Evaluation of Stress Distribution of Maxillary Anterior Segment during en Masse Retraction Using Posterior Mini Screw: A Finite Element Study

Round 1

Reviewer 1 Report

Abstract: Delete the first sentence of this section on lines 18 and 19. No descriptive sentence is needed here. Start directly with purpose.

Introduction: This chapter is well written. It doesn't need to be fixed.

Materials and methods: 112-114. There is no date and approval number of the ethics committee mentioned in the lines. Please add this information.

The study has no inclusion or exclusion criteria. Please specify them clearly.

There is no section on how statistical analysis is done. At the end of the material method section, please create a title about it. State them all clearly.

Discussion: The judgments in the sentences in lines 360-362 are based solely on the results of your own work. Please support this topic from the literature. Include other references.

References: References 2, 3, 16, 23, 26, 29, 30, 32, 33, 34, 37, 38, 42, 46, 48, 49, 51, 52 are very old. Please replace with new ones.

Author Response

 "Please see the attachment."

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript "Evaluation of stress distribution of maxillary anterior segment during en masse retraction using posterior mini screw" by Ali et al. was well organized, but some points need more details or clarification.

(1) No. 4 and 8 in Table 3 "right implant" and "left implant" must be defined in the main text or described in the legend.

(2) The second question relates to the significance of the results, i.e., how relevant or approvable are the data in terms of statistics?

(3) Could the authors add more information about the method/analysis design (for general readership) and how it relates to en masse retraction. Also how the results can be applied to improve clinical therapy or support patients.

Author Response

 "Please see the attachment."

Author Response File: Author Response.docx

Reviewer 3 Report

This manuscript presents a numerical investigation of the stress distribution of maxillary anterior segment during en masse retraction using posterior mini screw. This work is rather interesting but in some parts the investigation is not comprehensive and several modifications are required before it can be recommended for publication.

In the Introduction section please add a suitable reference in the first paragraph, line 44. Moreover, the authors should discuss the findings of some more studies regarding FE models for orthodontic applications in order to further prove the significance of their work. 

The authors should add a suitable schematic in order to depict all the mentioned medical terms.

Based on the material properties presented in Table 2, it seems that a simple elastic isotropic material model was used. The choice about using an elastic isotropic material model for all materials used in the model should be justified based on the actual mechanical behavior of these materials. For example, is this material model valid for both tooth and periodontal ligament?

Did the authors perform a mesh independence study in order to determine the number of elements used for each component of the model and the size of the elements in each region? This is essential in order to ensure the accuracy of the model.

In Figures 3a and b the height of the placement of the power arm should be indicated.

In Figure 4, it is shown that the bone region is divided into soft and hard bone. Why did the authors not use different material properties for soft and hard bone respectively?

The simulations presented in this work are few and the discussion about the FE models' results is not sufficient. It is suggested that the authors evaluate other alternatives apart from Model 1 and 2 or test additional placement heights in order to present a more comprehensive study. A comparison between the results of alternative models should be conducted and appropriate graphs should be added. Figures 4b and c as well as 5b and c should be enlarged and additional figures should be presented with zoom in the areas where the highest stresses and deformations occur.

Finally, more conclusions should be presented at the end of the paper, based on the findings from the simulations.

Author Response

 "Please see the attachment."

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

The authors performed only a few modifications to their manuscript, thus it is suggested that they perform all the necessary mandatory modifications before the manuscript can be evaluated again.

1) The authors should add a suitable figure to show all the medical terms mentioned in the manuscript, especially those mentioned in the FE model.

2) In Table 1, the authors mention three different regions of the model: tooth, periodontal ligament and bone.  However, in Table 2, only two material models are defined: tooth and bone. Thus, which material model is employed for the region of periodontal ligament? The authors should justify their choice.

3) The authors should perform a mesh independence study e.g. create models with increasing number of finite elements and compare their accuracy in order to choose the appropriate number of finite elements for their model. This is essential for a FE simulation in order to justify the number of elements used in each area.

4) The authors should clarify how the soft and hard bone were modeled in order to have the appropriate behavior. Did they use different material properties or are they simply different regions of the model? This should be clarified in the manuscript.

5) Given that the simulations are few the authors should conduct at least 2-3 more simulations with different placement heights and discuss them appropriately.

Author Response

"Please see the attachment"

Author Response File: Author Response.docx

Round 3

Reviewer 3 Report

The authors have performed some of the recommended corrections. The manuscript can now be accepted.