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Fit Accuracy and Shear Peel Bond Strength of CAD/CAM-Fabricated Versus Conventional Stainless Steel Space Maintainers: In Vitro Comparative Study

Prosthesis 2025, 7(6), 159; https://doi.org/10.3390/prosthesis7060159

by Marzia Kareem Ahmed^*

and Aras Maruf Rauf

Reviewer 1: Anonymous

Reviewer 2: Anonymous

Reviewer 3:

Aditi Gupta

Reviewer 4:

Andreea Kui

Prosthesis 2025, 7(6), 159; https://doi.org/10.3390/prosthesis7060159

Submission received: 5 November 2025 / Revised: 30 November 2025 / Accepted: 1 December 2025 / Published: 3 December 2025

(This article belongs to the Section Prosthodontics)

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This investigation introduces an innovative assessment of three materials employed in the construction of space maintainers for primary dentition. Its objective was to analyze and compare the fit accuracy and the shear–peel bond strength of bands from digitally manufactured space maintainers—Cobalt-Chromium (Co-Cr) and Polyetheretherketone (PEEK)—in relation to stainless-steel bands from conventional designs

Comment 1: Line 37: add reference:

BAUME LJ. Physiological tooth migration and its significance for the development of occlusion; the biogenesis of accessional dentition. J Dent Res. 1950 Jun;29(3):331-7. doi: 10.1177/00220345500290031301. PMID: 15428568.

Comment 2: In the introduction, it is important to explicitly address and clarify the differences in adhesion between primary and permanent teeth. This distinction must be emphasized, as the biological and structural characteristics of primary dentition—such as enamel composition, dentin thickness, and the presence of a more permeable substrate—may significantly influence the bonding performance of restorative and orthodontic materials. The results reported in the present investigation were obtained from permanent third molars, which possess distinct morphological and histological features compared to primary teeth. Consequently, these findings cannot be directly extrapolated to primary dentition, and any interpretation or clinical application must be undertaken with caution, acknowledging the inherent limitations of the study design.

Comment 3:

Reference 14 is not cited in the correct sequence; please review all references accordingly

Comment 4:

Considering the substantial number of in vitro studies reported in the literature that have been conducted on primary teeth, it would be highly valuable for the authors to provide a clear explanation and well‑reasoned justification for the decision to carry out the present investigation on permanent teeth. Such clarification would not only strengthen the rationale of the study but also assist readers in understanding the specific motivations behind this methodological choice, as well as its implications for the interpretation and applicability of the findings. For instance:

Danevitch, N., Frankenberger, R., Lücker, S., Gärtner, U., & Krämer, N. (2023). Dentin Bonding Performance of Universal Adhesives in Primary Teeth In Vitro. Materials (Basel, Switzerland), 16(17), 5948. https://doi.org/10.3390/ma16175948

Güzel KGU, Altun AC, Kirzioğlu Z. In Vitro Evaluation of Onlay Restorations on Primary Teeth. The International Journal of Artificial Organs. 2017;40(12):709-713. doi:10.5301/ijao.5000630

Comment 5:

The limitations identified should be explained in a separate section. Furthermore, it would be advisable to highlight the differences in cost that the implementation of these techniques would entail, considering the utility and the many years of proven effectiveness of the space maintainers currently in use.

Comment 6:

In order to further strengthen the methodological rigor and transparency of the manuscript, it would be highly advisable for the authors to consider adhering to the CRIS Guidelines (Checklist for Reporting In-vitro Studies). Including this reference and explicitly following its recommendations would not only enhance the robustness of the present investigation but also provide readers and reviewers with greater confidence in the reproducibility and reliability of the reported findings. Such alignment with established reporting standards contributes to the overall credibility of the study and facilitates meaningful comparison with other research in the field

Krithikadatta J, Gopikrishna V, Datta M. CRIS Guidelines (Checklist for Reporting In-vitro Studies): A concept note on the need for standardized guidelines for improving quality and transparency in reporting in-vitro studies in experimental dental research. J Conserv Dent. 2014;17(4):301-304. doi:10.4103/0972-0707.136338

Author Response

We would like to thank you for the careful evaluation of our manuscript and for the constructive comments provided. We have revised the manuscript thoroughly in accordance with all suggestions. Below, we provide a point-by-point response, with all modifications highlighted in the revised manuscript using the Track Changes function.

Comment 1: [Line 37: add reference:

Response 1: [Thank you for pointing this out. We have added the requested reference in line 37 of the revised manuscript.]

