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Updated: Jun 28, 2026
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An Improved Mechanical Testing Method to Assess Bone-implant Anchorage
Published on: February 10, 2014
Bicortical vs monocortical orthodontic skeletal anchorage
Bryan T Brettin1, Nicole M Grosland, Fang Qian
1Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa 52242, USA.
Summary
Bicortical miniscrew placement offers superior orthodontic anchorage and stability compared to monocortical placement. This in-vitro study demonstrates enhanced force resistance and reduced bone stress with bicortical screws, improving treatment outcomes.
Area of Science:
- Orthodontics and Dental Implantology
- Biomaterials and Biomechanics
- Skeletal Anchorage Systems
Background:
- Titanium miniscrews are utilized for orthodontic skeletal anchorage, but monocortical placement exhibits variable success rates.
- Monocortical placement, engaging only one cortical bone plate, has reported retention rates as low as 50%.
- Understanding the biomechanical differences between monocortical and bicortical placement is crucial for optimizing anchorage.
Purpose of the Study:
- To evaluate the hypothesis that bicortical miniscrew placement provides superior force resistance and stability compared to monocortical placement.
- To compare the anchorage capabilities of bicortical versus monocortical miniscrews in orthodontic applications.
- To assess the impact of bicortical placement on cortical bone stress and screw stability.
Main Methods:
- Forty-four titanium alloy miniscrews were placed monocortically and bicortically in 22 human maxillary and mandibular specimens.
- Specimens were subjected to tangential force loading, and deflection forces were measured.
- Bone thickness was measured, and statistical analyses (t-tests, correlation, Fisher exact tests) were performed; 2D finite-element models were also analyzed.
Main Results:
- Bicortical miniscrews demonstrated significantly greater deflection force resistance than monocortical screws in both maxilla and mandible (P <0.01).
- Mandibular sites exhibited higher force values than maxillary sites for both screw types.
- Bicortical screws showed significantly less mobility post-loading, and finite-element analysis confirmed lower cortical stress with bicortical placement.
Conclusions:
- Bicortical miniscrew placement offers superior anchorage resistance and stability for orthodontic tooth movement compared to monocortical placement.
- Bicortical placement effectively reduces cortical bone stress, enhancing the overall reliability of miniscrew anchorage.
- These findings support the clinical recommendation of bicortical placement for improved orthodontic anchorage outcomes.
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