Review Reports - Laboratory and Clinical Efficacy of 6% Hydrogen Peroxide At-Home Whitening Systems with Custom Trays

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The Introduction is overly verbose and fails to clearly articulate the specific knowledge gap this study aims to address. The authors should explicitly point out the current limitations in comparative efficacy studies regarding novel 6% hydrogen peroxide at-home whitening systems.
Given that the clinical section includes only a single case, the authors should explicitly state in the Methods or Discussion that the results are merely preliminary and exploratory in nature.
The in vitro section reports only the ΔEab values, lacking targeted interpretation of the individual L*, a*, and b* coordinates. Notably, the anomalous increase in the b* coordinate for the A90 group remains unexplained. Since this abnormal data compromises the rigor of the conclusions.
The attribution of efficacy differences to gel hydrophilicity and release rates is purely speculative and lacks experimental data. The authors should either cite supporting literature or conduct an in vitro release control experiment.

Comments on the Quality of English Language

Fine.

Author Response

Comments and Suggestions for Authors

The Introduction is overly verbose and fails to clearly articulate the specific knowledge gap this study aims to address. The authors should explicitly point out the current limitations in comparative efficacy studies regarding novel 6% hydrogen peroxide at-home whitening systems.

Thank you for this comment. On re-reading the Introduction, we agree that we failed to explicitly describe the knowledge gap, and we have revised the end of the section to make this clear. We have also shortened the Introduction slightly.

Given that the clinical section includes only a single case, the authors should explicitly state in the Methods or Discussion that the results are merely preliminary and exploratory in nature.

We appreciate this point. On consideration, we believe that the Discussion is the most appropriate place to handle this, and we have revised the section on limitations to explicitly include this issue.

The in vitro section reports only the ΔEab values, lacking targeted interpretation of the individual L*, a*, and b* coordinates. Notably, the anomalous increase in the b* coordinate for the A90 group remains unexplained. Since this abnormal data compromises the rigor of the conclusions.

We thank the reviewer for this insightful comment. We agree that the individual L*, a*, and b* coordinates provide additional information beyond the overall ΔEab value. We have added an explicit discussion of the trends in these coordinates to the results section, and added a paragraph on the anomalous change in b* to the Discussion. The present data do not allow a definitive explanation, and so we have noted the need for further investigation.

The attribution of efficacy differences to gel hydrophilicity and release rates is purely speculative and lacks experimental data. The authors should either cite supporting literature or conduct an in vitro release control experiment.

Thank you for this comment. We agree that our phrasing of these hypotheses in the Discussion was insufficiently clear that they are speculative, and we have revised to make this explicit.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript evaluates three dentist-supervised at-home whitening systems using a brown eggshell in vitro bleaching model and reports one illustrative clinical case. The tested products include two 6% hydrogen peroxide systems, TiON Take Home with Opalescence Go, and one 16% carbamide peroxide system, Angelus Home 16%. The main finding is that whitening efficacy differed substantially despite broadly comparable active peroxide content. The clinical case using TiON Take Home for 10 days showed a perceptible improvement consistent with the in vitro trend.
Drawbacks:
1. The in vitro comparison uses only three treated areas per condition, which is insufficient to support product-level conclusions robustly, especially when comparing commercial systems with different tray designs, gel matrices, and exposure protocols.
2. The eggshell model is useful as a screening method but has limited biological equivalence to human enamel and dentin. The manuscript acknowledges this, but the conclusions still lean toward clinical interpretation. No extracted human teeth, enamel slabs, or artificial saliva and pellicle model are used to validate whether the observed differences translate to real dental substrates.
3. The clinical component is only a single case without control, blinding, repeated measurements, sensitivity assessment, or follow-up. It should not be presented as clinical confirmation of efficacy; at most, it is an illustrative case.
4. Products differ not only by active ingredient but also by tray type, gel composition, viscosity, delivery system, exposure time, and number of applications. Therefore, attributing differences to system composition is plausible but experimentally unresolved.
5. With n=3 per group, normality testing has little value, and ANOVA and Tukey results may be unstable. The manuscript does not report exact p-values, confidence intervals, effect sizes, or diagnostic tests of assumptions.

Author Response

Comments and Suggestions for Authors

Drawbacks:
1. The in vitro comparison uses only three treated areas per condition, which is insufficient to support product-level conclusions robustly, especially when comparing commercial systems with different tray designs, gel matrices, and exposure protocols.

We thank the reviewer for this important comment. We acknowledge that the number of treated areas is limited and does not permit definitive product-level comparisons. We have made the exploratory and preliminary nature of this study explicit, and revised the Discussion to clearly acknowledge this limitation, tempering the conclusions accordingly.

The eggshell model is useful as a screening method but has limited biological equivalence to human enamel and dentin. The manuscript acknowledges this, but the conclusions still lean toward clinical interpretation. No extracted human teeth, enamel slabs, or artificial saliva and pellicle model are used to validate whether the observed differences translate to real dental substrates.

Thank you for this comment. We have further emphasised this point in the Discussion and Conclusion, and explicitly noted the potential value of experiments on teeth or enamel.

The clinical component is only a single case without control, blinding, repeated measurements, sensitivity assessment, or follow-up. It should not be presented as clinical confirmation of efficacy; at most, it is an illustrative case.

We entirely agree with this comment, and have revised the manuscript to avoid any risk of misinterpretation, explicitly referring to the case as illustrative.

Products differ not only by active ingredient but also by tray type, gel composition, viscosity, delivery system, exposure time, and number of applications. Therefore, attributing differences to system composition is plausible but experimentally unresolved.

In this study, the trays were not used, and the application and delivery systems were the same. W90 and G90 also used the same number of period of applications. Given that the only difference between the two systems in our experiment was the gel itself, we believe that we have grounds to suggest that a difference in composition is the most likely reason for the difference we observed, even though, as we note in the paper, we cannot say what this difference might be.

With n=3 per group, normality testing has little value, and ANOVA and Tukey results may be unstable. The manuscript does not report exact p-values, confidence intervals, effect sizes, or diagnostic tests of assumptions.

We thank the reviewer for this important statistical comment. We acknowledge that the small sample size limits the robustness of normality testing and parametric statistical analyses. We have revised the manuscript to explicitly acknowledge this limitation in the Discussion, and emphasise that the statistical analysis is also exploratory.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors The clarity of the images is insufficient. Comments on the Quality of English Language

Fine.

Author Response

The clarity of the images is insufficient.

RE: Thank you for your comment. All figures in the manuscript were prepared and submitted at a resolution of at least 300 dpi, which meets the journal's requirements. We carefully rechecked all figures and confirmed that no loss of image quality occurred during submission. Since the comment did not specify which figures or aspects of the image clarity were insufficient, we would appreciate any further guidance from the reviewer if additional improvements are required.