Comment 2: [In the introduction, it is important to explicitly address and clarify the differences in adhesion between primary and permanent teeth. This distinction must be emphasized, as the biological and structural characteristics of primary dentition—such as enamel composition, dentin thickness, and the presence of a more permeable substrate—may significantly influence the bonding performance of restorative and orthodontic materials. The results reported in the present investigation were obtained from permanent third molars, which possess distinct morphological and histological features compared to primary teeth. Consequently, these findings cannot be directly extrapolated to primary dentition, and any interpretation or clinical application must be undertaken with caution, acknowledging the inherent limitations of the study design.]

Response 2: [Thank you for this valuable comment. We have addressed and clarified the differences in adhesion between primary and permanent teeth in the revised manuscript. The distinction regarding the biological and structural characteristics of primary dentition, including enamel composition, dentin thickness, and permeability, is now emphasized. Page 2, lines 109-114.

Additionally, we have included a statement acknowledging the limitations of extrapolating these findings to primary dentition, given that our study used permanent third molars. These revisions can be found in the limitation section. Page 19, limitation section, lines 880-882).]

Comment 3: [Reference 14 is not cited in the correct sequence; please review all references accordingly]

Response 3: [Thank you for pointing this out. We have reviewed and corrected the reference sequence in the manuscript.]

Comment 4: [Considering the substantial number of in vitro studies reported in the literature that have been conducted on primary teeth, it would be highly valuable for the authors to provide a clear explanation and well‑reasoned justification for the decision to carry out the present investigation on permanent teeth. Such clarification would not only strengthen the rationale of the study but also assist readers in understanding the specific motivations behind this methodological choice, as well as its implications for the interpretation and applicability of the findings. For instance:

Güzel KGU, Altun AC, Kirzioğlu Z. In Vitro Evaluation of Onlay Restorations on Primary Teeth. The International Journal of Artificial Organs. 2017;40(12):709-713. doi:10.5301/ijao.5000630]

Response 4: [Thank you for this insightful comment. We have now included a clear explanation in the methodology regarding the decision to use permanent teeth in our study. Although there are many in vitro studies conducted on primary teeth, the use of permanent third molars in this investigation was primarily driven by their greater availability and the need for teeth with intact enamel surfaces suitable for standardized in vitro testing. Moreover, the complex morphology and greater size of permanent molars are more representative of the conditions encountered in clinical practice, making them a suitable model for assessing fit accuracy and bond strength in space maintainers. We have added this rationale in the revised manuscript. Page 3, section 2.2, lines 198-201

The references have been added, however, to the introduction section where we compared the primary with the permanent teeth (e.g., Danevitch et al. 2023 and Güzel et al. 2017), acknowledging the contrast between primary and permanent dentition in terms of morphology and bonding characteristics. Page 2, lines 109-114]

Comment 5: [The limitations identified should be explained in a separate section. Furthermore, it would be advisable to highlight the differences in cost that the implementation of these techniques would entail, considering the utility and the many years of proven effectiveness of the space maintainers currently in use.]

Response 5: [Thank you for your valuable comment. We have now addressed the limitations in a separate section, as you suggested. Page 19.

Additionally, we have highlighted the cost differences associated with implementing these digital fabrication techniques, taking into account the utility of space maintainers and the proven effectiveness of conventional methods currently in use. These revisions can be found in page 19, clinical significance section, lines 871-873.]

Comment 6: [In order to further strengthen the methodological rigor and transparency of the manuscript, it would be highly advisable for the authors to consider adhering to the CRIS Guidelines (Checklist for Reporting In-vitro Studies). Including this reference and explicitly following its recommendations would not only enhance the robustness of the present investigation but also provide readers and reviewers with greater confidence in the reproducibility and reliability of the reported findings. Such alignment with established reporting standards contributes to the overall credibility of the study and facilitates meaningful comparison with other research in the field

Response 6: [Thank you for the suggestion. I have now explicitly referenced the CRIS Guidelines (Checklist for Reporting In-vitro Studies) in the end of Materials and Methods section to strengthen the methodological rigor and transparency of the manuscript. I have also made sure to align the manuscript with the recommended standards to enhance the study's reproducibility and reliability.

This addition can be found in page 13, lines 463-465.]

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript presents a well-designed in-vitro comparison of digitally fabricated space maintainer bands (PEEK and Co–Cr) versus conventional stainless-steel bands. The study is clearly structured, the methodology is coherent, and the research topic is timely and clinically relevant. The combination of 3D fit evaluation using a dual-scan protocol and mechanical testing of shear peel bond strength is a notable strength, offering a comprehensive assessment of both geometric accuracy and adhesive performance. While the study is promising and potentially suitable for publication, several aspects would benefit from clarification or refinement to enhance methodological transparency, clinical relevance, and overall readability. The following comments are intended to guide the authors with specific and actionable suggestions.

