Knowledge and responsibility in CBCT practice among general and specialized Israeli dentists – a questionnaire based study
Cone Beam Computed Tomography (CBCT) use is widely expanding . CBCT technology provides volumetric data with high resolution and accuracy. It is used for a variety of indications such as dental implants, impacted teeth, endodontic pathologies, bone lesions, temporomandibular joint, airway studies and more . The Field Of View (FOV) of the CBCT scan performed is often larger than the Region Of Interest (ROI)  indicated in the referral request, and may include incidental findings, shown to occur in the head and the neck region in 17–93% of CBCT scans. These incidental findings may include pathologies in the sinuses, airway, odontogenic or non-odontogenic cysts or tumors, or soft-tissue calcifications , with 0.3-1.4% of the cases suspected to be malignant . CBCT scan output is diverse and may include (1) Cross Sectional Images (CSI), perpendicular to a line representing the center of a jaw, localized to a specific region requested by the referring clinician (ROI) ; (2) Digital Imaging and Communications in Medicine (DICOM) files with a viewer software, which creates a multiplanar reconstruction of the entire scanned volume allowing the visualization of data in multiple orientations such as: axial, coronal and sagittal as well as reformatted panoramic images, CSI etc .; (3) Radiologic interpretation report, describing the radiographic findings demonstrated in the scan within and outside the ROI ; or combination of these (Fig. ). There are international guidelines relating to the responsibility and training of the referring, the operating and the interpreting dentists who use CBCT . Various organizations around the world such as the ADA (American Dental Association) and the AAOMR (American Academy of Oral Radiology)  in the U.S. as well as the IRMER (Ionizing Radiation Medical Exposure Regulation)  in the United Kingdom and the RCDSO (Royal College of Dental Surgeons of Ontario)  in Ontario, Canada and IAEA (International Atomic Energy Agency) , all issued guidelines stating that all of the scanned volume must be interpreted by a trained medical professional (oral and maxillofacial radiology specialist or a trained specialist) and a detailed radiological report relating to areas inside and outside the ROI needs to be produced . Nonetheless, in many countries around the globe, issues regarding the medico-legal, ownership, interpretation and licensing of CBCT are currently partly formulated and regulated . Since the introduction of CBCT technology, many dental practitioners did not receive CBCT education or training in their undergraduate dental school. A position paper by the European Academy of DentoMaxilloFacial Radiology (EADMFR) describes the training requirements for the justification, acquisition and interpretation of dental CBCT . A recent survey among predominantly Turkish pediatric dentists showed that 36% had no knowledge of CBCT . Similarly, general knowledge about CBCT was described in another study, as 66.7% among endodontists and 56% among General Practitioners(GPs) . In another study, 63% of endodontists stated they have not undergone any training or continued education course in CBCT . A previous study of CBCT use among Israeli dentists conducted in 2012, has shown that although dentists are confident that they review the entire scanned volume in 77% of cases, they requested DICOM files in only 56% of cases. The conclusion of that study was that these dentists were not aware of the additional information present outside the data presented in the CSI . The aim of this study was to assess the clinical practice and general knowledge of CBCT among general and specialized dentists, and the influence of the dentists’ background on their CBCT output requests. Our hypothesis was that there is still a CBCT knowledge gap among most practicing dentists.   We used an anonymous survey including 20 multiple-choice questions, distributed via e-mail lists of known dentists in Israel, and during 3 local conferences during the beginning of 2020. The questionnaire focused on: (1) Demographics; (2) Clinical practice (including indications for CBCT, requested output and the definition of the entire volume, training, encountering incidental findings, referral (termed “referred to another specialist for consultation”) (3) Knowledge (Radiation dose, terminology, FOV vs. ROI); and (4) Legal issues (responsibility for the incidental findings which may be encountered in the scan, and the need of interpretation service (termed “radiologic interpretation CBCT report by a radiologist”) need for CBCT education, CBCT pre-purchasing requirement) (Appendix ). The needed sample size for our survey was calculated using the Raosoft software. Assuming a current estimate of 5,622 active local dentists and 12% active specialists , a sample size of 360 participants was calculated with 95% confidence interval and assuming 50% response rate. Data was tabulated into an excel spreadsheet and analyzed using SPSS statistics software version 23.0 (IBM, Chicago, IL, USA). Statistical significance was considered as p < 0.05. Numerical variables were presented as means and standard deviations, categorical variables were presented as frequencies and percentages. The associations between nominal variables were tested using Pearson Chi-squared test and Likelihood ratio. T-test was used to examine the associations between the nominal-dichotomous variables and the numeric variables and ANOVA was used to examine the association between a nominal variable with 3 or more options and a numeric variable. The study was approved by the institutional review board (0726-18-HMO).   