Title: 0978 - Resonance Frequency Analysis for Estimation of Osseointegration and Screw Loosening


Makiko Miyashita (Presenter)
Tohoku University Graduate School of Dentistry

Toru Ogawa, Tohoku University Graduate School of Dentistry
Hideki Naito, Department of Civil and Environmental Engineering, Tohoku University Graduate School of Engineering
Angelina Wang, Zhejiang Chinese Medical University
Keiichi SASAKI, Tohoku University Graduate School of Dentistry


Objectives: To evaluate the development of implant osseointegration and screw loosening by conducting a resonance frequency (RF) analysis in the rabbit tibia, and to correlate the results with histomorphometric measurements.

Methods: Six titanium implants were installed in the bilateral tibiae of one mature New Zealand White rabbit. A small 3D-accelerometer was mounted rigidly onto the implant abutment, and impulsive vibration was directly applied to the abutment to vibrate in two directions (x-axis: perpendicular to the tibia and implant, y-axis: parallel to the tibia). Also, implant stability was measured by the implant stability quotient (ISQ) value with Osstell®. These values were measured 13 times, from immediately after surgery until 8 weeks of healing. After sacrifice, micro-CT analyses (relative gray value, water=0, and implant=100), and histomorphometric analyses (bone-to-implant contact (BIC) and peri-implant bone volume/tissue volume (BV/TV)) were performed. RF values were recorded under 13 different screw conditions, i.e. the abutment screw was tightened with 10N torque, and was then loosened by 5° each time from 0° to 30° and 10° each time from 40° to 90°.

Results: For osseointegration, no consistent RF tendency was observed among the six implants in both directions. On the other hand, the ISQ values tended to decrease until 7 to 10 days after installation, and then gradually increased in most implants. The relative gray value, BIC, and BV/TV tended to increase in implants located distally. The ISQ values correlated strongly with these parameters. Regarding the screw loosening, the RF values in the y-axis direction significantly differed from the initial value between 5° and 20° (p<0.05, Dunnet-test).

Conclusions: Although this RF analysis has not reached predicting the progress of osseointegration, it can be used for the detection of screw loosening.

Disclosure Statement:
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: NONE