Abstract
Background
Radiographic evaluation is a simple and reliable way to assess the technical quality of root canal treatment. This study investigates the extent to which undergraduate dental students’ use of periapical radiographs to evaluate root canal filling quality conforms with a gold standard of evaluation established by expert endodontists; it also assesses their perceived confidence and self-reported estimated disagreement ranges (sEDR).
Methods
A total of 107 students evaluated 60 periapical radiographs using four predefined criteria for root canal filling quality: length, density, taper and procedural errors. The evaluations of four experienced endodontists established a “gold standard” that was used as the reference for assessing the extent to which students’ evaluations of each periapical radiograph agreed with predefined criteria. Perceived confidence and sEDR were also recorded. Students’ agreement with the gold standard was assessed using Cohen’s kappa (κ); diagnostic performance was assessed using sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). The significance level was set at p < 0.05.
Results
Agreement with the gold standard was moderate for length (κ = 0.41 and 0.48), slight for density (κ = 0.17 and 0.15) and slight to fair for taper (κ = 0.17 and 0.23) in fourth- and fifth-year students, respectively. It was poor for procedural errors overall (κ = 0.11). There were no significant differences in students’ agreement with the gold standard according to academic year, perceived confidence or sEDR (p > 0.05). For length, density and taper, fifth-year students showed higher sensitivity, PPV and NPV; whereas specificity was higher in fourth-year students.
Conclusions
Dental students demonstrated limited proficiency in radiographic evaluation of root canal filling quality, and their performance was independent of academic year, perceived confidence and sEDR. Clinical experience appears to improve recognition of non-ideal root canal fillings, whereas earlier training appears to improve recognition of ideal ones. Notably, perceived confidence and sEDR varied by academic year.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12909-026-08884-7.
Keywords: Education, Dental, Radiography, Dental, Root canal obturation, Self-assessment
Introduction
Radiography has played a central role in endodontics since the early 1900 s, when Dr Weston Price first introduced it as a tool to evaluate root canal fillings [1]. Today, periapical radiographs remain indispensable to endodontic practice, particularly for diagnosis, treatment planning, the evaluation of healing progression and assessment of the technical quality of root canal fillings [2]. Building upon this foundation, greater emphasis has been placed in the literature on the radiographic features of root canal fillings, which are regarded as key indicators for evaluating treatment outcomes [2–5].
The cohort study demonstrated the prognostic value of periapical radiographs in predicting long-term endodontic treatment success [3]. This finding is supported by further research linking radiographically inadequate root canal fillings to higher rates of post-treatment periapical pathology and reduced treatment success [6, 7]. Long-term follow-up studies have highlighted the importance of radiographic evaluation, particularly with regard to the technical quality of root canal fillings, in assessing periapical health. The presence of an inadequate taper as a strong predictor of persistent or emerging apical lesions over a 4- to 7-year period [8]. Radiographic images reveal that dense root canal fillings ending within 0–2 mm of the apex are associated with more favourable outcomes [3, 9]. Radiographs showing suboptimal master cone placement are linked to poor filling quality and to clinical or radiographic signs of treatment failure [10]. Although it is well established that radiographic appearance of root canal fillings alone may not fully reflect clinical success [11], the well-documented association between radiographic findings and endodontic treatment outcomes supports the continued use of periapical radiographic evaluation as a valuable adjunct in the assessment of root canal filling quality [3, 5].
Guidelines developed by the European Society of Endodontology (ESE) provide the basis for radiographic standards for evaluating root canal treatment quality [12]. According to these guidelines, an acceptable root canal filling should terminate within 0.5–2 mm of the radiographic apex, show no evidence of voids between the filling material and root canal walls, and exhibit a smooth, continuous taper from the coronal portion of the tooth to the apex. Clinicians particularly favour these criteria because they can be observed readily and consistently on standard periapical radiographs, thereby allowing a practical and objective evaluation [3].
The undergraduate dental curriculum prepares students for independent practice [13] by developing skills in taking patient histories, in clinical examination, in diagnostic testing and in radiographic interpretation [14]. Accordingly, the ability to evaluate periapical radiographs should be integrated into clinical decision-making [15]. Nevertheless, errors in radiographic interpretation among dental students remain common, underscoring the need for structured educational audits in dental schools [16]. As part of these efforts, students should be trained to interpret periapical radiographs accurately, with instructors placing particular emphasis on assessing the quality of root canal fillings.
Assessing student performance in dental education continues to be a challenging task. Given the inherent complexity of assessment, effective evaluation requires the active involvement of both instructors and students. In this context, self-assessment becomes a valuable tool for enhancing learning and supporting a more balanced evaluation framework [17]. As a metacognitive skill, it includes the ability to evaluate one’s own performance correctly and to recognise when one’s judgements may be right or wrong [18]. Perceived confidence also plays a key role in students’ diagnostic development, influencing how they interpret their own evaluations and the extent to which they trust them [19].
Although previous studies have examined the technical quality of root canal treatments performed by undergraduate students in detail [4, 5, 20], research focusing on students’ diagnostic proficiency in evaluating the outcomes of these treatments radiographically is scarce [21]. Moreover, the relationship between students’ objective performance in evaluating the quality of root canal fillings using periapical radiographs and their metacognitive self-perceptions, defined as perceived confidence and retrospective estimation of their own performance accuracy during evaluation, has not yet been examined. In this study, we evaluate the extent to which students’ assessments of root canal filling quality using periapical radiographs correspond to a gold standard established based on the evaluations of four experienced endodontists, and we assess their perceived confidence and self-reported estimated disagreement ranges (sEDR). Our hypotheses were that students’ evaluations would demonstrate at least a moderate level of agreement with the gold standard, and that their self-perceptions and academic year would be independent of their actual performance.
Materials and methods
Ethical approval
The present study was conducted and reported in accordance with the relevant items of PRIDASE 2024 (Preferred Reporting Items for Diagnostic Accuracy Studies in Endodontics) checklist [22]. Ethical approval was obtained from the Ethics Committee for Non-clinical Scientific Research of the Faculty of Dentistry, Ankara University (7/10.03.25), and by the Dean’s Office of the same faculty, in accordance with the principles of the World Medical Association’s (WMA) Declaration of Helsinki. Informed consent was obtained from all participants involved in this study.
Sample size justification
During the study’s planning phase, the target sample size was calculated assuming α = 0.05, an effect size of d = 0.5 and a power (1 − β) of 0.80, yielding a planned total of 128 participants, with approximately 64 students expected from the fourth year and 64 from the fifth year. However, as participation in the study was entirely voluntary, the final sample size was determined by the number of eligible students who consented to take part during the data collection period. Consequently, analyses were conducted on data from 107 participants who met the inclusion criteria. A medium effect size assumption was adopted in accordance with Cohen’s conventional benchmarks, as robust pre-existing evidence reporting effect sizes for directly comparable student performance or radiographic evaluation outcomes was not identified [23]. When the achieved sample re-evaluated using a chi-square -based power framework (degrees of freedom = 5, α = 0.05), the corresponding effect size was w = 0.347 and the achieved power was 0.802. In addition, the distribution of the inconsistencies variable was highly comparable across groups (fourth-year mean = 52.76; fifth-year mean = 52.78; median = 53; SD ≈ 2.7–2.8), supporting group balance and indicating that the final sample of 107 participants preserved the intended power level effectively.
