Review Reports

Round 1

Reviewer 1 Report

Hare are my comments and suggestions.

1) I would like to delete the two "different" in the title;

2) Please provide the references in Line 75;

3) The main purpose of running the pilot experiment was to determine the samples size. Please give more details on this. What the sample size was used in the study?

4) In Line 91, A reference model (ANKA-4 V CER....) was fabricated using hard plaster for dentistry. Please provide the type of hard plaster and the manufacturer. What is the ANKA-4 V CER? A scanner or anything else?

5) In Line 100, Please provide the country for all the scanners as this information for some of the scanners has been provided;

6) In Line 102, is there any difference to change the order of scanning, i.e. from Δ→•?

7) What did the letters of a, b,c,... in Tables 1, 1 and 2 mean?

8) There were no error bars in the Figures 3 and 4. Also what did the letters of a, b, c, d and e mean in Figure 5?  

9) The English in the manuscript could be improved. For example, in Line 214, "decrease" could replace with "minimise"?

10) Please rewrite the sentence of conclusion 3.

Author Response

We are grateful to the reviewers for their critical comments and useful suggestions that have helped us to greatly improve our paper. As indicated in the following responses, we have reflected all these comments in the revised version of our paper.

Reviewer #1

I would like to delete the two "different" in the title.

Response: We agree with the reviewer’s suggestion. We have deleted the two "different" in the title.

“Accuracy of 5 different intraoral scanners and 2 different laboratory scanners for a complete arch: A comparative in vitro study”

Please provide the references in Line 75.

Response: We agree with the reviewer’s suggestion. We have provided the references.

“In addition, there are few studies evaluating the scanning accuracy of a complete arch [10,14,15].”

The main purpose of running the pilot experiment was to determine the samples size. Please give more details on this. What the sample size was used in the study?

Response: We agree with the reviewer’s suggestion. We have added information so that the text is more readily comprehensible to a reader.

“First, to determine the sample size, a pilot experiment was conducted five times and using a power analysis software (G*Power v3.1.9.2, Heinrich-Heine-Universität, Düsseldorf, Germany), the number of samples was calculated to be 20 (actual power=99.2%; power=99%; α=.05). The results indicated that this study needed at least N = 20 subjects to ensure a power >99%.  The actual power achieved with this N (99.20%) is slightly higher than the requested power.”

In Line 91, A reference model (ANKA-4 V CER....) was fabricated using hard plaster for dentistry. Please provide the type of hard plaster and the manufacturer. What is the ANKA-4 V CER? A scanner or anything else?

Response: Thank you for your comment. We have addressed the issue that you point out.

 “A reference model (dental typodont, ANKA-4 V CER, Frasaco GmbH, Tettnang, Germany) was fabricated using dental stone (Type IV, Durone, Dentsply, Catanduva, Brazil) hard plaster for dentistry.”

In Line 100, Please provide the country for all the scanners as this information for some of the scanners has been provided.

Response:  We agree with the reviewer’s suggestion. We have provided the country for all the scanners.

“To obtain the CTM of the reference model, 5 types of intraoral scanners, including CS3500 (Carestream Dental, Atlanta, GA, USA), CS3600 (Carestream Dental, Atlanta, GA, USA), Trios2 (3Shape, Copenhagen, Denmark), Trios3 (3Shape, Copenhagen, Denmark), and i500 (MEDIT, Seoul, Republic of Korea) and 2 laboratory scanners, including E1 (3Shape, Copenhagen, Denmark) and DOF Freedom HD (DOF, Seoul, Republic of Korea) were used.”

In Line 102, is there any difference to change the order of scanning, i.e. from Δ→•?

Response: Thank you for your suggestion for improving the quality of the manuscript. Previous studies have shown that the accuracy may vary depending on the scanning procedure, i.e. from Δ→•. Therefore, the scanning procedure was performed in only one direction (•→Δ). We have added a reference that the accuracy may vary depending on the order of the scans.

“Based on the complete arch scan manufacturer’s instructions and a review of the literature on the accuracy of various scan strategies, the order of scanning was decided (Figure 2) [3].”

What did the letters of a, b,c,... in Tables 1, 1 and 2 mean?

Response: Thank you for your comment. The letters (a, b, c, ...) represent statistical results. Different letters represent statistically significant differences in scanner groups. These are shown below the table 1, 2.

There were no error bars in the Figures 3 and 4. Also what did the letters of a, b, c, d and e mean in Figure 5?

Response: We agree with the reviewer’s suggestion. We have added the error bars in the Figures 3 and 4. And we have added information in Figure 5.

“Comparison of the RMS value of the overall region according to the scanner. Different letters indicate the significant differences among the scanner groups by Mann-Whitney U-test and Bonferroni correction method (P<.0017).”

The English in the manuscript could be improved. For example, in Line 214, "decrease" could replace with "minimise"?

