Effect of Adhesive Application Method on the Enamel Bond Durability of a Two-Step Adhesive System Utilizing a Universal Adhesive-Derived Primer

Round 1

Reviewer 1 Report

The authors tested the bonding strength of three different adhesives. Two different surface pretreatments and three different thickness of adhesive were examined. The experiment and statistics were carefully performed, however the data was not presented well.  Table 3, 4 and 5 (missing table title) should be presented in the form of bar plots with error bars or box plots. The raw data can be kept in the manuscript or supplementary material.  The resolution of SEM images in Figure 3, 4 and 5 are too low to get any details, such as filler in the adhesives or the features of resin/enamel interfaces.  If limited by the total number of pages, pictures in larger size and higher resolution should be provided in the supplementary material.

Author Response

The authors very much appreciate your comments regarding this manuscript. We have carefully considered the comments regarding this manuscript have made revisions to the manuscript. I will summarize the changes made in the manuscript (highlighted) and provide the authors’ response to the comments expressed by you.

Reviewer’s concern 1

Table 3, 4 and 5 (missing table title) should be presented in the form of bar plots with error bars or box plots. The raw data can be kept in the manuscript or supplementary material.

Our response

We have added three graphs but would like to keep the numerical data in the text as it is.

Reviewer’s concern 2

The resolution of SEM images in Figure 3, 4 and 5 are too low to get any details, such as filler in the adhesives or the features of resin/enamel interfaces. If limited by the total number of pages, pictures in larger size and higher resolution should be provided in the supplementary material.

Our response

We have replaced the original images with higher resolution images.

Reviewer 2 Report

I think it's an interesting study of a new product.

Author Response

Our response

Thank you for your positive comment.

Reviewer 3 Report

The current article 'Effect of adhesive application method on the enamel bond durability of a two-step adhesive system utilizing a universal-adhesive-derived primer ' reports the methodological studies conducted to study the effiecient protocol towards achieving maximal adhesive strength by the dental adhesives. The article is well written and presented. I personally believe that the article can be accepted for publication in its original state.

Author Response

Reviewer No. 3

(x) English language and style are fine/minor spell check required

Comments and Suggestions for Authors

The current article 'Effect of adhesive application method on the enamel bond durability of a two-step adhesive system utilizing a universal-adhesive-derived primer ' reports the methodological studies conducted to study the efficient protocol towards achieving maximal adhesive strength by the dental adhesives. The article is well written and presented. I personally believe that the article can be accepted for publication in its original state.

Our response

Thank you for your positive comment.

We have checked the text and corrected some errors.

Reviewer 4 Report

Dear authors congratulations for your very interesting paper.

I have two minor suggestions

In section 2.2  of Material and Methods, I would like to see the number of bovine teeth used  before the details of  specimen preparation.

In section 5 of conclusions, I would suggest to be added the difference in the significance of ER mode and SEmode

Author Response

Reviewer No. 4

(x) English language and style are fine/minor spell check required

Comments and Suggestions for Authors

Dear authors congratulations for your very interesting paper.

I have two minor suggestions

Reviewer’s concern 1

In section 2.2 of Material and Methods, I would like to see the number of bovine teeth used before the details of specimen preparation.

Our response

We used 810 bovine teeth for SBS tests and 180 teeth for adhesive thickness measurements. We have added this in the text and Figure 1.

Reviewer’s concern 2

In section 5 of conclusions, I would suggest to be added the difference in the significance of ER mode and SE mode

Our response

We have added some sentences regarding the difference in the significance of ER mode and SE mode in the conclusion as follows: Although GU and OX showed significantly higher SBS values in ER mode than in SE mode at 24 h, no significant differences in the SBS values of the three adhesives were observed between the SE and ER modes at TC 30,000 in Group III.

Reviewer 5 Report

This manuscript by Takamizawa et al. presents a comparative study of different acrylic adhesives for tooth enamel in terms of different operational conditions. Systematic investigation of numerous conditions (3 different adhesives, 3 different modes of application, 3 different storage periods, 2 different etching methods) was performed, producing a significant amount of data. The readers in this field will likely find this article highly informative. Some modifications are suggested.

1. Due to the extensive amounts of data, it is difficult to deduce the major points in this study. It would be very helpful to the readers to summarize the findings in several bullet points or in a box.
2. What was the basis for choosing the methods in Groups I, II and III? Are they all commonly used methods? Explain the reason and provide citations.
3. Method sections needs more citations. Currently, there is only one citation.
4. Include a schematic figure.

- Minor comments –

1. The caption for Table 5 is missing

Author Response

Reviewer No. 5

Comments and Suggestions for Authors

This manuscript by Takamizawa et al. presents a comparative study of different acrylic adhesives for tooth enamel in terms of different operational conditions. Systematic investigation of numerous conditions (3 different adhesives, 3 different modes of application, 3 different storage periods, 2 different etching methods) was performed, producing a significant amount of data. The readers in this field will likely find this article highly informative. Some modifications are suggested.

Reviewer’s concern 1

Due to the extensive amounts of data, it is difficult to deduce the major points in this study. It would be very helpful to the readers to summarize the findings in several bullet points or in a box.

Our response

We have revised the conclusion.

From the results of this study, we can draw the following conclusions.

5. All the factors (adhesive application method, TC period, and adhesive system) significantly influenced the SBS values in SE mode (p < 0.001).
6. All the factors (adhesive application method, TC period, and adhesive system) significantly influenced the SBS values in ER mode (p < 0.001).
7. Although the application method and adhesive systems significantly influenced the thickness of the adhesive layer (p < 0.001), the etching mode did not have any influence (p = 0.974).
8. Although GU and OX showed significantly higher SBS values in the ER mode at 24 h than in the SE mode, no significant differences in the SBS values of the three adhesives were observed between the SE and ER modes at TC 30,000 in Group III.
9. The application method in Group II, which conformed to the manufacturers’ recommendations, resulted in an adhesive layer that was approximately 40–60 μm in thickness and appeared to be optimal for effective enamel bonding, regardless of the type of adhesive system or etching mode.
10. Within the limitations of this study, the new-generation two-step SE adhesive, which adopts a universal adhesive-derived primer and a hydrophobic bonding agent, showed superior bond performance to the conventional two-step adhesive systems.

Reviewer’s concern 2

What was the basis for choosing the methods in Groups I, II and III? Are they all commonly used methods? Explain the reason and provide citations.

Our response

As part of the design process for this study, we assumed that variations in clinical bonding procedures might result in the creation of different adhesive layer thicknesses. Such variation may occur in clinical situations due to misunderstanding of bonding procedures, cavity configuration, or errors in handling. We therefore designed protocols to generate adhesive layers of different thicknesses.

For instance, if the professionals misunderstand the bonding procedures of two-step adhesive systems, the adhesive layer may be thin. Because some single-step adhesive systems are required strong stream of air-blow due to enhancing evaporation water and solvents. On the other hand, small and narrow cavities may have thicker adhesive layer at the corner. 

We have added the first of the above paragraphs to the text.

Reviewer’s concern 3

Method sections needs more citations. Currently, there is only one citation.

Include a schematic figure.

Our response

We have added some citations and a flow diagram of this study.

Reviewer’s concern 4

The caption for Table 5 is missing

Our response

We have added a caption for Table 5.

Round 2

Reviewer 5 Report

The authors revised the manuscript well according to reviewers' suggestions.