PONE-D-21-35327Species-specific enamel differences in hardness and abrasion resistance between the permanent incisors of cattle (Bos primigenius taurus) and the ever-growing incisors of nutria (Myocastor coypus)PLOS ONE

Dear Dr. Clauss,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Both reviewers point out that many specificities of enamel thickness and occlusion differences between the studied species that should be presented and discussed in more details.

Please submit your revised manuscript by Feb 04 2022 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Cyril Charles

Academic Editor

PLOS ONE

Journal Requirements:

When submitting your revision, we need you to address these additional requirements.

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at 

https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and 

https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

2. Thank you for stating the following in the Acknowledgments Section of your manuscript: 

We thnk Andrea Gubler of the Division of Preventive Dentistry and Oral Epidemiology, Centre of Dental Medicine, University of Zurich, for the support of the lab work. DEW was supported by a European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (ERC CoG grant agreement no. 681450 to Thomas Tütken) and a Postdoctoral fellowship from the Japan Society for the Promotion of Science (KAKENHI Grant No. 20F20325).

We note that you have provided funding information that is not currently declared in your Funding Statement. However, funding information should not appear in the Acknowledgments section or other areas of your manuscript. We will only publish funding information present in the Funding Statement section of the online submission form. 

Please remove any funding-related text from the manuscript and let us know how you would like to update your Funding Statement. Currently, your Funding Statement reads as follows: 

The author(s) received no specific funding for this work.

Please include your amended statements within your cover letter; we will change the online submission form on your behalf.

3. Please include captions for your Supporting Information files at the end of your manuscript, and update any in-text citations to match accordingly. Please see our Supporting Information guidelines for more information: http://journals.plos.org/plosone/s/supporting-information. 

4. Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: This very interesting paper deals with the influence of enamel hardness on dental wear comparing two mammal species, cattle and nutria, presenting different dental characteristics. This study focusing on incisors provides counter-intuitive but intriguing results showing that dental wear tends to be more species-dependent than hardness-dependent and that other factors must be taken into account, which is discussed accordingly. As a result, this work raises a lot of questions on the differences observed between the two species, and some of them could probably be answered by studying closer taxa having more similar incisor properties (except hardness, and then crown height). My main (but sole) concern is thus the choice of species and of the tooth locus, which should be more accurately explained in relation to the main question of the study based on brachyodont vs hypselodont taxa. I understand that the availability of large samples of cattle and nutria from slaughterhouses could be one of the main criteria for having chosen these two species. However, they present too many different incisor characteristics (some of them are mentioned in the paper) in addition to crown height (e.g. only lower incisors in cattle, only one pair of incisors with only labial enamel in nutria, different enamel thicknesses and microstructures, high iron oxide enrichment in the enamel of nutria, different bite forces and jaw motions) which likely have an impact on wear and render these results more difficult to compare from a biomechanical viewpoint. For these reasons, study of molars (presenting less differences) or comparisons of cattle and nutria with other bovids (or cervids), rodents or with equids (having hypsodont incisors) could have been more appropriate to reduce the potential effect of other factors on wear compared to hardness or crown height. I have also a few minor comments on the manuscript, which deserves to be published pending these modifications.

- L. 71-81: you should precise the tooth loci investigated in the previous publications

- L. 177, 180, 186: write “Shapiro-Wilk”

- L. 313: write “We thank…”

Helder GOMES RODRIGUES

Reviewer #2: This is a well-executed, concise experimental study on enamel abrasion in the evergrowing incisors of Myocastor and the non-evergrowing lower incisors of Bos taurus. The authors have performed enamel hardness measurement by indentation and a brushing experiment with three different abrasive agents plus a control group.

The methodology is well described, the results are clearly outlined and the discussion is supported by the results.

When discussing the different wear rates in the incisors of Myocastor and Bos, the authors might consider the difference in enamel thickness. Rodent incisors generally have a comparatively thin labial enamel cover which together with the underlying softer dentine provides a sharp cutting edge. Enamel microstructure of rodent incisor enamel is among the most complex, if not the most complex, schmelzmuster within mammals, and it is assumed that this is closely related to the high stresses that occur in the enamel during the gnawing process (in order to prevent the enamel from failure). So the thinness of the rodent enamel may play an important role in the higher abrasive rate. Another factor is found in the antagonistic incisor – during the gnawing process, the incisor occlusal surfaces get in contact and therefore experience increased abrasion (self-sharpening mechanism). In the cattle, there are no upper incisors and therefore no tooth-tooth contact. Perhaps the authors can add a couple of sentences to the discussion considering these aspects.

If I got it right, the enamel samples from the nutria incisors were taken from the labial side, and were brushed from that side in the experiment. However, in the living animal enamel abrasion occurs on the occlusal surface of the incisors, which is at an angle to the labial side of the enamel cover. As the authors state in the introduction, enamel hardness is also thought to be dependent of the orientation of the enamel crystallites (e.g. radial enamel of the outer portion in rodent incisors is assumed to be particularly resistant against wear due to the steep inclination of the enamel prisms [wear occurs at a right angle to the c-axes]). When discussing the differences of the experimental enamel abrasion rate, this aspect would be worthwhile to be mentioned.

Line 93: …(Myocastor coypus), with hypselodont (evergrowing) teeth. Replace “teeth” with “incisors”, bescause the cheek teeth of Myocastor are not evergrowing.

**********

6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: Yes: Thomas Martin

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Species-specific enamel differences in hardness and abrasion resistance between the permanent incisors of cattle (Bos primigenius taurus) and the ever-growing incisors of nutria (Myocastor coypus)

PONE-D-21-35327R1

Dear Dr. Clauss,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Cyril Charles

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments: