ABSTRACT
Objectives
The aim of this study was to examine the frequency, types, and distribution of technical errors in periapical radiographic images taken by dental students, as well as to evaluate the effect of practical demonstration on these parameters.
Methods
The study involved a comprehensive evaluation of 960 periapical radiographic images taken by 80 junior year dental students, both prior to and following a demonstration conducted using a radiographic phantom. All images were obtained using the bisecting angle technique with photostimulable phosphor (PSP) plates, without the use of a film holder, and were assessed by four observers.
Results
One or more technical errors were identified in 783 of the 960 images (81.6%). The most common error was related to sensor positioning, both before and after the demonstration (57.3% and 55.6%, respectively). The highest proportion of errors was identified in the maxillary anterior region (26.8%), followed by the mandibular anterior region (21.6%). Errors were slightly more prevalent in the maxilla (53.6%) than in the mandible (46.4%). The frequency of technical errors before and after the demonstration was similar, with statistically significant differences noted only for crown cutoff, non‐parallel positioning to the occlusal plane, and shortening errors. A decrease in the total number of errors was observed in approximately two‐thirds of the students (61.25%).
Conclusion
These findings highlight the need to strengthen undergraduate dental education in radiographic techniques and radiation protection. Integrating structured instruction on radiographic errors and their correction earlier in the curriculum may enhance student competence. In addition to practical demonstrations, the incorporation of simulation‐based training, supervised clinical practice, and structured feedback could further improve radiographic skills and reduce technical errors.
Keywords: dental education, oral radiology, periapical radiography, photostimulable phosphor plate, radiographic errors
1. Introduction
Radiographic examination is a fundamental component of diagnosis and treatment in dentistry, with radiographs frequently serving as the primary diagnostic aid for clinicians. Periapical radiographs, providing detailed visualization of dental structures and surrounding bone, are the most commonly used type of intraoral radiographs in dental practice.
The two basic techniques used in periapical radiography are the paralleling and bisecting angle techniques. In the paralleling technique, the image receptor, placed in a holder, is positioned in the mouth parallel to the long axis of the tooth being examined, and the central x‐ray beam is directed perpendicularly to both the receptor and the tooth. The bisecting angle technique involves positioning the receptor as close as possible to the lingual (or palatal) aspect of the target tooth, with the central x‐ray beam directed perpendicular to an imaginary bisector of the angle formed between the long axis of the tooth and the receptor.
The adoption of digital receptors for periapical radiography has become increasingly widespread, with dental professionals worldwide transitioning from traditional film‐based radiography to digital imaging. Digital imaging technology offers numerous advantages over conventional radiography, including faster imaging, real‐time communication, elimination of darkroom processing and chemical use, access to advanced image enhancement tools, and a reduction in radiation dose [1, 2, 3, 4].
Radiographic errors may undermine the diagnostic quality of images and the accuracy of their interpretation [5, 6, 7]. Such errors may necessitate retakes, leading to inefficient use of professional time and resources, as well as an increased radiation exposure to patients, clinicians, radiology staff, and the environment [6, 8, 9, 10]. Therefore, it is crucial for dentists to improve their proficiency in radiographic techniques to produce clinically acceptable images and deliver accurate clinical services.
The principle of “as low as reasonably achievable (ALARA),” fundamental to radiation protection in daily practice, becomes even more critical in governmental dental schools due to the high probability of technical and processing errors arising from the substantial workloads and varying levels of expertise among the workforce [11, 12]. Despite advancements in digital technology, retakes remain a matter of concern with sensor usage, as proper positioning and angulation are still performed manually. The benefits of reduced radiation dose and increased workflow efficiency are compromised when retakes occur. In order to maximize the advantages of these technologies and minimize patient radiation exposure, it is essential that all users, including students, receive comprehensive education and effective training in clinical radiology [10]. As an integral part of a quality assurance program, the radiographic errors made by dental students should be identified, documented, and corrected to minimize the frequency of retakes and unnecessary radiation exposure to patients [5, 7].
Several studies have been conducted with the objective of examining the frequency and types of radiographic errors in dental schools. This study was designed to evaluate the frequency, types, and anatomical distribution of technical errors in periapical radiographic images taken by undergraduate dental students, as well as to determine the effect of practical demonstration on these parameters. The data obtained from this study are intended to contribute to the improvement of the quality of radiographic images taken by undergraduate dental students and the establishment of future clinical training protocols.
The following hypotheses were proposed: (1) The types of artifacts observed in periapical radiographs will vary depending on the anatomical region where the image is taken; (2) there will be no significant difference between anatomical regions regarding the effect of the practical demonstration; and (3) practical demonstration will improve students’ ability to acquire accurate periapical radiographs.
2. Materials and Methods
This study received approval from the Ethics and Research Committee of the Faculty of Dentistry at Marmara University (protocol no: 2022‐115). The anonymity of participating students was maintained, and the radiographic images were assigned numerical codes for identification purposes.