One point that requires clearer justification concerns the use of extracted third molars as the experimental model. Although ethically practical, third molars do not anatomically correspond to the clinical abutments for space maintainers, which are first molars. Their greater morphological complexity and deeper undercuts may influence RMS values and potentially exaggerate group differences. It would strengthen the Methods section to briefly explain why third molars were selected (availability, ethical considerations) and to clarify that their anatomical complexity provides a stringent model for assessing fit accuracy. In the Discussion, it would be helpful to acknowledge that extrapolation to first molars should be made with caution, even though the relative superiority of digital methods is likely to remain consistent.The clinical relevance of the numerical findings should be further developed. Fit accuracy values and SPBS values are reported correctly, but the practical meaning of these measurements for clinicians is not fully articulated. Adding a short explanatory paragraph would improve the manuscript. For example, noting that RMS values around 0.15 mm fall within the clinically acceptable range of 120–200 μm, while 0.34 mm exceeds this threshold, would help contextualize the importance of the results. Similarly, discussing whether the SPBS values observed for PEEK (median ~0.39 MPa) are likely to compromise long-term retention compared with Co–Cr and SS bands would make the implications of the mechanical testing clearer for clinical decision-making. The description of PEEK surface treatment should also be expanded. As the weak bonding performance of PEEK is a central element of the findings, the rationale behind the chosen surface-conditioning protocol deserves more detail. Briefly explaining why sandblasting followed by Signum Universal Bond was selected, and acknowledging alternative—but less clinically accessible—methods such as plasma treatment, sulfuric acid etching, or tribochemical coating would provide useful context and demonstrate awareness of the broader literature on PEEK adhesion. The interpretation of RMS values would benefit from a clearer connection to established thresholds in the literature. A concise sentence indicating that marginal discrepancies below 120 μm are considered ideal, and discrepancies up to 200–300 μm are generally acceptable, would allow readers to immediately appreciate the practical implications of the measurements. The Results section would be strengthened by the explicit reporting of effect sizes in addition to p-values. Including η² or Hedges’ g for fit accuracy and ε² for the Kruskal–Wallis test on SPBS would increase statistical transparency and allow readers to better appreciate the magnitude of the observed differences. These values are already mentioned in the Discussion, but they should also appear directly in the Results for completeness. Several minor revisions would improve clarity. The Introduction is somewhat lengthy and could be streamlined by reducing general epidemiological background and focusing more directly on conventional workflow limitations, digital fabrication advantages, and the rationale for comparing PEEK and Co–Cr. Figures are generally clear, but some labels—particularly in the deviation maps—could be enlarged for readability. It would also be helpful to state explicitly that all band selections and cementation procedures were performed by a single operator to eliminate inter-operator variability. Finally, if quantitative roughness data for the as-printed Co–Cr surfaces are unavailable, a brief note acknowledging this while explaining that the surfaces were intentionally left unpolished to preserve SLM micro-texture would be appropriate. From a language and style perspective, the manuscript is well written, though it would benefit from shortening some long sentences and ensuring consistent terminology throughout (e.g., using “shear peel bond strength (SPBS)” uniformly). Overall, the manuscript provides valuable experimental data and offers meaningful insight into the performance of digital versus conventional materials for space maintainers. With the clarifications and refinements suggested above, the work would be substantially strengthened and suitable for publication.

Author Response

Comment 1: [One point that requires clearer justification concerns the use of extracted third molars as the experimental model. Although ethically practical, third molars do not anatomically correspond to the clinical abutments for space maintainers, which are first molars. Their greater morphological complexity and deeper undercuts may influence RMS values and potentially exaggerate group differences. It would strengthen the Methods section to briefly explain why third molars were selected (availability, ethical considerations) and to clarify that their anatomical complexity provides a stringent model for assessing fit accuracy.]

Response 1: [I have provided a clearer explanation in the Materials and Methods section regarding the selection of third molars. While these teeth do not correspond directly to the clinical abutments (first molars), their use was driven by ethical considerations and availability. Additionally, I have highlighted that third molars' increased morphological complexity and deeper undercuts offer a stringent model for assessing fit accuracy. This explanation can be found in page 3, section 2.2, lines 198-201.]

Comment 2: [In the Discussion, it would be helpful to acknowledge that extrapolation to first molars should be made with caution, even though the relative superiority of digital methods is likely to remain consistent.]

Response 2: [Thank you for your insightful comment. I have addressed this point in the Discussion section by adding a note acknowledging that while the findings from third molars may provide valuable insights, extrapolation to first molars should be made with caution due to anatomical differences between the two. The revisions can be found on page 17, lines 644-648.]

Comment 3: [The clinical relevance of the numerical findings should be further developed. Fit accuracy values and SPBS values are reported correctly, but the practical meaning of these measurements for clinicians is not fully articulated. Adding a short explanatory paragraph would improve the manuscript. For example, noting that RMS values around 0.15 mm fall within the clinically acceptable range of 120–200 μm, while 0.34 mm exceeds this threshold, would help contextualize the importance of the results.]

