Effect of Chitosan on the Number of Streptococcus mutans in Saliva: A Meta-Analysis and Systematic Review

Round 1

Reviewer 1 Report

Reviewer Comments to author:

Thank you for selecting me as a reviewer for the article entitled “Effect of chitosan on the number of Streptococcus mutans in saliva: a meta-analysis and systematic review” submitted to the International Journal of Molecular Sciences. This meta-analysis and systematic review was conducted to determine the effect of chitosan on salivary Streptococcus mutans counts. Articles chosen for the meta-analysis all included collection of saliva from participants after treatment with chitosan or placebo and S. mutans levels were assessed based on growth of colonies on Mitis-Salivarius agar supplemented with 0.2U/mL Bacitracin.

 

Major concerns:

The PICO question is underdeveloped and unclear as to what is actually being compared. The selection process was not clear as to why articles were excluded, especially since later in the paper, the authors mention that they were only including chitosan chewing gum articles and an included paper did not use that.

Of the three articles included in the quantitative synthesis and four in the qualitative synthesis, there were 2 that came from the same set of authors that sampled the same population at Nagasaki dental school. This brings up concerns related to the impact of this particular bias towards a single research group and population tested into the final interpretation of the study. Additionally, Ref 35, that was included in the quantitative study is not a comparable study to include as it is sampling from a rat vs human, and is not chewing gum based chitosan application in the study.

The risk of bias assessment should be included as a part of the results and the forest plot should  normalizes the weight of each paper based on the risk of bias assessment (use PRISMA 2009 checklist)

There were only two locations with minimal participants in both trials which impacts the meta-analysis and critical appraisal.

The authors did not discuss the methods for saliva collection and experimental design of each paper. I as the reader had to go try and find the referenced articles to determine what was done.

Original results of the included studies were not reported, only pooled data analysis. This is confusing and difficult to interpret on its own, especially since all methods of collection and treatment were not identical. This pooled analysis should be removed.

 

Minor Comments

Overall:

·         “Streptococcus mutans” must be italicized in various parts of the article

·         Are citations supposed to go before or after the periods of the sentences that come from the citations?

Title: “Streptococcus mutans” needs to be italicized

Abstract: Lines 15-16 “investigate the efficacy of chitosan and to test its inhibitory effect on Streptococcus mutans” –Efficacy of chitosan meaning what?

Introduction:

Line 46: “It belongs to the group of polysaccharides.” –not sure what is meant to be here, but this is already in the intro in sentences above

Line 57: I would consider rephrasing “cause” EPS rich mileu and put EPS in parentheses instead of exopolysaccharide

Lines 57-58: why mention the serotypes? They have no relevance to the paper and are not brought up again.

Lines-76: Sentences ending in “permeability” and “leakage” need citations.

Line 77: What is S. mutans activism?

Lines77-78: Need citations

Line 80: replace germs with a more specific term

Line 88: The aim of the meta-analysis to search about chewing gum is not included in the abstract, not in the key terms, yet it seems to be very important in terms of which articles will be included

 

Materials and Methods:

Lines 95-96: outcome: --worded in a way that is difficult to read “number of bacteria on S. mutans”?

There was no mention of the method of collection of saliva collection and confirmation of S. mutans on the selective media, as it is not completely inhibitory against other microbes.

Also, S. mutans in culture (in vitro) should also be included because it will not be too much different than from saliva. S. mutans within biofilms, in the context of plaque would be more important to clinical efficacy of chitosan as an antibacterial for prevention of dental disease.  

 

Results:

Usually all SR/MA papers have a table of the characteristics of each paper included: population, experimental design, results etc. This along with risk of bias assessment should be included before the forest plot

Figure 1: Quantitative synthesis should be 3 articles according to the text in the manuscript (line149)

--What about saliva collection methods of each study?

