Prevalence and Distribution of Apical Periodontitis in Root Canal-Treated Teeth: A Cone-Beam Computed Tomography Study in a Saudi Subpopulation

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The aim of the study is to evaluate the prevalence of apical periodontitis (AP) detected by CBCT scans, particularly associated with root canal–treated teeth (AP-RCT), in the Saudi population. The study is valuable as an epidemiological contribution for this local population and for comparison with other populations. Some determinants, such as age and demographic groups, were analyzed, which could guide strategies for prevention and clinical monitoring.  The introduction provides a good contextualization of the topic under investigation, with a clear rationale. However, the aim of the study could be stated more directly and clearly. The methodology was described in bullet points, but Figure 2 could be replaced or improved with sharper, higher-quality images. Greater clarity regarding the data collection from the CBCT images should be established. The analyses were conducted between January 2017 and January 2021. The study should explicitly clarify how scans were included (e.g., consecutive analysis or not) and improve the inclusion and exclusion criteria for the collected data.  The results were clearly presented. The following study (Sexual Dimorphism in Apical Periodontitis Severity Detected by CBCT. J Endod. 2025 Dec;51(12):1744-1751. doi: 10.1016/j.joen.2025.08.020) could enrich the discussion, particularly in the context of this paragraph: "Most previous studies have reported no significant sex-related differences in the prevalence of AP. In contrast, the present study found a higher prevalence among females (58%) compared with males (42%). However, sex was not independently associated with AP-RCT in adjusted regression analyses, suggesting that this difference may reflect distributional rather than biological factors. The reasons for this difference remain unclear and warrant further investigation."  Even in the discussion, importantly, the present findings further support the notion that conventional radiography may underestimate the true prevalence of apical periodontitis, particularly when compared with three-dimensional imaging. This is consistent with previous research (Accuracy of cone beam computed tomography and panoramic and periapical radiography for detection of apical periodontitis. J Endod. 2008 Mar;34(3):273–279. doi: 10.1016/j.joen.2007.11.023), which reported that apical periodontitis was correctly identified in 54.5% of cases using periapical radiographs and only 27.8% with panoramic radiographs. The conclusions could be presented more directly, addressing only the study question without additional inferences.  Overall, the study provides important epidemiological data on AP in a Saudi population using novel CBCT technology, which offers a higher diagnostic accuracy compared with previous epidemiological studies using periapical radiographs.

Author Response

Comments and Suggestions for Authors

The aim of the study is to evaluate the prevalence of apical periodontitis (AP) detected by CBCT scans, particularly associated with root canal–treated teeth (AP-RCT), in the Saudi population. The study is valuable as an epidemiological contribution for this local population and for comparison with other populations. Some determinants, such as age and demographic groups, were analyzed, which could guide strategies for prevention and clinical monitoring.  The introduction provides a good contextualization of the topic under investigation, with a clear rationale.

 

However, the aim of the study could be stated more directly and clearly.

 

The methodology was described in bullet points, but Figure 2 could be replaced or improved with sharper, higher-quality images.

Response:
We thank the reviewer for this comment. The aim of the study was restated more clearly as suggested. Figure 2 has been revised and replaced with higher-resolution CBCT images with improved sharpness and contrast to enhance visualization of periapical findings across all planes. The updated figure better reflects the image quality used during radiographic assessment and improves clarity for the reader.

Greater clarity regarding the data collection from the CBCT images should be established. including scan retrieval, imaging parameters, evaluation protocol, and examiner calibration to enhance methodological transparency.

Response:
We thank the reviewer for this comment. To enhance methodological transparency, we clarified the CBCT data collection workflow in the Methods section by explicitly summarizing scan retrieval, standardized imaging parameters, evaluation protocol across multiplanar views, and examiner calibration procedures. These additions provide a clearer overview of how CBCT images were collected and assessed.The analyses were conducted between January 2017 and January 2021. The study should explicitly clarify how scans were included (e.g., consecutive analysis or not) and improve the inclusion and exclusion criteria for the collected data.  

The results were clearly presented. The following study (Sexual Dimorphism in Apical Periodontitis Severity Detected by CBCT. J Endod. 2025 Dec;51(12):1744-1751. doi: 10.1016/j.joen.2025.08.020) could enrich the discussion, particularly in the context of this paragraph: "Most previous studies have reported no significant sex-related differences in the prevalence of AP. In contrast, the present study found a higher prevalence among females (58%) compared with males (42%). However, sex was not independently associated with AP-RCT in adjusted regression analyses, suggesting that this difference may reflect distributional rather than biological factors. The reasons for this difference remain unclear and warrant further investigation."  