Response 3: [Thank you for the helpful suggestion. I have added a brief explanatory paragraph in the Discussion section to contextualize the clinical relevance of the RMS and SPBS values. Specifically, I have highlighted that RMS values around 0.15 mm fall within the clinically acceptable range of 120–200 μm, whereas 0.34 mm exceeds this threshold, the revisions can be found on page 16, lines 566-570.]

Comment 4: [Similarly, discussing whether the SPBS values observed for PEEK (median ~0.39 MPa) are likely to compromise long-term retention compared with Co–Cr and SS bands would make the implications of the mechanical testing clearer for clinical decision-making.]

Response 4: [Thank you for this important observation. We agree that the clinical implications of the SPBS values require clearer articulation. New explanatory sentenceS has now been added to the Discussion section stating that (page 18, shear peel bond strength section, lines 793–796).]

Comment 5: [The description of PEEK surface treatment should also be expanded. As the weak bonding performance of PEEK is a central element of the findings, the rationale behind the chosen surface-conditioning protocol deserves more detail. Briefly explaining why sandblasting followed by Signum Universal Bond was selected, and acknowledging alternative—but less clinically accessible—methods such as plasma treatment, sulfuric acid etching, or tribochemical coating would provide useful context and demonstrate awareness of the broader literature on PEEK adhesion.]

Response 5: [Thank you for this valuable suggestion. We agree that additional clarification regarding the PEEK surface-conditioning protocol was necessary. We have now expanded the description to explain the rationale for selecting 110-µm Al₂O₃ sandblasting followed by Signum Universal Bond, emphasizing its clinical availability, safety, and prior evidence supporting improved micromechanical retention and wettability. Furthermore, we have added a brief statement acknowledging alternative—though less accessible—conditioning methods such as plasma treatment, sulfuric-acid etching, and tribochemical silica coating. Page 18, shear peel bond strength section, lines 804-810.]

Comment 6: [The interpretation of RMS values would benefit from a clearer connection to established thresholds in the literature. A concise sentence indicating that marginal discrepancies below 120 μm are considered ideal, and discrepancies up to 200–300 μm are generally acceptable, would allow readers to immediately appreciate the practical implications of the measurements.]

Response 6: [Thank you for this helpful suggestion. We agree that linking the RMS deviations to established clinical thresholds strengthens the interpretation of our findings. Accordingly, we have added a clarifying sentence to the Discussion. Page 16, fit accuracy section, lines 566-570.]

Comment 7: [The Results section would be strengthened by the explicit reporting of effect sizes in addition to p-values. Including η² or Hedges’ g for fit accuracy and ε² for the Kruskal–Wallis test on SPBS would increase statistical transparency and allow readers to better appreciate the magnitude of the observed differences. These values are already mentioned in the Discussion, but they should also appear directly in the Results for completeness.]

Response 7: [Thank you for this valuable suggestion. We agree that reporting the effect sizes directly within the Results section improves the statistical transparency of the manuscript. Accordingly, η² (for Welch ANOVA / fit accuracy) and ε² (for the Kruskal–Wallis SPBS analysis) have now been added alongside the corresponding p-values in the Results.

Fit accuracy: page 14, section 3.1, lines 496-499.
SPBS: page 15, section 3.2, line 510.]

Comment 8: [The Introduction is somewhat lengthy and could be streamlined by reducing general epidemiological background and focusing more directly on conventional workflow limitations, digital fabrication advantages, and the rationale for comparing PEEK and Co–Cr.]

Response 8: [Thank you for this valuable comment. We agree that the Introduction contained long epidemiological detail and could be made more concise. Accordingly, we have streamlined the section by reducing general background information and focusing more on the limitations of conventional workflows, the advantages of digital fabrication, and the rationale for comparing PEEK and Co–Cr. Pages 1-2, lines 35-138.]

Comment 9: [Figures are generally clear, but some labels—particularly in the deviation maps—could be enlarged for readability.]

Response 9:[ Thank you for this observation. We agree that increasing the label size would improve readability. However, the deviation maps were generated directly from the 3D analysis software, and the export interface limits the degree to which font size can be modified. Despite these technical constraints, we have enlarged the images to the maximum extent possible without distorting the scale information. Page 8, figure 4.]

Comment 10: [ It would also be helpful to state explicitly that all band selections and cementation procedures were performed by a single operator to eliminate inter-operator variability.]

Response 10: [Thank you for this important observation. We agree that explicitly stating operator consistency strengthens the methodological clarity of the study. Therefore, clarifying sentences have been added to the Materials and Methods section.

