only brightness and contrast were adjusted.
Straight projection intraoral periapical radiographs were obtained using the digital imaging system Kodak (Carestream Dental LLC, Atlanta, GA, USA) with a parallel technique (exposure parameters - 60 kV, 7 mA and 0.3 sec). The images were captured and fixed using a sensor holder. A protractor was used to accurately angulate the X-ray beam for the parallel images [
All the obtained CBCT and DPR images were evaluated independently by 3 examiners with clinical experience using DPR and CBCT techniques and without knowledge of the clinical outcomes:
I and II - qualified endodontists;
III - oral and maxillofacial radiologist.
Prior to evaluation, the examiners were trained using examples of both techniques. Thus, 30 CBCT and 30 DPR images were used for discussion. All cases of disagreement were debated until a consensus was reached. The parameters assessed by three examiners from the DPR and CBCT images were adopted from Venskutonis et al. [
Assessment criteria of anatomical and treatment-related parameters adapted from Venskutonis et al. [17]
Parameters | Severity criteria |
---|---|
|
|
Size of periapical radiolucencya (S) |
S0: radiolucency does not exceed 2 times the width of the lateral periodontal ligament space; |
Relationship between dental root and periapical radiolucency (R) |
R1: radiolucency appears on one root; |
Location of radiographically detected bone destruction (D) |
D1: radiolucency around root apex; |
|
|
Canal obturation length (L) |
L0: no obturation material radiographically visible in pulp chamber and in root canal space; |
Obturation homogeneity (H) |
H0: no obturation material radiographically visible in root canal; |
Coronal seal (CS) |
CS0: no coronal restoration; |
Presence of complications/failures (root perforation, |
CF0: no; |
Post inside root canal (P) |
P0: no; |
Assessment criteria of anatomical and treatment-related parameters adapted from Venskutonis et al. [17]
aPeriapical lesion on the digital periapical radiography was defined as a radiolucency located in the periapical area of the tooth in connection with the apical part of the root exceeding at least twice the width of the periodontal ligament space [5].
For the cone-beam computed tomography images, the same criterion was applied, and the radiolucency had to be visible at least in two image planes.
The intra-examiner reliability assessment of CBCT and of DPR scorings was performed for each examiner on the basis of 30 DPR and 30 CBCT images of the randomly selected cases from the clinical study that had been scored independently twice, within a month period. The inter-observer reliability assessment as well as comparison of the diagnostic capability of two radiographic methods (CBCT and DPR) was performed on the basis of all 128 CBCT and 162 DPR images that had been evaluated independently by all three examiners.
Sample size calculation was performed following the protocol of the clinical trial, and was based on the data from the clinical study reported by Patel et al. [
The Cohen‘s kappa was used to assess intra-observer agreement while Fleiss kappa analysis was used to assess the inter-observer agreements of all 3 observers on each variable. The calculations were done separately for CBCT and DPR. The frequency distributions of all the parameters were obtained. The descriptive statistics was used to illustrate the numbers of root canals identified by three examiners. Comparison of the results obtained by CBCT and DPR was performed using McNemar and McNemar-Bowker tests. Significance level was set at P ≤ 0.05 and the 95% confidence interval (CI) [
The intra-examiner agreement estimates of three examiners varied from substantial to perfect, irrespective of which examination method (CBCT or DPR) was used. Thus, the Cohen’s kappa values for examiner I ranged from 0.84 to 1 and from 0.83 to 1, while for examiner II were 0.73 to 1 and from 0.62 to 1 and, for examiner III, from 0.66 to 1 and from 0.92 to 1, for CBCT and DPR readings, respectively.
The results of the inter-examiner agreement between three examiners using two examination methods are presented in
Inter-examiner agreement (Fleiss kappa values, and 95% confidence intervals [CI]) for CBCT and DPR
CBCT | DPR | |
---|---|---|
Kappa (95% CI) | Kappa (95% CI) | |
Periapical lesion (yes/no) | 0.955 (0.928; 0.977) | 0.904 (0.863; 0.938) |
Size of periapical radiolucency | 0.962 (0.937; 0.983) | 0.906 (0.87; 0.937) |
Relationship between root and radiolucency | 0.948 (0.922; 0.971) | 0.899 (0.864; 0.932) |
Location of bone destruction | 0.966 (0.939; 0.985) | 0.911 (0.874; 0.942) |
Root canal obturation (yes/no) | 0.987 (0.954; 1) | 0.967 (0.918; 1) |
Obturation length, mm | 0.982 (0.966; 0.992) | 0.96 (0.937; 0.977) |
Obturation homogeneity | 0.982 (0.961; 0.993) | 0.928 (0.895; 0.956) |
Coronal seal (yes/no) | 1 | 1 |
Coronal seal (adequate/inadequate) | 0.913 (0.866; 0.949) | 0.763 (0.693; 0.827) |
Complications (yes/no) | 0.96 (0.935; 0.981) | 0.833 (0.782; 0.874) |
Root perforation | 0.189 (-0.021; 0.401) | 1 |
Root canal not treated/missed | 1 | 1 |
Root resorption | 1 | 1 |
Root/tooth fracture | 1 | 1 |
Endodontically treated root with radiolucency | 0.969 (0.946; 0.989) | 0.888 (0.844; 0.926) |
Instrument fractures | 1 | 1 |
Post inside the root canal | 0.938 (0.865; 0.987) | 0.951 (0.876; 1) |
Inter-examiner agreement (Fleiss kappa values, and 95% confidence intervals [CI]) for CBCT and DPR
Fleiss kappa (statistically significant at the level P ≤ 0.05).