Response: We thank the reviewer for this valuable suggestion. The Discussion section has been revised to incorporate recent CBCT-based evidence by Estrela et al. (J Endod, 2025), which demonstrated sexual dimorphism in apical periodontitis. While females showed a higher prevalence of disease, males exhibited a greater proportion of larger and more severe lesions. This addition provides important context to our findings and supports the interpretation that sex-related differences may relate to lesion severity and disease behavior rather than prevalence alone.

Even in the discussion, importantly, the present findings further support the notion that conventional radiography may underestimate the true prevalence of apical periodontitis, particularly when compared with three-dimensional imaging. This is consistent with previous research (Accuracy of cone beam computed tomography and panoramic and periapical radiography for detection of apical periodontitis. J Endod. 2008 Mar;34(3):273–279. doi: 10.1016/j.joen.2007.11.023), which reported that apical periodontitis was correctly identified in 54.5% of cases using periapical radiographs and only 27.8% with panoramic radiographs.

Response: We thank the reviewer for this valuable suggestion. The recommended study by Estrela et al. (2025) has been carefully reviewed and is highly relevant to the interpretation of our findings regarding sex-related differences in apical periodontitis. Accordingly, we have revised the Discussion section to incorporate this reference.

 

The conclusions could be presented more directly, addressing only the study question without additional inferences.  Overall, the study provides important epidemiological data on AP in a Saudi population using novel CBCT technology, which offers a higher diagnostic accuracy compared with previous epidemiological studies using periapical radiographs.

Response: We thank the reviewer for this valuable comment. In response, the Conclusions section has been revised to be more concise and focused strictly on the primary study objectives and key findings, without extending into broader inferences. The revised conclusion now directly summarizes the prevalence and distribution of apical periodontitis, the association with root canal–treated teeth, and the main demographic and anatomical predictors identified through multivariable analysis. Any ancillary interpretations have been removed to ensure clarity and alignment with the study aims.

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript is titled “ Prevalence and Distribution of Apical Periodontitis in Root Canal–Treated Teeth: A Cone-Beam Computed Tomography Study in a Saudi Subpopulation.’ presents a well-designed retrospective cross-sectional study aim to investigate the prevalence and distribution of apical periodontitis (AP), with particular emphasis on root canal–treated teeth (AP-RCT), using cone-beam computed tomography (CBCT) in a Saudi subpopulation. The topic is clinically relevant, as CBCT-based epidemiological data remain limited in Middle Eastern populations. The results are generally well interpreted. However, several issues related to methodological justification and discussion depth should be addressed to strengthen the manuscript.

The use of CBCT allows for more accurate detection of apical periodontitis compared with conventional radiography, addressing a known limitation in many prevalence studies. While the authors acknowledge that CBCT scans were obtained for routine diagnostic purposes, the potential impact of selection bias requires explanation.

A limitation is the absence of data on the technical quality of root canal fillings, Length, density, and quality of coronal restorations. These factors are well-established determinants of AP-RCT. Consider adding a paragraph in the discussion that highlights how the inclusion of treatment quality variables could alter the observed results. Also, emphasize more clearly that AP-RCT prevalence cannot be interpreted as failure in the treatment. Please see how treatment quality may affect the risk of detecting AP in root-filled teeth in the following article:

https://www.eurendodj.com/index.php/pub/article/view/284

Expand the discussion on whether age serves as a surrogate for cumulative dental interventions and treatment-period effects. Consider discussing the higher prevalence of RCT in old patients, which may have affected the risk odds ratio in detecting AP in root-filled teeth in old patients.

Why were central incisors chosen to be the reference for the logistic model, even though they are the least prone to AP disease? Justify in the discussion such a selection.

Author Response

Comments and Suggestions for Authors

This manuscript is titled “ Prevalence and Distribution of Apical Periodontitis in Root Canal–Treated Teeth: A Cone-Beam Computed Tomography Study in a Saudi Subpopulation.’ presents a well-designed retrospective cross-sectional study aim to investigate the prevalence and distribution of apical periodontitis (AP), with particular emphasis on root canal-treated teeth (AP-RCT), using cone-beam computed tomography (CBCT) in a Saudi subpopulation. The topic is clinically relevant, as CBCT-based epidemiological data remain limited in Middle Eastern populations. The results are generally well interpreted. However, several issues related to methodological justification and discussion depth should be addressed to strengthen the manuscript.

The use of CBCT allows for more accurate detection of apical periodontitis compared with conventional radiography, addressing a known limitation in many prevalence studies. While the authors acknowledge that CBCT scans were obtained for routine diagnostic purposes, the potential impact of selection bias requires explanation.