Band selection: page 6, lines 273-274
Band cementation: page 11, lines 394-395]

Comment 11: [Finally, if quantitative roughness data for the as-printed Co–Cr surfaces are unavailable, a brief note acknowledging this while explaining that the surfaces were intentionally left unpolished to preserve SLM micro-texture would be appropriate.]

Response 11: [Thank you for this valuable observation. The manuscript has now been updated to acknowledge the absence of quantitative surface roughness measurements for the as-printed Co–Cr samples. A clarifying sentence has been added to the Materials and Methods section. Page 11, lines 381-385.]

Comment 12: [From a language and style perspective, the manuscript is well written, though it would benefit from shortening some long sentences and ensuring consistent terminology throughout (e.g., using “shear peel bond strength (SPBS)” uniformly).]

Response 12: [Thank you for this observation. We agree that the manuscript benefits from improved consistency in terminology and clearer sentence structure. Accordingly, we have carefully reviewed the full text and revised overly long sentences for clarity and readability. We have also standardized terminology throughout the manuscript, using the term “shear peel bond strength (SPBS)” uniformly in all sections.]

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The article compares PEEK and SLM-fabricated Co–Cr techniques to conventional methods of production for space maintainers in pediatric dental care. I think this is an important and relevant topic in pediatric prosthetics, as it allows for the immediate fabrication of more accurate and better-fitting prostheses.

The abstract clearly explains what the study did and found, but it might read better if it included a few key numbers to show the magnitude of the differences between groups.

The introduction does a solid job of establishing the clinical context and rationale for the study, moving smoothly from the problem of premature tooth loss to the role of space maintainers and the promise of digital fabrication. It effectively highlights the main areas of failure—such as debonding and material limitations—and uses these to define the study’s null hypothesis.

The study design is well-described, and the statistical analysis is appropriately presented. The digital bands (Co–Cr and PEEK) fit the teeth much better than the stainless-steel ones, with about half the gap size. However, when it came to bonding strength, Co–Cr and stainless steel performed better than PEEK, which did not bond as effectively. The results show that PEEK and Co–Cr bands achieved much better fit (≈0.15 mm vs. 0.34 mm for stainless steel), while Co–Cr and SS bonded roughly four times stronger than PEEK (≈1.5–1.6 MPa vs. 0.4 MPa).

The discussion concludes that digitally fabricated bands—both milled PEEK and SLM Co–Cr—achieved superior fit compared with conventional stainless-steel bands due to the precision of CAD/CAM workflows, while bond strength appeared to depend more on material properties, with Co–Cr and SS outperforming PEEK. It also notes that digital methods improve accuracy and patient comfort but still face challenges related to cost, training, and methodological variability.

Overall, this is a solid and timely study comparing digital and traditional fabrication techniques for space maintainers. Still, it could be clearer and more detailed in parts—especially in explaining how the bond test was conducted, how surface areas were measured, and what specific materials or surface treatments were used for bonding. The sample size explanation is brief, and using third molars instead of clinically relevant molars may limit generalizability. Including effect sizes, exact p-values, and simple visuals like RMS maps would make the findings easier to interpret and more compelling.

Finally, it might help to clarify in the abstract that SLM is an additive manufacturing technique and to briefly explain the rationale for using post-hoc tests in the statistical analysis of SPBS data—especially how conclusions were drawn despite the data lacking normality.

Author Response

Comment 1: [The abstract clearly explains what the study did and found, but it might read better if it included a few key numbers to show the magnitude of the differences between groups.]

Response 1: [Thank you for this helpful suggestion. We have revised the abstract to include essential numerical emphasizing the magnitude of differences. The revised abstract appears on page 1, lines 21-26]

Comment 2: [It could be clearer and more detailed in explaining how the bond test was conducted, how surface areas were measured, and what specific materials or surface treatments were used for bonding.]

Response 2: [We agree and have expanded the Methods section accordingly:

The SPBS protocol now includes clearer and more detailed explanation on how the bond test was conducted, loading direction, crosshead speed, and detachment criteria. Page 11, lines 396-404.
The surface area measurement procedure for digital bands (using Meshmixer software) and for SS bands (manual caliper measurement) is now described in more detail. Page 12, lines 430-440.
The specific materials or surface treatments were used for bonding. Page 10-11, lines 374-385.]

comment 3: [The sample size explanation is brief, and using third molars instead of clinically relevant molars may limit generalizability. Including effect sizes, exact p-values, and simple visuals like RMS maps would make the findings easier to interpret and more compelling.]