Eligibility of participants
Inclusion criteria
Figure 1 presents the flow of student participation. A convenience sample of 107 undergraduate dental students was included in this observational, cross-sectional study. The study’s inclusion criterion was enrolment in the fourth or fifth year of the undergraduate dental programme at the Faculty of Dentistry, Ankara University, during the 2024–2025 academic year. Announcements regarding the study were delivered verbally by the research team during theoretical courses for fourth- and fifth-year students and shared in WhatsApp groups used by the Student Affairs Office. The announcements included information about the aim of the study, as well as the date, time and location of the assessment session, and emphasised that participation was entirely voluntary. Students who wished to participate indicated their interest via an online polling tool created within the WhatsApp group. This poll remained open for one week. By the end of the announcement period, a total of 117 students had stated that they would take part in the study. 110 of these students were present at the scheduled session on the radiographic evaluation day. However, three students voluntarily chose to withdraw shortly after the assessment process had begun and were therefore excluded from the study. Consequently, a total of 107 students completed the study and were included in the final analysis. 66 of these participants were fourth-year students and 41 were fifth-year students. The gender distribution of the final sample was 55 females and 52 males.
Fig. 1.
Flowchart of student recruitment and inclusion in the final analysis
Exclusion criteria
Students were excluded from the study if they did not consent to participate; were not present during the evaluation session; did not complete the evaluation process; or were enrolled in the first, second or third year of their studies.
Educational background
The study was conducted in accordance with the undergraduate dental curriculum in effect at the time of the study; subsequent revisions to the curriculum did not affect the educational structure experienced by the participating students. The undergraduate dental curriculum at the Faculty of Dentistry, Ankara University, spans five years and is structured into preclinical and clinical phases. During the endodontic preclinical phase in the third year of the programme, students receive theoretical instruction and extensive preclinical training over both semesters. In the preclinical exercises, students perform root canal treatments on extracted human teeth, dental manikins, endodontic training blocks and haptic simulators under the supervision of experienced endodontists. The clinical phase comprises the fourth and fifth years. In the fourth year, students begin treating patients as novice clinicians, performing endodontic treatments on anterior and premolar teeth under the direct supervision of experienced endodontists. At the same time, they continue to receive theoretical instruction and gain limited initial experience in live radiographic interpretation. In the fifth year, students take on a more active clinical role, managing more complex cases (including molars and some simple retreatment cases) and gaining substantially greater exposure to radiographic diagnosis and outcome assessment. Although students do not receive a specific course on using periapical radiographs to evaluate root canal filling quality, they are taught the fundamental principles of this evaluation throughout their undergraduate endodontic education.
Preparation of the periapical radiograph set
An endodontist with five years of experience randomly selected a set of 60 periapical radiographs of teeth with completed root canal treatments; the endodontist was blinded to the study. The periapical radiographs used in this study were obtained from the radiology archive of the Department of Endodontics, Faculty of Dentistry, Ankara University. These radiographs were of patients who attended the faculty between January and May 2025 for various clinical reasons. All eligible radiographs were included regardless of treatment setting or operator experience. The periapical radiographs were obtained during routine clinical care using a Gendex Expert DC unit (Gendex Dental Systems, Hatfield, PA, USA) with a photostimulable phosphor plate (CS® Digital smart plate; Carestream Dental, Rochester, NY, USA), with exposure parameters adjusted according to clinical requirements. The images were scanned using the Carestream CS 7200 system (Carestream Dental LLC, Atlanta, GA, USA), and image processing and evaluation were performed using CS Imaging software (version 6.0.8.0.13; Carestream Dental, Rochester, NY, USA).
Only images showing at least a 3 mm portion of the periapical area, and that demonstrated sufficient diagnostic contrast and were free from radiographic artefacts, overlapping structures and anatomical superimpositions were included. In this study clinical and technical factors including the periapical status of the teeth, the root canal filling technique, the type of sealer and the root canal preparation method were not considered. Periapical radiographs were excluded if they belonged to patients under 18 years of age or to teeth that had undergone retreatment, that showed incomplete root development, apical resection, root resorption, mineral trioxide aggregate apical plug, or post placement. The periapical radiographs were reviewed in reverse chronological order, starting with the most recent images, and those meeting the inclusion criteria were included consecutively until a total of 60 periapical radiographs was reached, with attention given to representing all evaluation categories.
All images were anonymised, and any information that could reveal patient identity was removed. No post-hoc image manipulation or enhancement was performed, and images were viewed using only standard display settings. Each selected periapical radiograph was placed on a separate high-resolution PowerPoint slide (Microsoft®, Redmond, WA, USA) and labelled with a unique identification number, randomly assigned from a numerical sequence of 1 and 60. The tooth to be evaluated on each radiograph was indicated with a red arrow. Figure 2 presents representative periapical radiographs included for evaluation.
Fig. 2.
Representative examples selected from the periapical radiographs included in the study. The tooth to be evaluated is indicated by a red arrow on the radiographs. The numbers displayed in the upper left corner were used to ensure the correct matching of each radiograph during the evaluation process. In the following descriptions, numerical references indicate the corresponding periapical radiographs. The gold standard assessments were as follows: 5 length = optimum; density = moderate; taper = optimum; procedural error = absent. 13 length = optimum; density = inadequate; taper = inadequate; procedural error = absent. 27 length = overfilled; density = optimum; taper = optimum; procedural error = absent. 29 length = short; density = optimum; taper = optimum; procedural error = apical transportation. 32 length = optimum; density = optimum; taper = optimum; procedural error = absent. 40 length = short; density = inadequate; taper = inadequate; procedural error = absent. 57 length = optimum; density = optimum; taper = optimum; procedural error = absent
Establishment of the gold standard
As no universally accepted quantitative and observer-independent objective reference method exists for evaluating the quality of root canal fillings seen on periapical radiographs, an expert-based reference standard was established based on independent assessments performed by experienced endodontists. This provided the “gold standard” used in this study. Students’ evaluations of the root canal fillings seen on periapical radiographs were compared with this gold standard, which was used as the reference for subsequent analyses. Four endodontists, each with a minimum of five years of clinical experience, independently evaluated all 60 periapical radiographs. They were blinded to the study protocol and objective. Each endodontist independently assessed all the radiographs by evaluating four predefined criteria related to root canal filling quality and assigning a corresponding category to each criterion for each radiograph. The experts conducted these evaluations under the same physical conditions as the students, and their results were recorded in a standardised electronic spreadsheet. The criteria and corresponding category definitions used to evaluate the quality of root canal fillings are described below [5, 16, 20]:
Length: Optimum (0–2 mm short of apex), short (>2 mm from apex) and overfilled (beyond the apex).