Demographics The questionnaire was presented to 1,020 clinicians, of which 387 participated (38% response rate, 124 during conferences and 263 via e-mail). Respondents were GPs and specialists aged 44.2 ± 12.0 [range 25–81] years, with male to female ratio of 61% (236) to 39% (151). Their average professional dental experience was 16.8 ± 12.6 [range 1–57] years. Among specialists, their average professional experience as specialist was 9.5 ± 11.1 [range 1–50] years. Most (58.1%) of respondents were specialists, and the remainder (41.9%) were GPs. Among all respondents, 83.2% were graduated from dental schools in Israel. Most (68.5%) were graduated from the Hebrew University of Jerusalem, 14.7% were graduates of the Tel Aviv University and 16.8% were graduates of universities in other countries (in descending order: Eastern Europe, Jordan, Western Europe, USA, South America, Australia and South Africa). Most dentists (49.9%) practice in private clinics only, 31% practice in both private and public or corporate-dental-clinics, 14.7% in public clinics only and 3.1% in corporate clinics only. Most (55.3%) dentists worked in the greater Tel Aviv metropolitan region, 27.1% in the Jerusalem area, 11.1% in the north and 6.2% in the south. Clinical practice Of all respondents, 93% of dentists stated that they refer patients to CBCT scans. The indications for referral were dental implant planning (27%), impacted 3rd molars (24%), bone pathology (16%), endodontic assessment (14%), other impacted teeth (13%), orthognathic surgery (5%), and 1% other indications (TMJ, sialography, congenital abnormalities, trauma and periodontal) (Fig. ). As for the requested CBCT output, respondents were asked to choose which output they usually requested. The options were: CSI, DICOM files, an interpretation report or a combination of these. Most dentists (44.2%) requested CSI together with DICOM files, 31.3% request only CSI, 9.3% request radiologic report with or without CSI or DICOM files, and 7.7% request DICOM files only. Respondents were asked to specify how often they request DICOM files as an output. In 31.5% of cases dentists do not request DICOM files at all, while in 26.6% of cases they always request DICOM. When comparing GPs to specialists, specialists request DICOM files significantly more frequently ( p = 0.007, Table ). Regarding the way the DICOM files were being used, 46.4% of respondents stated that they read DICOM files with Viewer software, 17.1% use implant planning software, 26.2% use both and 10% use other software (such as orthodontic related-software). This preference did not correlate with age, or the type of training the dentists received. Respondents were further asked to state in which frequency they “review the full scanned volume”, without explaining precisely the meaning of the phrase. For simplicity, we combined the three partial options (a quarter, half and most cases) into one new category termed “partially” (Table ). When reviewing the results, about a third of the respondents (33.8%) stated they always review the entire scanned volume, while 13.5% stated they never review the entire volume (Table ). More than half of the respondents (52.6%) stated that they sometimes reviewed the entire scanned volume (the three partial options) (Table ). This result did not correlate with age, or the type of training they received (data not shown). Combining the data regarding reviewing the entire scanned volume with the respondents’ request for DICOM files, as a CBCT output, two interesting results were found. On the one hand, among respondents who stated they always review the entire scanned volume, 41.3% never request DICOM files, only 41.8% always request DICOM files, and 21.1% sometimes request DICOM files (Table ). Remarkably, on the other hand, among respondents who stated they never review the entire imaging volume, 11.2% always ask for DICOM files, 19.2% never request DICOM files, and 10.6% sometimes ask for DICOM files (Table ). Most (61.2%) respondents stated they had received CBCT training. There was a significant correlation between receiving CBCT training and younger age ( p = 0.001), fewer years of experience ( p = 0.001), as well as being specialists compared to GPs (66.6% vs. 53.7%, p = 0.01). Training in 50.6% of the dentists who had received training included both reading CSI and using DICOM-Viewer software. In 78.9%, this training was academic. Respondents who stated that they received academic training