-->PONE-D-25-54706-->-->Biaxial Strength under fatigue of 4YSZ: Surface Treatment and Resin Cement Viscosity effects-->-->PLOS One

Dear Dr. Tribst,

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Major revision is suggested by the reviewers for the manuscript.

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Additional Editor Comments:

Major revision is suggested by the reviewers for the manuscript.

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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

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

Reviewer #1: N/A

Reviewer #2: Yes

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-->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

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-->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

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-->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: 1. The novelty should be more precisely defined. The main contribution is the combined assessment of multiple surface treatments with two resin-cement viscosities on the fatigue biaxial strength of 4YSZ, rather than focusing solely on surface treatment or zirconia bonding in general.

2. The experimental design is interesting, but the use of only two monotonic specimens per condition to define the fatigue parameters is a clear limitation.

3. A stepwise fatigue test involving 10,000 cycles at 20 Hz is effective for initial screening; however, it does not accurately mimic long-term clinical fatigue as constant-amplitude, high-cycle fatigue protocols do.

4. The manuscript could improve by clearly explaining the reasons behind selecting 75 MPa as the initial fatigue stress and the use of 25 MPa increments. While these choices seem to be derived from the monotonic test, the rationale should be articulated more explicitly.

5. The method for determining cement layer thickness has certain limitations. Using a digital caliper to measure thickness indirectly—by subtracting pre- and post-cementation measurements—may not achieve the precision required for a nominal layer of approximately 50 µm, particularly when this variable is a key part of the interpretation.

6. The analysis of the interface that led to the conclusion of 'no viscosity effect' is too limited. The SEM assessment of cement penetration was only conducted for H-CTRL and L-CTRL, making it insufficient to assume that all treated groups exhibit the same interfacial behavior.

Reviewer #2: The manuscript presents an experimental investigation on the fatigue behavior of 4YSZ ceramics subjected to different surface treatments and resin cement viscosities. The topic is relevant to dental materials research, particularly for improving the mechanical reliability of zirconia-based restorations. The study is generally well-structured, and the experimental approach combining fatigue testing, surface characterization, and statistical analysis is appropriate. However, while the work provides useful insights, several methodological, analytical, and presentation-related issues limit its scientific rigor and broader impact.

Although, paper fits well to the submitted journal and, in general, it should be accepted for publication with following major revision suggestions:

1. The authors claim novelty in combining surface treatment with resin cement viscosity effects on 4YSZ. However, the incremental novelty is limited, as: Surface treatment effects on zirconia fatigue are already well established; The study confirms that viscosity has no significant effect, which aligns with existing literature.

2. The manuscript would benefit from clear positioning of its unique contribution, particularly: Why 4YSZ behaves differently from 3Y-TZP in this context; Whether the findings lead to clinically actionable recommendations.

3. The monotonic test sample size (n = 2) is insufficient for reliable estimation of fatigue parameters. This significantly weakens the reliability of the fatigue loading protocol derived from it. The fatigue test uses step-stress accelerated loading, but: No justification is provided for the chosen stress increments and cycle limits; The clinical relevance of 10,000 cycles per step is unclear.

4. The reported 100% statistical power appears unrealistic and likely results from: Overestimated effect size (f ≈ 1.5). Lack of clarity regarding: Whether assumptions for Two-way ANOVA are fully satisfied for fatigue data. Handling of censored data in survival analysis.

5. Weibull analysis is included but not sufficiently interpreted in terms of material reliability.

6. The discussion is largely descriptive and lacks deep mechanistic insight, particularly:

• No quantitative correlation between surface roughness (Ra/Rz) and fatigue strength.

• Limited discussion on crack initiation and propagation mechanisms in 4YSZ.

• The role of phase transformation (tetragonal → monoclinic) is mentioned but not experimentally supported.

7. Several grammatical and structural issues are present: Long sentences in the Introduction and Discussion reduce readability.

8. Some statements are repetitive (e.g., surface treatment dominance). Hypotheses should be more precisely defined.

9. Figures (SEM images) lack: Scale clarity in some cases. Quantitative annotations.

10. The manuscript relies heavily on prior zirconia studies but lacks: Discussion on recent advances in translucent zirconia systems. Comparison with alternative surface treatments (e.g., laser, plasma).

In conclusion, manuscript can be accepted after these suggested major revisions.

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Reviewer #1: No

Reviewer #2: Yes:Dr. Himanshu Pathak

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Biaxial Strength under fatigue of 4YSZ: Surface Treatment and Resin Cement Viscosity effects

PONE-D-25-54706R1

Dear Dr. Tribst,

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.

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Kind regards,

Gaurav Arora, Ph.D

Academic Editor

PLOS One

Additional Editor Comments (optional):

The reviewers have given acceptance to your manuscript.

Reviewers' comments:

Reviewer's Responses to Questions

-->Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.-->

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

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-->2. 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

**********

-->3. Has the statistical analysis been performed appropriately and rigorously? -->

Reviewer #1: N/A

Reviewer #2: Yes

**********

-->4. 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

**********

-->5. 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

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-->6. 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: The reviewers had addressed all the comments. There are further no comments and the manuscript can be accepted in its current form

Reviewer #2: Authors have revised the paper as per the suggested comments. Now, the paper may be accepted for the publication in this journal.

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-->7. 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:Dr. Himanshu Pathak

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