Density: Optimum (homogeneous filling with no visible voids), moderate (minor voids present but overall root canal filling likely to be adequate) and inadequate (obvious gaps compromising the seal and treatment).
Taper: Optimum (smooth, continuous taper from crown to apex), moderate (mostly conical with slight irregularities) and inadequate (inconsistent taper with clear irregularities).
Presence of procedural errors: Includes any detectable procedural errors reported in writing in an open-ended manner, such as ledge formation, broken instrument, missed canal, root canal perforation, transportation or zip. These written responses were subsequently mapped onto predefined standard error categories. This approach ensured that descriptions referring to the same error, despite variations in terminology used by different evaluators, were grouped consistently under a single category.
All four endodontists were blinded to each other’s assessments. To assess intraobserver reliability, each observer reanalysed the periapical radiograph set after a two-week interval. Following the completion of all assessments, the categories assigned by the four endodontists for each radiograph and each predefined criterion were compared to identify discrepancies. Agreement was defined as evaluations in which at least three of the four endodontists assigned the same category for a given criterion. Evaluations meeting this condition were accepted as representative of the gold standard directly. When evaluations were evenly split or when all four endodontists assigned different categories, agreement was considered not to have been achieved. For all evaluations in which agreement was not achieved, a face-to-face consensus meeting involving all four endodontists was convened. During this meeting, the four expert endodontists reviewed the relevant radiographs together and discussed their differing evaluations until they reached a single final decision. The decision reached through this consensus process was accepted as the gold standard (reference standard) for that category for the given criterion. The complete set of final category level gold standard decisions assigned to each predefined criterion for every radiograph constituted the overall gold standard reference dataset used in the study. Following consensus, no disagreements remained. To assess evaluation consistency, interobserver and intraobserver agreement analyses were performed.
Radiographic evaluation process
This study was conducted in May 2025, shortly before the end of the academic year. Owing to this timing, it was assumed that fourth- and fifth-year students had completed the majority of their relevant theoretical and clinical training. The students’ evaluation process was conducted in the preclinical laboratory at the Faculty of Dentistry, Ankara University. The laboratory includes 200 individual dental workstations designed for student training, each of which is equipped with a monitor connected to a central computer system. Before undertaking their evaluation, the students received a 15-min training session on the criteria for evaluating the quality of root canal fillings seen in periapical radiographs. This was delivered by an endodontist who had two years of clinical experience and was not involved in the study. Afterwards, the students received a link to an online questionnaire (Google Forms, Google, Inc., Mountain View, CA, USA) on their smartphones, which was shared through the class-based WhatsApp groups. The first page of the online survey included an informed consent statement, and participants who did not provide consent could not proceed to the subsequent pages. The demographic section was designed to collect information on participants’ academic year and gender. Students evaluated each image using a structured form with predefined criteria and one open-ended item to report any procedural error before proceeding to the next image.
Each dental workstation included a 28-inch Ultra HD LED monitor (Samsung LU28E590D, Samsung Electronics Co., Ltd., Suwon, South Korea) connected to a centralised computer system, enabling synchronised projection of radiographic images across all screens. To ensure standardisation and consistency in image viewing, the monitors featured a screen resolution of 3840 × 2160 pixels (Ultra HD), a screen brightness of 370 cd/m2 and a contrast ratio of 1000:1. All the monitors supported up to 10-bit colour depth and were calibrated for accurate grayscale reproduction suitable for radiographic evaluation. The ambient lighting in the laboratory was controlled at approximately 300 lx. Each workstation ran Windows 11 Pro and was powered by a desktop computer equipped with an Intel® Core™ i3-10100F processor (3.60 GHz) and 16 GB of RAM, with image rendering handled by an NVIDIA GeForce GTX 1630 GPU (NVIDIA Corporation, Santa Clara, CA, USA).
The periapical radiographs appeared sequentially on PowerPoint slides, with no fixed evaluation time per image. A proctor used Google Forms’ real-time response tracking feature to monitor the completion of each evaluation. The next image was shown only after all the responses for the current image had been submitted. After all the images had been evaluated, the participants rated their perceived confidence on a 5-point Likert scale (from 1 = no confidence at all to 5 = completely confident) and estimated for how many of the 60 images they believed might disagree with the gold standard on at least one of the four criteria. The disagreement ranges provided for estimation were 0–12, 13–24, 25–36, 37–48 or 49–60. Participants took a 15-min break at the midpoint of the evaluation, after assessing the first 30 periapical radiographs, to minimise visual fatigue. Table 1 presents the criteria and categories included in the questionnaire for students’ evaluation of root canal fillings seen on periapical radiographs, as well as the self-perception items related to their perceived confidence and sEDR.
Table 1.
Criteria and categories included in the questionnaire for students’ evaluation of root canal fillings seen on periapical radiographs, as well as self-assessment items related to their perceived confidence and sEDR
| Periapical Radiograph Number: | |||
|---|---|---|---|
| Section | Item | Predefined Criteria For Root Canal Filling Quality | Categories |
| Evaluation criteria | 1 | Length |
Optimum Short Overfilled |
| 2 | Density |
Optimum Moderate Inadequate |
|
| 3 | Taper |
Optimum Moderate Inadequate |
|
| 4 | Presence of procedural errors | Write down any complications you observed in the periapical radiograph (e.g., ledge, broken instrument, missed canal, perforation, transportation, zip) | |
| Self-perception assessments | 5 | How confident are you in evaluating all periapical radiographs? |
1 = Not confident at all 5 = Very confident |
| 6 | For how many radiographs do you think your evaluation might differ from the gold standard? |
0–12 13–24 25–36 37–48 49–60 |
|
A total of 107 dental students participated in this study. Each student independently evaluated 60 anonymised periapical radiographs using a structured questionnaire. For each periapical image, they assessed four evaluation criteria (items 1–4). Thus, each student provided 240 individual evaluations (60 images × 4 items). In addition, two self-perception questions were included at the end of the evaluation to measure each student’s overall self-confidence (item 5) and sEDR (self-reported estimated disagreement range) (item 6) in evaluating periapical radiographs.
Statistical analysis
Statistical analyses were performed using IBM SPSS Statistics 22 software (IBM Corp., Armonk, NY, USA). Before undertaking data analysis, the distributions of the variables were assessed with the Shapiro–Wilk normality test to determine whether the assumptions of the parametric tests were satisfied. Nonparametric tests were used for continuous variables that did not follow a normal distribution. Pearson’s chi-squared (χ2) test was applied to evaluate relationships between categorical variables . Interobserver agreement was calculated using Fleiss’ kappa, whereas intraobserver agreement was calculated using Cohen’s kappa. Agreement was evaluated using Cohen’s kappa (κ), which was interpreted according to the Landis and Koch scale: κ < 0.00 indicated poor, 0.00–0.20 slight, 0.21–0.40 fair, 0.41–0.60 moderate, 0.61–0.80 substantial, and 0.81–1.00 almost perfect agreement [24]. The Kruskal–Wallis H test was used to compare continuous variables across groups. As the omnibus test did not indicate a statistically significant difference (p > 0.05), no post-hoc pairwise comparisons were conducted. A significance level of p < 0.05 was used for all analyses. In order to enable the calculation of diagnostic accuracy measures, including sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV), these categories were subsequently dichotomised for each criterion. For the length criterion, the “optimum” category was classified as “ideal,” while the “short” and “overfilled” categories were classified as “non-ideal.” For the density and taper criteria, the “optimum” and “moderate” categories were classified as “ideal,” whereas the “inadequate” categories was considered “non-ideal.” Diagnostic performance measures were calculated based on these dichotomised classifications, using the gold standard as the reference.
