Anchorage Loss Evaluation during Maxillary Molars Distalization Performed by Clear Aligners: A Retrospective Study on 3D Digital Casts
Round 1
Reviewer 1 Report
This is a well designed and fairly well written article of narrow scope. It looks at one thing only, anchorage loss in the upper arch relating to the premolars and canines during molar distalization. I accept the results for what they are and these results are of clinical interest, however by their own admission, the authors did not look at anterior anchorage loss nor the final results at the completion of treatment. For what it is, it is a valid contribution to the professional literature.
Author Response
Point 1: This is a well designed and fairly well written article of narrow scope. It looks at one thing only, anchorage loss in the upper arch relating to the premolars and canines during molar distalization. I accept the results for what they are and these results are of clinical interest, however by their own admission, the authors did not look at anterior anchorage loss nor the final results at the completion of treatment. For what it is, it is a valid contribution to the professional literature.
Response 1: Dear Reviewer, thank you for your comments and your approval.
Reviewer 2 Report
This study is relevant in the field of modern orthodontics and tries to answer a very popular question in the everyday clinical practice. This study has many limitations due to the analysis, that was selected. However, due to the overall lack of evidence in the field this article has merit. The authors have already addressed these limitations to a degree, and but the manuscript still needs some improvements.
Major concerns
1) Interoperator error testing is important to improve the validity of the results. If possible Bland-Altman plots should be used, as the ICC does not report the effect size of the found differences and tends to average them.
2) The lack of a control group should be addressed in the limitations and the discussion of the article.
Minor concerns
1) Please report the full definition of the abbreviation CAT at the first appearance in the manuscript.
2) Avoid one-sentence paragraphs in the discussion as it inhibits the natural flow of the text.
3) There are repeated arguments in the discussion. Shortening it would improve the overall readability. The same can be said for the introduction, especially for the 3rd paragraph.
P.S. (for future research). Ideally superimposition techniques should be used to minimize operator error and to be able to accurately measure rotational changes, tipping and translation. These measurements could be possible with the Viewbox 4 software that was used in this study, by superimposing the two models with the 3rd ruga as reference. Then one can manually select each crown at T2, create a new model of it and superimpose it on the T1 model. This positional change is then registered as rotation, tipping and translation in the properties of the moved crown.
Author Response
This study is relevant in the field of modern orthodontics and tries to answer a very popular question in the everyday clinical practice. This study has many limitations due to the analysis, that was selected. However, due to the overall lack of evidence in the field this article has merit. The authors have already addressed these limitations to a degree, and but the manuscript still needs some improvements.
Dear Reviewer, thanks for your comments.
Point 1: Interoperator error testing is important to improve the validity of the results. If possible Bland-Altman plots should be used, as the ICC does not report the effect size of the found differences and tends to average them.
Response 1: Dear Reviewer, thanks for your annotation. As a unique operator made and repeated the measurements (always the same operator), we decided to assess only the intra-operator reliability, because none of us except this clinician worked on the measurements.
Point 2: The lack of a control group should be addressed in the limitations and the discussion of the article.
Response 2: Dear Reviewer thanks for your suggestion. We added this information in the limitations and discussion sections. “Moreover, the absence of a comparison between CAT therapy and conventional distalization treatment as control group can be considered a limitation of the study.”
Point 3: Please report the full definition of the abbreviation CAT at the first appearance in the manuscript.
Response 3: Dear Reviewer, thanks for your note. We reported the exact definition of the abbreviation CAT in the text: “clear aligners treatment: CAT”
Point 4: Avoid one-sentence paragraphs in the discussion as it inhibits the natural flow of the text. 3) There are repeated arguments in the discussion. Shortening it would improve the overall readability. The same can be said for the introduction, especially for the 3rd paragraph.
Response 4: Dear Reviewer, thanks for your suggestion. We improved the introduction and the discussion section.
Reviewer 3 Report
Introduction:
Claims not supported by the references (I find those references to be inappropriate):
"Therefore, the orthodontic treatment with removable clear aligners (CAT) has become an increasingly common comfortable and more hygienic alternative to conventional fixed appliances [15-17]."
Materials and Methods:
Please, describe more detailed: "For each patient, the ClinCheck was planned by the same operator with the same standardized distalization protocol, which consisted of 50% sequential distalization till the achievement of the Class I molar and premolars relationships, mesial out of upper first molars simultaneously with distalization movements and retraction “en masse” of the anterior group."
Please, describe more detailed, how did you perform measurements, how did you position scans for measurements, to ensure comparison between two scans? Did, possibly, derotation of molars influence your results, or was it pure translation? Your method has limitations, maybe you should rephrase some findings?
Can you compare your results to the predicted tooth movement (in Clincheck)?
Why did you not include incisors into evaluation, as other researchers also report even more anchorage loss in those teeth?
Can you discriminate anchorage loss between those who wore Class II elastics poor and others? Also, it is not clear in the M&M section that you evaluated cooperation for CA and elastics separately, please clarify.
The sentence beginning from the line 137 is not clear, please, clarify (" Whenever aligners fit was poor, new scans were taken and a prescription form was set up to continue treatment until the same final position was realized in the first approved ClinCheck.").
When you describe landmarks for measurements, please choose "or/and", is it left or right, or is it left and right....? Also, when you describe premolar cusps, you always have the same text "of the cusp of the second first right or/and left premolar", please correct, is it "first" or "second", is it "and" or "or"?
Discussion:
please, clarify, add reference to your claims: "In fact, CA is a closed system of forces and the applied distalization movement could produce a plastic deformation of its structure, which "stretches" distally and produces a reaction force in the anterior part of the arch."
