Review History


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Summary

  • The initial submission of this article was received on August 12th, 2024 and was peer-reviewed by 3 reviewers and the Academic Editor.
  • The Academic Editor made their initial decision on September 24th, 2024.
  • The first revision was submitted on April 18th, 2025 and was reviewed by 3 reviewers and the Academic Editor.
  • A further revision was submitted on June 14th, 2025 and was reviewed by 3 reviewers and the Academic Editor.
  • A further revision was submitted on June 26th, 2025 and was reviewed by the Academic Editor.
  • The article was Accepted by the Academic Editor on June 26th, 2025.

Version 0.4 (accepted)

· Jun 26, 2025 · Academic Editor

Accept

Dear authors,

We are pleased to inform you that your manuscript, "Impact of kombucha, coffee, and turmeric beverages on the color stability of a single-shade versus a multi-shade resin-based composite," has been accepted for publication in PeerJ.

Congratulations, and thank you for your contribution.

Best regards,

[# PeerJ Staff Note - this decision was reviewed and approved by Gwyn Gould, a PeerJ Section Editor covering this Section #]

Version 0.3

· Jun 23, 2025 · Academic Editor

Minor Revisions

Dear Authors,

Thank you for submitting your latest version.
Please check all the comments of Reviewer 2.
I agree that you should clearly indicate which experimental groups exceed the key ΔE thresholds.

Kind regards

Reviewer 1 ·

Basic reporting

Dear Author(s): Thank for submitting the revised manuscript. In my view, you could address all issues.

Experimental design

-

Validity of the findings

-

Additional comments

-

Reviewer 3 ·

Basic reporting

The manuscript presents a well-structured, timely, and relevant in vitro study evaluating the color stability of single-shade and multi-shade resin-based composites (RBCs) after immersion in kombucha, turmeric, and coffee. The methodology is rigorous, sample size is justified statistically, and the use of both ΔE*ab and ΔE00 provides a robust framework for color assessment. The topic holds clinical significance, especially with the rising popularity of health-oriented beverages.

Experimental design

No comment.

Validity of the findings

No comment.

Additional comments

Major Comments:
Discussion Overlength and Redundancy:
The discussion section is overly long and reiterates background content that was already covered in the introduction (e.g., photoinitiator mechanisms, TEGDMA behavior). It would benefit from being more concise and focused on the interpretation of the study’s specific results.

Clarity on Clinical Relevance:
Although ΔE00 values are calculated, the clinical implications (compared to perceptibility and acceptability thresholds) are not always clearly aligned with the actual findings. A clearer summary table or visual showing which groups exceed ΔE thresholds would improve clinical translatability.

Hypothesis Placement and Framing:
The null hypotheses appear at the end of the introduction. Repositioning them earlier—immediately after the study aim—would provide better structure. Also, the hypotheses could be stated more precisely.

Terminology Consistency:
Use consistent terminology when referring to materials (e.g., always "Vittra APS Unique (single-shade)" and "Tetric N-Ceram (multi-shade)" after the first mention).

Minor Comments:
Several long and complex sentences can be split for improved clarity.

Ensure consistent past tense use in the results and discussion sections.

Clarify whether measurements of surface roughness were considered or excluded.

Figures 5 and 6 may be redundant; consider combining them for conciseness.

Reviewer 4 ·

Basic reporting

All of my comments and suggested improvements from the first review were adressed in a adequate manner.

Experimental design

All of my comments and suggested improvements from the first review were adressed in a adequate manner.

Validity of the findings

All of my comments and suggested improvements from the first review were adressed in a adequate manner.

Additional comments

All of my comments and suggested improvements from the first review were adressed in a adequate manner.

Version 0.2

· Jun 6, 2025 · Academic Editor

Minor Revisions

Dear Author,

Based on the reviewer’s comments, I recommend minor revisions. Please update the manuscript accordingly and respond to each of the reviewers’ points in your next submission.