2.1. Study Sample
Students at the Marmara University Faculty of Dentistry receive comprehensive education and training in digital radiography, with the expectation that they will use digital systems during their clinical practice. In the second semester of their sophomore year, they are introduced to intraoral radiographic techniques through a series of lectures. In their junior year, they undergo a brief review of the previous academic year and additionally participate in a demonstration in groups using a radiographic phantom, on which they are subsequently required to take images. This is followed by patient assignments during their senior and intern years.
In this study, to minimize potential selection bias and ensure instructional consistency, 86 out of 172 junior dental students who had received radiographic training from a single educator (B.G.), were intentionally selected. The remaining students, who had been trained by a different educator, were excluded to eliminate variability in teaching methodology and to control for potential confounding variables. Of the 86 selected students, 2 declined to participate, and the data from 4 students who did not attend the demonstration were excluded from the analysis, as illustrated in the workflow diagram (Figure 1). The final study sample comprised a total of 960 periapical radiographic images taken by 80 junior dental students during the Oral and Maxillofacial Radiology courses—480 images taken before and 480 after the demonstration. Each student acquired a total of 12 periapical images (6 before and 6 after the demonstration), covering the right maxillary and mandibular anterior, premolar, and molar regions. Students were allowed only a single attempt per image; retakes were not permitted.
FIGURE 1.
Workflow diagram of the study.
All periapical radiographic images were taken from a radiographic phantom (Nissin Dental Products INC, Kyoto, Japan) using the bisecting angle technique without a film holder. The phantom head used in this study is an x‐ray simulator designed for practicing intraoral dental radiography. It features an x‐ray‐compatible jaw model that allows students to practice intraoral projection techniques and acquire basic radiographic skills, including receptor placement and tube angulation, for different intraoral regions. The unit is portable, can be installed in a dental chair or used independently, and includes a free‐moving finger arm for sensor positioning. A dental x‐ray unit (Evolution X 3000‐2C, New Life New Life Radiology Srl, Italy) fitted with a short open‐ended transparent plastic cone, size 2 photostimulable phosphor (PSP) plates (VistaScan, Dürr Dental, Bietigheim‐Bissingen, Germany), and a PSP scanner (VistaScan Mini, Dürr Dental, Bietigheim‐Bissingen, Germany) were used to obtain the images. The images were taken in standard acquisition mode (70 kVp, 8 mA, 0.08 s) and saved in Joint Photographic Expert Group (JPEG) format.
2.2. Demonstration
Following the pre‐demonstration exposures, an approximately 60‐min practical demonstration on acquiring periapical radiographic images from these regions was performed by a single educator (B.G.), who has 25 years of experience in oral and maxillofacial radiology.
Aimed at improving students’ practical skills and reducing technical radiographic errors, the demonstration followed a systematic approach, beginning with an overview of the relevant radiographic technique. This was followed by a step‐by‐step demonstration of the imaging procedure. Students were encouraged to ask questions and clarify any uncertainties during the session.
2.3. Radiological Assessment
For each radiographic image, the region displayed and type of error were recorded. This study focused exclusively on operator‐related errors, which were classified based on criteria established with reference to oral radiology textbooks to ensure consistency among observers [13, 14].
The following criteria were considered by all observers when evaluating technical errors in periapical images: sensor positioning errors (placement too high/low from the occlusal plane [crown cutoff/apices cutoff], lack of centering the area to be imaged, non‐parallel positioning to the occlusal plane, incorrect placement of the long axis, and plate placed upside down), projection geometry errors (improper vertical angulation [elongation/shortening] and improper horizontal angulation [superimposition]), and miscellaneous errors (cone cutting, bending of the plate within the mouth [distortion], mirror image, and double image).
2.4. Observer Evaluation
Technical errors in periapical radiographic images were evaluated under standardized conditions (quiet room with subdued ambient lighting and a 40 cm viewing distance) using a single medical monitor (NEC MD242C2 24‐inch monitor with 1920 × 1200 resolution—Hiliex Advanced Medical Technologies, California, USA) by four well‐trained observers, excluding the educator who conducted the demonstrations to minimize observation bias. To assess intra‐observer agreement, 100 randomly selected radiographic images were re‐evaluated by each observer under the same conditions four weeks after the initial evaluation (Figure 1). In instances of inter‐observer disagreement, a consensus was reached through joint discussion.
2.5. Success Criteria
As a criterion of success, a reduction in the number of technical radiographic errors in the periapical radiographs obtained after the practical demonstration was considered a “success,” whereas no change or an increase in the number of errors was considered a “failure.”
2.6. Statistical Analysis
Data were analyzed using IBM SPSS Statistics version 27 software (SPSS, Chicago, IL, USA). Descriptive statistics were calculated using Pearson's chi‐square test, while the McNemar test was used to assess the effect of the demonstration. Binary logistic regression analysis was applied to determine the relationship between the changes in the number of errors following the demonstration and the success of the demonstration. Statistical significance was set at p < 0.05. Intra‐ and inter‐rater reliability were assessed using Cohen's Kappa coefficient.
