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Year : 2022  |  Volume : 12  |  Issue : 2  |  Page : 204-209

Analysis of endodontic radiographic imaging repeat rate: A cross-sectional study in an undergraduate clinical setting

1 Department of Endodontics, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
2 Department of Operative Dentistry, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia

Date of Submission15-Dec-2021
Date of Decision27-Jan-2022
Date of Acceptance27-Jan-2022
Date of Web Publication20-Apr-2022

Correspondence Address:
Dr. Maysoon Haji Albahiti
Department of Endodontics, Faculty of Dentistry, King Abdulaziz University, Jeddah
Saudi Arabia
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/sej.sej_241_21

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Introduction: Inexperienced undergraduate dental students tend to take unnecessary radiographs during endodontic treatment, which has an adverse effect on clinical workflow. The aim of this study was to quantify the repeat rate of endodontic periapical radiographs taken by senior dental students during endodontic treatment stages and to analyze the prevalence of radiographic errors that led to repeated radiographs. In addition, the average number of visits required to complete the treatment was determined.
Materials and Methods: A total of 583 cases that included 5689 periapical radiographs were collected from the records of a completed academic year. The periapical images were divided according to tooth type and the stages of the treatment procedure. The prevalence of error types, number of visits, and repeated images exceeding the number of radiographs allowed for completion of the treatment were evaluated. The collected data were statistically analyzed.
Results: The overall repeat rates of anterior, premolars, and molars were 36%, 36%, and 39%, respectively (P = 0.66). The highest repeat rates were recorded during instrumentation (44%-55%), followed by obturation (36%–46%). The most common error types were working length adjustment (27%–33%), missing apex (24%–28%), and obturation adjustment (19%–24%). The mean number of visits was higher than recommended for all tooth types.
Conclusions: The repeated rates of radiographs and number of visits were higher than recommended. A set of recommendations were formulated to optimize quality assurance and deliver a better-quality health service to the patients.

Keywords: Digital radiography, endodontic, number of visits, radiographic errors, repeat rate

How to cite this article:
Albahiti MH, Abuhaimed TS, Al-Noman B, Hashim R. Analysis of endodontic radiographic imaging repeat rate: A cross-sectional study in an undergraduate clinical setting. Saudi Endod J 2022;12:204-9

How to cite this URL:
Albahiti MH, Abuhaimed TS, Al-Noman B, Hashim R. Analysis of endodontic radiographic imaging repeat rate: A cross-sectional study in an undergraduate clinical setting. Saudi Endod J [serial online] 2022 [cited 2022 Nov 30];12:204-9. Available from: https://www.saudiendodj.com/text.asp?2022/12/2/204/343556

  Introduction Top

Root canal treatment (RCT) is considered a highly challenging procedure among undergraduate students due to limited direct visualization of the working field and anatomical diversity of the root canal systems. To develop the clinical skills needed for carrying out predictable treatment, periapical radiographs are required at multiple stages for accurate diagnosis and recording of treatment steps.[1] In addition, the standard of care in endodontics entails the acquisition of accurate radiographic records taken at different horizontal angulations to visualize structures that would be otherwise hidden in the buccolingual dimension.[2],[3]

The number of radiographic acquisitions should be limited to the minimum necessary to obtain essential diagnostic information following the ALARA principle (as low as reasonably achievable) and in accordance with the guidelines of the American Dental Association recommendations.[4] However, due to their limited experience, undergraduate students often get faulty or nondiagnostic images, which inevitably entail image retakes.[5]

Besides unnecessary exposure to radiations, repeated imaging inadvertently compromises clinical workflow efficiency in many aspects, such as loss of valuable clinical time and wasteful use of technological resources,[6],[7],[8] in addition to patient's inconvenience from multiple visits to the X-ray room. Therefore, controlling imaging repeats is a necessity.

Although the implementation of digital radiography has helped reduce radiations dose and processing time,[9],[10],[11] it has failed to reduce repeat rate[12],[13],[14],[15] mainly because of the size and bulkiness of the sensors[16] and the fact that operators find it convenient to take multiple images which may reverse the edge of digital radiography.[10],[12]

Repeat rate analysis is frequently used for quality control and optimization of radiography protocols.[17],[18],[19] It is simply calculated as the percentage of the number of repeat images to the total number of images taken. According to the Conference of Radiation Control Program Directors (CRCPD), the overall recommended repeat rate is <10%.[17] Previous dental studies showed that dental imaging repeat rate among students ranged from 3% to 11%.[20],[21],[22],[23] However, a significantly higher rate was found in relation to RCT (34%).[24]

Analysis of the repeat rate and number and types of errors in repeated images give important information to identify underlying didactic and training deficiencies in endodontics and radiographical imaging and guide their rectification. Literature showed that amongst the common errors which led to retakes are improper poisoning of the sensor or tube, improper angulation, and missing apical areas of teeth.[20],[22],[25] In endodontic imaging, it is more challenging to obtain diagnostic radiographs due to the presence of tooth isolation devices which may require special training courses.

