Histological Evaluation of Multisonic Technology for Debridement of Vital and Necrotic Pulp Tissues from Human Molar Teeth. An Observational Study

Round 1

Reviewer 1 Report

Thank you for the opportunity to review the present manuscript. The work is interesting since it is referred to a new device and procedure for root canal system cleaning and disinfection. However, the authors have not included an additional experimental group where a conventional disinfection approach is carried out. That should be done to see whether any differences are observed between a conventional approach and the Gentle wave procedure. This is a major limitation for the study and should be mentioned in the Discussion section.

Thank you again 

Author Response

Thank you so much for your review. As you mentioned in your comments, the study referred to a new device and procedure for root canal system cleaning and disinfection. Our purpose designing the present study, was to learn and understand better the mode of action of the device. This is an observational study and we did not consider adding a comparative group, because of what is stated in the discussion, concerning the lack of evidence in the literature (discussion section lines 308-312) that any other  technique has not been able to proof  to be as effective in the debridement of the root canal system. Currently, we have an in-vivo study going on, extracting the tooth right after GW procedure. On this present project we have included an ultrasonic irrigation group so it can be compared.

This is a major limitation for the study and should be mentioned in the Discussion section: Discussion section lines 315-324. Plus the fact of the use of 350-400 ml when using GW compared to 10-20 ml when use positive pressure of ultrasonic irrigation. Standardization was impossible to accomplished.

Thank you so much for your comments 

Author Response File: Author Response.docx

Reviewer 2 Report

A group with conventional instrumentation and irrigation technique should have been added to have a direct comparison using this methodology.

Author Response

A group with conventional instrumentation and irrigation technique should have been added to have a direct comparison using this methodology.

Thank you so much for your kind review and comments. Being GW a new technology and a new way to perform an important aspect of the root canal therapy (pulp tissue debridement), we design the present project to learn and better understand its mechanism of action.  Literature lacks to provide any evidence that shows a better mechanism for the  debridement of the pulp tissue from the root canal system. Comparison with any other irrigation technique is difficult, specially in the standardization on the amount of the solution used. This project was designed as an "Observational Study" with the sole purpose of learning more from this technology. 

Thank you so much for your comments

Author Response File: Author Response.docx

Reviewer 3 Report

Dear authors, I would like to take the present moment to congratulate the authors for conducting the present study.

Here goes a few of my consideration:

ABSTRACT

The first two sentences apparently are not part of the Manuscript. May the authors double check?

“Featured Application: This study demonstrates that the multisonic technology is effective at pulp tissue debridement of main root canal, lateral canals and difficult to reach areas of the root canal system. This is important because the ability to reach the complex areas of the root canal system has not been demonstrated by any other technique or technology.

Authors are encouraged to provide a concise description of the specific appli-cation or a potential application of the work. This section is not mandatory.”

Please replace the following sentence “Four teeth served as histologic controls” for the following one “Four non-treated teeth served as histologic controls”.

Please correct the word “ef-fective”

INTRODUCTION

Please correct the words “Eth-ylenediaminetetraacetic”, “tradi-tional” and “periap-ical” and review the entire manuscript regarding this grammatical issues

METHODS

I do not understand the objective of the following procedure: “Digital periapical radiographs (Buccal and mesial views) were taken to evaluate the teeth for similarities in root length, number of root canals and root curvature, independent of the pulpal and periapical diagnosis.”

Did the authors intend to pair the samples? Or just to exclude heavy deviant specimens? What were the results of these evaluation and did they interfere in the following process?

DISCUSSION

One major flaw of this paper is the lack of a proper control group. And the paragraph “When these results were compared to a meta-analysis done by Moreira et al. [25], on the efficacy of ultrasonic irrigation, this study showed better results on removal of bacteria from the main canal, isthmuses and lateral canals, leaving bacteria only within dentinal tubules. Another histological evaluation on the efficacy of ultrasonic irrigation, Gutarts et al. [58] showed significantly better canal and isthmuses cleanliness values at the 2 mm level when ultrasonic was used for 1 minute after hand or rotary instrumentation to larger taper preparation. Our findings suggested better root canal debridement at any of the three root levels, even with a minimal instrumentation of 20/.04 and is independent of the shape of the root canal. Compared to Varela et al. [59], this study shows pulp tissue debridement with the use of minimal instrumentation. With the use of GentleWave, less instrumentation of the root canal system is needed and an apical enlargement to a 20/.04 is sufficient to achieve pulp tissue removal and disinfection in most of the canals. This finding is consistent with a previous study where non-instrumented premolars were evaluated with a scanning electron microscopy and demonstrated that predentin and tissue was removed [40]. Also, Molina et al. [28] histologically evaluated mandibular and maxillary molars that were instrumented to 15/.04 and they found the canals free of pulp tissue in 97.2% of mesial root and 96.52% in the distal root, which is similar to the results of the present study.” Is highly biased.

If the author wish to compare the procedures with a ultrasonic irrigation they could have done the introduction of that as a proper control group. The question is why the authors did not want to add that group? Since the procedures of this study are different from the Moreira study this comparison cannot be done. Please re-formulate this biased comment or remove it. Although the comparisons with other studies is highly advisable the authors cannot make comments as our technique is better or worse because you have not conducted a proper control group. So you must compare with this type of appreciations

Please debate the strength of the study.

Please debate the limitations of the study (at this level two issues must be exposed: 1) The non use of a proper control group with another method of root canal debridement is a study limitation, 2) the reasons of why not using a proper control group should be debated)

Future studies recommendations should include comparative studies with other debridement techniques such as sonic and ultrasonic agitation.

CONCLUSIONS

The authors are showing their fragilities regarding study designs when conducting the following comment in the conclusion: “In this study which used histological examination, the multisonic technology combined with minimal instrumentation, was effective for removal of vital and necrotic pulp tissue from the root canal system and inaccessible areas when compared to traditional treatments cited in the literature.”. This comparison is methodologically wrong. Please remove the “when compared to traditional treatments cited in the literature.”

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 4 Report

Dear authors

My questions are mainly about M & M.

1. The curvature of the roots can affect pulp tissue remnant
2. Considering the number of the teeth included, I think the authors included many factors (pathologic status, zone, location). 
3. Did the authors perform sample size calculation?
4. why did authors divide the tooth groups with Vital / Necrotic pulp tissue?

There are some grammatical errors: especially hypen mark. 

Are there any limitations in your study? I think there should be a small paragraph regarding the limitation for fairness.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Dear authors, I have no more concerns. Thank you.