3. Results
To provide an overview of the study population, the general demographic characteristics of the participants are presented in Table 1. To evaluate potential selection bias, baseline characteristics of the intentionally selected and non‐selected students were compared. As shown in Table 2, no statistically significant differences were observed between the two groups in terms of age, sex, GPA, or nationality (p > 0.05 for all comparisons). These findings confirm that the groups were comparable and that the selection strategy did not introduce systematic bias into the study sample.
TABLE 1.
General demographic characteristics of the study participants (n = 80).
| Variable | n (%)/mean ± SD |
|---|---|
| Age (years) | 22.38 ± 0.68 |
| Sex | |
| Male | 30 (37.5%) |
| Female | 50 (62.5%) |
| GPA | 2.88 ± 0.14 |
| Nationality | |
| domestic | 79 (98.8%) |
| International | 1 (1.2%) |
Abbreviation: GPA, grade point average (calculated on a 4.00 scale).
TABLE 2.
Comparison of baseline characteristics between intentional and unintentional groups.
| Variable |
Intentional group (n = 86) |
Unintentional group (n = 86) |
p |
|---|---|---|---|
| Age (years, mean ± SD) a | 22.38 ± 0.7 | 22.24 ± 0.75 | 0.211 |
| Sex (male/female) b | 35/51 | 28/58 | 0.268 |
| GPA (mean ± SD) a | 2.88 ± 0.14 | 2.85 ± 0.15 | 0.265 |
| Nationality (domestic/international) b | 85/1 | 84/2 | 0.56 |
Abbreviation: GPA, grade point average (calculated on a 4.00 scale).
Independent samples t‐test.
Pearson's chi‐square test.
One or more technical errors were detected in 81.6% of all periapical radiographic images. The level of inter‐observer agreement was almost perfect (94%).
Table 3 presents the distribution of types of technical periapical radiographic errors by anatomical location. The highest number of errors was observed in the maxillary anterior region (26.8%). Errors were least frequent in the mandibular molar region (7%). Overall, slightly more errors were identified in the maxilla (53.6%) than in the mandible (46.4%).
TABLE 3.
The distribution of types of technical periapical radiographic errors by anatomical location.
| Region | |||||||
|---|---|---|---|---|---|---|---|
| Type of error |
Max. anterior n (%) |
Max. premolar n (%) |
Max. molar n (%) |
Mand. anterior n (%) |
Mand. premolar n (%) |
Mand. molar n (%) |
Total n (%) |
| Sensor positioning errors | 259 (15.2%) | 125 (7.4%) | 130 (7.5%) | 174 (10.1%) | 180 (10.6%) | 97 (5.5%) | 965 (56.3%) |
| Crown cutoff | 13 (0.8%) | 11 (0.6%) | 3 (0.2%) | 6 (0.3%) | 23 (1.3%) | 10 (0.5%) | 66 (3.9%) |
| Apices cutoff | 110 (6.4%) | 13 (0.8%) | 72 (4.2%) | 13 (0.8%) | 57 (3.4%) | 35 (2.0%) | 300 (17.7%) |
| Lack of centering the area to be imaged | 63 (3.7%) | 20 (1.2%) | 23 (1.3%) | 132 (7.7%) | 41 (2.4%) | 17 (1.0%) | 296 (17.3%) |
| Non‐parallel positioning to the occlusal plane | 41 (2.4%) | 59 (3.5%) | 23 (1.3%) | 12 (0.7%) | 42 (2.5%) | 12 (0.7%) | 189 (11.0%) |
| Incorrect placement of the long axis | 7 (0.4%) | 0 (0.0%) | 0 (0.0%) | 2 (0.1%) | 2 (0.1%) | 0 (0.0%) | 11 (0.6%) |
| Plate placed upside down | 25 (1.5%) | 22 (1.3%) | 9 (0.5%) | 9 (0.5%) | 15 (0.9%) | 23 (1.3%) | 103 (6.0%) |
| Projection geometry errors | 160 (9.3%) | 90 (5.2%) | 38 (2.2%) | 60 (3.5%) | 45 (2.7%) | 12 (0.7%) | 405 (23.6%) |
| Elongation | 63 (3.7%) | 11 (0.6%) | 19 (1.1%) | 24 (1.4%) | 19 (1.1%) | 12 (0.7%) | 148 (8.6%) |
| Shortening | 0 (0.0%) | 6 (0.3%) | 7 (0.4%) | 1 (0.1%) | 1 (0.1%) | 0 (0.0%) | 15 (0.9%) |
| Superimposition | 97 (5.6%) | 73 (4.3%) | 12 (0.7%) | 35 (2.0%) | 25 (1.5%) | 0 (0.0%) | 242 (14.1%) |
| Miscellaneous errors | 39 (2.3%) | 39 (2.3%) | 37 (2.1%) | 134 (7.9%) | 77 (4.5%) | 14 (0.8%) | 340 (19.9%) |
| Cone cutting | 21 (1.2%) | 35 (2.0%) | 33 (1.9%) | 20 (1.2%) | 34 (2.0%) | 11 (0.6%) | 154 (9.0%) |
| Bending of the plate | 13 (0.8%) | 1 (0.1%) | 0 (0.0%) | 113 (6.6%) | 35 (2.0%) | 0 (0.0%) | 162 (9.5%) |
| Mirror image | 5 (0.3%) | 1 (0.1%) | 4 (0.2%) | 0 (0.0%) | 7 (0.4%) | 3 (0.2%) | 20 (1.2%) |
| Double images | 0 (0.0%) | 2 (0.1%) | 0 (0.0%) | 1 (0.1%) | 1 (0.1%) | 0 (0.0%) | 4 (0.3%) |
| Total | 458 (26.8%) | 254 (14.9%) | 205 (11.8%) | 372 (21.5%) | 301 (17.8%) | 123 (7.0%) | 1710 (100%) |
Abbreviations: Mand., mandibular; Max., maxillary.
