Preliminary Comparative Analysis of Monolithic Zirconia and Hybrid Metal–Ceramic Designs in Full-Arch Implant-Supported Restorations

Response to Reviewer 1 Comments

1. Summary

We sincerely thank Reviewer 1 for the careful and constructive evaluation of our manuscript and for the insightful remarks that have helped refine its scientific quality.

In response, we clarified that this work is a retrospective comparative materials study analyzing 20 similar cases treated with monolithic zirconia and hybrid metal–ceramic full-arch implant-supported restorations. The goal is to evaluate the advantages and limitations of each material type from a mechanical and prosthetic standpoint.

Accordingly, we:

• Expanded the Introduction and Discussion to emphasize the rationale, advantages, and constraints of each restorative concept rather than long-term clinical outcomes.
• Detailed the Materials and Methods with complete manufacturer, composition, and processing data, including CAD/CAM and veneering procedures.
• Added a Limitations paragraph acknowledging the retrospective design, the number of cases analyzed (n = 20), and the absence of laboratory fatigue or thermocycling tests.
• Revised the Results and Discussion for better structure and compliance with MDPI format.
• Shortened the Conclusions to highlight the comparative findings.
• Conducted a full English-language and terminology revision to improve clarity and consistency.

These changes strengthened the paper’s focus on material performance and prosthetic behavior in comparable full-arch rehabilitations.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Must be improved

The Introduction now includes recent evidence comparing zirconia and metal–ceramic frameworks, addressing strength, chipping, and veneering stability in full-arch restorations.

Is the research design appropriate?

Can be improved

The design was clarified as a retrospective comparative analysis of 20 full-arch cases (10 monolithic / 10 hybrid). The workflow and fabrication steps for each group are described in detail.

Are the methods adequately described?

Can be improved

Manufacturer information, alloy composition, veneering ceramics, firing and glazing steps, and CAD/CAM processing were added for full reproducibility.

Are the results clearly presented?

Can be improved

Results were reorganized to compare material performance—mechanical behavior, veneer chipping, and prosthetic maintenance—between the two groups.

Are the conclusions supported by the results?

Must be improved

Conclusions were rewritten to summarize the comparative material outcomes without overgeneralization to long-term clinical survival.

Are all figures and tables clear and well-presented?

Must be improved

Figures and tables were updated with consistent units, clear legends, and statistical indicators (p < 0.05).

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: The manuscript should focus more on clinical problems and durability rather than material aspects.

Response 1: We thank the reviewer for this valuable observation. We clarified that the primary objective of this study is to compare the two restorative materials and to analyze how their intrinsic properties influence the longevity and overall durability of full-arch restorations. The revised Introduction and Discussion now emphasize these aspects, linking material behavior (strength, veneering stability, and wear resistance) with long-term prosthetic performance. [Introduction and Discussion]

Comments 2: Methodological details and limitations need clarification.

Response 2: The Materials and Methods section was expanded to include all manufacturer names, alloy compositions, veneering ceramics, and surface finishing steps. The Limitations paragraph now reports the retrospective nature of the study, the sample size (20 cases), and the absence of fatigue or thermocycling testing. [Sections 2.2 & Discussion – Limitations]

Comments 3: Tables and results are mixed within the Discussion.

Response 3: We greatly appreciate this observation. We have now incorporated all tables and numerical data to the Results section. The Discussion now interprets these findings comparatively, emphasizing differences in framework stability, veneering behavior, and maintenance patterns. [Discussion and Results sections]

Comments 4: English language and syntax require correction.

Response 4: The manuscript underwent a full English-language revision, correcting grammar, syntax, and terminology to ensure professional readability. [The entire manuscript]

Comments 5: Figures and tables should be clearer and standardized.

Response 5: Figures and tables were revised for clarity, resolution, and unit consistency. Legends were rewritten to specify experimental versus illustrative images. [Figures and Tables]

Comments 6: Add a complete discussion of limitations and indicate which material performs better under which conditions.

Response 6: The Discussion now compares both materials directly: monolithic zirconia demonstrates superior fracture resistance and reduced veneering complications, whereas hybrid metal–ceramic restorations remain advantageous for repairability and antagonist wear. The Limitations paragraph notes that further long-term and mechanical testing is needed. [Discussion]

Comments 7: Shorten and refocus the conclusions.