Results
Interobserver and intraobserver agreement
Interobserver agreement was calculated using Fleiss’ kappa and found a value of 0.81, indicating almost perfect agreement. Intraobserver agreement was assessed using Cohen’s kappa for each observer, with κ values of 0.87 for Observer 1, 0.82 for Observer 2, 0.78 for Observer 3 and 0.85 for Observer 4, indicating substantial to almost perfect agreement.
Length evaluation
Table 2 presents the agreement between the gold standard and length, density and taper evaluations according to academic year. Figure 3 presents the percentage distribution of agreement between fourth- and fifth-year students’ evaluations and the gold standard. Fourth-year students showed moderate agreement (κ = 0.41, p < 0.0001). Their agreement across the overfilled, short and optimum categories was 57.3%, 76.1% and 49.2%, respectively. Fourth-year participants categorised root canal fillings that were considered optimum according to the gold standard as either overfilled or short in 50.8% of the periapical radiographs of root canal-filled teeth. Fifth-year students also showed moderate agreement (κ = 0.48, p < 0.0001). Their agreement across the overfilled, short and optimum categories was 58.4%, 78.3% and 59.2%, respectively.
Table 2.
Agreement of length, density and taper evaluations with the gold standard, by academic year
| Evaluation Criteria |
Academic Year | Categories | Overfilled (n, %) | Short (n, %) | Optimum (n, %) | Total (n, %) | Kappa | p |
|---|---|---|---|---|---|---|---|---|
| Length | Fourth Year | Overfilled | 567(57.3) | 101 (6.7) | 190 (13.1) | 858 (21.7) | 0.41 | 0.0001 |
| Short | 267 (27.0) | 1155 (76.1) | 548 (37.7) | 1970 (49.7) | ||||
| Optimum | 156 (15.8) | 262 (17.3) | 714 (49.2) | 1132 (28.6) | ||||
| Total | 990 (100.0) | 1518 (100.0) | 1452 (100.0) | 3960 (100.0) | ||||
| Fifth Year | Overfilled | 359 (58.4) | 34 (3.6) | 89 (9.9) | 482 (19.6) | 0.48 | 0.0001 | |
| Short | 143 (23.3) | 738 (78.3) | 279 (30.9) | 1160 (47.2) | ||||
| Optimum | 113 (18.4) | 171 (18.1) | 534 (59.2) | 818 (33.3) | ||||
| Total | 615 (100.0) | 943 (100.0) | 902 (100.0) | 2460 (100.0) |
| Inadequate (n, %) | Moderate (n, %) | Optimum (n, %) | Total (n, %) | |||||
|---|---|---|---|---|---|---|---|---|
| Density | Fourth Year | Inadequate | 965 (45.7) | 158 (19.9) | 184 (17.4) | 1307 (33.0) | 0.17 | 0.0001 |
| Moderate | 808 (38.3) | 390 (49.2) | 471 (44.6) | 1669 (42.1) | ||||
| Optimum | 339 (16.1) | 244 (30.8) | 401 (38.0) | 984 (24.8) | ||||
| Total | 2112 (100.0) | 792 (100.0) | 1056 (100.0) | 3960 (100.0) | ||||
| Fifth Year | Inadequate | 527 (40.2) | 93 (18.9) | 92 (14.0) | 712 (28.9) | 0.15 | 0.0001 | |
| Moderate | 571 (43.5) | 217 (44.1) | 279 (42.5) | 1067 (43.4) | ||||
| Optimum | 214 (16.3) | 182 (37.0) | 285 (43.4) | 681 (27.7) | ||||
| Total | 1312 (100.0) | 492 (100.0) | 656 (100.0) | 2460 (100.0) | ||||
| Taper | Fourth Year | Inadequate | 874 (53.0) | 274 (27.7) | 291 (22.0) | 1439 (36.3) | 0.17 | 0.0001 |
| Moderate | 527 (31.9) | 385 (38.9) | 521 (39.5) | 1433 (36.2) | ||||
| Optimum | 249 (15.1) | 331 (33.4) | 508 (38.5) | 1088 (27.5) | ||||
| Total | 1650 (100.0) | 990 (100.0) | 1320 (100.0) | 3960 (100.0) | ||||
| Fifth Year | Inadequate | 517 (50.4) | 121 (19.7) | 138 (16.8) | 776 (31.5) | 0.23 | 0.0001 | |
| Moderate | 336 (32.8) | 246 (40.0) | 255 (31.1) | 837 (34.0) | ||||
| Optimum | 172 (16.8) | 248 (40.3) | 427 (52.1) | 847 (34.4) | ||||
| Total | 1025 (100.0) | 615 (100.0) | 820 (100.0) | 2460 (100.0) |
A kappa statistic was used to evaluate agreement with the gold standard. Cohen’s kappa (κ) values were interpreted according to the Landis and Koch scale: κ < 0.00 poor, κ = 0.21–0.40 fair, κ = 0.41–0.60 moderate, κ = 0.61–0.80 substantial and κ = 0.81–1.00 almost perfect agreement. Statistical significance was set at p < 0.05. Columns represent the gold standard; rows represent student evaluations. Percentages (%) are presented as column percentages.
Fig. 3.
Stacked bar charts illustrate the distribution (%) of agreement between the evaluations of fourth-year (4th) and fifth-year (5th) dental students and the gold standard regarding root canal fillings, based on the criteria of length, density and taper
Density evaluation
Fourth-year students showed slight agreement (κ = 0.17; p < 0.0001). Their agreement across the inadequate, moderate and optimum categories was 45.7%, 49.2% and 38.0%, respectively. Fifth-year students also showed slight agreement with the gold standard (κ = 0.15; p < 0.0001). Their agreement across the inadequate, moderate and optimum categories was 40.2%, 44.1% and 43.4%, respectively.
Taper evaluation
Fourth-year students showed slight agreement (κ = 0.17; p < 0.0001). Their agreement across the inadequate, moderate and optimum categories was 53.0%, 38.9% and 38.5%, respectively. The fifth-year students showed fair agreement (κ = 0.23; p < 0.0001). Their agreement across the inadequate, moderate and optimum categories was 50.4%, 40.0% and 52.1%, respectively.
Diagnostic accuracy measures
Table 3 presents the diagnostic performance of fourth- and fifth-year dental students evaluating root canal filling quality according to length, density and taper criteria. Fifth-year students showed higher sensitivity, PPV and NPV for length, density and taper, whereas fourth-year students consistently demonstrated higher specificity across these criteria.