were significantly younger ( p = 0.015), with no significant difference between GPs and specialists. Regarding the frequency of encountering incidental findings, most (85.9%) dentists reported they have, at least once, encountered incidental findings within a CBCT scan. In 52.1% of the cases, the findings were in both soft tissue and bone (jaw), in 45.9% of cases findings were only in the jaw, and in 1% of cases findings were in soft tissue alone. When such findings had been encountered, almost all respondents (93.9%) stated they referred the patient to a specialist for consultation. Only 6.1% of respondents reported that they do not refer to a specialist for consultation at all. When asked of the reason they did not refer for a consultation, in 85.1% of cases the respondents were confident in their ability to independently address and manage the incidental findings. In 7% of cases, the reason was that the patient was unwilling to pay for the consultation. Of all referrals, 40.8% referred to Oral and Maxillofacial Surgeons, followed by 25.8% to Oral Medicine specialists, 14% to Orthodontists, 13.4% to Ear, Nose and Throat (ENT) specialists, and 2.6% to other specialists (Periodontists and Radiologists). About half the respondents (47.5%) reported that in most of cases, they were satisfied with the “response of the consultant” (e.g. periodontist, endodontist etc.). Specifically, 24.5% of dentists were always satisfied, whereas 1.8% reported that the answer was not satisfactory in any case. Almost all (94.5%) respondents replied that they are interested in having a service providing a “adiologic interpretation CBCT report by a radiologist”, regardless of age or type of CBCT training they received. Knowledge assessment Knowledge questions included questions about CBCT radiation dose and terminology. 70.3% and 61.2% of respondents had correct answers regarding radiation dose and the terminology of cross-sectional images, respectively. Most (88.8%) were aware of the fact that not all of the scanned volume was demonstrated in the CSI. As for practical issues, 45.2% had correct answers for the following question: “If a patient is referred for imaging of a localized site for implant planning, would the contralateral side of the jaw, be necessarily included?” Most (71.8%) respondents were aware that the FOV and ROI may be different. Overall, most respondents did relatively well in their knowledge test (68.1% average points). Correct answers correlated with young age in all questions ( p < 0.001), and with fewer years of practice ( p < 0.001) (Fig. ). When comparing GPs to specialists, there was in average scores, and no significant difference in the number of correct answers to specific questions, except for the question regarding the difference between FOV and ROI (76% of specialists vs. 66% of GPs had correct answers, p = 0.03). Legal issues and responsibility Regarding the awareness of the possible existence of incidental findings within the scanned volume, almost all respondents (95.5%) stated that they were aware of their existence in CBCT, regardless of their age or type of CBCT training they received. Furthermore, the respondents were asked who they believe, should be responsible for reviewing the entire scanned volume. While 41.7% replied it should be the referring clinician, 57.1% thought it should be a trained radiologist, and in 6.6% of cases the answer was both the referring clinician and a trained radiologist. Most (70.7%) respondents answered that they would be willing to participate in a CBCT continuing education course, regardless of their age or type of CBCT training previously received. Finally, almost all (93.4%) respondents believed a CBCT course should be a pre-purchasing mandatory requirement.   The questionnaire was presented to 1,020 clinicians, of which 387 participated (38% response rate, 124 during conferences and 263 via e-mail). Respondents were GPs and specialists aged 44.2 ± 12.0 [range 25–81] years, with male to female ratio of 61% (236) to 39% (151). Their average professional dental experience was 16.8 ± 12.6 [range 1–57] years. Among specialists, their average professional experience as specialist was 9.5 ± 11.1 [range 1–50] years. Most (58.1%) of respondents were specialists, and the remainder (41.9%) were GPs. Among all respondents, 83.2% were graduated from dental schools in Israel. Most (68.5%) were graduated from the Hebrew University of Jerusalem, 14.7% were graduates of the Tel Aviv University and 16.8% were graduates of universities in other countries (in descending order: Eastern Europe, Jordan, Western Europe, USA, South America, Australia and South Africa). Most dentists (49.9%) practice in private clinics only, 31% practice in both private and public or corporate-dental-clinics, 14.7% in public clinics only and 3.1% in corporate clinics only. Most (55.3%) dentists worked in the greater Tel Aviv metropolitan region, 27.1% in the Jerusalem area, 11.1% in the north and 6.2% in the south.   