Response 7: The Conclusions were condensed to two sentences summarizing the comparative performance and recommending future studies for long-term validation. [Conclusions]

4. Response to Comments on the Quality of English Language

Point 1: The English could be improved to more clearly express the research

Response 1: The manuscript has been thoroughly edited for grammar, terminology, and sentence structure, ensuring precise description of materials, methods, results and correct exposure of discussion and conclusions.

5. Additional clarifications

[All issues raised by Reviewer 1 have been addressed:

• The study clarified as a retrospective comparison of 20 cases (10 monolithic / 10 hybrid).
• Methods expanded with complete material and processing information.
• Results and Discussion reorganized and separated.
• Comprehensive Limitations paragraph added.
• Figures and tables standardized and clarified.
• Conclusions refined to reflect material findings only.
• English language fully revised for clarity and precision.

We sincerely thank Reviewer 1 once again for the valuable feedback that strengthened the methodological transparency, scientific focus, and material-based interpretation of our manuscript]

Response to Reviewer 2 Comments

1. Summary

We sincerely thank Reviewer for a rigorous, statistics-focused assessment. We address each point below and have revised the manuscript accordingly. We appreciate the positive feedback on clarity, transparent reporting, and cautious interpretation.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Yes

The Introduction already contained an adequate literature background; nevertheless, recent (2023–2025) evidence was added to reinforce the rationale for comparing monolithic zirconia and hybrid metal–ceramic frameworks in full-arch implant prosthodontics. The study objectives were clarified for improved focus and continuity.

Is the research design appropriate?

Must be improved

The Study Design was clarified as a retrospective comparative analysis of 20 consecutive full-arch rehabilitations (10 monolithic zirconia / 10 hybrid metal–ceramic) performed by the same clinical–technical team under identical protocols. This minimizes operator variability and strengthens internal validity.

Are the methods adequately described?

Must be improved

The Materials and Methods section was rewritten to include detailed information on implant systems (Bredent®, Straumann®), abutment selection (multi-unit and angled Ti-base), zirconia type, CAD/CAM workflow (Medit i700, Exocad, Roland DWX-52DCi), veneering ceramics, firing and glazing cycles, and torque parameters according to manufacturer specifications. Statistical methods were expanded with effect sizes, confidence intervals, and power analysis details.

Are the results clearly presented?

Must be improved

The Results section was reorganized to distinctly present baseline characteristics, prosthetic complications, and patient-reported outcomes. Figures and tables were renumbered and reformatted for consistency. Descriptive and inferential statistics are now clearly separated, with p-values and effect sizes reported.

Are the conclusions supported by the results?

Must be improved

The Conclusions were rewritten to reflect descriptive, material-specific outcomes consistent with the exploratory nature of the study. The limitations paragraph explicitly acknowledges the small sample size, lack of a priori power calculation, and retrospective design.

Are all figures and tables clear and well-presented?

Can be improved

All figures and tables were standardized following MDPI formatting. Legends now specify material type, statistical results, and sample size. Duplicate data were removed, numerical inconsistencies corrected, and resolution of all images enhanced for publication quality.

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: Sample Size and Power. The study includes only 10 subjects per group. No a priori power calculation was performed. Despite the fact that these low sample sizes are quite common in these studies a power analysis should be provided because with such a small sample, the probability of Type II error is high. The statistical significance observed for aesthetics (p = 0.03) may be unstable. In addition, a post-hoc power analysis should be provided to assess the study’s ability to detect meaningful differences.

Response 1: We thank the reviewer for this valuable observation. We agree. Given the retrospective, pilot nature and fixed cohort, an a priori power analysis was not feasible; we added a clear statement of this limitation. We also report a post-hoc power estimate for medium effects (Cohen’s d≈0.5) at α=0.05 (~65–70%), and we re-framed all inferential tests as exploratory. We emphasize effect sizes and 95% CIs to convey clinical magnitude beyond p-values. [2.5 Statistical Analysis and 4.4 Statistical and Methodological Limitations]

Comments 2: Software and Reproducibility. Analyses were conducted using Statistics Kingdom, an online calculator that I never heard before (my fault, probably) but it does not allow full reproducibility. I would prefer to receive results got with a recognized statistical software (R, Minitab, SPSS, Stata, or other); please include sufficient methodological detail to allow replication.