In the undergraduate clinic at King Abdulaziz University, Faculty of Dentistry (KAUFD), the use of digital radiographic imaging during RCT steps is based on the Comprehensive Case Clinic Clinical Guide which includes guidelines to maintain the standard of care in Endodontics. Students are expected to follow those guidelines to record and ensure adequate treatment steps while maintaining a safe environment.

The aim of this study was to quantify the repeat rates of radiographs taken at KAUFD by senior dental students during RCT based on different types of teeth and stages of treatment. The types and prevalence of errors leading to radiographic repeats and the number of visits required for treatment completion were also evaluated.

  Materials and Methods Top

The current study was a retrospective cross-sectional study conducted by collecting and reviewing all digital periapical radiographs of root canal treated clinical cases completed by undergraduate senior dental students at KAUFD in the academic year 2018-2019. Ethical approval was obtained by the Research Ethics Committee of KAUFD (reference number 116-11-20).

All radiographs were taken by the students using the Vario DG radiograph unit (Sirona Dental Systems GMbH, Bensheim, Germany) and Phosphor Storage Plates size 1 and 2 (VistaScan imaging plates, Durr Dental, Bissingen, Germany) under bisecting angle technique. The plates were scanned with VistaScan Mini Scanner (Durr Dental, Bissingen, Germany). The exposure setting was at 70 kVp and exposure time was set according to tooth type. All images were saved automatically to the patients' records on the dental operating software R4 (Kodak, Rochester, NY, USA).

The required number of radiographs and clinical visits expected for completion of RCT of different types of teeth according to endodontic department guidelines at KAUFD are represented in [Table 1]. The baseline requirement for each case was five radiographs, in addition to images at a shifted horizontal angle for teeth with multiple roots. Therefore, the repeated images were defined as those images exceeded the number of radiographs allowed for completion of RCT (i.e., required additional exposure to the patient as defined by CRCPD[17]).
Table 1: King Abdulaziz University, Faculty of Dentistry guidelines for the number of periapical radiographic images and number of visits required and allowed for completion of root canal treatment

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The periapical images were divided according to tooth type; anteriors, premolars and molars, and further subdivided according to the stages of the procedure to preoperative, instrumentation, obturation, and postoperative.

Data were collected from the archives for all submitted cases including patient file number, tooth type, number of total and repeated periapical radiographs taken at every step of RCT, and number of visits required to finish each case. Progress notes and evaluation records were used to verify teeth with treatment complications, such as persistent infection, perforations, or separated instruments; and those were excluded.

Before data collection, a pilot study of 500 radiographs was conducted to identify the reasons for retakes. Five types of errors were determined as follows: Adjusting working length (WL), adjusting obturation, blurring, apical area missing, and improper angulation (vertical or horizontal). If an image had multiple deficiencies, the single deficiency that contributed most to the retake was recorded. For example, during WL estimation if a radiograph was diagnostic but showed an incorrect WL that required a repeat, it was placed under the category of adjusting WL but if the radiograph had a missing apex or too angulated rendering it nondiagnostic, it was placed under the category of missing apex or improper angulation, respectively. The segregation of images was performed by two calibrated endodontic instructors.

All data were transferred to an excel sheet (Microsoft, Redmond, WA, USA) to calculate the total number of repeats and the repeat rates for each tooth type and stage of RCT. The prevalence of error types was also calculated according to tooth type and stage of RCT.

The number of visits was determined from the dates of starting to completion of each case. The prevalence of completed cases, which had at least one incidence of repeat was calculated as well.

Data were statistically analyzed using the One-Way ANOVA test (SPSS, IBM Inc., Chicago, IL, USA) to compare the difference in repeat rates between tooth types. Descriptive analysis was used to analyze the repeat rate of radiographs according to the stage of RCT and types of errors. t-test was used to determine the significance in the number of visits required for completion of treatment compared to the course guideline.