Response: We thank the reviewer for this comment. The Discussion has been revised to clarify that all CBCT scans were obtained for routine diagnostic purposes unrelated to apical pathology, minimizing targeted selection. We also explicitly acknowledge that CBCT-based studies may overrepresent patients with more complex dental conditions, a limitation shared by most CBCT epidemiological investigations, and note that the higher prevalence observed is likely influenced by the superior diagnostic sensitivity of CBCT.

A limitation is the absence of data on the technical quality of root canal fillings, Length, density, and quality of coronal restorations. These factors are well-established determinants of AP-RCT. Consider adding a paragraph in the discussion that highlights how the inclusion of treatment quality variables could alter the observed results.

Response: We thank the reviewer for this important comment. We have now explicitly addressed this limitation in the Discussion by acknowledging the absence of data on root canal filling length, density, and coronal restoration quality—all of which are established determinants of AP-RCT. We further clarified that inclusion of these treatment quality variables could potentially modify the observed associations and help distinguish technical from biological or demographic contributors to apical periodontitis. This has been added to strengthen interpretation of our findings and to highlight directions for future research.

Also, emphasize more clearly that AP-RCT prevalence cannot be interpreted as failure in the treatment. Please see how treatment quality may affect the risk of detecting AP in root-filled teeth in the following article:

https://www.eurendodj.com/index.php/pub/article/view/284

Response:
We thank the reviewer for this important comment. We have revised the Discussion to clarify that the presence of apical periodontitis in root canal–treated teeth should not be interpreted as definitive treatment failure. A new paragraph was added emphasizing that AP-RCT detection is strongly influenced by technical factors such as obturation quality and coronal restoration integrity, as well as by the higher sensitivity of CBCT. We also highlighted that the absence of treatment quality variables is a study limitation and that their inclusion could modify the observed associations, with supporting literature cited accordingly.

Expand the discussion on whether age serves as a surrogate for cumulative dental interventions and treatment-period effects. Consider discussing the higher prevalence of RCT in old patients, which may have affected the risk odds ratio in detecting AP in root-filled teeth in old patients.

Response:
Thank you for this important comment. We have revised the Discussion to explicitly clarify that the presence of apical periodontitis in root canal–treated teeth should not be interpreted as definitive evidence of endodontic treatment failure. A new paragraph was added emphasizing that AP-RCT detection is influenced by multiple factors, including obturation quality, coronal restoration integrity, host response, and the higher sensitivity of CBCT, which may reveal residual or healing periapical changes not visible on conventional radiographs. We also acknowledged the absence of detailed treatment quality variables as a study limitation and discussed how inclusion of these parameters could modify the observed associations. These revisions provide a more balanced interpretation of AP-RCT prevalence and address the reviewer’s concern.

 

 

Why were central incisors chosen to be the reference for the logistic model, even though they are the least prone to AP disease? Justify in the discussion such a selection.

Response: Central incisors were intentionally selected as the reference category because they represent a low-risk tooth group for apical periodontitis due to simpler anatomy and lower caries susceptibility. This choice facilitates clearer interpretation of relative odds and highlights the increased disease burden in posterior teeth. A justification for this methodological decision has been added to the Discussion.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear respected Authors; Several fundamental issues are present in the manuscript that require substantial clarification and improvement. These concerns relate to the alignment between the title, aim, and conclusion. Addressing these points is essential to ensure the scientific validity and clarity of the work.

1. The study is described as cross-sectional, but since all CBCT scans were collected retrospectively in 2017–2021, it would be more accurate to call it a “retrospective cross-sectional study.” Additionally, the ethical approval and data collection were completed in 2021, yet the manuscript was submitted in 2026, and the newest references also date to 2021. The authors should clarify the reasons for this time gap and consider updating the literature to include more recent references to ensure the study’s relevance and methodological transparency.
2. While CBCT provides high-resolution 3D imaging and improves the detection of periapical lesions, it cannot provide 100% certainty for the diagnosis of apical periodontitis. Some radiolucencies may represent scar tissue or other non-inflammatory bone defects rather than true AP. The authors should acknowledge this limitation and clarify that the diagnosis in the study is based on radiographic findings rather than histological confirmation
3. The reported prevalence of apical periodontitis in root canal–treated teeth (68.5%) appear relatively high compared with most studies in the literature, which typically report 20–50% prevalence in RCT teeth using 2D radiographs and 50–60% using CBCT. The authors should discuss possible reasons for this elevated prevalence, including the higher sensitivity of CBCT in detecting small lesions, population-specific factors, variation in endodontic treatment quality, and the potential inclusion of residual healing or scar tissue. Providing a comparison with other CBCT-based studies would help contextualise these findings and strengthen the discussion.
4. The conclusion emphasises the diagnostic value of CBCT and its role in evaluating endodontic treatment outcomes. However, the study’s design only assessed the prevalence and distribution of apical periodontitis in a Saudi subpopulation; no comparison with other imaging modalities or reference standards was performed to evaluate CBCT accuracy. The authors should revise the conclusion to directly reflect the study title and objective, focusing on the prevalence and distribution findings, rather than implying diagnostic superiority or outcome assessment.