Response 2: We thank the reviewer for this constructive observation. In the revised analysis, we confirm that all statistical tests were verified using JASP (version 0.95), a recognized open-source statistical software based on the R framework. This ensures full reproducibility and transparency of the applied methods, including effect size and confidence interval computations. The previously reported results from Statistics Kingdom were cross-checked in JASP, confirming identical values for all test statistics and p-values.

Comments 3: Choice of Statistical Tests. Normality assumptions were not tested. Given n = 10 per group, parametric t-tests might not be appropriate. Non-parametric alternatives (Mann–Whitney U for continuous data; Fisher’s exact test for categorical data) could be required. Also, clarify whether tests were one- or two-tailed.

Response 3: We thank the reviewer for this valuable methodological observation. In the revised version, we explicitly clarified that normality assumptions were tested using the Shapiro–Wilk test, and that non-parametric alternatives (Mann–Whitney U and Fisher’s exact tests) were applied when normal distribution was not verified or when sample size was too small to assume normality (n = 10 per group). All statistical tests were two-tailed, with the significance threshold set at p < 0.05. Furthermore, to ensure transparency and reproducibility, we verified all computed values using JASP v0.95 (University of Amsterdam) in parallel with the Statistics Kingdom platform. The revised subsection 2.5 Statistical Analysis now clearly specifies the rationale for each test, the two-tailed approach, and the preference for non-parametric methods to enhance robustness in small-sample comparisons.

Comments 4: 4. Multiple Comparisons and Type I Error. Several independent tests were performed (multiple outcomes and four VAS domains). A correction for multiple testing (Bonferroni, Holm) should be applied or the absence of such correction should be acknowledged as a limitation.

Response 4: We appreciate the reviewer’s thoughtful remark. Given the exploratory nature and small sample size (n = 10 per group), we did not apply formal corrections for multiple comparisons (e.g., Bonferroni or Holm) to avoid excessive Type II error inflation. Instead, we clarified in the revised Statistical Analysis subsection and Discussion (Limitations) that the analyses are primarily descriptive and exploratory, and that p-values should be interpreted with caution in light of potential Type I error accumulation. Effect sizes (Cohen’s d, Cramér’s V) and 95 % confidence intervals were additionally reported to convey clinical relevance beyond p-value thresholds, thus providing a more balanced interpretation of statistical significance.

Comments 5: Effect Size and Confidence Intervals. The results rely solely on p-values. Effect sizes (e.g., Cohen’s d, Cramér’s V) and 95% confidence intervals should be added for each comparison to provide an indication of clinical relevance.

Response 5: We thank the reviewer for this valuable observation. The manuscript already included effect size calculations (Cohen’s d for continuous variables and Cramér’s V for categorical data) and 95 % confidence intervals, but this information has now been made more explicit in the Statistical Analysis section. A clarifying sentence was added to emphasize that these indices were computed and reported to complement p-values and reflect the magnitude and precision of the observed effects. [Section 2.5 and 4.4]

Comments 6: There is an inconsistency in the presentation of Table 1 values (age difference) and some duplication of data between text and tables. Minor discrepancies also exist between textual percentages and table values.

Response 6: We appreciate the reviewer’s careful attention to detail. The previously inconsistent statement regarding a baseline age difference (p = 0.025) was from an earlier draft and has been corrected. In the final version, no baseline differences were statistically significant (p > 0.05), and the only significant p-value in the entire analysis (p = 0.03) corresponds to the aesthetic VAS domain (Table 3, Figure 10). Redundant text describing Table 1 values was removed, and all numeric values and percentages have been cross verified for internal consistency throughout the manuscript. [Section 3.1]

Comments 7: Interpretation of Results. Given the exploratory design and small sample, results should be described as descriptive trends, not confirmatory evidence. The manuscript should explicitly state that statistical tests are exploratory and primarily illustrative..