Response 3: [The following changes have been made:

The sample size description has been expanded. Page 4-5, lines 176-179, 192-195, 222-225.
We added a detailed justification for using third molars, noting their accessibility, ethical appropriateness for in-vitro use, and intact enamel. We also explicitly acknowledge the variations regarding their anatomy between third molars and first molars which limits the generalizability of the results.
- Justification: page 3, section 2.2, lines 198-201
- Variations: page 17, lines 644-648
We agree. Effect sizes were added for the main SPBS and RMS comparisons, and exact p-values are now reported throughout the Results.
regarding the inclusion of RMS visuals to enhance the interpretation of the results. We have already provided an RMS deviation map in the manuscript (Figure 4 (h), Figure 5, and Figure 6) to visually represent the fit accuracy of the different materials. However, we are happy to further highlight this visual in the revised manuscript and ensure its clarity and relevance for readers.

Comment 4: [Finally, it might help to clarify in the abstract that SLM is an additive manufacturing technique and to briefly explain the rationale for using post-hoc tests in the statistical analysis of SPBS data—especially how conclusions were drawn despite the data lacking normality.]

Response 4: [Thank you for your comment.

This clarification has been added to the abstract. Page 1, line 14.
The Statistical Analysis subsection has been updated to clarify that SPBS was non-normally distributed; therefore, Kruskal–Wallis was used with Bonferroni-adjusted Mann–Whitney U post-hoc comparisons. The rationale for reporting adjusted results is clearly stated. Page 13, section 2.7, lines 457-458]

Author Response File: Author Response.docx

Reviewer 4 Report

Comments and Suggestions for Authors

The manuscript titled "Fit Accuracy and Shear Peel Bond Strength of CAD/CAM Fabricated Versus Conventional Stainless Steel Space Maintainers: An In-Vitro Comparative Study "addresses an interesting topic in pediatric dentistry, exploring both fit accuracy and shear peel bond strength with a clear experimental design. While the work has merit, the current version is overly lengthy and contains redundant arguments and methodological details. Several claims extend beyond the presented evidence, and key aspects of the methodology, sample handling, and statistical reporting require clearer justification or correction. Substantial restructuring would improve the manuscript's focus, reduce redundancy, and align claims more tightly with the data.

1. The Abstract is informative but dense as it includes levels of statistical detail that are unnecessary at this stage and does not mention essential numerical results that would help readers understand the magnitude of the effects. Some sentences are long and difficult to follow. Therefore it should be rewritten to deliver the study's purpose, methods, and core numerical findings in a streamlined manner.

2. The Introduction provides useful background information, but it contains repeated explanations of premature tooth loss, the function of space maintainers, and the advantages of digital workflows. Several pieces of information about digital fabrication are extensive and lack precise citation support. PEEK and Co-Cr are thoroughly introduced, but the links to their performance in this specific application could be clearer. The identified knowledge gap is valid; however, the narrative would benefit from more concise framing and the removal of redundant content.

3. The Methods section is comprehensive, but it contains an impressive amount of information and figure descriptions that interrupt the flow. Some aspects require attention:
• The sample numbers differ between the abstract and the methods section and must be corrected.
• The randomization process is mentioned but not described.
• The variability introduced by using third molars, which differ anatomically from first molars, requires stronger justification.
The lack of thermocycling, the absence of a standardized seating force, and the differences in treatment between materials are not adequately addressed.
Sometimes, the terminology is inconsistent (SPBS vs. SBS), and the cementation procedures lack clarity regarding pressure and control.
4. The Results also require a clearer presentation. Table formatting is inconsistent, the units for RMS are not stated, and the IQR values vary between sections. Effect sizes are reported for only one comparison, though reporting them for additional comparisons would strengthen the interpretation of the results. Figures and text often duplicate each other, making the section longer than necessary. Again, terminology varies between SPBS and SBS, which creates ambiguity. The ARI findings are clear, but the descriptive statements sometimes drift into interpretations that should be introduced in the Discussion section.

5. The Discussion seems to be far too long and contains substantial redundancy. Many paragraphs mention ideas about digital accuracy, operator variability, scanner advantages, and 3D evaluation methods. Comparisons with prior studies often imply definitive explanations for discrepancies without acknowledging other possible sources of variation. The statements about bonding (e.g., surface energy and chemical reactivity) seem accurate; however, they should be presented as informed interpretations rather than measured outcomes. The aesthetic analysis is interesting, yet it is not well integrated with the mechanical findings. The section's limitations are scattered and need to be consolidated into a focused, transparent paragraph. In addition, the clinical implications should also be articulated accurately in a separate paragraph.

6. The conclusions reflect the general findings but require more conservative phrasing. The claim that Co–Cr provides the "most balanced" performance is not fully supported by the statistics because the SPBS difference between Co–Cr and SS was not significant after correction. Recommendations regarding PEEK bonding should be more cautious, since no alternative protocols were evaluated. The final paragraph should be revised to reflect the in vitro nature of the study and avoid overextending conclusions beyond the presented data.