Reviewer 1 ·

Basic reporting

In this study, ‘Impact of kombucha, coffee, and turmeric drinks on the color stability of a single-shade resin-based composite’ is evaluated. There are improvements compared to the previous version. Besides this, only one parameter was investigated.
Comments for the sections
Title
The title should be more descriptive. Example ;
“Impact of kombucha, coffee, and turmeric beverages on the color stability of single-shade versus multi-shade resin-based composites”

Experimental design

-

Validity of the findings

Table (Results)
-Table 3 shows the main factors and their interactions. There should be another table showing the differences within and between groups.

Additional comments

-

Reviewer 4 ·

Basic reporting

Abstract:
• The abstract is clearly written.
• The aims of the study are presented clearly.
• The description of the methods is understandable.
• The most relevant results are given.
Introduction
• Relevant and actual literature is well presented.
• In lines 112 ff you postulate, that you investigated the effect of “drinks with health benefits”. In this context you mention black coffee. In my opinion, there is a lack of information. In general, caffeine is known for it’s negative effects on the human body. Some examples are nervousness, insomnia, nausea, headaches, anxiety disorders, perceptual disorders, cardiac arrhythmia, increased respiratory rate, and even gastrointestinal disorders. The dose is particularly relevant here.
Since the amount of coffee consumed also has a direct influence on the discoloration of plastics, this connection still needs to be established.

Experimental design

Materials and Methods
• The methods are presented in an understandable way.
• Why did you choose a sample strength of 2 mm?
• Did you pour the mould with one increment, or did you use multiple increments?

Validity of the findings

Results
• The results are presented completely.
• The figures support the presentation of the results in an adequate manner.

Discussion
• Why did you decide for the tested materials, and why did you not evaluate more RCRs?

Additional comments

None

·

Basic reporting

• The manuscript addresses the influence of certain solutions on the color stability over time of two resin composites: a single-shade material (Vittra APS Unique - FGM) and a conventional universal resin composite (Tetric N-Ceram - Ivoclar). Several previous studies have investigated the issue of staining in resin-based materials. The novelty highlighted by the authors lies in the use of a recently launched single-shade resin composite and the evaluation of staining solutions that have been little explored in the literature. To some extent, this does bring an element of innovation to the study, which may contribute additional scientific evidence to the existing body of knowledge on the topic.
• The manuscript presents clear English language.
• The choice of materials is not well justified regarding the commercial brands, especially considering that these materials have significantly different compositions. The authors emphasized that the main focus of the study was to compare single-shade resin composites with multi-shade ones. In this context, wouldn’t it have been more appropriate to include a multi-shade material with APS technology to eliminate this variable? Or perhaps a single-shade material with a different photoinitiator system? How did the selection of specific commercial brands influence the results of the study?

Experimental design

• On what estimates was the sample size calculation based? Was a pilot study conducted? The manuscript lacks sufficient information to justify the estimated sample size.
• Other methodological aspects were addressed in previous review rounds and appear to have been adequately revised. However, it is worth noting that certain additional considerations could have strengthened the study, such as the measurement of surface roughness of the specimens and the inclusion of a broader range of materials.
• Results: "Vittra APS Unique and Tetric-N-Ceram materials showed the greatest color change after 18 days of immersion in the turmeric solution." Please revise. Turmeric solution results in the greatest color change for all evaluations, not only after 18 days.
• Figure 4 displays the number of days at the top and the labels T1, T2, and T3 at the bottom. Revise this.

Validity of the findings

• The results obtained are consistent and appear to have been adequately measured. However, the Discussion section lacks a more thorough examination of the factors that the authors suggest influenced the observed outcomes. Much of the section focuses on comparisons with previous studies addressing similar conditions, but there is limited contribution from a materials science perspective. I believe it would be beneficial for the authors to place greater emphasis on these aspects in their discussion.

Additional comments

• Abstract: The conclusion presented is quite broad, considering that only two materials (one from each category) were tested. It would be more appropriate and cautious for the conclusions to be drawn specifically in relation to the materials evaluated in this study, as other material characteristics may have influenced the final results.

