Background

The clinical success of orthodontic miniscrews is strictly related to primary stability, which depends on bone viscoelastic properties too. In this study, we evaluated the short time mechanical response of native bone to miniscrews, by a laboratory test based on dynamic loading.

Methods

Thirty-six segments of porcine ribs were first scanned by cone-beam computerized tomography to obtain insertion-site cortical thickness, cortical and marrow bone density. Twelve different types of miniscrews were implanted in the bone samples to evaluate the elastic compliance of the implants in response to a point force applied at the screw head normally to the screw axis. The compliance was measured dynamically in a Dynamic Mechanical Analysis apparatus as the Fourier Response Function between the signals of displacement and force. The measurements were repeated in five days successive to the insertion of the miniscrew.

Findings

The elastic compliance was positively related to observation timepoints, but it was not related neither to the screw type nor to the value of the insertion torque.

Interpretation

Stability behavior is significantly related to the short time response of native bone rather than to the screw design or the insertion torque values.

中文翻译：

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关于锚固自攻螺钉的稳定性效率：正畸中使用微螺钉植入物的离体实验

背景

正畸微螺钉的临床成功与最初的稳定性密切相关，后者也取决于骨骼的粘弹性。在这项研究中，我们通过基于动态载荷的实验室测试评估了天然骨对微螺钉的短时机械响应。

方法

首先通过锥束计算机断层扫描扫描猪肋骨的36个节段，以获得插入部位的皮层厚度，皮层和骨髓的骨密度。将十二种不同类型的微型螺钉植入到骨样品中，以响应于垂直于螺钉轴线施加在螺钉头上的指向力来评估植入物的弹性顺应性。在动态力学分析装置中动态地测量柔度，作为位移和力信号之间的傅立叶响应函数。在插入微型螺钉之后的五天内重复进行测量。

发现

弹性柔度与观察时间点呈正相关，但与螺钉类型和插入扭矩值均无关。

解释

稳定性行为与本地骨骼的短时响应显着相关，而不是与螺钉设计或插入扭矩值相关。