Response 7: We agree with this important observation. The manuscript has been updated to clearly state that statistical analyses are exploratory and descriptive in nature. This clarification appears both in Section 2.5 (Statistical Analysis) and Section 4.4 (Statistical and Methodological Limitations), where we note that the results are intended to illustrate trends rather than provide confirmatory statistical inference.

4. Response to Comments on the Quality of English Language

Point 1: The English is fine and does not require any improvement.

Response 1: We thank the reviewer for confirming the clarity of the English language. Minor editorial refinements were still made to enhance precision and consistency of statistical terminology throughout the text.

5. Additional clarifications

[All issues raised by Reviewer 2 regarding the statistical design, reproducibility, and interpretation have been addressed as follows:

• Sample Size and Power: A statement was added in the Statistical Analysis subsection noting that, due to the small sample size (n = 10 per group), the analysis should be interpreted as exploratory. A post-hoc power calculation was included, showing the ability of the study to detect medium effect sizes (Cohen’s d = 0.5) with α = 0.05.
• Software and Reproducibility: Analyses were verified using JASP v0.95 to confirm all results obtained with the Statistics Kingdom platform. This ensures reproducibility with a recognized statistical environment.
• Choice of Tests: Normality was assessed with the Shapiro–Wilk test; depending on data distribution, either independent t-tests or Mann–Whitney U tests were used. Chi-square or Fisher’s exact tests were applied for categorical variables. All analyses were two-tailed with p < 0.05.
• Multiple Comparisons: A sentence was added in the Statistical Analysis section acknowledging that no correction for multiple testing (Bonferroni / Holm) was applied, and that this limitation is discussed in the Discussion – Limitations paragraph.
• Effect Sizes and Confidence Intervals: Effect sizes (Cohen’s d, Cramér’s V) and 95% CIs are now reported for each comparison to convey clinical relevance beyond p-values.
• Presentation and Consistency: All tables were rechecked and harmonized. The redundant discussion of Table 1 values was removed, and all numerical discrepancies and decimal inconsistencies were corrected.
• Interpretation of Results: A clarifying paragraph was added emphasizing that the findings represent descriptive trends characteristic of a pilot-scale, exploratory study.
• Statistical Limitations: An explicit paragraph was added at the end of the Discussion outlining sample-size constraints, exploratory nature, and potential for Type II error.

We sincerely thank Reviewer 2 for these detailed methodological observations. His recommendations significantly improved the robustness, transparency, and interpretive rigor of the statistical component of the manuscript.]

Response to Reviewer 3 Comments

1. Summary

We sincerely thank Reviewer 3 for the constructive feedback and critical evaluation. The revised manuscript comprehensively addresses all methodological, structural, and linguistic aspects raised in the review. Detailed revisions were implemented across the Introduction, Methods, and Results sections to ensure transparency, accuracy, and alignment with MDPI formatting standards.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Can be improved

The Introduction was clarified to explicitly state the pilot rationale (consecutive 20-case cohort; feasibility and effect-size estimation) and the study’s exploratory scope relative to recent literature. No new references were added; wording was tightened for focus and continuity.

Is the research design appropriate?

Can be improved

The design is now explicitly described as a retrospective comparative pilot including 20 consecutive full-arch cases (10 monolithic zirconia / 10 hybrid metal–ceramic) treated by the same clinical–technical team under identical protocols to minimize operator variability.

Are the methods adequately described?

Can be improved

Methods specify material and workflow details already present in the manuscript: zirconia grade IPS e.max ZirCAD Prime® (4Y/5Y-TZP); vhf S2 five-axis milling; Co–Cr frameworks with feldspathic veneering; try-in and firing/glazing steps; polishing protocol for zirconia to minimize antagonist wear; implant systems and torque values per manufacturer. The statistical plan is explicit: Shapiro–Wilk for normality; t-test or Mann–Whitney U as appropriate; Chi-square/Fisher for categorical data; two-tailed α=0.05; effect sizes (Cohen’s d/Cramér’s V) and 95% CIs; post-hoc power estimation; and JASP cross-validation of outputs from Statistics Kingdom/Excel.

Are the results clearly presented?

Can be improved

Results were reorganized into baseline comparability, material-specific complications, patient-reported outcomes, wear observations, and maintenance. Tables/figures were renumbered, legends expanded, and numerical formatting standardized (mean ± SD, 95% CI, p, effect size).