Author Response

Comments and Suggestions for Authors

Dear respected Authors; Several fundamental issues are present in the manuscript that require substantial clarification and improvement. These concerns relate to the alignment between the title, aim, and conclusion. Addressing these points is essential to ensure the scientific validity and clarity of the work.

1. The study is described as cross-sectional, but since all CBCT scans were collected retrospectively in 2017–2021, it would be more accurate to call it a “retrospective cross-sectional study.” Additionally, the ethical approval and data collection were completed in 2021, yet the manuscript was submitted in 2026, and the newest references also date to 2021. The authors should clarify the reasons for this time gap and consider updating the literature to include more recent references to ensure the study’s relevance and methodological transparency.

Response:
We thank the reviewer for this important clarification. The study design has been revised throughout the manuscript and is now consistently described as a retrospective cross-sectional study. We have clarified in the Materials and Methods that CBCT scans were retrospectively retrieved from 2017–2021 following ethical approval in 2021, with data anonymization and analysis completed thereafter. The time interval between data collection and submission reflects extended data analysis, advanced statistical modeling, manuscript refinement, and integration of additional CBCT-based analyses. To ensure scientific relevance, we have updated the Discussion to include recent CBCT-based literature, including studies addressing sex-related differences and diagnostic performance, thereby strengthening the contextual interpretation of our findings.

 

1. While CBCT provides high-resolution 3D imaging and improves the detection of periapical lesions, it cannot provide 100% certainty for the diagnosis of apical periodontitis. Some radiolucencies may represent scar tissue or other non-inflammatory bone defects rather than true AP. The authors should acknowledge this limitation and clarify that the diagnosis in the study is based on radiographic findings rather than histological confirmation

Response:
We thank the reviewer for this important comment. The limitation has now been explicitly acknowledged in the Discussion. We clarified that the diagnosis of apical periodontitis in the present study was based on radiographic criteria derived from CBCT imaging rather than histological confirmation, and that CBCT cannot reliably differentiate active inflammatory lesions from healing changes, scar tissue, or other non-inflammatory periapical bone alterations. This clarification has been incorporated into the limitations section to ensure accurate interpretation of the findings.

 

1. The reported prevalence of apical periodontitis in root canal-treated teeth (68.5%) appears relatively high compared with most studies in the literature, which typically report 20–50% prevalence in RCT teeth using 2D radiographs and 50–60% using CBCT. The authors should discuss possible reasons for this elevated prevalence, including the higher sensitivity of CBCT in detecting small lesions, population-specific factors, variation in endodontic treatment quality, and the potential inclusion of residual healing or scar tissue. Providing a comparison with other CBCT-based studies would help contextualise these findings and strengthen the discussion.

 

Response: The Discussion was expanded to explain that this higher prevalence is likely related to the superior sensitivity of CBCT in detecting small, residual, healing, or remodeling periapical lesions that may not represent active disease. We also discuss population-specific factors, potential variation in endodontic treatment quality, and the inability of CBCT to distinguish with certainty between active inflammation and scar or healing tissue. Recent CBCT-based studies were cited to support these explanations and to place our findings within the context of existing literature.

 

1. The conclusion emphasises the diagnostic value of CBCT and its role in evaluating endodontic treatment outcomes. However, the study’s design only assessed the prevalence and distribution of apical periodontitis in a Saudi subpopulation; no comparison with other imaging modalities or reference standards was performed to evaluate CBCT accuracy. The authors should revise the conclusion to directly reflect the study title and objective, focusing on the prevalence and distribution findings, rather than implying diagnostic superiority or outcome assessment.

Response:
We thank the reviewer for this insightful comment. The Conclusions section has been revised to strictly reflect the study design and objectives. All statements implying diagnostic accuracy, superiority of CBCT, or evaluation of endodontic treatment outcomes have been removed. The revised conclusion now focuses exclusively on the prevalence and distribution of apical periodontitis and its associated factors in the studied Saudi subpopulation, in full alignment with the cross-sectional epidemiological nature of the study and its stated aims.