CBCT = cone-beam computed tomography; DPR = digital periapical radiography.
Counts of observed root canals in teeth with apical periodontitis, by examination method
Types of |
CBCT observed counts (n) of root canals, |
DPR observed counts (n) of root canals, |
||||
---|---|---|---|---|---|---|
I | II | III | I | II | III | |
1 canal/per root | 59 | 59 | 57 | 64 | 64 | 56 |
MB1 canal | 81 | 81 | 81 | 81 | 81 | 81 |
MB2 canal | 18 | 18 | 18 | 18 | 18 | 18 |
ML canal | 29 | 29 | 29 | 28 | 28 | 28 |
DB canal | 61 | 61 | 60 | 60 | 60 | 61 |
DL canal | 12 | 12 | 12 | 10 | 10 | 12 |
Distal canal | 27 | 27 | 27 | 28 | 28 | 26 |
Buccal canal | 36 | 36 | 39 | 31 | 31 | 39 |
Palatal canal | 72 | 72 | 73 | 70 | 70 | 74 |
Lingual canal | 8 | 8 | 9 | 5 | 5 | 8 |
Total | 403 | 403 | 405 | 395 | 395 | 403 |
Counts of observed root canals in teeth with apical periodontitis, by examination method
n = number of observed cases with the respective type of root canal.
CBCT = cone-beam computed tomography; DPR = digital periapical radiography.
When the observations of the study parameters obtained by CBCT and by DPR were compared, the majority of the scorings did not differ between the methods, for all the examiners (
The P-values for the estimated differences in the observations obtained by DPR and CBCT, by three examiners
Variables | P-value | ||
---|---|---|---|
Examiners | |||
I | II | III | |
Periapical lesion (yes/no)a | 0.109 | 0.201 | 0.165 |
Size of radiolucencyb | 0.001 | 0.002 | 0.002 |
Relationship between root and radiolucencyb | 0.389 | 0.4 | 0.132 |
Location of bone destructionb | 0.112 | 0.199 | 0.138 |
Presence of root canal obturation (yes/no)a | 0.125 | 0.227 | 0.039 |
Obturation length, mmb | 0.361 | 0.167 | 0.222 |
Obturation homogeneityb | 0.168 | 0.015 | 0.21 |
Coronal seal (yes/no)a | 1 | 1 | 1 |
Coronal seal (adequate/inadequate)b | 0.394 | 0.182 | 0.853 |
Presence of complications/failuresa | 0.62 | 0.91 | 0.712 |
Root perforationa | 0.5 | 0.625 | 0.0001 |
Endodontically treated root with radiolucencya | 0.275 | 0.254 | 0.089 |
Instrument fracturesa | 0.25 | 0.25 | 0.25 |
Post inside the root canala | 1 | 0.739 | 0.739 |
The P-values for the estimated differences in the observations obtained by DPR and CBCT, by three examiners
aMcNemar test (statistically significant at the level P ≤ 0.05);
bMcNemar-Bowker test (statistically significant at the level P ≤ 0.05).
DPR = digital periapical radiography; CBCT = cone-beam computed tomography.
Distribution of scores for size of radiolucency, between CBCT and DPR, related to examiners I, II and III
DPR | ||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Size of radiolucency | ||||||||||||||||
S0 | S1 | S2 | S3 | Total | ||||||||||||
I | II | III | I | II | III | I | II | III | I | II | III | I | II | III | ||
230 | 224 | 226 | 28 | 30 | 32 | 12 | 14 | 13 | 0 | 0 | 0 | 270 | 268 | 271 | ||
27 | 31 | 33 | 70 | 67 | 70 | 0 | 0 | 0 | 0 | 0 | 0 | 97 | 98 | 103 | ||
0 | 1 | 0 | 4 | 4 | 2 | 21 | 21 | 24 | 0 | 0 | 0 | 25 | 26 | 26 | ||
0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 3 | 3 | 3 | 3 | 3 | 3 | ||
257 | 256 | 259 | 102 | 101 | 104 | 33 | 35 | 37 | 3 | 3 | 3 | - | - | - |
Distribution of scores for size of radiolucency, between CBCT and DPR, related to examiners I, II and III
DPR = digital periapical radiography; CBCT = cone-beam computed tomography.