Table 3.
Diagnostic performance of student assessments according to evaluation criteria and academic year
| Criterion | Academic Year | Sensitivity | Specificity | PPV | NPV |
|---|---|---|---|---|---|
| Length | Fourth Year | 49.2 | 83.3 | 63.1 | 73.9 |
| Fifth Year | 59.2 | 81.8 | 65.3 | 77.6 | |
| Density | Fourth Year | 38.0 | 79.9 | 40.7 | 78.0 |
| Fifth Year | 43.4 | 78.0 | 41.8 | 79.1 | |
| Taper | Fourth Year | 38.5 | 78.0 | 46.7 | 71.7 |
| Fifth Year | 52.1 | 74.4 | 50.4 | 75.6 |
Sensitivity and specificity represent the ability of student assessments to correctly identify ideal and non-ideal evaluations according to the gold standard. PPV indicates positive predictive value and NPV indicates negative predictive value. All values are presented as percentages (%).
Evaluation of procedural errors
Table 4 presents the distribution of students’ procedural error evaluations compared with the gold standard. Procedural errors were evaluated using an overall agreement analysis including all students, due to the complexity and multi-category nature of their classification. Overall agreement with the gold standard was poor (κ = 0.01). Students frequently correctly identified root canal treatments that did not exhibit procedural errors. Based on correct identification rates, perforation (79/214,36.9%) and broken instrument (165/749, 22.0%) were the most accurately recognised error types. However, transportation (1/107, 0.9%) was the most poorly detected procedural error, followed by missed canal (13/535, 2.4%), ledge (3/107, 2.8%) and zip (9/107, 8.4%).
Table 4.
Students’ evaluations of procedural errors
| Gold Standard | ||||||||
|---|---|---|---|---|---|---|---|---|
| Students’ Procedural Error Evaluations | Ledge | Broken Instrument | Missed Canal | Perforation | Transportation | Zip | None | Total |
| Ledge | 3 | 10 | 8 | 0 | 2 | 18 | 70 | 111 |
| Ledge + Perforation | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 1 |
| Ledge + Transportation | 0 | 1 | 0 | 0 | 0 | 0 | 1 | 2 |
| Broken Instrument | 0 | 165 | 3 | 0 | 0 | 0 | 12 | 180 |
| Broken Instrument + Perforation | 0 | 1 | 0 | 0 | 1 | 0 | 1 | 2 |
| Missed Canal | 1 | 5 | 13 | 1 | 0 | 1 | 28 | 49 |
| Missed Canal + Perforation | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 2 |
| Perforation | 0 | 19 | 2 | 79 | 2 | 14 | 95 | 211 |
| Perforation + Zip | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 1 |
| Perforation + Zip + Broken Instrument | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 1 |
| Sinus Perforation | 0 | 0 | 0 | 0 | 0 | 0 | 2 | 2 |
| Transportation | 0 | 1 | 4 | 0 | 1 | 8 | 6 | 20 |
| Zip | 0 | 3 | 1 | 0 | 2 | 9 | 12 | 27 |
| None | 103 | 542 | 504 | 133 | 99 | 57 | 4052 | 5490 |
| Total | 107 | 749 | 535 | 214 | 107 | 107 | 4280 | 6099 |
Cross-tabulation of students’ evaluations of procedural errors against the gold standard. Each cell represents the frequency of a specific match between the student-evaluated error type and the gold standard.
Comparison of perceived confidence and sEDR according to academic year
Table 5 presents a comparison of the perceived confidence levels and sEDR by academic year. Students’ perceived confidence levels show significant variation across academic years (χ2 = 277.7, p < 0,0001). Descriptively, 53.0% of fourth-year students and 65.9% of fifth-year students reported moderate confidence. 1.5% of fourth-year students and 4.9% of fifth-year students reported no confidence.
Table 5.
Comparison of perceived confidence levels and sEDR, by academic year
| Category |
Fourth Year (n, %) |
Fifth Year (n, %) |
Total (n, %) |
p | |
|---|---|---|---|---|---|
| Perceived Confidence | No confidence at all | 60 (1.5) | 120 (4.9) | 180 (2.8) | 0.0001 |
| Slightly confident | 180 (4.5) | 0 (0.0) | 180 (2.8) | ||
| Moderately confident | 2100 (53.0) | 1620 (65.9) | 3720 (57.9) | ||
| Quite confident | 1140 (28.8) | 540 (22.0) | 1680 (26.2) | ||
| Completely confident | 480 (12.1) | 180 (7.3) | 660 (10.3) | ||
| Total | 3960 (100.0) | 2460 (100.0) | 6420 (100.0) | ||
| sEDR | 0–12 | 1500 (37.9) | 660 (26.8) | 2160 (33.6) | 0.0001 |
| 13–24 | 1260 (31.8) | 960 (39.0) | 2220 (34.6) | ||
| 25–36 | 840 (21.2) | 600 (24.4) | 1440 (22.4) | ||
| 37–48 | 300 (7.6) | 60 (2.4) | 360 (5.6) | ||
| 49–60 | 60 (1.5) | 180 (7.3) | 240 (3.7) | ||
| Total | 3960 (100.0) | 2460 (100.0) | 6420 (100.0) |
Pearson’s Chi-squared test was used to determine the statistical significance of differences between groups. Statistical significance was set at p < 0.05. sEDR: Self-reported estimated disagreement ranges
The sEDR show a significant difference across academic years (χ2 = 292.7, p < 0,0001). Descriptively, a greater percentage of fourth-year students (37.9%) reported sEDR corresponding to 0–12 compared with fifth-year students (26.8%).
Comparison of the number of disagreements with the gold standard across levels of perceived confidence
Table 6 presents comparisons of the number of disagreements between students’ evaluations and the gold standard according to perceived confidence, sEDR, and academic year. There was no significant difference between the disagreements across different levels of perceived confidence (H value [χ2] = 3.05, p = 0.548).
Table 6.