Among sensor positioning errors, the most frequent were apices cutoff (17.7%), followed closely by lack of centering the area to be imaged (17.3%). Within the category of projection geometry errors, superimposition was the most common (14.1%). These three predominant errors were mainly observed in anterior regions, with apices cutoff (6.4%) and superimposition (5.6%) occurring in the maxillary anterior region, and a lack of centering the area to be imaged (7.7%) in the mandibular anterior region. Another frequent error in the mandibular anterior region was bending of the plate (6.6%), classified under miscellaneous errors.
Figure 2 shows the number of technical errors made by dental students both before and after the demonstration, while Table 4 presents the change in the frequency of these errors after the demonstration along with the statistical significance.
FIGURE 2.
The number of types of technical errors before and after demonstration.
TABLE 4.
Change in the frequency of types of technical radiographic errors before and after demonstration.
| Type of error | Before | After | p |
|---|---|---|---|
| Crown cutoff | 8.98% | 4.8% | * 0.013 |
| Apices cutoff | 32.08% | 30.42% | 0.342 |
| Lack of centering the area to be imaged | 31.25% | 30.42% | 0.800 |
| Non‐parallel positioning to the occlusal plane | 23.43% | 16.11% | * 0.002 |
| Incorrect placement of the long axis | 1.46% | 0.83% | 0.549 |
| Plate placed upside down | 11.67% | 9.79% | 0.368 |
| Elongation | 15.00% | 15.83% | 0.841 |
| Shortening | 2.71% | 0.42% | * 0.007 |
| Superimposition | 25.63% | 25.21% | 0.861 |
| Cone cutting | 18.13% | 13.96% | 0.068 |
| Bending of the plate | 16.25% | 17.5% | 0.644 |
| Mirror image | 2.92% | 1.25% | 0.115 |
| Double image | 0.63% | 0.21% | 1.000 |
Note: McNemar test,
p < 0.05.
Comparison of pre‐ and post‐demonstration performance revealed that technical errors remained largely similar, with a few exceptions. Statistically significant differences were observed for apices cutoff, non‐parallel positioning to the occlusal plane, and shortening errors between the pre‐ and post‐demonstration performances (Table 4).
Anatomical region‐based analysis showed statistically significant decreases in several errors, including apices cutoff in anterior regions, non‐parallel positioning to the occlusal plane in mandibular molars, a lack of centering the area to be imaged in maxillary molars, shortening in maxillary posterior regions, and superimposition in maxillary molars, between performances before and after the demonstration (Table 5). Although the frequency of apices cutoff decreased in the mandibular anterior region, there was a statistically significant increase in this error in the maxillary anterior region (Table 5).
TABLE 5.
Change in the frequency of technical radiographic errors before and after demonstration by anatomical location.
| Type of error | Max. anterior | Max. premolar | Max. molar | Mand. anterior | Mand. premolar | Mand. molar | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Before | After | Before | After | Before | After | Before | After | Before | After | Before | After | ||
| Crown cutoff | 12.5% | 3.75% | 8.75% | 5% | 2.5% | 1.25% | 5% | 2.5% | 15% | 12.5% | 10% | 2.5% | |
| p | 0.065 | 0.549 | 1.000 | 0.687 | 0.824 | 0.070 | |||||||
| Apices cutoff | 61.25% | 76.25% | 6.25% | 10% | 48.75% | 41.24% | 12.5% | 3.75% | 37.5% | 33.75% | 26.25% | 17.5% | |
| p | * 0.031 | 0.549 | 0.405 | * 0.002 | 0.710 | 0.210 | |||||||
| Lack of centering the area to be imaged | 37.5% | 41.25% | 11.25% | 13.75% | 21.25% | 7.5% | 81.25% | 83.75% | 25% | 26.25% | 11.25% | 10% | |
| p | 0.766 | 0.791 | * 0.019 | 0.804 | 1.000 | 1.000 | |||||||
| Non‐parallel positioning to the occlusal plane | 64.1% | 41.03% | 43.75% | 30% | 16.25% | 12.5% | 8.75% | 6.25% | 27.5% | 25% | 12.5% | 2.5% | |
| p | 0.137 | 0.072 | 0.629 | 0.727 | 0.845 | * 0.039 | |||||||
| Incorrect placement of the long axis | 5% | 3.75% | — | — | — | — | 1.25% | 1.25% | 2.5% | 0% | — | — | |
