Changes and Remodeling of Intersegmental Interferences following Bilateral Sagittal Split Ramus Osteotomy in Patients with Mandibular Prognathism

Round 1

Reviewer 1 Report

The article presented for evaluation is based on the analysis of changes of the madnibular angle, the intergonial width and the total angle directly after surgery and 1 year after surgery in patients with mandibular prognatism subjected to orthognathic surgery procedures. The title of the article suggests that the authors should evaluate the facial appearance of patients with mandibular prognatusm after orthognathic surgery and correlate the results with the craniometric measurements. Changes in the appearance of the face are influenced not only by the changes in the facial skeleton, but also the alterations in the configuration of soft tissues caused by the changes in the craniofacial skeleton.

The aim of the research work presented in the last paragraph of the Introduction also does not correspond to the title of the article.

Specific comments:

1. For the article entitled "Factors affecting postoperative facial appearance in patients with mandibular prognathism: Mandibular angle, mandibular width, and ramus angulation", it is necessary to make specific measurements of the face on the photos of the face and correlate them with the appropriate measurements of the facial skeleton.
2. The "Metrials and Methods" section lacks a description of how the adequate measurements were performed. Were the measurements performed by one researcher? What was the precision and repeatability of the performed measurements? For example, the statement "intergonial width decreased by 0.01mm on average immediately after surgery" seems to be below the detection capability in the measurements performed on CBCT images.
3. When considering changes in the angle of the mandible as a result of orthognathic surgery in patients with mandibular prognathism, it is necessary to provide baseline measurements including the angle of the mandibular base in relation to the base of the maxilla and the skull base. Changes in the mandible angle as a result of surgery in patients with mandibular prognatism depend on vertical alterations of the facial skeleton in these patients.
4. In the Discussion section there is a paragraph: “Removing the posterior part of the distal segment of the mandible is done in order to reduce post-operative relapse in cases with mandibular prognathism. The rationale of this method was to reduce the traction force of the pterygo-masseteric sling applied on the distal segment of the mandible following setback. The bilateral 'Internal angle reduction' is an additional procedure to further reduce post-operative relapse. " Is it the authors personal opinion? If not, please add adequate references.
5. In the "Discussion" section, please add a paragraph about the practical significance of the performed research for a maxillofacial surgeon dealing with orthognathic surgery.
6. The conclusions of the article concerning the mandible remodeling do not correspond to the title and purpose of the work and must be redrafted.

Author Response

The article presented for evaluation is based on the analysis of changes of the mandibular angle, the intergonial width and the total angle directly after surgery and 1 year after surgery in patients with mandibular prognathism subjected to orthognathic surgery procedures. The title of the article suggests that the authors should evaluate the facial appearance of patients with mandibular prognathism after orthognathic surgery and correlate the results with the craniometric measurements. Changes in the appearance of the face are influenced not only by the changes in the facial skeleton, but also the alterations in the configuration of soft tissues caused by the changes in the craniofacial skeleton.

The aim of the research work presented in the last paragraph of the Introduction also does not correspond to the title of the article.

Specific comments:

1. For the article entitled "Factors affecting postoperative facial appearance in patients with mandibular prognathism: Mandibular angle, mandibular width, and ramus angulation", it is necessary to make specific measurements of the face on the photos of the face and correlate them with the appropriate measurements of the facial skeleton.
   
   

We appreciate the reviewer’s valuable comment. We used each measurement value to predict facial and skeletal changes in the front and lateral side due to intersegmental interference and condylar changes after BSSO. Although soft tissue changes were not directly analyzed, we have thought that skeletal changes could reflect soft tissue changes. We therefore changed the title of the manuscript as per your comment avoiding any misunderstanding. The new title reads ‘Changes and Remodeling of Intersegmental Interferences following Bilateral Sagittal Split Ramus Osteotomy in Patients with Mandibular Prognathism.’

1. The "Materials and Methods" section lacks a description of how the adequate measurements were performed. Were the measurements performed by one researcher? What was the precision and repeatability of the performed measurements? For example, the statement "intergonial width decreased by 0.01mm on average immediately after surgery" seems to be below the detection capability in the measurements performed on CBCT images.

Thank you for the reviewer’s comment. The authors used the Marosis m-view 5.4 system, which can measure up to 0.01mm. Each measurement was repeated three times by the single investigator (MAJ). A landmark that does not change before and after surgery was used to avoid differences and a method of calculating the average of similar measurements was adopted after excluding values with significant differences in each measurement. Statistical significance of the preoperative and postoperative comparison values unobtainable for some results.

 

 

1. When considering changes in the angle of the mandible as a result of orthognathic surgery in patients with mandibular prognathism, it is necessary to provide baseline measurements including the angle of the mandibular base in relation to the base of the maxilla and the skull base. Changes in the mandible angle as a result of surgery in patients with mandibular prognathism depend on vertical alterations of the facial skeleton in these patients.
   