Comparison of the number of disagreements with the gold standard according to perceived confidence level, sEDR, and academic year
| Number of Disagreements | ||||
|---|---|---|---|---|
| n | Median (Min–Max) | Mean ± SD | ||
| Perceived Confidence Level | No confidence at all | 3 | 52 (48–52) | 50.67 ± 2.30 |
| Slightly confident | 3 | 54 (51–59) | 54.67 ± 4.04 | |
| Moderately confident | 62 | 53 (48–58) | 52.97 ± 2.55 | |
| Quite confident | 28 | 53 (47–59) | 52.50 ± 3.25 | |
| Completely confident | 11 | 52 (49–56) | 52.36 ± 2.50 | |
| Total | 107 | 53 (47–59) | 52.77 ± 2.78 | |
| 0–12 | 36 | 53 (48–58) | 52.86 ± 3.09 | |
| 13–24 | 37 | 53 (48–59) | 52.59 ± 2.39 | |
| sEDR | 25–36 | 24 | 52 (47–58) | 52.46 ± 2.81 |
| 37–48 | 6 | 55 (51–59) | 54.50 ± 2.88 | |
| 49–60 | 4 | 54 (48–56) | 52.75 ± 3.40 | |
| Total | 107 | 53 (47–59) | 52.77 ± 2.78 | |
| Academic Year | Fourth Year | 66 | 53 (48–59) | 52.76 ± 2.83 |
| Fifth Year | 41 | 53 (47–59) | 52.78 ± 2.72 | |
| Total | 107 | 53 (47–59) | 52.77 ± 2.78 | |
Students self-reported their confidence levels on a 5-point Likert scale, while sEDR was assessed using a 5-level range-based scale, as presented in the table. The Kruskal–Wallis test was used to compare disagreement numbers across perceived confidence levels and sEDR categories (both p > 0.05) whereas differences between academic years were analysed using the Mann–Whitney U test ( p > 0.05). Min: Minimum; Max: Maximum; SD: Standard deviation. sEDR: self-reported estimated disagreement ranges
Comparison of the number of disagreements with the gold standard across sEDR
There was no significant difference between the sEDR and the actual numbers of disagreements (H value [χ2] = 2.3, p = 0.671). Only four students showed agreement between their sEDR and the actual number of disagreements.
Comparison of disagreements with the gold standard by academic year
There was no significant difference between academic years (Z value = -0.019, p = 0.985).
Discussion
With this study, the agreement between dental students’ assessments and an expert-based gold standard regarding the technical quality of root canal fillings was evaluated, as well as the students’ perceived confidence during evaluation and their retrospective estimations of performance. The students demonstrated poor to moderate agreement with the number of disagreements remaining similar regardless of academic year, perceived confidence, and sEDR. This indicates limited success, and leaves the main hypothesis only partially supported.
Fourth-year students misidentified nearly half of the root canal fillings with optimum length as overfilled or short. In contrast, fifth-year students showed better recognition of optimum root canal filling length. As clinical experience increases, the ability to recognise radiographic patterns and interpret images holistically tends to improve, leading to greater diagnostic accuracy and more intuitive decision-making [21]. However, when overall agreement was considered, students in both academic years achieved a moderate level of agreement regarding the length criterion. Although there is no conclusive evidence that short fillings are easier to detect, the descriptive results of this study suggested a higher identification rate for such cases. This may be due to their more pronounced apparent deviation from the apex on radiographs.
Students demonstrated low performance in evaluating density, which may indicate that density is particularly subjective and challenging to assess, partly due to the difficulty of recognising its radiographic features. From this, it may be inferred that dental curricula may benefit from including, improved visual calibration, guided training with reference cases, and clearly defined benchmarks for the radiographic evaluation of root canal fillings. It should also be taken into account that the radiopacity of root canal filling materials varies depending on their chemical composition [25]. As the students made their evaluations without access to clinical background information, they did not know the type of sealer used; consequently, differences in the radiopacity of root canal filling materials may have altered the radiographic appearance and influenced students’ interpretation of filling density.
Fifth-year students exhibited approximately a 14% higher correct identification rate than fourth-year students in identifying the optimum taper. Nevertheless, agreement with the gold standard remained suboptimal in both groups. This may be explained partly by the students’ limited clinical experience, which can make it challenging to distinguish insufficient instrumentation from biologically appropriate and conservative shaping, thereby contributing to lower agreement rates in the taper category.
Higher sensitivity, PPV and NPV across all assessment criteria among fifth-year students indicate their improved identification of non-ideal root canal fillings, while lower specificity suggests a widening acceptance threshold. In contrast, the consistently higher specificity demonstrated by fourth-year students across all criteria may reflect a greater tendency to recognise ideal root canal fillings and to avoid classifying them as non-ideal during earlier stages of training.
Maqbool et al. [26] confirm that undergraduate students possess a high level of theoretical perception regarding the causes and prevention of procedural errors such as broken instrument. In contrast, this study focuses on how these procedural errors are recognised radiographically. Root canal fillings without procedural errors were frequently identified correctly. Perforation and broken instrument were the most accurately recognised error types; however, students showed critical limitations in detecting subtler errors such as transportation, missed canal, ledge and zip. Taken together, these findings highlight the importance of considering how theoretical knowledge translates into radiographic diagnostic skills within dental education. Although varying projection angles may enhance the ability of dental students to detect some procedural errors, the present study assessed only radiographically detectable errors using a single projection angle, which is unlikely to have influenced the identification of clearly visible errors.
Before graduation, dental students should acquire theoretical knowledge and adequate clinical skills in endodontics [27]. Tavares et al. [7] demonstrated a clear link between students’ conceptual understanding and practical performance, underscoring the need for balanced training. Educational approaches that support the integration of theory and practice may therefore be particularly relevant in endodontic education. Although methods such as patient surveys, standardised patient encounters and computer-based clinical scenarios [28, 29] have proven effective in medical education, they are not yet widely adopted in endodontic training [30]. Integrating these approaches into continuous radiographic training, which is essential for improving endodontic outcomes [10], could further strengthen students’ endodontic radiographic evaluation skills.
Visual literacy refers to the ability to interpret visual information in radiographs, enabling trained personnel to identify both normal and pathological conditions [31]. Studies have shown that targeted instruction can improve this ability [32, 33]. Because evaluation habits form early [33], educational programs that enable students to interpret radiographs, participate in guided discussions and learn basic imaging concepts can enhance those students’ radiographic evaluation skills. Consequently, within endodontic practice, such educational approaches may support more accurate and reliable radiographic assessment of root canal filling quality [34].
In this study, students estimated their disagreement ranges, thereby reflecting on their performance through a structured self-assessment process. Tuncer et al. reported that students overestimated their performance and perceived themselves as above average [35], whereas Awooda et al. reported underestimation of performance [36]. Despite these differences, both studies indicate that students’ self-assessments do not relate to their actual performance particularly closely. In line with this observation, the sEDR values the students provided in this study were not found to be associated with the number of actual disagreements. This finding highlights the broader concern that, without proper guidance, self-assessment may become inconsistent and unreliable [37]. Despite its widespread inclusion in dental curricula, self-assessment alone may fail without adequate training, a structured framework [13], opportunities to compare with expert standards [38, 39] and sufficient metacognitive awareness [40]. Without this support, self-assessment risks becoming superficial, lacking genuine reflection and self-awareness [13, 19]. To address this issue, education should set clear standards, provide feedback and offer opportunities for guided reflection to support accurate self-assessment [41]. Feedback from instructors helps students to adjust their self-perceptions and develop a realistic view of their clinical skills, making self-assessment both more reliable and more meaningful [41].
Based on the observed distribution of responses, the majority of both fourth- and fifth-year students reported a moderate level of self-confidence. However, there was no relationship between perceived confidence and actual evaluation performance, echoing the findings developed by Baaij and Özok [42]. Descriptively, fifth-year students reported more extreme levels, both high and low, that may indicate greater self-awareness and a more realistic view of clinical responsibility with increasing experience [19, 35]. In contrast, the more uniform responses observed among fourth-year students may indicate a more homogeneous pattern of confidence reporting [43].