  Results Top

During one academic year, a total of 6600 radiographs from 694 cases were submitted. One hundred and eleven cases were excluded due to treatment complications. The remaining 583 cases (130 anterior, 226 premolar, and 227 molars) accounting for 5689 radiographs were analyzed. Among those, 2320 radiographs were repeats giving an overall repeat rate of 37.8%. The repeat rates of anterior, premolar, and molars were 36.6%, 36.1%, and 39.9%, respectively with no significant difference found between different types of teeth [P = 0.66, [Table 2]].
Table 2: Number of images and repeat rate

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[Table 3] shows the repeat rate according to the stage of treatment. A similar trend was seen amongst all teeth where the highest repeat rates were recorded in the instrumentation stage (45%–55%), followed by obturation (37%–46%). In anterior teeth, the repeat rate in the preoperative stage (32%) and postoperative stage (28%) were higher than those of premolar and molar which averaged 10% and 20%, respectively.
Table 3: Repeat rate according to stage of treatment

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The prevalence of errors showed that the most common type of error is WL adjustment (27%-34%) followed by missing apex (24%-28%) and the obturation (19%–24%) [Table 4].
Table 4: Number and percentage of types of errors

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Most of the cases were completed with at least one incidence of image retake. About 64%, 66%, and 84% of anterior, premolar, and molar cases required repeats of at least one image.

The number of visits required to complete RCT was statistically higher than recommended by the school for all types of teeth (P = 0.01).

  Discussion Top

Repeat rate is one of the parameters used to assess the quality of clinical workflow where frequent use of radiographic imaging is required.[15] The goal of the current study was to evaluate the repeat rate of endodontic radiographs acquired by undergraduate senior dental students and to identify the prevalence of imaging errors and their impact on the number of clinical visits required to complete RCT.

There is an abundance of data on repeat rates in medical imaging literature, in which the reported values ranged between 5% and 15%.[8],[26],[27] Unfortunately, dental literature on repeat rates is very scarce. Only a few studies are available which reported repeat rates values between 3% and 34%.[20],[22],[23],[24] This wide range reflects the different methodology used such as types of acquisition (periapical, bitewing, panorama, etc.), type of sensor (film-based or digital sensor), different operators (students or radiographers), and subjective definition of a repeat image. Nevertheless, the general recommendations provided by the CRCPD state that repeat rates below 10% should be the goal of any institution.[17]

The results of the current study showed that the overall repeat rate of endodontic radiographs was 37.8%. Such a high rate could be explained from several aspects. Most of the undergraduate students had treated the limited number of cases when they start their senior year (2nd year of clinical endodontics) and probably never treated a molar case which means their lack of experience would make them more prone to retake radiographs.[5] In addition, image acquisition for patients during RCT is more difficult than routine acquisitions due to the presence of rubber dam isolation devices and endodontic instruments which hinder visibility and positioning of the sensor or the X-ray tube. Moreover, unlike other treatments, RCT requires multiple radiographs to document each step which increases the likelihood of errors. Another possible reason is the subjective definition of repeated radiographs. In this report, all radiographs exceeded the allowed number were considered repeats even if they were diagnostic. Moreover finally, digital radiography has shown more repeat rates than regular film radiography.[12],[13],[14],[15]

In agreement with the current study, Yusof et al. found that the repeat rate among dental students was 34.3%, which included different types of radiographs.[24] When endodontic periapical radiographs were separated, the repeat rate ranged between 35.6% and 51.9% depending on which step of RCT was analyzed. On the contrary, other studies showed a lower repeat rate ranging from 5% to 11% which included routine radiographs as well as different types of radiographs such as bitewings, occlusal, and extraoral radiographs which typically have lower repeated rates.[21] This emphasizes the fact that repeat rates of teeth subjected to endodontic treatment are higher than those related to teeth during routine radiographic acquisition. It may be suggested that the repeat rate of endodontic radiographs could be normalized to a higher level. However, it is still a concern that the repeat rate found in this study was high and necessitates an urgent reevaluation and remediation of the current endodontic and radiographic training of dental students.

The overall repeat rate among different types of teeth did not show a significant difference. The values were 36.5%, 35.1%, and 39.9% for anterior, premolar, and molars, respectively. It may be concluded that the challenges of taking radiographs during RCT impose difficulties on all teeth equally. One study reported the repeat rate in different anatomical areas and found higher repeat rate in the maxillary arch compared to the mandibular arch.[20] In the current report, there was no difference in the overall repeat rate between maxillary and mandibular teeth (data is not shown).

