Influence of the Number of Microthreads on Marginal Bone Loss: A Five-Year Retrospective Clinical Study in Humans

Round 1

Reviewer 1 Report

Dear Authors, the study described in the paper is interesting.

The role of these aspects in dentistry needs further studies that could be an innovative issue in this field and that could be oper a creative matter debate in literature by adding new information.

The introduction section resumes the existing knowledge regarding this topic but it needs to be improved by discussing the existing literature.

The Authors should be better specifie, at the end of the introduction section, the ratio of the study and the aim. 

The material and methods and discussion sections appear well organized.

The conclusions should be reinforced highlighting the strengths and weaknesses of the study.

Best regards

Author Response

Referee 1

Thank you for taking the time to review my paper. I appreciate your feedback and am grateful for the opportunity to address your questions.

Comments and Suggestions for Authors

The role of these aspects in dentistry needs further studies that could be an innovative issue in this field and that could be oper a creative matter debate in literature by adding new information.

1. The introduction section resumes the existing knowledge regarding this topic but it needs to be improved by discussing the existing literature.
2. The Authors should be better specifie, at the end of the introduction section, the ratio of the study and the aim. 
3. The material and methods and discussion sections appear well organized.
4. The conclusions should be reinforced highlighting the strengths and weaknesses of the study.

Best regards

In response to referee's suggestions:

1. In agreement with the referee, we have expanded the discussion by considering the existing literature and including the following paragraph in the section on discussion:” In the 1970's the accepted paradigm was that dental implants should have as polished a neck as possible to prevent plaque accumulation. For this reason, most implant manufacturers at this time adopted this design. However, finite element studies showed that stress peaks, and especially with shear forces, the stress is concentrated in the crestal bone surrounding the polished collars. Since cortical bone is 65% less resistant to shear forces than to compressive forces, we could say that the loss of bone level that occurred during the first year of function could be attributed to the lack of adequate distribution of mechanical stress between the coronal region of the implant and the surrounding bone. [4] For this purpose, we have carried out the present 5-year study comparing the result between 3 or 9 microthreads with an extension between 1 and 3 mm on the surface of the crestal module.“
2. We have expanded the purpose of this study at the end of the introduction by including the following paragraph: “Despite the literature on this topic, there remain gaps in the current research. For example, most of the research in this field has focused on finite element studies with limited research on the clinical impact in humans. It has long been proven that the presence of a rough surface or the presence of microthreads improves the distribution of mechanical stress, especially shear forces. However, we do not know the minimum number of spires required to achieve this effect, or the maximum number of spires above which no improvement would be noticeable. In addition, potential risks remain to be determined, especially during long-term follow-up periods. Therefore, more research is needed to determine the role of the number of microthreads and the potential risks of increased incidence of peri-implant disease and bone loss in humans.”
3. Thanks for your kind comment.
4. We have expanded the conclusion of this study including the following paragraph: “The conclusions should be reinforced highlighting the strengths and weaknesses of the study about dental implant microthreads. This study about dental implant microthreads was a clinical investigation into the effects of the number of microthreads on bone level. The results showed that bone level was stable regardless of the number of microthreads studied. Specifically, the presence of microthreads demonstrated its ability to maintain bone level during a 5-year follow-up, without finding differences between 3 or 9 microthreads. At the same time, the study had some weaknesses. For example, the study did not consider the effects of microthreads geometry neither the surface roughness of the implant. Hence, different geometries or roughness may have different clinical behaviour. Additionally, the study did not assess the effects of microthreads on the long-term success of dental implants (more than 5 years). Another limitation that we should consider is the platform-switched and the level of insertion of an implant. As has been demonstrated, both variables can be of paramount importance in the maintenance of the bone level [52]. Therefore, further research is needed to fully understand the effects of microthreads geometry on implant longevity and surface roughness.”

 

I hope this explanation is helpful and that it adequately answers your question. Thank you again for your time and consideration.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors,

I read with great interest the manuscript entitled "Influence of the Number of Microthreads on Marginal Bone Loss: A 5-year Retrospective Clinical Study in Humans" submitted to Applied Sciences.

I think the topic is very topical and interesting, however I suggest some changes to improve the quality of the manuscript.

- Minor check of english grammar form

- Introduction: I suggest to stress the role of biological width in MBL referring to recent literature.

"Many variables are related to marginal bone loss, including surgical trauma, occlusal 33 overload, peri-implantitis, microgap, biologic width, and implant crest module [4–6]." Reference n.4 is too old, I suggest to add this interesting recent manuscript about MBL [PMID: 36725016].

