Department of Orthodontics, University of Ferrara, Ferrara, Italy.
Angle Orthod. 2010 Jan;80(1):145-52. doi: 10.2319/122908-662.1.
To test the hypothesis that palatal bone is not able to support titanium miniscrews (11 mm in length and 2 mm in diameter) when subjected to forces normally generated during orthodontic treatment.
The miniscrew-palatal bone system was modeled and analyzed using the commercial finite element method software ANSYS Multiphysics 10.0; tests were done in both a state of total osseointegration and in the absence of it. Calculations were carried out in both cases in configurations where the miniscrew was inserted into two different palatal regions: in the first it was anchored in one layer of cortical bone and in the underlying trabecular bone; in the second, two layers of cortical bone and the trabecular bone in between were involved. Two different loads were taken into account, 240 gf and 480 gf, both of which are within the normal range for orthodontic treatment, and applied to the miniscrew heads.
The results demonstrated that the miniscrew inserted into the palate can be anchored to bone and loaded within normal orthodontic force range without exceeding the stress levels that lead to bone fracture. The osseointegrated system was characterized by a lower level of stress than the nonosseointegrated one, but anchorage within the second layer of cortical bone markedly reduced the stress on the trabecular bone, thereby improving the stability of the implant, also in the absence of osseointegration.
The hypothesis is rejected. Miniscrews loaded within the normal orthodontic force range do not exceed the stress levels that lead to bone fracture.
验证下述假设，即在上颌骨承受正畸治疗中产生的正常力的情况下，无法将长度为 11 毫米、直径为 2 毫米的钛质微螺钉（miniscrew）固定于腭骨。
使用商业有限元方法软件 ANSYS Multiphysics 10.0 对微螺钉-腭骨系统进行建模和分析；在完全骨整合和未完全骨整合两种状态下进行测试。在两种情况下，均对微螺钉植入两个不同的腭骨区域的配置进行了计算：第一种情况，微螺钉固定于一层皮质骨和下方的小梁骨；第二种情况，涉及两层皮质骨和其间的小梁骨。考虑了两种不同的负载，240 gf 和 480 gf，两者均在正畸治疗的正常范围内，并施加于微螺钉头部。
结果表明，植入腭骨的微螺钉可以在不超过导致骨折的骨应力水平的情况下，与骨骼固定并承受正常正畸力范围内的负载。与非骨整合系统相比，整合系统的骨整合系统的应力水平较低，但在第二层皮质骨内固定可显著降低小梁骨上的应力，从而提高植入物的稳定性，即使在没有骨整合的情况下也是如此。
该假设被否定。在正常正畸力范围内负载的微螺钉不会超过导致骨折的骨应力水平。