Conclusion:
Claim not supported by results: "Therefore, the use of the specific protocol with Class II elastics is essential to prevent the anchorage loss."
Please, check again English language throughout the text, there are some mistakes, like "Digital casts before treatment (T1) and at the achievement of first Class I molar relationship..." in Line 18.
Author Response
Point 1: Claims not supported by the references (I find those references to be inappropriate): "Therefore, the orthodontic treatment with removable clear aligners (CAT) has become an increasingly common comfortable and more hygienic alternative to conventional fixed appliances [15-17]."
Response 1: Dear Reviewer, thanks for your note. We added the right reference.
Point 2: Please, describe more detailed: "For each patient, the ClinCheck was planned by the same operator with the same standardized distalization protocol, which consisted of 50% sequential distalization till the achievement of the Class I molar and premolars relationships, mesial out of upper first molars simultaneously with distalization movements and retraction “en masse” of the anterior group."
Response 2: Dear Reviewer, thanks for your suggestion. We added more details about the treatment protocol in the materials and methods section. “Sequential distalization of upper arch protocol consists in moving one tooth at a time, beginning from the upper second molars. When the second molars have completed two thirds of their way, the first molars move back and so on, until the “en masse” retraction of the incisors group. Class II elastics were used to support distal movements and provided from the start of treatment.”
Point 3: Please, describe more detailed, how did you perform measurements, how did you position scans for measurements, to ensure comparison between two scans? Did, possibly, derotation of molars influence your results, or was it pure translation? Your method has limitations, maybe you should rephrase some findings?
Response 3: Dear Reviewer, thanks for your notes. As we stated at the end of the discussion section the analysis applied didn’t consider the exact root positions and the degree of crown tipping and it is a limitation of the study. For the analysis, we used the palatal rugae and the mid-palatal raphe as reference axis since in literature it’s reported they are reliable structures and our patients didn’t undergo to orthopaedic treatment that could modify the palate.
Point 4: Can you compare your results to the predicted tooth movement (in Clincheck)?
Response 4: Dear Reviewer, thanks for your comment. We didn’t make this analogy because the comparison between the obtained movement and the predicted movement by the Clincheck wasn’t the aim of the research. It will be of course a starting point for a further research.
Point 5: Why did you not include incisors into evaluation, as other researchers also report even more anchorage loss in those teeth?
Response 5: Dear Reviewer, thanks for your comment. We decided to evaluate only the anchorage loss of the premolars and canines because in some patients the incisors started to be aligned before the achievement of the first molar occlusion relationship and this could represent a bias in the measurements. In fact one of the advantage of CAT is the possibility to plan the molar backward movement and teeth alignment simultaneously, thus reducing treatment duration.
Point 6: Can you discriminate anchorage loss between those who wore Class II elastics poor and others? Also, it is not clear in the M&M section that you evaluated cooperation for CA and elastics separately, please clarify.
Response 6: Dear Reviewer, thanks for your suggestion. We clarify the concept in the M&M section: “A single operator through two different interviews appraised patient’s compliance with aligners and with elastics. Compliance was assessed on a 3 points Likert-type scale (poor, moderate, good) [25]. Compliance was rated poor when the patient wore the aligners for less than 16 hours per day, moderate when the use was between 16 and 20 hours per day, and good when the patient wore the aligners full time, as recommended by the clinicians. The same scale was used to assess the cooperation with elastics.”.
As regards the different cooperation with Class II elastics, we have the results of the anchorage loss of all the patients (with both good and poor collaboration) but we didn’t want to add too many examined variables to this study. Our aim was to evaluate if anchorage loss on premolars and canines is present in the clear aligners therapy. However we are collecting a larger sample for a second research in which we will compare the different cooperation with the degree of anchorage loss.
Point 7: The sentence beginning from the line 137 is not clear, please, clarify (" Whenever aligners fit was poor, new scans were taken and a prescription form was set up to continue treatment until the same final position was realized in the first approved ClinCheck.").
Response 7: Dear Reviewer, thanks for your note. The sentence was rephrased “If the aligners lost their fitness due to the poor cooperation, new scans were necessary but the prescription form of the therapy was set up to continue treatment until the same final position decided in the first approved ClinCheck.”
Point 8: When you describe landmarks for measurements, please choose "or/and", is it left or right, or is it left and right....? Also, when you describe premolar cusps, you always have the same text "of the cusp of the second first right or/and left premolar", please correct, is it "first" or "second", is it "and" or "or"?
Response 8: Dear Reviewer, thanks for your note. The landmarks description was correct.
Point 9: please, clarify, add reference to your claims: "In fact, CA is a closed system of forces and the applied distalization movement could produce a plastic deformation of its structure, which "stretches" distally and produces a reaction force in the anterior part of the arch."
Response 9: Dear Reviewer, thanks for your note. We added the reference for the sentence.
Point 10: Claim not supported by results: "Therefore, the use of the specific protocol with Class II elastics is essential to prevent the anchorage loss."
Response 10: Dear Reviewer, thanks for your advice. We crossed out this claim from the conclusion section.
Point 11: Please, check again English language throughout the text, there are some mistakes, like "Digital casts before treatment (T1) and at the achievement of first Class I molar relationship..." in Line 18.
Response 11: Dear Reviewer, thanks for your note, we checked the English language.
Reviewer 4 Report
Dear Authors,
very well designed paper, with important results. I have no other suggestions.
Author Response
Dear Authors, very well designed paper, with important results. I have no other suggestions.
Dear Reviewer, thank you for your comments and your approval.
Round 2
Reviewer 2 Report
The manuscript is now much better. Nothing further to comment.
