Development of evaluation system for dental implant mobility (stability)

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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.