Background

Self-tapping screws have been extensively used for dental implants. Their biomechanical behavior is highly associated with their clinical success, particularly for screws used for immediate implant placement and restoration, because occlusal forces can directly affect the loading transfer at the bone–implant interface after implantation. The effect of implant design on the initial stability of self-tapping screws remains unclear. This study explored the biomechanical behaviors of implant stability in standardized implants with different design features.

Methods

Six types of dental implants were designed using computer-aided design/computer-aided manufacturing technology, including three types of cutting flute shapes (spiral, straight, and non–self-tapping) combined with two types of screw features. Peak insertion torque values were first recorded; initial stability levels were subsequently evaluated in terms of the maximum force and resistance to lateral loads using an electrodynamic test system.

Findings

The peak insertion torque values, maximum force, and resistance to lateral loads of the non–self-tapping groups were higher than those of the self-tapping groups by 17%–90% (p < 0.01). The peak insertion torque values of the Straumann implant with a spiral flute was higher than that of the original straight flute by 20% (p < 0.001). However, compared with the original spiral flute, the Nobel Biocare implant with straight flute had a 23% higher maximum force (p = 0.016) and 24.5% higher resistance (p = 0.012) under lateral loading.

Interpretation

Changing the flute design would affect initial implant stability. Non–self-tapping implants exhibited superior initial stability than did self-tapping implants.

中文翻译：

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螺钉设计特征对即刻种植体植入和修复初始稳定性的影响

背景

自攻螺钉已广泛用于种植牙。它们的生物力学行为与其临床成功高度相关，特别是对于用于即刻种植体植入和修复的螺钉，因为咬合力可以直接影响植入后骨-种植体界面处的负荷转移。种植体设计对自攻螺钉初始稳定性的影响仍不清楚。本研究探讨了具有不同设计特征的标准化种植体中种植体稳定性的生物力学行为。

方法

使用计算机辅助设计/计算机辅助制造技术设计了六种类型的牙种植体，包括三种类型的切削槽形状（螺旋、直线和非自攻）结合两种类型的螺钉特征。首先记录峰值插入扭矩值；随后使用电动测试系统根据最大力和对横向载荷的阻力来评估初始稳定性水平。

发现

非自攻组的峰值插入扭矩值、最大受力和抗侧向载荷均高于自攻组17%~90%（p  < 0.01）。带螺旋槽的 Straumann 种植体的峰值插入扭矩值比原来的直槽高 20% ( p  < 0.001)。然而，与原来的螺旋槽相比，带有直槽的 Nobel Biocare 植入物 在横向载荷下的最大力高出 23% ( p  = 0.016) 和阻力高出 24.5% ( p = 0.012)。

解释

改变凹槽设计会影响初始种植体的稳定性。非自攻种植体表现出比自攻种植体更好的初始稳定性。