Of all respondents, 93% of dentists stated that they refer patients to CBCT scans. The indications for referral were dental implant planning (27%), impacted 3rd molars (24%), bone pathology (16%), endodontic assessment (14%), other impacted teeth (13%), orthognathic surgery (5%), and 1% other indications (TMJ, sialography, congenital abnormalities, trauma and periodontal) (Fig. ). As for the requested CBCT output, respondents were asked to choose which output they usually requested. The options were: CSI, DICOM files, an interpretation report or a combination of these. Most dentists (44.2%) requested CSI together with DICOM files, 31.3% request only CSI, 9.3% request radiologic report with or without CSI or DICOM files, and 7.7% request DICOM files only. Respondents were asked to specify how often they request DICOM files as an output. In 31.5% of cases dentists do not request DICOM files at all, while in 26.6% of cases they always request DICOM. When comparing GPs to specialists, specialists request DICOM files significantly more frequently ( p = 0.007, Table ). Regarding the way the DICOM files were being used, 46.4% of respondents stated that they read DICOM files with Viewer software, 17.1% use implant planning software, 26.2% use both and 10% use other software (such as orthodontic related-software). This preference did not correlate with age, or the type of training the dentists received. Respondents were further asked to state in which frequency they “review the full scanned volume”, without explaining precisely the meaning of the phrase. For simplicity, we combined the three partial options (a quarter, half and most cases) into one new category termed “partially” (Table ). When reviewing the results, about a third of the respondents (33.8%) stated they always review the entire scanned volume, while 13.5% stated they never review the entire volume (Table ). More than half of the respondents (52.6%) stated that they sometimes reviewed the entire scanned volume (the three partial options) (Table ). This result did not correlate with age, or the type of training they received (data not shown). Combining the data regarding reviewing the entire scanned volume with the respondents’ request for DICOM files, as a CBCT output, two interesting results were found. On the one hand, among respondents who stated they always review the entire scanned volume, 41.3% never request DICOM files, only 41.8% always request DICOM files, and 21.1% sometimes request DICOM files (Table ). Remarkably, on the other hand, among respondents who stated they never review the entire imaging volume, 11.2% always ask for DICOM files, 19.2% never request DICOM files, and 10.6% sometimes ask for DICOM files (Table ). Most (61.2%) respondents stated they had received CBCT training. There was a significant correlation between receiving CBCT training and younger age ( p = 0.001), fewer years of experience ( p = 0.001), as well as being specialists compared to GPs (66.6% vs. 53.7%, p = 0.01). Training in 50.6% of the dentists who had received training included both reading CSI and using DICOM-Viewer software. In 78.9%, this training was academic. Respondents who stated that they received academic training were significantly younger ( p = 0.015), with no significant difference between GPs and specialists. Regarding the frequency of encountering incidental findings, most (85.9%) dentists reported they have, at least once, encountered incidental findings within a CBCT scan. In 52.1% of the cases, the findings were in both soft tissue and bone (jaw), in 45.9% of cases findings were only in the jaw, and in 1% of cases findings were in soft tissue alone. When such findings had been encountered, almost all respondents (93.9%) stated they referred the patient to a specialist for consultation. Only 6.1% of respondents reported that they do not refer to a specialist for consultation at all. When asked of the reason they did not refer for a consultation, in 85.1% of cases the respondents were confident in their ability to independently address and manage the incidental findings. In 7% of cases, the reason was that the patient was unwilling to pay for the consultation. Of all referrals, 40.8% referred to Oral and Maxillofacial Surgeons, followed by 25.8% to Oral Medicine specialists, 14% to Orthodontists, 13.4% to Ear, Nose and Throat (ENT) specialists, and 2.6% to other specialists (Periodontists and Radiologists). About half the respondents (47.5%) reported that in most of cases, they were satisfied with the “response of the consultant” (e.g. periodontist, endodontist etc.). Specifically, 24.5% of dentists were always satisfied, whereas 1.8% reported that the answer was not satisfactory in any case. Almost all (94.5%) respondents replied that they are interested in having a service providing a “adiologic interpretation CBCT report by a radiologist”, regardless of age or type of CBCT training they received.   Knowledge questions included questions about CBCT radiation dose and terminology. 