Evaluation of Cross-Sectional Root Canal Shape and Presentation of New Classification of Its Changes Using Cone-Beam Computed Tomography Scanning

Round 1

Reviewer 1 Report

The goal of this research was to assess the cross-sectional root canal shape and to present a new classification of its changes. The study is based on the analysis of cone beam computed tomography, which is a current methodology for this type of analysis. The objective of the study is relevant, because better knowledge of the true root canal shape before treatment will improve clinical practice.

However, the present manuscript presents numerous flaws that need to be addressed before publication. My main concern is the fact that authors focused their analysis on four categories for cross-sectional root canal shape (round, oval, long oval or ribbon) and other relevant categories have been previously described (conical-pyramidal; eight-shaped; C-shaped; calcified; trapezoidal; drop-shaped), which reduces the clinical information accuracy that can result from the analysis of data of the present study.

 

Some specific concerns/suggestions:

Keywords

Authors should change “root canal” to “Root canal anatomy” and include “cone beam computed tomography”.

 

Introduction

P1L30 – the sentence “Root canal system is the most important factor in endodontic treatment,...” is an overemphasis of the importance of anatomy and is misleading considering the current endodontic scientific evidence. In fact, success of endodontic treatment is more dependent on the etiology of the pulpal disease (Chugal, N. et al. Endodontic infection: Some biologic and treatment factors associated with outcome. OOO2003); microbial control (Sjogren, U. et al. Influence of infection at the time of root filling on the outcome of endodontic treatment of teeth with apical periodontitis. IEJ1997) and mastering the therapeutic techniques (Mente, J. et al. Treatment Outcome of Mineral Trioxide Aggregate in Open Apex Teeth. JOE2013). Knowledge of root canal morphology is important for clinicians to master therapeutic techniques and in this way will have a part in improving the clinical outcomes;

P1L40 –  “Kim & Peroca” must be corrected to Kim and Pécora;

The introduction needs to show the gap in knowledge that this research want to fill.

 

Material and Methods

P2L61 – Please add the references to the cited studies;

P2L73 – authors should provide distances to anatomical references to improve the localization of each cross-sectional area evaluated.

 

Results

The legend of Table 2 needs to be improved. In this reviewer opinion, this classification is just the translation of the 8 Vertucci’s types of root canal configurations (longitudinal) into cross-sectional views. Endodontic community already know that root canals can present no change in cross-sectional shape (Vertucci’s Type I, IV, VIII) or present changes in the middle and/or apical thirds (Vertucci Type II,III,V-VII);

P4L110 – Cross-sectional root canal shape for superior central incisors is described in this study as round, however, the majority of studies describe it as triangular, please explain this discrepancy;

P4L118 – We know, from previous studies, that mandibular incisors (central and lateral) have a significant prevalence of 2 root canals. Where are they reported in the present study?;

P5L136 – Cross-section of coronal mesiobuccal canals in upper molars have been previously described as “drop shaped”. However, this format is not presented in this study. Is the category included in the “oval shaped”  or other shape-group in the present report?;

P6L147 – Please define “ribbon another type”;

P6L150 – Table 3 is incongruent with previous published studies. We know that some of the 2 rooted maxillary pre-molars present 3 root canals. However, this table does not show this possibility. No maxillary pre-molars with 3 canals were found in this study?.

 

Discussion

In this reviewer opinion, from a clinical point of view, more important than knowing if the shape changes from coronal to apical direction, is to have a better idea of the most prevalent shape in each of these areas. Unfortunatelly, this is not addressed in the present study nor discussed.

The second paragraph is based on outdated concepts of root canal preparation. To address non-round cross-section root canals, manufacturers have developed off-centered design instruments, adjustable instruments and “scratching instruments” (TRUShape, XP-Endo, SAF…). This should be discussed and give a wider perpective of the challenges of root canal preparation, instead of focusing excessively on the clinical problems created by non-round section canals;

P8L192 – correct the author name to Pécora;

P9L216 – “…these results are in agreeable…” please correct. Moreover, this observation is expected, as we know that physiological deposition of tertiary dentin along the life of human beings will change the morphology of root canals, resulting in narrowing and rounding.

Author Response

We have revised the manuscript as requested

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript is innovative and well written. 

Please, explain better the population of this study and why people underwent to the CBCT exam. 

Please explain carefully what do you mean for coronal, middle and apical. I.e. 2 mm from the root canal end for apical part

Please, add some citation, I suggest the following manuscript: 

• Valenti-Obino F, Di Nardo D, Quero L, et al. Symmetry of root and root canal morphology of mandibular incisors: A cone-beam computed tomography study in vivo. J Clin Exp Dent. 2019;11(6):e527‐e533. Published 2019 Jun 1. doi:10.4317/jced.55629; for the CBCT evaluation of manibular incisors
• Di Nardo, D., Gambarini, G., Miccoli, G., Di Carlo, S., Iannarilli, G., Lauria, G., Seracchiani, M., Khrenova, T., Bossù, M., & Testarelli, L. (2020). Sonic vs Ultrasonic activation of sodium hypoclorite for root canal treatments. In vitro assessment of debris removal from main and lateral canals. Giornale Italiano Di Endodonzia, 34(1). https://doi.org/10.32067/GIE.2020.34.01.12; for the effect of sodium hypoclorite activation 

Please check english language with the help of a english native speaker

The references style should be done in accordance with the journal style, please modify. 

Author Response

We have revised the manuscript as requested

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The goal of this research was to assess the cross-sectional root canal shape and to present a new classification of its changes.

The manuscript has been changed superficially after this reviewer comments, and the main issues were not properly addressed. Some statements are misleading and not scientifically supported and, in this reviewer opinion, this research adds very limited information to the existent knowledge about root canal morphology.

 

Some specific issues that still remain in this manuscript, after the first review:

 

1. No modifications were performed in the abstract to adapt to the new manuscript content;
2. P1L41-42 and P1 43-44, the information in these 2 sentences is the same, however, authors used 2 references for the first one and 3 references for the second one. This is not a sound use of the bibliographic references;
3. P2L60-64, the statement in this paragraph is not correct, because one of the most used classifications, Vertucci’s, already analyzes the root canal shape in the 3 thirds to attribute its type;
4. Instead of using the designation of “one-rooted” change to “single-rooted”;
5. P9L174, it is not true that this is the first study to analyze the cross-sectional root canal shape and its changes during its course to apex among different age groups, this has been performed by  other authors, as Estrela et al (2015) Frequency of Root Canal Isthmi in Human Permanent Teeth Determined by Cone-beam Computed Tomography.JOE; Teixeira et al (2003). A preliminary in vitro study of the incidence and position of the root canal isthmus in maxillary and mandibular first molars. Int Endod J .

Reviewer 2 Report

The authors made all the changes according to the reviewer's requests.

So it can be accepted in present form.