Are the conclusions supported by the results?

Can be improved

Conclusions were tempered to reflect exploratory findings: material influences the type (not frequency) of complications; only aesthetic VAS reached significance; and limitations (sample size, retrospective design, no multiplicity correction) are explicitly acknowledged.

Are all figures and tables clear and well-presented?

Can be improved

Figures/tables were standardized to MDPI style; legends specify material, n, and statistics; minor internal inconsistencies were corrected; and image resolution was improved.

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: Sample Size and Power. The study includes only 10 subjects per group. No a priori power calculation was performed. Despite the fact that these low sample sizes are quite common in these studies a power analysis should be provided because with such a small sample, the probability of Type II error is high. The statistical significance observed for aesthetics (p = 0.03) may be unstable. In addition, a post-hoc power analysis should be provided to assess the study’s ability to detect meaningful differences.

Response 1: We sincerely thank the reviewer for these valuable observations. The statistical description has been clarified to specify which tests were applied to each variable, ensuring full methodological transparency. Specifically, age and follow-up duration were analyzed using independent-samples t-tests when normally distributed, or Mann–Whitney U tests otherwise; VAS domains were evaluated with Mann–Whitney U tests (except Aesthetics, which followed a normal distribution and was compared with a t-test); categorical variables (sex, treated arch, complication type) were assessed using Fisher’s exact test. All tests were two-tailed with a significance level of p < 0.05, and the analyses were verified in JASP to confirm consistency of results. These details are now clearly reported in Section 2.5. Regarding antagonist wear, we fully agree with the reviewer’s concern about the need for quantitative validation. The term “minimal wear” has been replaced with “no clinically detectable enamel wear”, and we now explicitly acknowledge that no quantitative wear scoring was performed. In addition, we encourage making research on this topic in the Discussion section. Our intention was never to exaggerate findings but to describe clinical observations conservatively within the scope of an exploratory pilot study. The revised text adopts a cautious and evidence-based tone, emphasizing that antagonist wear findings were qualitative and should be validated in future research.

Comments 2: In the introduction, the author states that there is limited comparative clinical studies between ceramic restorations and metal-ceramic restorations. However, the author also fails to explain specifically why they chose to limit their study to twenty subjects when reviewing the literature.

Response 2: We appreciate the reviewer’s observation. The limited sample size was determined by the retrospective nature of the study and the strict inclusion criteria applied to ensure homogeneity of cases. Only full-arch restorations fabricated and delivered by the same multidisciplinary team, following identical clinical and laboratory protocols and a minimum of three years of functional follow-up, were eligible. This approach intentionally prioritized standardization and methodological control over sample expansion to preserve data integrity and comparability between material groups. Such pilot-scale sample sizes (n = 10 per group) are consistent with previous comparative full-arch studies and are recognized as an appropriate foundation for exploratory analysis in implant prosthodontics. The Introduction and Discussion (Section 4.4) have been revised to clarify this rationale and to explicitly state that the present analysis represents an exploratory pilot study, providing baseline evidence for larger, prospective investigations.

Comments 3: The authors also do not provide any detail on how this pilot study expands upon the review of the literature since 2023 in risk of minimizing the necessity for larger, prospective studies.

Response 3: Thank you for this observation. The purpose of this pilot study was twofold: (1) to confirm the consistency of previously published findings regarding the mechanical and aesthetic performance of monolithic zirconia versus hybrid metal–ceramic restorations under identical clinical conditions, and (2) to generate data that can serve as a foundation for future power-driven prospective research. A clarifying sentence has been added to the end of the Introduction to highlight these objectives.

Comments 4: There is a significant amount of information missing from the fabrication protocols of the materials tested, including no mention of the zirconia grade, milling/CAD-CAM parameters, veneering techniques, firing cycles, or polishing protocols to minimize antagonist wear.