70.3% and 61.2% of respondents had correct answers regarding radiation dose and the terminology of cross-sectional images, respectively. Most (88.8%) were aware of the fact that not all of the scanned volume was demonstrated in the CSI. As for practical issues, 45.2% had correct answers for the following question: “If a patient is referred for imaging of a localized site for implant planning, would the contralateral side of the jaw, be necessarily included?” Most (71.8%) respondents were aware that the FOV and ROI may be different. Overall, most respondents did relatively well in their knowledge test (68.1% average points). Correct answers correlated with young age in all questions ( p < 0.001), and with fewer years of practice ( p < 0.001) (Fig. ). When comparing GPs to specialists, there was in average scores, and no significant difference in the number of correct answers to specific questions, except for the question regarding the difference between FOV and ROI (76% of specialists vs. 66% of GPs had correct answers, p = 0.03).   Regarding the awareness of the possible existence of incidental findings within the scanned volume, almost all respondents (95.5%) stated that they were aware of their existence in CBCT, regardless of their age or type of CBCT training they received. Furthermore, the respondents were asked who they believe, should be responsible for reviewing the entire scanned volume. While 41.7% replied it should be the referring clinician, 57.1% thought it should be a trained radiologist, and in 6.6% of cases the answer was both the referring clinician and a trained radiologist. Most (70.7%) respondents answered that they would be willing to participate in a CBCT continuing education course, regardless of their age or type of CBCT training previously received. Finally, almost all (93.4%) respondents believed a CBCT course should be a pre-purchasing mandatory requirement.   This study evaluated CBCT use, knowledge and medico-legal issues among Israeli dentists, and the influence of their background on these parameters. The results show a widespread use of CBCT, for common indications including dental implant, impacted third molars and bone pathology, as widely reported in the literature . Conventional (plain radiography) imaging education has always been taught in dental graduate studies, whereas volumetric imaging has only gradually been employed. A survey of US, UK, and Australian dental schools showed that the majority of responding schools do not include instruction in higher level use of CBCT for undergraduate students . In the current study, about third of the respondents stated that they request only CSI as the output, and they do not use DICOM files at all. In addition, among respondents who stated they always review the entire scanned volume, 41.3% never ask for DICOM files, and only 41.8% always ask for DICOM files. The CSI, which represents specific slices from within the ROI, does not represent the entire 3-dimentional CBCT available data. Thus, important findings may be overlooked . Indeed, various parameters may affect the selected CSI dimensions. Examples include: the distance between two slices (often called “steps”), the bucco-lingual width or the superior-inferior height. These may affect the portion of scan volume being represented within the CSI slice. Thus, incidental findings in the scanned volume may not be included in the selected CSI. These findings may be present in between two slices in case of wide “steps”, or located beyond the bucco-lingual width or the superior-inferior height (such as sialolith in the mandible, or antral pathologies, respectively). Moreover, information from a few CSI may be different from series of many CSI . As DICOM files are necessary for reviewing the entire scanned volume, it seems that many of the study respondents did not understand the meaning of scanned volume reviewing. These observations suggest a gap in understanding of the limitation of CSI as well as their inability to present the entire scanned volume for review. In addition, only 33.8% of respondents stated they always review the entire scanned volume, although almost all of them (95.5%) stated that they were aware of the existence of incidental findings in CBCT, and although most of them (85.9%) reported that they have encountered incidental findings themselves within a CBCT scan at least once. This practice did not correlate with age, or the type of the CBCT training they received. Many organizations worldwide including AAOMR , ADA , EADMFR , IRMER , RCDSO , agree that all volumetric data should be reviewed and interpreted, but it is not always clear who is responsible for the task. 41.7% of the respondents in the current survey believed it is the responsibility of the referring clinician, while 57.1% thought it should be a trained radiologist, and 6.6% thought that it should be both. Furthermore, every country has its own regulations and accepted practice regarding the interpretation of CBCT scans. Hence, in many countries, interpretations by maxillofacial radiologists are not standard. The authors believe that GPs should, therefore, be knowledgeable about the use and interpretations of CBCT. GPs should be able to examine the entire scanned volume, recognize abnormal findings, and when needed, refer