Author Response

Comment 1: [The Abstract is informative but dense as it includes levels of statistical detail that are unnecessary at this stage and does not mention essential numerical results that would help readers understand the magnitude of the effects. Some sentences are long and difficult to follow. Therefore, it should be rewritten to deliver the study's purpose, methods, and core numerical findings in a streamlined manner.]

Response 1: [Thank you for this valuable comment. We agree that the abstract would benefit from clearer structure and more concise presentation of the key numerical findings. Accordingly, we have rewritten the abstract to remove excessive statistical detail, streamline sentence structure, and highlight the essential quantitative results that reflect the magnitude of the study outcomes. The revised abstract appears on Page 1, Lines 10–26 of the updated manuscript.]

Comment 2: [The introduction provides useful background information, but it contains repeated explanations of premature tooth loss, the function of space maintainers, and the advantages of digital workflows. Several pieces of information about digital fabrication are extensive and lack precise citation support. PEEK and Co-Cr are thoroughly introduced, but the links to their performance in this specific application could be clearer. The identified knowledge gap is valid; however, the narrative would benefit from more concise framing and the removal of redundant content.]

Response 2: [Thank you for this thoughtful and constructive comment. We agree that the introduction contained redundancy and several extended descriptions that could be streamlined for clarity. We have revised the section to remove repeated explanations of premature tooth loss and space maintainer function, condensed the digital workflow description, and ensured that all statements regarding digital fabrication methods are now supported by appropriate citations. Additionally, we strengthened the connection between material properties (Co–Cr and PEEK) and their expected performance in band-and-loop space maintainers to better establish the rationale for this investigation. These revisions improve clarity while maintaining a logical flow toward the study’s knowledge gap. The revised text appears in the Introduction, Page 2, (Paragraphs 1 and 2, Lines 35–114), (paragraph 4, lines 124-127), (paragraph 5, lines 136-138), (paragraph 7, line 145).]

Comment 3: [ The Methods section is comprehensive, but it contains an impressive amount of information and figure descriptions that interrupt the flow. Some aspects require attention:

The sample numbers differ between the abstract and the methods section and must be corrected.
The randomization process is mentioned but not described.
The variability introduced by using third molars, which differ anatomically from first molars, requires stronger justification.
The lack of thermocycling, the absence of a standardized seating force, and the differences in treatment between materials are not adequately addressed.
Sometimes, the terminology is inconsistent (SPBS vs. SBS), and the cementation procedures lack clarity regarding pressure and control.]

Response 3: [Thank you for this detailed and helpful comment. We appreciate the reviewer’s attention to clarity and methodological rigor. We have revised the Methods section to address all of the points raised.

1. We agree that some figure-style descriptions in the Methods section disrupted the narrative flow. We have removed non-essential figure descriptions and information that disrupted the flow, resulting in a more concise and continuous methodology.
These revisions appear in materials and methods (page 6, section 2.4, lines 257-274), (page 7, section 2.5, line 323), (page 12, section 2.6, lines 435-439).

2. We corrected the discrepancies in sample numbers by giving it a better explanation in the methods section, which was caused by the difference between the number of the teeth samples and band samples, as we have 52 extracted teeth but 78 band samples to ensure full consistency across the Abstract, Methods, and Results.
Updated in methods section 2.2 (Page 3, Lines 192-195).

3. clear explanation of the randomization protocol, which was implemented during the study but unintentionally omitted from the initial submission, has now been inserted.
Added to: Methods Section 2.2 Sample Collection (Page 4, Lines 222–225).

4. We expanded the rationale for using extracted third molars.
Revised in: Methods Section 2.2 (Page 3, Lines 198–201).

5. Addressing the lack of thermocycling, seating force control, and material-dependent procedural differences. These issues have now been acknowledged in the Methods.
Added to: Methods Section 2.6 (Page 10-11, Lines 374–404).

6. All terminology has been standardized to shear peel bond strength (SPBS) throughout the manuscript.
Corrected throughout Methods, Results, and Discussion

7. We revised the description of cement application and seating to specify the pressure control and ensure reproducibility.
Revised in: Methods Section 2.6 (Page 11, paragraph 3, Lines 390–395).]

Comment 4: [The Results also require a clearer presentation. Table formatting is inconsistent, the units for RMS are not stated, and the IQR values vary between sections. Effect sizes are reported for only one comparison, though reporting them for additional comparisons would strengthen the interpretation of the results. Figures and text often duplicate each other, making the section longer than necessary. Again, terminology varies between SPBS and SBS, which creates ambiguity. The ARI findings are clear, but the descriptive statements sometimes drift into interpretations that should be introduced in the Discussion section.]