A meta-analyses has shown that single-item scales can be as valid and reliable as multi-item scales in evaluating specific constructs [44]. In this study, the confidence levels of the students regarding self-perception were measured using a single-item global rating scale. Theoretical approaches to measuring self-efficacy was also considered. According to Bandura [45], self-efficacy measurements should be adapted to the functional context. Therefore, in line with the aim of this study, we focussed on capturing task-specific confidence rather than a general personality trait. Due to the nature of the measurement tool, students’ reported confidence levels reflect their momentary perceptions of their performance. Consequently, these results should not be interpreted as a standardised psychometric measurement.
The periapical status of the teeth was not taken into account in this study. In real clinical practice, clinicians often evaluate the quality of root canal fillings in the presence of periapical lesions. However, the presence or absence of periapical lesions may still have influenced the students’ interpretation and should be acknowledged as a study limitation. Another limitation is the unequal distribution of fourth- and fifth-year students. This imbalance likely relates to the intensive and time-consuming nature of the study and its voluntary design, which may have discouraged participation and resulted in a smaller final sample size than initially planned. Although the sample size that was achieved maintained adequate statistical power, the lower response rate may limit the generalisability of the findings. Future studies with larger and more representative samples are warranted to further validate these results. In addition, educational interventions could be implemented, and the same students re-evaluated to assess improvement. Furthermore, students’ ability to evaluate the quality of root canal fillings could be assessed using advanced imaging techniques, such as cone-beam computed tomography.
Conclusion
This study revealed that students possess limited proficiency in evaluating the quality of the root canal fillings seen on periapical radiographs. Students demonstrated comparable actual performance in this task, independent of their academic year, self-reported confidence or sEDR. However, subjective perceptions of confidence and sEDR varied across academic years. Although fifth-year students demonstrated better detection of non-ideal root canal fillings, earlier stages of training favoured recognition of ideal ones. Overall, these findings indicate a need to reconsider interpretation skills and self-perception related to the radiographic assessment of the quality of root canal treatments in undergraduate dental education.
Supplementary Information
Acknowledgements
The authors would like to express their deepest gratitude to the students at the Ankara University Faculty of Dentistry for their participation in this study.
Abbreviations
- sEDR
Self-reported estimated disagreement range
- LED
Light-emitting diode
- Ultra HD
Ultra High Definition
- cd/m2
Candelas per square metre
- GPU
Graphics processing unit
- Sd
Standard deviation
Authors’ contributions
Emine Odabaşı Tezer: conceptualisation (equal); investigation (lead); writing – review and editing (lead) Fadi Nahas: conceptualisation (equal); formal analysis (equal); writing – original draft preparation. Alhabab Shbitah: writing – review and editing; formal analysis (equal) İrem Dilara Kılıç: investigation (equal); visualisation (lead); data curation (lead). Ahmet Bölük: investigation (equal); data curation. Meltem Dartar: conceptualisation (equal); supervision (lead); and validation (lead).
Funding
No funding was received for this study.
Data availability
The data that support this study’s findings are available from the corresponding author upon reasonable request.
Declarations
Ethics approval and consent to participate
Ethical approval was granted by the Ethics Committee for Nonclinical Scientific Research of the Faculty of Dentistry, Ankara University (protocol number 7/10.03.25). All procedures were performed in accordance with the World Medical Association (WMA) Declaration of Helsinki. Informed consent was obtained from all participants involved in this study.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
References
- 1.Setzer FC, Lee SM. Radiology in endodontics. Dent Clin North Am. 2021;65(3):475–86. [DOI] [PubMed] [Google Scholar]
- 2.Gröndahl HG, Huumonen S. Radiographic manifestations of periapical inflammatory lesions: how new radiological techniques may improve endodontic diagnosis and treatment planning. Endod Topics. 2004;8(1):55–67. [Google Scholar]
- 3.Bołtacz‐Rzepkowska E, Pawlicka H. Radiographic features and outcome of root canal treatment carried out in the Łódź region of Poland. Int Endod J. 2003. 10.1046/j.0143-2885.2003.00608.x. [DOI] [PubMed] [Google Scholar]
- 4.Burke F, Lynch CD, Ní Ríordáin R, Hannigan A. Technical quality of root canal fillings performed in a dental school and the associated retention of root-filled teeth: a clinical follow-up study over a 5-year period. J Oral Rehabil. 2009;36(7):508–15. [DOI] [PubMed] [Google Scholar]
- 5.Ahmed A, Foschi F, Duncan HF, McColl E: Investigating the technical quality of undergraduate endodontic treatment in a primary care-based dental school. Br Dent J. 2024;1–5. [DOI] [PubMed]
- 6.Ng YL, Mann V, Gulabivala K. A prospective study of the factors affecting outcomes of non-surgical root canal treatment: part 2: tooth survival. Int Endod J. 2011;44(7):610–25. [DOI] [PubMed] [Google Scholar]
- 7.Tavares LG, Lima SM, Lima MG, Arruda MP, Menegazzi TC, Rezende TM. Undergraduate dentistry students’ perception of difficulties regarding endodontic treatment. Aust Endod J. 2019;45(1):98–105. [DOI] [PubMed] [Google Scholar]
- 8.Santos SMC, Soares JA, Costa GM, Brito-Júnior M, Moreira AN, de Magalhães CS. Radiographic parameters of quality of root canal fillings and periapical status: a retrospective cohort study. J Endod. 2010;36(12):1932–7. [DOI] [PubMed] [Google Scholar]
- 9.Ng YL, Mann V, Rahbaran S, Lewsey J, Gulabivala K. Outcome of primary root canal treatment: systematic review of the literature – Part 2. Influence of clinical factors. Int Endod J. 2008;41(1):6–31. [DOI] [PubMed] [Google Scholar]
- 10.Ng JM, Lee YY, Chippagiri P, Ahanin E, Parolia A. Effect of quality of radiographs taken during root canal treatment on technical quality of root canal fillings and endodontic outcome. Restor Dent Endod. 2025;50(1):e3. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Hansrani V. Assessing root canal fillings on a radiograph – an overview. Br Dent J. 2015;219(10):481–3. [DOI] [PubMed] [Google Scholar]
- 12.Quality guidelines for endodontic treatment. consensus report of the European Society of Endodontology. Int Endod J. 2006;39(12):921–30. [DOI] [PubMed] [Google Scholar]
- 13.Burrows R. Understanding self-assessment in undergraduate dental education. Br Dent J. 2018;224(11):897–900. [DOI] [PubMed] [Google Scholar]