The repeat rate was clearly different when associated with different treatment stages. This could give insight into where students tend to retake radiographs. Further analysis of the underlying types of errors would help identify common deficiencies and enable us to apply appropriate corrective measures. The current results showed that for all types of teeth, a trend was seen where repetition was highest during instrumentation (44%–55%), followed by obturation (36%–46%), while preoperative and postoperative stages showed the lowest repeat rates. In agreement with these numbers, one study reported repeat rates being highest during instrumentation (51.9%), followed by master cone (MC) trial (48.4%), then obturation (42.2%).[24]

The most common error which led to retake images was adjusting WL, accounting for (28%–34%) of errors. In the current curriculum at KAUFD, students are taught to depend on electronic apex locators (EAL) rather than radiographs. This is based on well-documented evidence that EALs have higher accuracy and are more consistent than radiographs in the estimation of WL.[28] However, due to their limited experience and the innate behavior of depending on the visual confirmation, students lean toward taking multiple radiographs to confirm WL.[29] This is also in agreement with Fong et al. who reported that only 19% of undergraduate students used EAL.[30]

During obturation, most of the repeated radiographs were seen at an intermediate stage after a few accessory cones were inserted along the MC (19%–23%). The obturation method being taught at the school is the cold lateral condensation technique, during which access cavities often get clogged with gutta-percha cones. Higher tactile skills are required for completing the process and the novice student could tend to take several radiographs to check on their progress and examine the density of obturation material.

A substantial number of retakes were attributed to positioning errors. Missing apex and improper angulation contributed to (24%–28%) and (14%–22%) of all errors, respectively. Those imaging errors are known to be the result of poor positioning of the sensor/film, the X-ray tube, or both. Positioning errors are particularly expected when tooth isolating devices are placed during instrumentation and obturation. Understanding common errors are important to make corrective measures, which could be aimed in two directions. One is toward endodontic knowledge, such as reinforcement of using the EAL and improving preclinical training on obturation technique. The second direction is toward radiography knowledge which includes training on the use of paralleling devices for teeth under isolation to overcome positioning errors.

Another parameter evaluated in this study was the percentage of cases which had at least one repeat image during the full course of treatment. It was found that 84% of molars and 66% of premolars required repeats during instrumentation. This rate was higher than a study by Mupparapu et al. which reported that 45% of cases required at least one repeat.[23] Their analysis was on radiographs taken for routine full mouth series, which may explain the discrepancy with the current study. The impact of this finding is not only unnecessary radiation exposure but also a compromise of clinical efficiency. On a typical clinical working day, the students use 4 different X-ray rooms. Taking in mind that a single acquisition may take up to 15 min on average, a class of about 90 students on the clinical floor will face long queues for radiography. This loss in clinical time is greatly amplified with the increase in the number of repeated radiographs. The ramification of this clinical behavior was seen on the number of visits to complete the treatment. All types of teeth required a greater average number of visits than recommended (2.5, 3.6, and 4.6 for anterior, premolar and molars, respectively) which accounts for 20%–40% extra clinical time. Similar numbers were reported by others which may indicate a common problem among undergraduate students.[30] Even though undergraduate programs should focus on the quality of cases rather than quantity, this extra time was probably not utilized towards mastering the treatment but rather wasted on taking unnecessary radiographs.

The clinical efficiency of dental students is an important outcome of education. It is the ultimate desire of dental schools to offer high quality, low risk, environment friendly, and time-efficient management to patients. High radiographic imaging repeat rates and the extra number of visits required to complete RCT negate good clinical practice, which must be rectified.

The findings of this study have allowed us to develop the following recommendations: (1) students should not be solely responsible for the decision of repeating a radiograph and permission of the supervising faculty is warranted; (2) regular audit should be performed on patients' files to monitor imaging; (3) introduction of a repeat image index that could be used as part of student assessment; (4) reinforcement of the superior role of EAL over radiographs for measurement of WL during RCT; (5) reinforcement of the use of intra-operative film positioning devices; (6) introduction of an endodontic radiography training module in the preclinical year where students practice in simulated settings; and finally, (7) improve the quality of endodontic training especially in obturation steps.

This study was limited by the number of radiographs that were saved on the electronic patient record systems. Any additional radiographic exposure that might have not been saved due to unsatisfactory quality was not included, which means the results are probably underestimating the repeat rate. An investigation that includes radiography equipment output data would give an insight into the magnitude of this discrepancy. Finally, the effect of implementing the above recommendations on the repeat rate of radiographs should be further investigated to improve the quality of dental education and patient care.

  Conclusions Top

The repeat rates of radiographs and number of visits were higher than recommended by the school. The most common type of error was WL adjustment. A set of recommendations were formulated to optimize quality assurance and deliver a better-quality health service to the patients.

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Conflicts of interest

There are no conflicts of interest.

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  [Table 1], [Table 2], [Table 3], [Table 4]


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