Response 4: [Thank you for this detailed and constructive feedback. We have addressed all points as follows:

Table formatting has been standardized, Units for RMS (mm) have been explicitly added, IQR presentation has been unified and all statistical values are now presented using a consistent structure (page 13, Table 1).
Effect sizes have now been reported for all relevant comparisons, including η² for Welch ANOVA (page 14, lines 496-499) and ε² for Kruskal–Wallis outcomes (page 15, lines 510).
Textual duplication with figures has been reduced by removing redundant descriptive phrases and retaining only essential numeric results (page 15, lines 525–530).
Terminology has been standardized throughout the manuscript, consistently using “SPBS” (shear-peel bond strength) to avoid ambiguity.
Descriptive statements related to ARI outcomes have been revised to avoid interpretive language in the Results section; interpretive statements were relocated to the Discussion (page 15, lines 525-530).]

Comment 5: [The Discussion seems to be far too long and contains substantial redundancy. Many paragraphs mention ideas about digital accuracy, operator variability, scanner advantages, and 3D evaluation methods. Comparisons with prior studies often imply definitive explanations for discrepancies without acknowledging other possible sources of variation. The statements about bonding (e.g., surface energy and chemical reactivity) seem accurate; however, they should be presented as informed interpretations rather than measured outcomes. The aesthetic analysis is interesting, yet it is not well integrated with the mechanical findings. The section's limitations are scattered and need to be consolidated into a focused, transparent paragraph. In addition, the clinical implications should also be articulated accurately in a separate paragraph.]

Response 5: [Thank you for this insightful and detailed comment. We agree that the Discussion required restructuring to reduce redundancy, improve clarity, and better separate interpretation from results.

Accordingly, we have made the following revisions:

Repeated explanations related to digital accuracy, operator variability, scanning principles, and 3D evaluation methodology were trimmed or merged.
When contrasting our findings with the literature, we revised the language to avoid implying definitive causal explanations. Additional potential sources of variation (were now acknowledged.
Updated on page 17, lines 638-643.
Statements regarding surface energy and chemical reactivity of materials (e.g., PEEK vs. Co–Cr) were rewritten to present them as evidence-based interpretations rather than measured outcomes of our study.
Updated on page 18, lines 804-806
The aesthetic considerations paragraph was revised and repositioned to better connect it with the mechanical performance findings.
Updated on page 19, lines 859-864
All limitations previously scattered throughout the Discussion were consolidated into a single focused subsection
page 19, lines 876-884
A new clearly delineated subsection was added to articulate the practical relevance of the fit-accuracy and SPBS findings for clinical decision-making.
page 19, lines 867-873

These revisions substantially improved the structure, clarity, and readability of the Discussion while ensuring that interpretations remained appropriately supported.]

Comment 6: [The conclusions reflect the general findings but require more conservative phrasing. The claim that Co–Cr provides the "most balanced" performance is not fully supported by the statistics because the SPBS difference between Co–Cr and SS was not significant after correction. Recommendations regarding PEEK bonding should be more cautious, since no alternative protocols were evaluated. The final paragraph should be revised to reflect the in vitro nature of the study and avoid overextending conclusions beyond the presented data.]

Response 5: [Thank you for this constructive comment. The conclusion section has been revised to adopt more conservative and evidence-aligned phrasing. Specifically, the previous statement implying that Co–Cr provided the “most balanced” performance has been removed, as the SPBS difference between Co–Cr and stainless steel was not statistically significant after correction. Recommendations regarding PEEK bonding have also been moderated, acknowledging that no alternative bonding protocols were evaluated in this study. Furthermore, the final paragraph has been rewritten to clearly reflect the in-vitro nature of the investigation and to avoid extending the findings beyond the experimental conditions. The revised conclusion can be found in the updated manuscript on page 19, lines 873-879.]

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors:

Following a careful review of the modifications introduced in manuscript prosthesis-4000228, I am pleased to inform you that the requested changes have been duly addressed. We have verified that the revisions have been implemented in accordance with the observations previously indicated, which reflects your commitment to improving the quality and clarity of the work.

In light of this, I confirm that the article is now ready to proceed to the next stage of the editorial process. I sincerely appreciate the effort and dedication you have invested in refining the manuscript, as such responsiveness greatly facilitates the advancement of the publication process.

Please do not hesitate to reach out should you require any further clarification or assistance during the forthcoming steps.

Author Response

We sincerely thank the reviewer for the positive evaluation and for confirming that the revised manuscript has adequately addressed all previous comments. We appreciate the reviewer’s time, constructive input, and supportive feedback throughout the review process.

Reviewer 4 Report

Comments and Suggestions for Authors

The manuscript is improved

Author Response

We sincerely thank the reviewer for the positive assessment of the revised manuscript. We appreciate the reviewer’s time and effort in evaluating our work during both review rounds.

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Fit Accuracy and Shear Peel Bond Strength of CAD/CAM-Fabricated Versus Conventional Stainless Steel Space Maintainers: In Vitro Comparative Study

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