At the end of the introduction, I suggest including the null hypothesis of the study.

Methods: There are too many sub-sections. I suggest summarising and reducing them.

Discussions: This part is in accordance with the results.

I suggest to add a study limitation part at the end of this section

After the changes in the text, I suggest another round of revision.

Author Response

Referee 2

Thank you for taking the time to review my paper. I appreciate your feedback and am grateful for the opportunity to address your questions.

Comments and Suggestions for Authors

1. Minor check of english grammar form

 

2. Introduction: I suggest to stress the role of biological width in MBL referring to recent literature.

 

3. "Many variables are related to marginal bone loss, including surgical trauma, occlusal 33 overload, peri-implantitis, microgap, biologic width, and implant crest module [4–6]." Reference n.4 is too old, I suggest to add this interesting recent manuscript about MBL [PMID: 36725016].

 

4. At the end of the introduction, I suggest including the null hypothesis of the study.

 

5. Methods: There are too many sub-sections. I suggest summarising and reducing them.

 

6. Discussions: This part is in accordance with the results.

 

7. I suggest to add a study limitation part at the end of this section

 

8. After the changes in the text, I suggest another round of revision.

 

Answers

1. English grammar form has been revised through AME
2. In agreement with the referee, we consider that the role of the supracrestal insertion (previously called biological width) is fundamental and one of the possible causes of bone loss in dental implants. Therefore, and in accordance with his suggestion, we have included the following paragraph: “The exact effect of subcrestal insertion on dental implant stability is still under investigation. However, research has shown that subcrestal insertion may help improve implant stability and reduce the risk of failure. Studies have demonstrated that inserting a dental implant slightly subcrestal can help increase primary stability, reduce micro-movement, and improve implant osseointegration. Additionally, subcrestal insertion may help reduce crestal bone resorption and decrease the risk of implant failure.”
3. This study provides a useful insight into the effects of implant placement on peri-implant marginal bone changes. W agree that this study is analyzing early marginal bone modifications around platform-switched implants with conical connections placed 1 or 2 mm subcrestally. However,our study focuses on the presence of microthreads and not so much on the platform change, since the two designs studied have an equal platform change (>0.4 mm). We acknowledge that our research has certain limitations, such as the small sample size and the limited scope of our study. we have included the following setence as an important part of our limitations “Another limitation that we should consider is the platform-switched and the level of insertion of an implant. As has been demonstrated, both variables can be of paramount importance in the maintenance of the bone level [52].” [52] Stacchi C, Lamazza L, Rapani A, Troiano G, Messina M, Antonelli A, Giudice A, Lombardi T. Marginal bone changes around platform-switched conical connection implants placed 1 or 2 mm subcrestally: A multicenter crossover randomized controlled trial. Clin Implant Dent Relat Res. 2023 Feb 1. doi: 10.1111/cid.13186. Epub ahead of print. PMID: 36725016.
4. The null hypothesis has been introduced at the end of the introduction: “The null hypothesis of the study is that there is no significant difference between the number of microneedles and bone level in implants followed for 5 years.”
5. The referee is right, but we consider that these sections can help to replicate our experience by facilitating all the steps of our method.
6. We agree with the referee and have included the limitations of our study.”The conclusions should be reinforced highlighting the strengths and weaknesses of the study about dental implant microthreads. This study about dental implant microthreads was a clinical investigation into the effects of the number of microthreads on bone level. The results showed that bone level was stable regardless of the number of microthreads studied. Specifically, the presence of microthreads demonstrated its ability to maintain bone level during a 5-year follow-up, without finding differences between 3 or 9 microthreads. At the same time, the study had some weaknesses. For example, the study did not consider the effects of microthreads geometry neither the surface roughness of the implant. Hence, different geometries or roughness may have different clinical behaviour. Additionally, the study did not assess the effects of microthreads on the long-term success of dental implants (more than 5 years). Another limitation that we should consider is the platform-switched and the level of insertion of an implant. As has been demonstrated, both variables can be of paramount importance in the maintenance of the bone level [52]. Therefore, further research is needed to fully understand the effects of microthreads geometry on implant longevity and surface roughness.”

 

7. Thanks for your kind comment.

 

8. We agree with your comment, and hope to improve our work with your future suggestions.

 

I hope this explanation is helpful and that it adequately answers your question. Thank you again for your time and consideration.