the scan to a maxillofacial radiologist for consultation. Alternatively, it may be a common practice that all CBCT scans are reviewed by a maxillofacial radiologist, who would generate a report with all the radiographic findings, which will then be correlated clinically, by the clinician. Some international guidelines distinguish between small and medium-large FOVs with respect to the identity of the interpreter who is generating the report. For instance, a trained GP or DMFR specialist should make the radiological report for CBCT scans that are 8 × 8 cm or smaller. For larger CBCT scans, a DMFR specialist or a medical radiologist should make the report . Requesting and saving the DICOM files in the patient’s records is important for several reasons. First, for reviewing the entire scanned volume within and outside the ROI, in search of incidental findings with clinical significance. Second, for avoiding unnecessary repetition of imaging and increasing patients’ radiation dose for possible future treatment for regions outside the ROI. Third, for follow-up of pathology (volume assessment and monitoring). Sometimes, dental imaging centers provide the referring clinician with CSI only, and the entire scanned volume (DICOM files) is not stored and can become unavailable if needed in the future. The major limitation is the large amount of memory required for back-up. Unless a national cloud storage is available, it is recommended that the DICOM files be kept either in the patient’s records within the clinic or by the patient. Our questionnaire included two questions which may seem similar: one refers to the satisfaction with the answer the respondents got “from a consultant”, following referral due to an incidental finding in the scan, while the second one was about the possibly which of the respondentshaving,”a radiological interpretation” available to them. We included both questions since currently, there is no national practice requiring the routine generation of radiological interpretation, by a maxillofacial radiologist. Thus, clinicians may refer a scan or an image from a scan for a consultation to various kinds of experts: maxillofacial surgeons, oral medicine specialist, ENT specialists, maxillofacial radiologists or a medical radiologists. Therefore – there was a need to first inquire about the satisfaction with the answer they got from the “consultation” about the findings. Most participating dentists showed fair knowledge in the knowledge test, with an average score of 68.1% correct answers. A main knowledge gap was that most of them were unaware that often there is a difference between the region of interest (ROI) they request in the referral and the actual scanned volume, depending on the protocol and on the CBCT machine (differences in the FOV and ROI size) . For example, an ROI could be CBCT of the lower right molar, but the actual scanned volume could include the left mandible, depending on the CBCT machine and protocol being used. Corrects answers in the knowledge test significantly correlated with younger age. This is not surprising, as we found a significant correlation between receiving CBCT training and younger age. Most (61.2%) respondents stated they had received CBCT training. In our study, in 78.9% of cases, this training was academic. Respondents who stated that they received academic training were significantly younger. We did not inquire about whether training was at the undergraduate or graduate level. Limitations of the current study may include bias as most participants were specialists, which represent only 10% of the dentists in Israel, and that most respondents were graduates from the Hebrew University of Jerusalem (one of the two dental schools that exist in Israel). In addition, since this questionnaire was distributed electronically, participants who responded may be more technological compared to those who declined. Moreover, this was a voluntary survey, entitled CBCT use questionnaire. It is reasonable to assume that clinicians who are not familiar or who are not comfortable with CBCT technology were less willing to participate in such a survey. All of the above created a bias in our results and show an optimistic view and may not reflect the real status. Therefore, future work should aim to reach all relevant practicing dentists to obtain a more representative sample. Strengths of the study include the assessment of CBCT detailed practice, including CBCT output, as well as actual in-depth knowledge of CBCT among dentists, with useful information to be used in continued education courses and for academic undergraduate curriculum development.   Based on the results of the study, more CBCT continuing education courses are needed, with emphasis on clinical practice and CBCT output. In addition, as GPs acquire and utilize CBCT technology, CBCT must be included in undergraduate dental education to ensure that future practitioners are properly trained for safe and up-to-date professional use of this imaging modality.   Below is the link to the electronic supplementary material. Supplementary Material 1   