   

The authors agree with the reviewer’s point. Firstly, the authors did not set the skull base landmark line on the lateral side, but we took it based on the patient's FH plane in the process of taking the lateral cephalogram. Also, in the PA cephalogram, based on the line connecting the most superior point of orbit as a horizontal landmark to measure the angulation of the ramus consistently and the tangent value between the angulations of the ramus was measured. Soft tissue to hard tissue ratios varies in the horizontal and vertical planes, which can make it difficult to predict soft tissue changes after surgery. Therefore, as the reviewer pointed out, this is a limitation of this paper as we did not measure soft tissue changes.

1. In the Discussion section there is a paragraph: “Removing the posterior part of the distal segment of the mandible is done in order to reduce post-operative relapse in cases with mandibular prognathism. The rationale of this method was to reduce the traction force of the pterygo-masseteric sling applied on the distal segment of the mandible following setback. The bilateral 'Internal angle reduction' is an additional procedure to further reduce post-operative relapse. " Is it the authors personal opinion? If not, please add adequate references.
   
   

Firstly, since the authors generally want patients to have a smooth, small and narrow facial profile. The authors evaluated the patient's facial appearance before and during surgery, and performed angle reduction and reshaping to improve the facial profile in patients with prominent mandible angles. This reduction was performed both internally and externally in the gonial angle region, and it reduces the intersegmental interference, and through osseous remodeling through this process, muscle atrophy or volumetric decrease of the masseteric muscle are also reported in previous studies [19-20]. As the reviewer pointed out, considering the amount of relapse, it can be seen that the remodeling of the bone fragments and the effect of muscle contraction and improvement of the appearance are considered to have more priority than the aspect where the distal segment has been removed. -Yang DB, Park CG. Mandibular contouring surgery for purely aesthetic reasons. Aesthetic Plast Surg. 1991;15:53– 60. --Baek SM, Baek RM, Shin MS. Refinement in aesthetic contouring of the prominent mandibular angle. Aesthetic Plast Surg. 1994;18:283–289. -- Yang DB, Song HS, Park CG. Unfavorable results and their resolution in mandibular contouring surgery. Aesthetic Plast Surg. 1995;19:93–102.

 

1. In the "Discussion" section, please add a paragraph about the practical significance of the performed research for a maxillofacial surgeon dealing 

Thank you for the reviewer’s comment. The main point of this study is that the mandibular width temporarily increases immediately following BSSO setback. Then gradually this results in a consistently aesthetic result due to the decrease of the mandibular width. This occurs as a result of bone remodeling after 1 year representing changes and remodeling of the mandibular intersegmental interferences. As per the reviewer’s suggestion, two insertions were added to the Discussion section to describe the ‘practical significance’ of the removal of interferences at the Gonial angle.

 

Author Response File: Author Response.docx

Reviewer 2 Report

I suggest revising the manuscript and improving the writing of the first paragraph of  the "results".
The title does not reflect the study described in the manuscript, since the authors did not evaluate facial esthetics. I suggest changing the title by eliminating this reference.
In the discussion, the authors should explain the behavior of the cephalometric variables studied for each of the groups.It is important to know whether it is possible to predict changes in these cephalometric variables through the magnitude of mandibular setback.

Author Response

I suggest revising the manuscript and improving the writing of the first paragraph of the "results".
The title does not reflect the study described in the manuscript, since the authors did not evaluate facial esthetics. I suggest changing the title by eliminating this reference.
In the discussion, the authors should explain the behavior of the cephalometric variables studied for each of the groups. It is important to know whether it is possible to predict changes in these cephalometric variables through the magnitude of mandibular setback.

As the reviewer suggested, the authors revised the first paragraph of the Results section and the title of the manuscript to “Changes and Remodeling of Intersegmental Interferences Following Bilateral Sagittal Split Ramus Osteotomy in Patients with Mandibular Prognathism” as being more appropriate.   As the amount of mandibular setback was small, the mandibular angle showed a greater tendency to decrease 12 months after surgery (GIII<GII<GI), but this was not statistically significant The intergonial width There was no correlation with the amount of mandibular setback (Table 4.) In addition, the greater the amount of mandibular setback, the greater the decrease in total angulation (G I<GII<GIII),

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

I accept all the changes made to the original manuscript and I am satisfied with the authors' explanations to my remarks.

Please clarify the sentcence "Axial Condyle axis is Becktor et al. [6]
according to the maximum near-lateral dimension of the condyle". (lines 133-134)

Author Response

I appreciate for your kind review and comment.

The sentence has been corrected as below.

"The condylar axial axis was drawn from the outermost part or the condylar lateral pole to the innermost part of the medial pole of the condyle, in its greatest mesio-lateral dimension, as described originally by Becktor et al. [6]"