| p | 1.000 | — | — | 1.000 | 0.500 | — | |||||||
| Plate placed upside down | 16.25% | 15% | 15% | 12.5% | 6.25% | 5% | 6.25% | 5% | 10% | 8.75% | 16.25% | 12.5% | |
| p | 1.000 | 0.824 | 1.000 | 1.000 | 1.000 | 0.664 | |||||||
| Elongation | 35% | 43.75% | 5% | 8.75% | 7.5% | 16.25% | 18.75% | 11.25% | 12.5% | 11.25% | 11.25% | 3.75% | |
| p | 0.265 | 0.549 | 0.143 | 0.210 | 1.000 | 0.146 | |||||||
| Shortening | — | — | 7.5% | 0% | 8.75% | 0% | 0% | 1.25% | 0% | 1.25% | — | — | |
| p | — | * 0.031 | * 0.016 | 1.000 | 1.000 | — | |||||||
| Superimposition | 58.75% | 62.5% | 38.75% | 52.5% | 13.75% | 1.25% | 26.25% | 17.5% | 15% | 16.25% | — | — | |
| p | 0.742 | 0.082 | * 0.006 | 0.248 | 1.000 | — | |||||||
| Cone cutting | 17.5% | 8.75% | 20% | 23.75% | 26.25% | 15% | 11.25% | 13.75% | 25% | 17.5% | 8.75% | 5% | |
| p | 0.118 | 0.629 | 0.108 | 0.804 | 0.307 | 0.549 | |||||||
| Bending of the plate | 6.25% | 10% | 0% | 1.25% | — | — | 67.5% | 73.75% | 23.75% | 20% | — | — | |
| p | 0.508 | 1.000 | — | 0.486 | 0.719 | — | |||||||
| Mirror image | 6.25% | 0% | 1.25% | 0% | 5% | 0% | — | — | 2.5% | 6.25% | 2.5% | 1.25% | |
| p | 0.063 | 1.000 | 0.125 | — | 0.453 | 1.000 | |||||||
| Double image | — | — | 1.25% | 1.25% | — | — | 2.5% | 0% | — | — | — | — | |
| p | — | 1.000 | — | 1.000 | — | — | |||||||
Note: McNemar test,
Abbreviations: Mand., mandibular; Max., maxillary.
p < 0.05.
Following the practical demonstration, 49 students met the success criterion, while 31 did not, yielding a success rate of 61.25%. Binary logistic regression analysis showed that two of the three technical errors with statistically significant post‐demonstration reductions were significantly associated with students who were considered successful after training (Table 6).
TABLE 6.
Effect of demonstration success on selected technical radiographic errors.
| Demonstration | Type of error | p | Exp(B) | 95% CI for Exp(B) | Sensitivity | Specificity | |
|---|---|---|---|---|---|---|---|
| Lower | Upper | ||||||
| Success/failure | Non‐parallel positioning to the occlusal plane | * 0.016 | 4.163 | 1.310 | 13.234 | 68.1% | 71.4% |
| Crown cutoff | * 0.040 | 3.255 | 1.057 | 10.029 | |||
| Shortening | 0.522 | 2.623 | 0.137 | 50.257 | |||
Note: Binary logistic regression.
*p < 0.05.
4. Discussion
Dentists should be proficient in radiographic techniques to ensure high‐quality images while minimizing unnecessary radiation exposure to patients. Therefore, educators in this field need to explore methods to address the challenges associated with learning these techniques and tackle issues observed in clinical practice, as highlighted in various studies. The complexity of mastering periapical radiographic techniques, which are among the most frequently used intraoral radiographic methods in dentistry, coupled with the frequent errors associated with these techniques, has led educators to investigate alternative methodologies and educational strategies.
All three hypotheses of our study—(1) the types of artifacts observed in periapical radiographs will vary depending on the anatomical region where the image is taken; (2) there will be no significant difference between anatomical regions regarding the effect of the practical demonstration; and (3) practical demonstration will improve students’ ability to acquire accurate periapical radiographs—were accepted.
The frequency and types of errors in periapical radiographs taken by dental students have been investigated in several studies (Table 7). In addition to, some studies have examined the influence of various factors, including periapical radiographic techniques, radiographic image receptors, receptor holders, and the anatomical locations of the teeth being radiographed, on the rate of errors.
TABLE 7.
Similar previous studies listed chronologically with the author(s), country, sample, technique, receptor type, setting, operator, error rate, and most frequent technical error.