Version 0.1 (original submission)

· Sep 24, 2024 · Academic Editor

Major Revisions

Please address all comments from the reviewers. The area of concern include methodology, statistical analyses and conclusion. The article also requires English proofreading.

[# PeerJ Staff Note: It is PeerJ policy that additional references suggested during the peer-review process should *only* be included if the authors are in agreement that they are relevant and useful #]

Reviewer 1 ·

Basic reporting

In this study ‘Effect of popular probiotic and caffeinated drinks on the color stability of single-shade resin-based composite dental restorative materials’ is evaluated. This is meaningful data for dental clinicians. Although tables and figures are also sufficient, one single-shade and one multi-shade resin composites were tested. Besides this, only one parameter was investigated. The title should be revised.

Experimental design

-Why didn't you prepare disc-shaped specimens?
-Single-shade material diversity should be increased in this study. Only one single-shade composite resin was used. Is it sufficient to use one type of single shade composite resin for the study? Please reconsider your study design.
-Although the CIEDE2000 color difference is reported to be a better indicator of human perceptibility and acceptability of shade differences between tooth colors, the CIELAB color difference formula was used in this study. Many current studies adopt the CIEDE2000 color difference formula and the AT and PT values based on this formula.
- Please could used for ‘ΔEab instead of ‘ΔEX’ in CIE formula.
-How sample standardization was done in the measurement of color values?
- Besides color change, why didn't you measure surface roughness in this study?
-SPSS 17 citation must be given correctly. Please see the link; SPSS 17 https://www.ibm.com/support/pages/how-cite-ibm-spss-statistics-or-earlier-versions-spss
- Were samples kept in a dark box or were they left exposed to ambient light after fabrication?
-Power analysis regarding sample size in the study should be added to the methods section.

Validity of the findings

-The study findings are adequately explained.
-Why was the three-factor interaction not shown in table 2 even though it was significant?
-Limitations related to single-shade and multi-shade composites should be added.

Additional comments

-

Reviewer 2 ·

Basic reporting

In general, this study reflects the authors' concern regarding the color stability of restorative materials due to the consumption of popular beverages, which tends to be an important issue. However, the authors should work on English language (the manuscript needs English editing).

Experimental design

The methodological aspects of this research seem intact and well-defined. However,I noticed a few minor issues:
1. In the "Short Abstract" (first page) and "Abstract" (lines 43, 44) sections, the number of subgroups and the duration of sample immersion are reported differently than in the “Materials & Methods” section (lines 151, 156).

2: Please consider adding some details about your samples (e.g 8*5*2 mm blocks of RBCs) in the "Abstract" section.

3: Line 175: There seems to be an extra (-) in the unit of (1200 mW/cm2).

4: I suggest moving "lines 200-204" to the "Discussion" section.

Validity of the findings

This study contains valuable insights based on valid data and solid analysis. I would like the authors to clarify the following points:

1. Since only one of the variables was not normally distributed, why did they not ignore it and use a more powerful analysis, such as Repeated Measure Two-way ANOVA?

2. Considering using GLM is sensible, it is not appropriate to merge samples from different groups, due to the significant effect of three-way interaction on deltaE (e.g. lines 268-271: when comparing different time frames, it is not statistically sound to merge all the various material and beverage samples tested in a single time together). Instead, the effect of time must be calculated independently in each material and beverage group.

Additional comments

1. In order to make the text easy to understand for readers and to avoid repeating the full name and brand of RBCs or instruments, I recommend using abbreviations. Please remember to define them first when they are mentioned and then use the same abbreviation throughout the text (For instance, in line 253, "material V and material T.." are suitable abbreviations, but are not defined beforehand). If you prefer to use the full names, please make sure that you use the consistent form in the text.

2. Lines 299-315: This paragraph is very similar in structure to the introduction (lines 120-137). Please consider rewriting one of them and avoid repeated information.