Figure 2: duplicated, tough to read with text size compared to manuscript text size, needs to include units of measurement

Lines 168-169: sentence about serotypes is seemingly just thrown in without any basis. The manuscript does not present any information about serotypes tested in any of the articles. While there are multiple serotypes, there is usually only one serotype found within the oral cavity of a person (Reference).

 

Discussion:

Line 203: Chitosan cannot have a “strategy”, it is a polysaccharide

Please review citations in the discussion as many are listing articles that have nothing to do with the sentence. For example

·         Lines 208-209: Reference 27 is listed but the sentence is about the current meta-analysis., similar in lines 210-212

·         Line 214-215: needs citation for lower cytotoxicity of chitosan.

There are many mentions of “our study” with references after them. These need extensive review.

3.5.1 and 3.5.2 are not related to the study findings and do not belong in the discussion

Figure 6. Why is this the best way to sample S. mutans after chewing gum? Would it be worthwhile to sample enamel plaque? Is the pre-gum sampling a good representation of what would be remaining after chewing gum? Why does the gum have xylitol in it, wouldn’t that impact the potential interpretation of chitosan effects?

 

 

English language was quality. Minor errors present. 

Author Response

Dear Reviewer,

Thank you for giving me the opportunity to submit a revised draft of our manuscript. We have been able to incorporate changes to reflect most of the suggestions provided by the reviewers. We have attached our “point-by-point response”. We would like to thank for your reflections and suggestions.

We hope the corrected text can meet all your requirements and expectation. All changes to the manuscript are indicated in the text by yellow highlighting.

Sincerely,

Virág Róna DMD

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear Authors,

I would like to congratulate you on a very interesting study. Although the antibacterial molecular mechanism of chitosan against Streptococcus mutans  has been widely explored and documented in the scientific literature, it is the first meta-analysis on the use of chitosan in the dental field. The Introduction is very interesting, and provides a good foundation for the research objective. An aim of the study was to demonstrate the potential use of chitosan for the reduction of S. mutans. The Methods of the study are properly selected. The findings  of this systematic review and meta-analysis are reported in accordance with the Cochrane Handbook and the PRISMA 2020 guidelines. The Results of the analysis are precisely described.  The Discussion is well conducted regarding the molecular structure of chitosan and its applications in dentistry. In Conclusion you correctly conclude the need for further research to  obtain more significant findings.

Author Response

Dear Reviewer,

Thank you very much for your kind and thorough review of our study.

Your feedback is greatly appreciated, and we're delighted to hear that you found our research interesting and well-structured.

We attached our revision letter.

Sincerely,

Virág Róna DMD

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Thank you for the poin-by-point rebuttle and commentary. With clarification and revisions that the authors provided, the article is suitable for publication with some minor edits remaining. 

Chewing gum was not included in the search terms for the studies, yet was the form of chitosan treatment the authors were analyzing. However, if all studies where chitosan was not incorporated into chewing gum were removed, then this is acceptable.

Figure 1- flow chart still seems incorrect – Qualitative (n=4), Quantitative (n=3)? (referring to lines 149-150, “After the selection process, a total of four articles were included in the qualitative 149 synthesis and three in the quantitative synthesis”)

Figure 6 needs a legend for the symbols used

New Figure 2 is a Table, and should be labeled that way

Once Streptococcus mutans is written out once, then the rest should be S. mutans. Still incidences of S. mutans that need to be italicized.

Author Response

Dear Reviewer,

Thank you for your thoughtful review and feedback on our article. We genuinely appreciate the time and effort you've invested in providing us your valuable insights. Your comments have been important in enhancing the quality of our work, and we are grateful for your input.

We attached below the point-by-point answer letter for your comments and made the minor changes in our manuscript.

In the exclusion phase every article was removed which did not investigate chitosan containing chewing gum.

We look forward to your continued support and guidance throughout the publication process.

Once again, thank you for your time and expertise in assisting us in refining our research. Your dedication to ensuring the quality of our work is greatly appreciated.

Sincerely,

Virág Róna, DMD

Author Response File: Author Response.pdf