The Effect of Increasing Thread Depth on the Initial Stability of Dental Implants: An In Vitro Study

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript aims to investigate the influence of varying thread depths on the primary stability of dental implants in low-density bone using in vitro methods. The manuscript in its current form requires a Major Revision before it can be considered for publication. Below are detailed comments and questions aimed at improving the quality and clarity of the manuscript:

1) The rationale behind choosing the specific thread depths (4, 4.5, 5, and 5.5mm) is not fully explained. Why were these particular depths selected? Would it be beneficial to include an explanation that correlates these depths with clinical relevance or commonly used implant systems?

2) The choice of using D3-type artificial bone blocks needs further justification. How well does D3-type artificial bone simulate the clinical conditions of soft bone? Are there any limitations to using artificial bone instead of cadaveric or clinical samples?

3) The manuscript mentions the use of Osstell ISQ for measuring implant stability. Were there any calibrations or validations performed before using the device? How was measurement reliability ensured?

4) The manuscript mentions Bonferroni correction in multiple comparisons. However, the risk of Type II errors due to this conservative approach should be discussed, especially given the small sample size.

5) The correlation between IT and ISQ values is presented, but the manuscript should include a scatter plot with a regression line to visually represent this correlation.

6) The sample size of 24 implants seems limited. Was a power analysis performed to determine if this sample size is adequate to detect significant differences? If not, please discuss the potential impact of the small sample size on the study’s conclusions.

7) There is a lack of critical analysis regarding potential biases or confounding factors in the study. For example, could the uniformity of the artificial bone block affect the generalizability of the results?

8) The conclusion should not only summarize the findings but also suggest practical recommendations for clinicians based on the results. What thread depth would be ideal in clinical practice, and under what conditions?

Comments on the Quality of English Language

The manuscript would benefit from a thorough review of language and grammatical errors. Consider professional editing to improve clarity and readability.

Author Response

General comments) This manuscript aims to investigate the influence of varying thread depths on the primary stability of dental implants in low-density bone using in vitro methods. The manuscript in its current form requires a Major Revision before it can be considered for publication. Below are detailed comments and questions aimed at improving the quality and clarity of the manuscript:

Response to General Comments: Thank you for the valuable review of this paper. The authors have made changes to address it and we find that the resulting paper has improved with your insights.

Comment 1) The rationale behind choosing the specific thread depths (4, 4.5, 5, and 5.5mm) is not fully explained. Why were these particular depths selected? Would it be beneficial to include an explanation that correlates these depths with clinical relevance or commonly used implant systems?

Response 1: All these implants have a 3.3mm implant core and an increasing thread depth providing implants with a total width of 4, 4.5, 5 and 5.5mm. These commercially available implants (Anyridge, Megagen, South Korea) were selected in order to answer the question in study by providing a 0.5mm sequential increase using diameters commonly used in posterior soft bone areas.

Comment 2) The choice of using D3-type artificial bone blocks needs further justification. How well does D3-type artificial bone simulate the clinical conditions of soft bone? Are there any limitations to using artificial bone instead of cadaveric or clinical samples?

Response 2. The protocol used is an in vitro pre-clinical study and the use of cadaveric or clinical samples was not considered for this work due to unavailable logistical and ethical requirements (it is, no doubt, something to consider in future related work. Commercially available (Bone Models, Spain) D3 artificial bone blocks were used in an attempt to standardize the protocol and correlate the results to clinical findings in the same bone-type. It is a limitation of this study and is reported as such. Suggestion of future research using cadaveric or clinical samples was inserted in the “limitations” section of the Discussion.

Comment 3) The manuscript mentions the use of Osstell ISQ for measuring implant stability. Were there any calibrations or validations performed before using the device? How was measurement reliability ensured?

Response 3. A calibrated investigator (Chiara C.) did all the measurements. Ahead of the protocol, a 4x10 implant placed in the same bone blocks was submitted to SmartPeg manual placement and ISQ measurements 5 times a day for 3 days in all V, P, M and D positions. Non-parametric Friedman test was used and no significant difference between measurements was observed. The information regarding a calibrated investigator was added to M&M.

Comment 4) The manuscript mentions Bonferroni correction in multiple comparisons. However, the risk of Type II errors due to this conservative approach should be discussed, especially given the small sample size.

Response 4. Bonferroni correction was performed because non-parametric Kruskal-Wallis test was used for multiple comparisons and due to the small sample size in order to reduce the risk of false positives. Information on this was added to the M&M.

 

Comment 5) The correlation between IT and ISQ values is presented, but the manuscript should include a scatter plot with a regression line to visually represent this correlation.

Response 5. Thank you for the suggestion, Fig.4 was added to the manuscript to answer this.

Comment 6) The sample size of 24 implants seems limited. Was a power analysis performed to determine if this sample size is adequate to detect significant differences? If not, please discuss the potential impact of the small sample size on the study’s conclusions.

Response 6. All available samples were used for this study. Sample size calculation was not performed due to this fact. The small sample size is a clear limitation of this study and affects the external validity of the results. The conclusions are valid for the sample in test and suggestions are made according to our results. Information on this limitation and the effect it has in the interpretation of the results has been added to the manuscript to further address the reviewer’s observation.