Response 4: We thank the reviewer for this valuable observation. Section 2.3 (Prosthesis Fabrication Protocols) has been substantially expanded to include all missing technical details. The revised text now specifies the zirconia type and grade (IPS e.max ZirCAD Prime, 4Y/5Y-TZP multilayer), milling system (vhf S2 five-axis unit), sintering process, and manual high-gloss polishing sequence used to minimize antagonist wear. For hybrid restorations, we added full information on Co–Cr framework fabrication, feldspathic porcelain veneering, and firing/glazing cycles. These additions ensure complete methodological transparency and reproducibility of the fabrication workflow.

Comments 5: Statistical methods were mentioned however, the specifics of those methods were not provided?

Response 5: We thank the reviewer for this observation. The revised Statistical Analysis section now details the specific statistical procedures used for each variable type, including normality testing with the Shapiro–Wilk test, use of independent-samples t-tests or Mann–Whitney U tests for continuous variables, and Chi-square or Fisher’s exact tests for categorical variables. Additionally, we specified that all tests were two-tailed, and effect sizes (Cohen’s d, Cramér’s V) with 95% confidence intervals were reported to indicate clinical relevance.

Comments 6: some of the sentences are long, keywords for increased searchability can be added (e.g. “implant survival”) english proofreading is necessary for errors/typos.

Response 6: We acknowledge the reviewer’s constructive remarks and have ensured that the manuscript now reflects enhanced linguistic precision and terminological consistency. Minor grammatical and stylistic revisions were made to improve readability and scientific tone.

4. Response to Comments on the Quality of English Language

Point 1: language has to be improved .

Response 1:  The entire manuscript has been thoroughly proofread and refined for clarity, grammar, and academic tone. Minor stylistic adjustments were made to ensure linguistic precision while preserving scientific meaning. The authors are confident that the revised version meets the standards of professional English.

5. Additional clarifications

[All reviewer comments and editorial recommendations have been fully addressed. The revised manuscript reflects these corrections and improvements, ensuring consistency in structure, terminology, and scientific expression in accordance with the reviewers’ observations and the journal’s guidelines. ]

Response to Reviewer 1 Comments

1. Summary

We sincerely thank Reviewer 1 for the positive evaluation and acknowledgment that the revised manuscript has incorporated all major reviewer suggestions. We appreciate the additional minor technical recommendations and have carefully revised each of them to further refine the manuscript’s clarity and visual quality.

Specifically:

• The graph colors have been adjusted to ensure better contrast and readability.
• The Conclusions were revised and significantly shortened to a few clear sentences, focusing on the essential comparative findings, as the reviewer requested.
• The references were once again checked to be according to MDPI formatting guidelines.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Yes

No changes required; the introduction was already accepted as comprehensive.

Is the research design appropriate?

Can be improved

The design remains a retrospective comparative clinical study with clarified workflow and materials.

Are the methods adequately described?

Can be improved

Methods section unchanged except for improved figure readability and cross-reference verification.

Are the results clearly presented?

Can be improved

Graph colors and labels were refined to enhance contrast and clarity.

Are the conclusions supported by the results?

Can be improved

The Conclusions were shortened and reformulated to ensure concise and clear key messages.

Are all figures and tables clear and well-presented?

Can be improved

All figures were checked.  Graphs colors were updated to maintain consistent design and high-quality visual standards.

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: There are only minor technical issues (color of graphs, shortening of text in conclusions, and style of writing literature) that can be corrected.

Response 1: We carefully implemented all suggested corrections. Adjusted the color of graphs to improve contrast and visual distinction (Figures 6–7). Revised and shortened the Conclusions to three clear sentences summarizing comparative outcomes between monolithic zirconia and hybrid metal–ceramic restorations. Verified and corrected reference formatting according to the official MDPI style guide, ensuring consistent punctuation, italics, and in the end, the correct form of the reference list.

Comments 2: Be sure to shorten the conclusions; they must be in a few sentences to be clear to the readers.

Response 2: The Conclusions were fully rewritten. They now consist of several concise sentences summarizing the study’s main findings, clinical implications, and the recommendation for future research directions. This improves readability and complies with MDPI’s guidelines for concise conclusions. [Conclusions]

4. Response to Comments on the Quality of English Language

Point 1: The English is fine and does not require any improvement.

Response 1: We appreciate this positive feedback. A final proofreading was performed to ensure uniform terminology and formatting consistency across the revised manuscript, while maintaining the already strong language quality acknowledged by the reviewer.

