A New Method to Evaluate Trueness and Precision of Digital and Conventional Impression Techniques for Complete Dental Arch

Round 1

Reviewer 1 Report

The authors present an interesting study about using a new method to evaluate the precision of both conventional and digital impressions.

Please read the instructions for authors and modify your manuscript presentation accordingly.

I suggest the manuscript keywords be improved: for instance, adding 3-dimensional accuracy, conventional impressions, digital impressions, or computerized coordinate measuring machine (CMM)

Line 67: “in vivo” is most appropriately used for animal studies. I suggest replacing it for "clinical study"

Line 77: the phrase is incomplete, please check it

Lines 79-83: I suggest removing the references to the materials and methods from this section.

Line 204: please add a reference to support the statement information

Lines 217-219: please do not refer to tooth position since no teeth were evaluated but cylinders instead

Lines 219-221: this information is repeated from the introduction section. I suggest removing it.

Lines 227-228: the authors refer that: “this new method can be applied to evaluate the accuracy of any physical or digital model”. However, as the authors previously stated, natural teeth have an irregular configuration that prevents the use of CMM techniques. So I suggest this statement be corrected.

Lines 254-256: The authors concluded that conventional impression showed more accuracy when compared to complete-arch digital scans. They refer that this is also previously reported but failed to provide a possible explanation for this, which can justify the obtained results. Please add it in the discussion section.

Figures 7 and 8: do the authors have some explanation why the most evident differences are on the positions 22-27? Please discuss these findings.

Author Response

Dear Reviewer 1

Thanks for the review and the comments you gave me. I tried to follow every advice and the followings are my answers

COMMENT

Line 67: “in vivo” is most appropriately used for animal studies. I suggest replacing it for "clinical study"

Answer: As I know, in vivo studies also include human as well as animal studies. Plese reconsider your comments.

COMMENT

Line 77: the phrase is incomplete, please check it

Answer: However, best-fit alignment inherently includes superimposition errors; therefore, best-fit alignment seems to be suitable for the evaluation of one quadrant, not for greater scan areas such as the complete arch.”

For better understanding the meaning of sentence, I replaced “comma” with “semicolon”, and “but” with “not”

COMMENT

Lines 79-83: I suggest removing the references to the materials and methods from this section.

Answer: I really appreciated your advice. I added this reference to emphasize the limitations of best fit method. This is why I tried a new method for the complete arch digital scan. I prefer this reference in the introduction. Please reconsider your comments.

COMMENT

Line 204: please add a reference to support the statement information

Answer: I added the references. Those were provided by the manufacturers.

COMMENT

Lines 217-219: please do not refer to tooth position since no teeth were evaluated but cylinders instead

Answer; Thanks for the comment. I replaced tooth with cylinder.

COMMENT

Lines 219-221: this information is repeated from the introduction section. I suggest removing it.

Answer: I appreciate your comment. I think the sentence is better to be left to introduce the following sentence. Please reconsider your comment.

COMMENT

Lines 227-228: the authors refer that: “this new method can be applied to evaluate the accuracy of any physical or digital model”. However, as the authors previously stated, natural teeth have an irregular configuration that prevents the use of CMM techniques. So I suggest this statement be corrected.

Answer: This method can be applied to any physical or digital models with 14 cylinders. Therefore, any new impression method, which is conventional or digital, van be assessed with the new method as long as the cylinder model is used.

COMMENT

Lines 254-256: The authors concluded that conventional impression showed more accuracy when compared to complete-arch digital scans. They refer that this is also previously reported but failed to provide a possible explanation for this, which can justify the obtained results. Please add it in the discussion section.

Answer: Thanks for the thoughtful comment. I think the main purpose of this study was to introduce a new method to assess the accuracy of complete arch impression. The comparison of accuracy between conventional and digital impression was less important even it was a secondary aim of this study. Even the conventional impression showed more accurate results compared to the digital method, I can only guess the reason, not the fact. The reason maybe the accumulation error during stitching images, however, this guess was not verified in my study. The current study only showed the greater dispersion of raw data in digital impression. I think your request is beyond the scope of the current study.

Comment

Figures 7 and 8: do the authors have some explanation why the most evident differences are on the positions 22-27? Please discuss these findings.

Answer: 

It’s very complicated and hardly understood the reason. I think it is due to the set up of 3D part coordinate system. 

The origin is 11C, and 17C was on the X axis, the delta values in 22-27Cs were more exposed

I think it was not right to compare the amount of distortion between right and left quardrant.

More important thing is the relative amount of dispersion between the impression method

Threfore, this method is more applicable for the comparison of different method.

As I mentioned in the last part of discussion, 

Quantitative as well as qualitative analysis e included in the future studies.

Reviewer 2 Report

Hello---

The manuscript is well written with good description of the methods used and the analysis. 

In the Introduction section, authors pointed out significance of their study as a new tool to accurately compare the conventional and intraoral digital impressions. In the methods section, authors have adequately described the method/software used with relation to outcomes. I liked that authors have well defined some of the terms, especially "trueness" and "precision", which can be confusing otherwise. In the statistical analysis section, it was a good point to check any errors based on operators, especially when the p value is 1.0.

In the discussion section, authors have discussed the results where they showed the new method is completely reliable to evaluate the 3-D accuracy of complete arch impression. Also, by introducing 3-D technique by assuming the cylindrical shape for tooth, increases the accuracy for testing conventional and digital impression technique. This can provide a good tool further for behavior prediction. Authors are correct about admitting that the new method has limitation because tooth doesn't necessarily fit in a cylinder geometry (more of free dimensional), but its definitely a better fit than regular 2-D models. 

Author Response

Dear Reviewer

Thanks for the encouraging comments about the current study. I really appreciated.

Sincerely