- 14.Baaij A, Kruse C, Whitworth J, Jarad F. EUROPEAN SOCIETY OF ENDODONTOLOGY undergraduate curriculum guidelines for endodontology. Int Endod J. 2024;57(8):982–95. [DOI] [PubMed] [Google Scholar]
- 15.Undergraduate curriculum guidelines for endodontology. Int Endod J. 2001;34(8):574–80. [DOI] [PubMed] [Google Scholar]
- 16.Donnelly A, Coffey D, Duncan HF. A re-audit of the technical quality of undergraduate root canal treatment after the introduction of new technology and teaching practices. Int Endod J. 2017;50(10):941–50. [DOI] [PubMed] [Google Scholar]
- 17.Woolliscroft JO, TenHaken J, Smith J, Calhoun JG. Medical students’ clinical self-assessments: comparisons with external measures of performance and the students’ self-assessments of overall performance and effort. Acad Med. 1993;68(4):285–94. [DOI] [PubMed] [Google Scholar]
- 18.Kruger J, Dunning D. Unskilled and unaware of it: how difficulties in recognizing one’s own incompetence lead to inflated self-assessments. J Pers Soc Psychol. 1999;77(6):1121–34. [DOI] [PubMed] [Google Scholar]
- 19.Gabbard T, Romanelli F: Do student self-assessments of confidence and knowledge equate to competence? Am. J. Pharm. Educ. 2021;85:8505. [DOI] [PMC free article] [PubMed]
- 20.Elsayed RO, Abu‐bakr NH, Ibrahim YE. Quality of root canal treatment performed by undergraduate dental students at the University of Khartoum, Sudan. Aust Endod J. 2011;37(2):56–60. [DOI] [PubMed] [Google Scholar]
- 21.Hegde S, Gao J, Vasa R, Cox S. Factors affecting interpretation of dental radiographs. Dentomaxillofac Radiol. 2023;52(2):20220279. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Pigg M, Nagendrababu V, Duncan HF, Abbott PV, Fouad AF, Kruse C, et al. PRIDASE 2024 guidelines for reporting diagnostic accuracy studies in endodontics: explanation and elaboration. Int Endod J. 2025;58(1):6–36. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.Cohen J. Statistical power analysis for the behavioral sciences. Routledge; 2013. [Google Scholar]
- 24.Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics. 1977;33(1):159–74. [PubMed] [Google Scholar]
- 25.Candeiro GT, Correia FC, Duarte MA, Ribeiro-Siqueira DC, Gavini G. Evaluation of radiopacity, pH, release of calcium ions, and flow of a bioceramic root canal sealer. J Endod. 2012;38(6):842–5. [DOI] [PubMed] [Google Scholar]
- 26.Maqbool M, Asogan VM, Akram Z, Then B, Noorani TY. Can perception of fractured endodontic files benefit 1st degree dental students and dental educators: a questionnaire-based survey. J Dent Educ. 2024;88(10):1330–41. [DOI] [PubMed] [Google Scholar]
- 27.Fong W, Heidarifar O, Killough S, Lappin M, El Karim I. An audit on technical quality of root fillings performed by undergraduate students. Int Endod J. 2018;51:e197–203. [DOI] [PubMed] [Google Scholar]
- 28.Oliven A, Nave R, Baruch A. Long experience with a web-based, interactive, conversational virtual patient case simulation for medical students’ evaluation: comparison with oral examination. Med Educ Online. 2021;26(1):1946896. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 29.Amini R, Hernandez NC, Keim SM, Gordon PR. Using standardized patients to evaluate medical students’ evidence-based medicine skills. J Evid Based Med. 2016;9(1):38–42. [DOI] [PubMed] [Google Scholar]
- 30.Goyal D, Alghahtani F, Santos JN, Graziotin R, Hieawy A. Undergraduate endodontic curricula across Canadian Dental Schools: a cross-sectional analysis. J Dent Educ. 2025;89(1):116–29. [DOI] [PubMed] [Google Scholar]
- 31.Yenawine P. Thoughts on visual literacy. In: Handbook of research on teaching literacy through the communicative and visual arts. edn. Routledge; 2004. p. 845–6.
- 32.Shapiro J, Rucker L, Beck J. Training the clinical eye and mind: using the arts to develop medical students’ observational and pattern recognition skills. Med Educ. 2006;40(3):263–8. [DOI] [PubMed] [Google Scholar]
- 33.Mangione S, Peitzman SJ, Gracely E, Nieman LZ. Creation and assessment of a structured review course in physical diagnosis for medical residents. J Gen Intern Med. 1994;9:213–8. [DOI] [PubMed] [Google Scholar]
- 34.Naghshineh S, Hafler JP, Miller AR, Blanco MA, Lipsitz SR, Dubroff RP, et al. Formal art observation training improves medical students’ visual diagnostic skills. J Gen Intern Med. 2008;23(7):991–7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 35.Tuncer D, Arhun N, Yamanel K, Çelik Ç, Dayangaç B. Dental students’ ability to assess their performance in a preclinical restorative course: comparison of students’ and faculty members’ assessments. J Dent Educ. 2015;79(6):658–64. [PubMed] [Google Scholar]
- 36.Awooda EM, Elzaki WM, Al-Nazhan SA. Agreement between students’ self/peer and faculty assessments of the radiographic technical quality of root canal treatment performed during preclinical and clinical endodontic courses. Saudi Endod J. 2025;15(1):53–8. [Google Scholar]
- 37.Alghilan MA, Munaga S, Aldakhil A. A comparison of dental students’ self-assessment and instructors’ assessment in competency examinations in a preclinical operative dentistry course. Adv Med Educ Pract. 2025;16:177–88. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 38.Zheng B, He Q, Lei J. Informing factors and outcomes of self-assessment practices in medical education: a systematic review. Ann Med. 2024;56(1):2421441. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 39.Mays KA, Branch-Mays GL. A systematic review of the use of self-assessment in preclinical and clinical dental education. J Dent Educ. 2016;80(8):902–13. [PubMed] [Google Scholar]
- 40.Kornmehl DL, Ohyama H. Self-assessment in dental education: a decade of insights and perspectives in preclinical operative dentistry. J Dent Educ. 2025;89(4):543–7. [DOI] [PubMed] [Google Scholar]
- 41.Tonni I, Gadbury-Amyot CC, Govaerts M, Ten Cate O, Davis J, Garcia LT, et al. ADEA-ADEE shaping the future of dental education III: assessment in competency-based dental education: ways forward. J Dent Educ. 2020;84(1):97–104. [DOI] [PubMed] [Google Scholar]
- 42.Baaij A, Özok AR. Influence of method of teaching endodontics on the self-efficacy and self-perceived competence of undergraduate dental students. Eur Endod J. 2018;3(1):31–7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 43.Croskerry P, Norman G. Overconfidence in clinical decision making. Am J Med. 2008;121(5):S24–9. [DOI] [PubMed] [Google Scholar]
- 44.Wanous JP, Reichers AE, Hudy MJ. Overall job satisfaction: how good are single-item measures? J Appl Psychol. 1997;82(2):247. [DOI] [PubMed] [Google Scholar]
- 45.Bandura A. Guide for constructing self-efficacy scales. Self-efficacy beliefs of adolescents. 2006;5(1):307–37. [Google Scholar]
Associated Data
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Supplementary Materials
Data Availability Statement
The data that support this study’s findings are available from the corresponding author upon reasonable request.