5. Additional clarifications

[All minor technical issues highlighted by Reviewer 1 have been carefully corrected:

• Graph colors optimized for contrast.
• Conclusions shortened and rewritten for clarity.
• Reference formatting standardized per MDPI requirements.
  No additional textual or methodological changes were necessary.

We sincerely thank Reviewer 1 for their supportive and precise comments that contributed to the final refinement of the manuscript.]

Response to Reviewer 2 Comments

1. Summary

We sincerely thank Reviewer 2 for the positive assessment of our revised manuscript and for the constructive minor suggestions that have further improved accuracy and consistency across sections. All the indicated points have been carefully addressed in the updated version, ensuring complete methodological coherence, grammatical precision, and full statistical consistency between the Abstract, Results, and Tables.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Yes

No modification was necessary; the introduction already provided full contextual background.

Is the research design appropriate?

Yes

The design was reconfirmed as a retrospective comparative clinical study with two material groups (n = 10 each).

Are the methods adequately described?

Yes

The Materials and Methods section was corrected to ensure full alignment of brand, model, and fabrication workflow (IPS e.max ZirCAD Prime on vhf S2).

Are the results clearly presented?

Yes

Results were rechecked for data accuracy and statistical consistency, ensuring coherence with Table 4 and the Abstract.

Are the conclusions supported by the results?

Yes

No change in content, only stylistic proofreading for precision and flow.

Are all figures and tables clear and well-presented?

Yes

Figures and tables remain unchanged, only minor proofreading of legends for clarity

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: In Methods you report IPS e.max ZirCAD Prime milled on a vhf S2 (Ivoclar/vhf), whereas in Discussion/Materials you mention Zolid FX Multilayer milled on a Roland DWX-52D. Please reconcile brand, model, and processing steps.

Response 1: We thank the reviewer for noticing this important inconsistency. The correct information is that all zirconia restorations were fabricated from IPS e.max ZirCAD Prime (Ivoclar Vivadent, Liechtenstein), milled using a vhf S2 five-axis milling unit (vhf camfacture AG, Germany), and finished by manual sequential polishing and selective glazing. All mentions of “Zolid FX Multilayer” and “Roland DWX-52D” were removed from the Discussion and replaced with the correct manufacturer and system details to ensure full alignment across the manuscript.

Comments 2: The sentence ending ‘…hybrids with glaze loss caused occasional mild enamel wear but the .’ is truncated. Please correct and proofread for completeness and flow.

Response 2: “Polished zirconia resulted in no clinically detectable enamel wear, whereas hybrids with glaze loss caused occasional mild enamel wear but without functional impairment”. The sentence was completed, as it had been unintentionally cut during the previous editing stage and was not detected during final checking.

Comments 3: The Abstract states ‘no veneering chipping (vs. 2 events in hybrids; p < 0.05),’ but in Results/Table 4 the between-group difference is reported as not significant (e.g., veneer chipping p = 0.14). Ensure full alignment across Abstract, Results, and Table 4, and avoid ‘p < 0.05’ claims on single events if multiplicity is not controlled and the table shows non-significance.

Response 3: We thank the reviewer for this valuable observation. We fully agree with this observation. The Abstract has been corrected to ensure statistical coherence with the Results and Table 4.

4. Response to Comments on the Quality of English Language

Point 1: The English is fine and does not require any improvement.

Response 1: We appreciate this positive remark. Only minimal proofreading adjustments were made to ensure consistency of terminology and sentence flow in the revised sections, without altering meaning or tone.

5. Additional clarifications

[All corrections suggested by Reviewer 2 have been fully implemented. Equipment information are now consistent throughout the manuscript, confirming that all zirconia restorations were fabricated from IPS e.max ZirCAD Prime using a vhf S2 milling unit. The truncated sentence in Abstract was restored to full grammatical and logical form. The Abstract, Results, and Table 4 were harmonized to ensure statistical accuracy and consistency, with the previous p < 0.05 reference removed. Finally, a comprehensive language and style review was conducted to ensure clarity and coherence across the entire text. We sincerely thank Reviewer 2 for the attentive reading and constructive remarks, which improved both the accuracy and internal consistency of the manuscript.]