Response: Thank you for your comment. We have addressed the issue that you point out.

“To minimize decrease the impact of this variation in this study, a single operator (K.S.) conducted the evaluations after sufficiently practicing the use of each intraoral scanner.”

Please rewrite the sentence of conclusion 3.

Response: Thank you for your comment. We have addressed the issue that you point out.

“3. Both types of intraoral and laboratory scanners showed better accuracy in the anterior region compared to the posterior region (P<.001), so care should be taken in the posterior region scanning.”

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript topic is actual and the paper has merit. It could be attractive, adequate and interesting for the journal readers. However there are some point that authors should address in order to have a final more complete paper. Authors should underline the limitation of the value of the study, and the clinical rationale and implication of the presented study should be added. At this stage the paper seems to be directed to dental practitioners and not researchers. Please emphasize the clinical application of the study, and its scientific rationale.

References are inadequate. Introduction section is poor. Some more references about the recent digital workflow in dentistry just published have to be added. Please add the following ones:

Cervino, Gabriele et al. “Dental Restorative Digital Workflow: Digital Smile Design from Aesthetic to Function.” Dentistry Journal vol. 7,2 30. 28 Mar. 2019, doi:10.3390/dj7020030

At the same time discussion is poor.

In the discussion section authors should compare the results of the present study with others one presented and published in the literature. 

Author Response

We are grateful to the reviewers for their critical comments and useful suggestions that have helped us to greatly improve our paper. As indicated in the following responses, we have reflected all these comments in the revised version of our paper.

Reviewer #2

Authors should underline the limitation of the value of the study, and the clinical rationale and implication of the presented study should be added. At this stage the paper seems to be directed to dental practitioners and not researchers. Please emphasize the clinical application of the study, and its scientific rationale.

Response: Thank you for your accurate comment. We have addressed the issue that you point out.

“To minimize the impact of this variation in this study, a single operator (K.S.) conducted the evaluations after sufficiently practicing the use of each intraoral scanner. This presented study shows the overall accuracy of scanning for the complete arch, but it does not mean the recommended scan range for fixed prostheses. Therefore, according to the results of presented study, dental practitioners can be applied to the dental clinic with the intraoral scanners recommended for the scanning of the complete arch. The use of the recommended intraoral scanner for complete arch allows the acquisition of virtual models with excellent accuracy (<100 µm).”

References are inadequate. Introduction section is poor. Some more references about the recent digital workflow in dentistry just published have to be added. Please add the following ones:

Cervino, Gabriele et al. “Dental Restorative Digital Workflow: Digital Smile Design from Aesthetic to Function.” Dentistry Journal vol. 7,2 30. 28 Mar. 2019, doi:10.3390/dj7020030

Response: Thank you for your suggestion for improving the quality of the manuscript. As the reviewer points out, we have added content and reference to the introduction section.

“The introduction of intraoral scanners in the 1980s allowed the use of a fully digital workflow [1,3], which reduced the errors that may occur from the operator’s experience and the materials (impression material and plaster) used [1-3]. The recent digital workflow in dentistry has been improving the range of application and the accuracy of prosthetic fabrication due to the continuous development of dental CAD / CAM system [6].”

At the same time discussion is poor.

In the discussion section authors should compare the results of the present study with others one presented and published in the literature.

Response: Thank you for your suggestion for improving the quality of the manuscript. We have carefully considered your comments. As the reviewer points out, we have added content to the discussion section.

“Many previous studies have evaluated the accuracy of complete arch using intraoral scanners. In the studies by Park et al., the accuracy of complete arch using intraoral scanner of Trios 2, Trios 3, CS3500, and CS3600 showed 343.4 ± 56.4 µm, 183.9 ± 49.7 µm, 209.9 ± 53.7 µm, and 118.9 ± 42.1 µm, respectively. The reason for the poor accuracy compared to the results of this presented study is due to the difference in alignment method between CRM and CTM. The alignment method by Park et al. confirmed the distortion of the arch by aligning only the teeth at which the scan begins, but in this presented study, the accuracy of the entire arch was determined by aligning all the scanned teeth. In the studies by Michael Braian et al., 5 intraoral scanners were used to evaluate the accuracy of the complete arch. The accuracy of the complete arch in the 5 intraoral scanners was <193 µm, and the use of the intraoral scanner to scan the complete arch was not recommended. The results of this presented study ranged from 44.2 to 164.1 µm, and 3 intraoral scanners (CS3500, CS3600, and Trios3) were recommended, with the exception of 2 intraoral scanners (Trios2 and i500). The reason for this result is the difference in the evaluation method of accuracy. The evaluation method of accuracy by Michael Braian et al. analyzed the accuracy through the error of the arch distance, but in this presented study, it was evaluated as 3D analysis of the accuracy by inspection software.”

Author Response File: Author Response.pdf