Author Response File: Author Response.docx

Reviewer 3 Report

Introduction

- add the study hypotheses at the end of the paragraph

Materials and methods

- State the inclusion/exclusion criteria for the patient enrolling. Example, systemic patients, ages, hospitalized patient, etc. Please be as more as accurate to ensure the reproducibility of the study. Currently, they are only described related to the radiographic images.

- I had some confusion in the inclusion criteria currently stated. What do you mean with ''Patients who met the Albrektsson success criteria.'' ? I know the criteria, but I'm not understanding how they can be an inclusion criteria. otherwise, it means that you excluded all the implants that failed or that were categorized under survival but not success, leading to a non sense in the study. Please clarify this important point. In addition, add the reference where the criteria that you followed are stated. 

- Did you perform any soft or hard tissue graft?  Please revised the M&M section paying attention to the carefully description of the sample.

- Were all the implants single unit? or did u evaluate also multi-unit implants?

Discussion:

- Discuss if the study hypotheses were accepted or rejected.

- Discuss the results of the study related to marginal bone loss with other implant' designs. For this propose discuss and cite this paper doi: 10.1111/cid.13113

 

Author Response

Referee 3

Thank you for taking the time to review my paper. I appreciate your feedback and am grateful for the opportunity to address your questions

Comments and Suggestions for Authors

Introduction

1- add the study hypotheses at the end of the paragraph

Materials and methods

2- State the inclusion/exclusion criteria for the patient enrolling. Example, systemic patients, ages, hospitalized patient, etc. Please be as more as accurate to ensure the reproducibility of the study. Currently, they are only described related to the radiographic images.

3- I had some confusion in the inclusion criteria currently stated. What do you mean with ''Patients who met the Albrektsson success criteria.'' ? I know the criteria, but I'm not understanding how they can be an inclusion criteria. otherwise, it means that you excluded all the implants that failed or that were categorized under survival but not success, leading to a non sense in the study. Please clarify this important point. In addition, add the reference where the criteria that you followed are stated. 

4- Did you perform any soft or hard tissue graft?  Please revised the M&M section paying attention to the carefully description of the sample.

5- Were all the implants single unit? or did u evaluate also multi-unit implants?

Discussion:

6- Discuss if the study hypotheses were accepted or rejected.

7- Discuss the results of the study related to marginal bone loss with other implant' designs. For this propose discuss and cite this paper doi: 10.1111/cid.13113

Answer to referee 3:

1. We have added our working hypothesis at the end of the introduction. “The null hypothesis of the study is that there is no significant difference between the number of microneedles and bone level in implants followed for 5 years.”
2. We have specified the inclusion criteria, specifying age and general health status according to ASA criteria. "The patients were over 18 years of age. ASA stage 1 or 2, patients requesting outpatient treatment."
3. We agree with the referee and have clarified when the success criteria were applied. We value the success at the moment of discovering the implants 2 months after their insertion, and before delivery of the prosthesis. In this way we ruled out bone loss due to other causes (surgical trauma, integration failures). We have specified these criteria in synthesis and the moment of their application. “At the time of discovery of the impalts (2 months after insertion) the implants were considered successful when they met the Albrektsson success criteria. In summary: absence of mobility, absence of pain, absence of radiographic radiolucency, absence of invasion of anatomical structures.”
4. We agree with the referee and have specified in material and methods that the patients included in the study did not receive any additional soft or hard tissue augmentation procedures. "Patients who did not require guided tissue regeneration or bone grafting techniques."
5. Implants were considered as the unit of measurement. We have specified in material and methods that "implants were considered as the unit of measurement and only one implant per patient was studied, being this the first implant inserted in the case of needing several implants."
6. We agree with the referee and have included the following sentence in the discussion: “The study on the effect of microthreads on bone loss yielded results supporting the hypothesis that microthreads can reduce bone loss with no difference found between 3 or 9 microthreads or between 1 or 3 mm.”
7. We have included and discussed the requested article. "Currently, many of the accepted paradigms have been questioned. In order to guarantee an adequate clinical outcome, we no longer look for the longest and widest implants possible, since short but well-designed implants are capable of obtaining an adequate clinical outcome. [53]”

 

We hope this explanation is helpful and that it adequately answers your question. Thank you again for your time and consideration.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Dear Authors

All my suggestions have been addressed. Now the manuscript has been improved and it is suitable for publication.

Best regards 

Reviewer 2 Report

Authors improved manuscript quality.

Reviewer 3 Report

The Authors modified the manuscript correctly.