Reviewer 3 ·

Basic reporting

Title and Introduction
1. The title could be improved, as there is no need to include “Single-Shade Resin-Based Composite Dental Restorative Materials.” You can omit “Dental Restorative Materials.” Additionally, the title mentions "popular probiotic and caffeinated drinks," but the study was conducted with turmeric, kombucha, and coffee. This needs refinement. Consider something like "Comparative Effect of [names of the beverages]..." or "Impact of [names of the beverages] on Color Stability..."
2. The English language should be elevated to an academic standard.
3. The text needs to be organized into coherent paragraphs.
4. Lines 60-68 require improvement. The ideas are fragmented, and the text should be reformulated to ensure fluency and cohesion. For instance, the repetition of the word “patients” causes redundancy. While the information is relevant, it needs to be presented more clearly. The authors wrote, “Proper color matching of the restorative material with the adjacent tooth structure is crucial for successful dental treatment (Piccoli et al. 2019). Dentin, enamel, surrounding structures, and restorations all play a role in tooth color (AlSheikh 2019).” These sentences could be combined into a single, more cohesive idea.
5. Line 126: "...popular probiotic, antioxidant, and caffeinated beverages..." – The use of the word "popular" can be simplified or replaced with something more precise for academic writing.
6. The study provides a relevant justification and raises research questions that are essential in the literature.
7. I suggest not mentioning the resin brands in the objective; this can be explored in the methodology section. At this stage, the focus should be on comparing single-shade vs. multi-shade resins.

Experimental design

Methods
1. The article was approved by an ethics committee.
2. In Figure 1, I suggest replacing “after 6 days, after an additional 6 days, after another additional 6 days” with the terminology used in the body of the text: “after 6 days, after 12 days, and after 18 days.”
3. In Table 1, add the batch numbers of the RBCs used.
4. Why was CIELAB used instead of CIEDE 2000? I suggest including the CIEDE 2000 model and analyzing the ΔE values according to the 50:50% perceptibility and acceptability thresholds for both colorimetric analysis systems. I recommend reviewing the following references:
o Durand, L.B.; Ruiz-López, J.; Perez, B.G.; Ionescu, A.M.; Carrillo-Pérez, F.; Ghinea, R. et al. Color, lightness, chroma, hue, and translucency adjustment potential of resin composites using the CIEDE2000 color difference formula. J Esthet Restor Dent. 2021, 33, 836-843.
o Sharma, G.; Wu, W.; Dalal, E.N. The CIEDE2000 color-difference formula: Implementation notes, supplementary test data, and mathematical observations. Color Res Appl. 2005, 30, 21-30.
o Gómez-Polo, C.; Portillo Muñoz, M.; Lorenzo Luengo, M.C.; Vicente, P.; Galindo, P.; Martín Casado, A.M. Comparison of the CIELab and CIEDE2000 color difference formulas. J Prosthet Dent. 2016, 115, 65-70.

[# PeerJ Staff Note: It is PeerJ policy that additional references suggested during the peer-review process should *only* be included if the authors are in agreement that they are relevant and useful #]

5. How was the sample size calculated?

Validity of the findings

Results and Discussion
1. The content between lines 302 and 310 reads like a methodology section. I believe this can be removed from this part of the article. After a restatement of the study’s objectives and null hypotheses, the resins can be discussed in relation to their compositional characteristics.
2. The study’s limitations need to be addressed in more detail.
3. Throughout the article, the terminology for the control resin should be standardized. Are the authors referring to it as the conventional resin or the multi-shade resin? I suggest adopting the term "multi-shade," as the term "conventional" may confuse readers (conventional in relation to what? Incremental technique? Multiple color shades?).
4. Include recent publications on the clinical color stability of single-shade resins.

Conclusion
1. The conclusion should be strengthened by emphasizing the clinical significance of the color stability of single-shade resins. Additionally, future studies should be suggested to address any gaps identified in this article. It would also be beneficial to provide recommendations regarding the maintenance or monitoring of restorations using single-shade resins.

Additional comments

This is a good article on the color stability of new single-shade composite resins, which can be accepted for publication after some significant reviews and responses.

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