| Author(s) | Country | Sample | Technique | Receptor type | Setting | Operator | Error rate (%) | Most frequent technical error (%) |
|---|---|---|---|---|---|---|---|---|
|
Crandell [26] |
USA | 16‐film complete‐mouth surveys |
Bisecting angle (without film holders) |
Conventional film | Patient | Dental and dental hygiene students | 8.4% | Improper film positioning (39.5%) |
|
Bean [29] |
USA | 14‐film complete‐mouth surveys |
Bisecting angle and paralleling (no film holders in the bisecting) |
Conventional film | Patient | Dental students |
25% (bisecting angle technique) 11% (paralleling technique) |
Apices cutoff |
|
Mourshed [15] |
USA |
18‐film complete‐mouth surveys (5578 periapical radiographs) |
Bisecting angle (using a film holder and different types of cones) |
Conventional film | Patient | Junior and senior dental students | 47.3% | Improper film positioning (41.8%) |
|
Mourshed and McKinney [16] |
USA | 8726 periapical radiographs |
Bisecting angle and paralleling (using different types of film holders and cones) |
Conventional film | Patient | Junior and senior dental students | 49.9% | Improper film positioning (18.5%) |
|
Patel [8] |
USA |
21‐film complete‐mouth surveys (6763 periapical radiographs) |
Paralleling (using different types of film holders and cones) |
Conventional film | Patient | Junior dental students | 13.1% | Improper film positioning (49.9%) |
|
Patel and Greer [25] |
USA |
1150 complete‐mouth surveys (24,150 radiographs) |
Paralleling (using different types of film holders and cones) |
Conventional film | Patient | Junior dental students | 9.24% | Improper film positioning (64.9%) |
|
Sommers et al. [18] |
USA |
18‐film full mouth series (n = 56) |
Paralleling (using film and sensor holders) |
Conventional film and CCD sensor | Radiographic phantom | Junior dental hygiene students |
69% (with CCD sensor) 39% (with conventional film) |
Vertical angulation in CCD (53%), horizontal angulation in film‐based system (65%) |
|
Felippe et al. [5] |
Brazil |
1823 endodontic periapical radiographs |
Not specified (taken with and without film holders) |
Conventional film | Patient | Undergraduate dental students | Not specified | Improper film positioning (not specified) |
|
Peker and Alkurt [9] |
Turkey |
1700 randomly selected periapical radiographs |
Bisecting angle (without film holders) |
Conventional film | Patient | Junior and senior dental students | 35.94% | Improper angulation (34.92%) |
|
Haghnegahdar et al. [6] |
Iran | 3188 periapical radiographs | Bisecting angle | Conventional film | Patient | Senior dental students | 3.6% | Improper film positioning (35.4%) |
|
Jayasinghe et al. [7] |
Sri Lanka |
1523 working length periapical radiographs |
Bisecting angle (without film holders) |
Conventional film | Patient | Final year dental students | Not specified | Overlapping (16.9%) |
|
Elangovan et al. [27] |
India | 13,104 periapical radiographs | Bisecting angle | Conventional film | Patient | Final year students and interns | 27% | Cone cutting (26.1%). |
|
Yusof et al. [17] |
Malaysia |
8030 digital intraoral images (5746 periapical and 2284 bitewing) |
Bisecting angle | CMOS sensor | Patient | Undergraduate clinical dental students | 54.4% | Improper film positioning (22.6%) |
|
Masserat et al. [28] |
Iran | 2292 periapical radiographs | Bisecting angle | Conventional film | Patient | Dental students | 12.9% | Elongation (19.6%) |
|
Pachêco‐Pereira et al. [10] |
Canada |
1886 digital intraoral images (1296 bitewing and 590 periapical) |
Not specified (using sensor holders) |
CMOS and PSP sensors | Patient | Junior dental hygiene students | Not specified | Apices cutoff (10.5%) |
|
Senior et al. [19] |
Canada |
9397 digital intraoral images (3814 periapical,5540 bitewing, 43 occlusal) |
Paralleling (using sensor holders) |
CMOS and PSP sensors | Patient | Junior and senior dental students | Not specified | Apices cutoff (43%) |
|
Hasan et al. [12] |
Pakistan | 600 digitalized images of endodontic periapical radiographs | Bisecting angle | Conventional film | Patient | Undergraduate students | 60.2% | Improper film positioning (18.8%) |
|
Presotto et al. [4] |
Brazil |
840 digital periapical radiographic images |
Not specified (using sensor holders) |
CMOS and PSP sensors | Radiographic phantom | Senior dental students | Not specified | Absence of a safety margin (35.7%) in CMOS, overlapping (23.1%) in PSP system |
|
Present study 2024 |
Turkey |
960 digital periapical radiographic images |
Bisecting angle (without film holders) |
PSP sensors | Radiographic phantom | Junior dental students | 81.6% | Improper sensor positioning (56.5%) |
Abbreviations: CCD, charge‐coupled device; CMOS, complementary metal oxide semiconductor; PSP, photostimulable phosphor; USA, United States of America.
The frequency of errors reported in studies evaluating the quality of radiographs obtained by students varies considerably, as shown in Table 7. This variability may be attributed to differences in study designs, including the type of intraoral radiographic technique used (bisecting or paralleling), sensor types, presence and type of the receptor holding devices, the x‐ray cone used, and the experience level of the students (junior, senior, or intern). In addition to, factors such as whether the study was conducted on patients or a radiographic phantom, the clinical setting in which the study was performed (radiology, endodontics, or pediatric dentistry), and variations in observer judgement may also affect the results [8, 15, 16, 17]. Consequently, direct comparison of the findings of these studies with the current study may not be appropriate.