Analysis of the treatment-related parameters showed that in 19 - 24% cases the root canals had been scored by all three examiners as non-obturated (L0) by DPR, however, had a record of obturation material visible in CBCT images. The difference reached the significance level for examiner III. Furthermore, the differences were found for obturation homogeneity such that 17, 19, 23% of cases (examiners I, II, III) had been rated by CBCT as H1 (homogenous), but by DPR - as H0 (no obturation). In 11, 13, 14% of cases the DPR scores were H2 (non-homogenous), in contrast to the CBCT scores (H1), as reported by the examiners I, II and III, respectively. Conversely, the CBCT images in 16, 19, 24% of cases were rated H2 while they were seen as homogenous (H1) on the DPR images, by three examiners.
A statistically significant difference in the number of root perforations observed by means of CBCT, was estimated for one examiner (III), the radiologist. Thus, this examiner recorded 25 canals with root perforation present in the CBCT images, but only one case was visible in DPR images. The majority of the recorded root perforations were in molars.
The present results showed that the majority of the diagnostic parameters used in this study could be evaluated reliably by both examination methods. Thus, analysis of the anatomical parameters (presence, size, location of the periapical radiolucency) and of the important treatment-related parameters such as root canal obturation length, homogeneity and coronal seal, confirmed that the recordings could be reproduced by the same examiner or by another examiner to the extent of almost perfect agreement, either using DPR or CBCT technique. Most likely, the high level of reproducibility of the recordings was achieved by the extensive training of the examiners prior to the study. Furthermore, a detailed description of the scoring criteria facilitated communication and understanding between the different specialists and a substantial agreement in the scorings. As reported previously, the diagnostic capability of the radiographic images may vary depending on the clinical experience of the examiners as well as on their education [
Comparison of the diagnostic capability of two radiographic methods based on the total study sample revealed that the majority of the scorings of different study parameters provided by three examiners were comparable between the methods. However, all the examiners identified more root canals using CBCT than DPR. The root canal counts mostly differed in the premolars and molars, the variations attributed particularly to the lingual and buccal canals. These findings are in agreement with the results of other studies [
In contrast to the common belief that CBCT is able to detect significantly more periapical lesions [
For one examiner, statistically significant difference between two methods of radiographic diagnosis was estimated for the number of identified root perforations. The radiologist recorded 25 cases with root perforation present on the CBCT images that had been missed by DPR. Comparison of the recordings provided by the other two examiners (endodontists) did not reach the significant difference. Such variation in the recordings could be explained by the finding that both methods have low sensitivity to diagnose root perforations. The potential problem with DPR images is that the two-dimensional projection may not be able to identify perforations hidden due to the anatomical concavity of the root. As concerns the CBCT technique, Shemesh et al. [
Two earlier studies reported that the coronal seal and the obturation quality of the root canals were significantly associated with failure of endodontic treatment [
To conclude the results of the present study, there was not enough support for justification of the CBCT diagnostic priority, in teeth with apical periodontitis. Given the fact that the CBCT technique provides high radiation doses for the patients, the DPR imaging should be the first choice radiography method as an adjunct to clinical acumen in decision-making process before the endodontic treatment. Only in selected cases, when the character of detectable pathology is questioned by DPR and by clinical tests, additional radiographic examination using CBCT should be considered. These assumptions are in agreement with the position statement of the European Society of Endodontology [
This study concluded that the radiographic assessment of the majority of anatomical and treatment-related parameters could be performed with acceptable reliability and the high level of inter-examiner agreement between three examiners. Cone-beam computed tomography and digital periapical radiographic methods in teeth with apical periodontitis demonstrated similar level of diagnostic capability, although variations related to identification of some treatment-related errors (root perforations, incomplete canal obturations) had been recognized.
The authors want to thank Per-Erik Isberg (Department of Clinical Sciences Lund, Lund University, Malmö, Sweden) and Irena Nedzelskiene (Clinic of Dental and Oral Pathology, Lithuanian University of Health Sciences, Kaunas, Lithuania) for statistical support.
This research is self-funded and has not received any external financial grants.
The authors deny any conflicts of interest related to this study.
All the authors declared absence of any conflicts of interest.
All authors have contributed significantly and are in agreement with this manuscript.