Development of evaluation system for dental implant mobility (stability)

我们之前已经开发了一种牙齿移动的自动诊断系统，用于测量人类牙周组织的生物力学特性。由于该系统的阻抗头太大，无法测量种植体基牙和磨牙的迁移率，因此研制了一种简化的测试仪，称为T-M测试仪。对齿面施加单频振动，测量加速度响应，计算出基牙的机械迁移率。该探头的牙齿运动传感器采用了一套双压电陶瓷圆盘。因此，它体积小、重量轻，适合口试。利用人工模型验证了换能器的基本特性和测量探头的临床适用性，并将T-M测试仪应用于种植体，以确定牙周组织和种植体周围的粘弹性特性的差异。结果表明：T-M测试仪可以测量种植体的活动性。种植体的移动指数得分小于牙齿。我们应用与T-M测试仪相同的原理，开发了种植体移动(IM)检查器。为了获得合适的测量条件，我们对天然牙齿进行了IM检查器的测试。此外，我们还通过义齿模型和种植模型验证了其性能。在临床试验中，IM检查器能够评估种植体的移动(稳定性)和种植体整合的长期变化，新开发的IM检查器具有足够的测量可靠性，可以在口腔临床中客观地估计种植体的移动。

We have previously developed an automatic diagnostic system for tooth mobility, for measuring the biomechanical properties of human periodontium. Since the impedance head of the system is too large to measure mobility in an implant abutment and a molar, a simplified testing instrument called T-M tester was developed. A single-frequency vibration is applied to the tooth surface, an acceleration response is measured, and then the mechanical mobility of the priodontium is calculated. The tooth-movement transducer of the probe utilized a set of bimorph piezoelectric ceramic disks. It is therefore small, light, and suitable for oral examination. The basic characteristics of transducer and clinical applicability of the measurement probe are confirmed using an artificial model.The T-M tester was applied to implants to determine the difference of viscoelastic properties between periodontium and peri-implantium. The obtained results were as follows : it was possible to measure the implant mobility by T-M tester. Mobility-Index scores of the implants were smaller than those of teeth.We applied the same principle of T-M tester and developed an Implant Movement (IM) checker. In order to obtain the appropriate measuring conditions, we examined the IM checker on natural teeth. Moreover, we verified its performance by using artificial tooth models and implant models. In clinical trials, IM checker was able to evaluate the implant mobility (stability) and long-term change of implant integration.The newly developed IM checker had sufficient measuring reliability and we could objectively estimate the implant movement in dental clinics.