The two main techniques for periapical radiography are the bisecting angle and paralleling techniques, each with distinct advantages and limitations [13, 14]. The paralleling technique ensures high accuracy by producing radiographic images with minimal dimensional distortion and simplifies the procedure through the use of a beam alignment device, which eliminates the need for manual adjustment of horizontal and vertical angulations. This technique also facilitates easy standardization and consistent image reproduction. However, placement of the receptor can be challenging, particularly in pediatric patients or adults with small mouths and shallow palates, and the beam alignment device may cause discomfort by impinging on oral tissues. In contrast, the bisecting angle technique offers greater flexibility as it can be performed without a beam alignment device when patient anatomy restricts its use. However, it is less accurate due to potential dimensional distortion and more complex, requiring precise determination of the bisecting line between the tooth axis and the film plane, along with correct beam alignment. Despite these challenges, the bisecting angle technique, routinely used at our faculty, was selected for use in this study. While the paralleling technique is preferred for its accuracy, diagnostic images can be obtained with the bisecting technique, when necessary; thus, practitioners should be capable of obtaining radiographs of acceptable quality using either technique [16].
Some studies have used different imaging receptors [4, 10, 18, 19]. Sommers et al. [18] compared film‐ and sensor‐based systems, finding a statistically significant increase in technical errors with the charge‐coupled device (CCD) system, with the type of error varying depending on the imaging system used. Pachêco‐Pereira et al. [10] reported that sensor positioning errors were more frequent with CCD sensors compared to PSP sensors. Similarly, Senior et al. [19] and Presotto et al. [4] observed a higher frequency of errors with complementary metal‐oxide semiconductor (CMOS) sensors compared to PSP sensors. These findings were attributed to technical challenges such as difficulties with sensor holders, the rigidity and thickness of the sensor, its small active surface area, and the handling of the sensor cord in the oral cavity [4, 10, 18, 19]. In contrast, PSP systems, which are cord‐free and resemble conventional dental films in size and active surface area, offer the advantage of easier placement within the oral cavity with minimal patient discomfort, despite requiring a short scanning time for image display [3, 19, 20, 21, 22, 23, 24]. To facilitate a smooth transition from film‐based radiography to digital imaging, our institution adopted the PSP digital system, which was used in this study.
Yusof et al. [17] and Senior et al. [19] investigated the frequency of retakes for intraoral radiographic images taken by dental students throughout the course of their education. Their findings indicated that the retake rate was highest among junior dental students and decreased as students advanced through their clinical years. Junior dental students were selected for this study to ensure reliable before‐and‐after comparisons. The authors attributed the high retake rate to limited technical skills and insufficient knowledge of radiation protection at this early stage of training. Patel and Greer [25] noted that dental students need to perform at least 20–25 complete‐mouth radiographic examinations (equivalent to 280–350 periapical radiographs) to achieve basic technical proficiency. Thus, it should not be surprising that there was no significant reduction in error rate following the demonstration in our study.
The radiographic images used in this study were taken from a radiographic phantom. While this approach allows junior students to gain experience without subjecting patients to unnecessary radiation, actual patient exposures are generally easier to perform due to the flexibility of soft tissues. However, patients may also complicate the adaptation of the imaging receptor due to gagging or discomfort [18]. Thus, the findings of this study may not be directly generalizable to clinical practice. It has been determined that most studies in the literature regarding radiographic errors have been conducted on patients, with only a limited number of studies utilizing radiographic phantoms, making direct comparisons impossible (Table 7) [4, 18]. The phantom head used in the study is a standard model for educational purposes and does not replicate anatomical variations commonly found in human dentition, such as lingual tori, narrow arch morphology, deep or shallow palatal vaults, or malposed teeth with crowding. Consequently, using a phantom head may not fully simulate the challenges students might face when adapting radiographic techniques to individual patient anatomies. However, as the primary aim of our study was to evaluate basic technical errors, this standardization is expected to enhance the reliability of the results.
To minimize the risk of selection bias and ensure instructional consistency, students trained by a single educator were intentionally selected. This design choice eliminated variability due to differences in instructional methods, which could otherwise confound the assessment of training effectiveness. To verify the comparability of the selected and non‐selected groups, baseline characteristics, including age, sex, GPA, and nationality, were statistically compared. No significant differences were observed between the groups (all p > 0.05), confirming their homogeneity (Table 2). Scholarship status was not assessed, as all students in our public university receive state‐funded tuition. Due to national data protection regulations, variables such as ethnicity, geographic origin, and socioeconomic status could not be collected. Moreover, the standardized national university entrance exam used in our country ensures academic equivalence across incoming student cohorts. Taken together, these measures confirm that the selection approach did not introduce systematic bias and preserved the internal validity of the study.
Most published studies on intraoral radiographic technical errors have focused on the bisecting angle technique [6, 7, 9, 12, 15, 17, 26, 27, 28], some evaluated the paralleling technique [8, 18, 19, 25], while a few examined both techniques [16, 29]. Previous studies using the bisecting angle technique reported one or more technical errors in 3.6%–63.8% of periapical radiographs. In this study, using the bisecting angle technique, one or more technical errors were detected in a total of 81.6% of the periapical radiographic images. According to the results of the studies, the paralleling technique appears to be superior to the bisecting angle technique in reducing the number of radiographic errors [8]. This finding may be interpreted as an indication of an inherent limitation of the bisecting angle technique [12, 16]. While the paralleling technique is preferred due to its accuracy and minimal dimensional distortion, the bisecting angle technique remains essential in cases where anatomical constraints prevent the use of beam alignment devices. Given its routine application at our faculty, the bisecting angle technique was selected for this study.