Comment 7) There is a lack of critical analysis regarding potential biases or confounding factors in the study. For example, could the uniformity of the artificial bone block affect the generalizability of the results?

Response 7 Limitations section in the Discussion has been improved to further answer the reviewer valuable comments. Also, in the “ISQ results discussion”, the subject is addressed.

Comment 8) The conclusion should not only summarize the findings but also suggest practical recommendations for clinicians based on the results. What thread depth would be ideal in clinical practice, and under what conditions?

Response 8. Conclusions section has been updated (within the limitations of this study) to better address a recommendation for clinicals based on the results by suggesting that, when there is sufficient bone available and in the presence of soft bone, a deeper threaded implant can have an increased initial stability.

 

Comment 9) Comments on the Quality of English Language

The manuscript would benefit from a thorough review of language and grammatical errors. Consider professional editing to improve clarity and readability.

Response 9. Manuscript language and grammar have been reviewed to answer the reviewer comment.

Reviewer 2 Report

Comments and Suggestions for Authors

The present article, "The Effect of Increasing Thread Depth on the Initial Stability of Dental Implants: An In Vitro Study", was undertaken to evaluate how dental implant thread depth could affect primary stability, with varied focus on low-density bone, D3. Twenty-four dental implants of differing thread depths were divided into four groups and tested in type D3 artificial bone blocks. This study therefore shows that deeper threads could be more suitable for the achievement of primary stability required for softer bones, with which the success of dental implants is identified in many immediate loading protocols.

It also acknowledges its specific limitations, such as the in vitro nature of this research work, the use of artificial bone blocks with only one density type of D3, and that only one drilling protocol was tested. These factors must be considered when interpreting the results and their applicability to clinical practice.

This is an interesting article. The research parameters are well-defined, and the article is well-written, though the clinical implication is already rather general knowledge.

Author Response

Comments 1: 

The present article, "The Effect of Increasing Thread Depth on the Initial Stability of Dental Implants: An In Vitro Study", was undertaken to evaluate how dental implant thread depth could affect primary stability, with varied focus on low-density bone, D3. Twenty-four dental implants of differing thread depths were divided into four groups and tested in type D3 artificial bone blocks. This study therefore shows that deeper threads could be more suitable for the achievement of primary stability required for softer bones, with which the success of dental implants is identified in many immediate loading protocols.

It also acknowledges its specific limitations, such as the in vitro nature of this research work, the use of artificial bone blocks with only one density type of D3, and that only one drilling protocol was tested. These factors must be considered when interpreting the results and their applicability to clinical practice.

This is an interesting article. The research parameters are well-defined, and the article is well-written, though the clinical implication is already rather general knowledge.

 

Response 1: Thank you for your review and general comments.

Reviewer 3 Report

Comments and Suggestions for Authors

The work is very well done, the content really interesting. The introduction is clear and comprehensive and the materials and methods accurately described. I suggest including in the conclusion that further clinical studies are needed to confirm the results obtained.

I also suggest implementing the bibliography by inserting appropriate citations about factors influencing the primary stability of implants. 

Jamil S. Unlocking implant success: the impact of surgical techniques on primary stability in the posterior maxilla. Evid Based Dent. 2024 Aug 10. doi: 10.1038/s41432-024-01051-1.

Nagni, M.; Pirani, F.; D’Orto, B.; Ferrini, F.; Cappare, P. Clinical and Radiographic Follow-Up of Full-Arch Implant Prosthetic Rehabilitations: Retrospective Clinical Study at 6-Year Follow-Up. Appl. Sci. 2023, 13, 11143. https://doi.org/10.3390/app132011143. 

Khan MW, Inayat N, Zafar MS, Zaigham AM. A resonance frequency analysis to investigate the impact of implant size on primary and secondary stability. Pak J Med Sci. 2024 Jul;40(6):1261-1266. doi: 10.12669/pjms.40.6.8213.

Author Response

Comments 1: 

The work is very well done, the content really interesting. The introduction is clear and comprehensive and the materials and methods accurately described. I suggest including in the conclusion that further clinical studies are needed to confirm the results obtained.

I also suggest implementing the bibliography by inserting appropriate citations about factors influencing the primary stability of implants. 

Jamil S. Unlocking implant success: the impact of surgical techniques on primary stability in the posterior maxilla. Evid Based Dent. 2024 Aug 10. doi: 10.1038/s41432-024-01051-1.

Nagni, M.; Pirani, F.; D’Orto, B.; Ferrini, F.; Cappare, P. Clinical and Radiographic Follow-Up of Full-Arch Implant Prosthetic Rehabilitations: Retrospective Clinical Study at 6-Year Follow-Up. Appl. Sci. 2023, 13, 11143. https://doi.org/10.3390/app132011143. 

Khan MW, Inayat N, Zafar MS, Zaigham AM. A resonance frequency analysis to investigate the impact of implant size on primary and secondary stability. Pak J Med Sci. 2024 Jul;40(6):1261-1266. doi: 10.12669/pjms.40.6.8213.

 

Response 1: Thank you for your review and comments. Future research information and limitations of present results were introduced in the Discussion section to address your comment. Suggested bibliography was not added to the manuscript by Editor decision.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I have reviewed the re-submission, and the authors have carefully amended their manuscript following the additional reviewers' suggestions.