Consistent with the findings of previous studies, the most frequently detected error in this study was improper sensor positioning (56.5%) [5, 6, 8, 15, 16, 17, 25, 26]. Improper receptor positioning accounted for 18.8%–41.8% of all errors in studies using the bisecting angle technique and 49.9%–64.9% in studies using the paralleling technique. Research has shown that receptor positioning errors are more prevalent with the paralleling technique than with the bisecting angle technique. The use of film‐holding devices that are difficult to position intraorally may explain the difference in error rates between the two techniques [25]. The high frequency of improper receptor positioning may be attributed to the movement of the receptor in the patient's mouth prior to x‐ray exposure during daily clinical routine [6, 15]. In some cases, patient‐related factors, such as a shallow mouth floor, low palatal vault, severe gag reflex, or young age may also be the primary cause [17]. To eliminate these factors, the radiographic images in our study were taken from a radiographic phantom.
Previous studies have reported that horizontal angle errors range from 1.7% to 65% of total errors, with a higher percentage when the bisecting angle technique is used [25]. In this study, errors resulting from incorrect horizontal angulation accounted for 14.1% of total errors. Superimposition due to incorrect horizontal angulation was most frequently observed in the maxillary anterior region. Notably, incorrect horizontal angulation (14.1%) was more common than incorrect vertical angulation (9.5%). This finding may be explained by the presence of a table of optimum vertical angles on the control panel of the x‐ray unit used in the study.
Statistically significant differences in technical errors with respect to anatomical regions have been reported by several authors [7, 9, 25]. Previous studies have consistently found a higher error rate in the maxilla compared to the mandible [7, 9, 18]. The posterior regions have been identified as the most common sites for all error types [6, 9, 25]. In addition to, improper receptor positioning has been reported more frequently in the molar regions than in other intraoral areas [8, 9, 25]. In this study, although a slightly higher number of total errors was observed in maxillary teeth (53.6%) compared to mandibular teeth (46.4%), the highest number of errors was unexpectedly found in the maxillary anterior region (26.8%), followed by the mandibular anterior region (21.5%). The maxillary anterior region was also identified as the most common site for sensor positioning errors. This finding is consistent with the study by Jayasinghe et al. [7], which also reported the highest number of errors in the maxillary anterior region, followed by the maxillary premolar region. These findings highlight the anatomical complexity of specific intraoral regions, particularly in relation to sensor placement. Accordingly, we propose the development of anatomically customized digital sensors in varying sizes and configurations to better accommodate region‐specific anatomical challenges. Such adaptations could reduce positioning errors and enhance image quality. The design, manufacture, and clinical implementation of these sensors should be prioritized, as they have the potential to reduce retakes and thereby contribute to minimizing patient radiation exposure.
Unlike previous studies, this study also examined the change in performance before and after the demonstration. The practical demonstration was conducted by a single educator, ensuring consistency and effectiveness in the educational process. This approach minimized variability in teaching styles and content delivery, allowing all students to receive uniform instruction. While, technical errors before and after the demonstration were generally similar, with only minor exceptions, a decrease in the total number of errors was observed in approximately two‐thirds of the students, suggesting positive outcomes from the training. The limited number of technical errors that showed improvement were directly related to the successful students, indicating that the training was particularly effective in addressing these specific errors. Nevertheless, the high overall error rate indicates a need for additional instructional strategies beyond the practical demonstration. Educational approaches such as simulation‐based radiographic modules, increased exposure to supervised clinical sessions, structured feedback loops, and peer‐assisted learning formats could be integrated into undergraduate curricula. These multimodal methods may enhance students’ technical competency and help further reduce the incidence of radiographic errors in early‐stage learners.
The current literature contains a wide range of studies examining technical radiographic errors. However, there is a limited number of studies evaluating the impact of practical demonstration on these errors made by dentistry students. The lack of substantial improvement in certain errors following the demonstration on the radiographic phantom remains unclear and warrants further investigation from an educational perspective.
5. Conclusion
The high error rate observed in this study underscores the need to revise undergraduate training in radiographic techniques and radiation protection. Identifying the frequency and types of errors provided valuable insights for improving student performance and developing supplementary educational materials, such as technical manuals and instructional videos. Introducing targeted training on radiographic errors and their correction at the beginning of the practical course may be beneficial. In addition to practical demonstrations, incorporating simulation‐based learning, supervised practice, and structured feedback into the curriculum may further improve students’ radiographic skills. Further research is needed to optimize the educational experience in dental radiology for students while concurrently minimizing radiation exposure to patients.
Conflicts of Interest
The authors declare no conflicts of interest.
Acknowledgments
We thank our colleague Dr. Sukru Can Akmansoy for his assistance with data analysis and interpretation.
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