Measurement System of Tooth / Implant Movement in Animal Test

Objectives: It is very effective but considerably difficult to measure movement of tooth/implant objectively. In animal test, a small measurement system of movement is required. Some instruments are marketed for mobility measurement, such as PERIOTEST and OSSTELL. But they are too big in animal test, e.g. rat. In this study, we have developed a suitable measurement system of movement for animal test. Methods: The measurement system constitutes of a measuring probe, an interface and a computer. The probe is 7.8mm in diameter, 77mm in length. The piezoelectric actuator of the probe applies a random vibration of 10-2400 Hz to the tooth surface, and force(F) and acceleration(A) signals are detected by the transducer of probe. The mechanical mobility (integral of A/F) is calculated from these signals and it indicates the tooth movement. The artificial models were made in which the model teeth (clinical tooth mobility: M0-M3) were embedded and the artificial implant models were also made in which the metal bars of 3, 4, 5mm diameters were embedded. The mechanical mobility of these models and the incisor(I) and the second molar(M) of rats was measured. Results: The magnitude of mechanical mobility (850-1200Hz) of M0-M3 models and three implant models were discriminated with p<0.01 (t-test). The reproducibility of 12 measurements of the rat teeth was 4.0% or less. The tooth mobility of the maxillary M was slightly bigger than that of the I but the mandibular I was looser than the M. Conclusion: The developed measurement system for animal test had a sufficient reliability for evaluation of movement of the tooth/implant. It was confirmed in the measurement of artificial models and the teeth of the rats. Acknowledgements: This work was supported by the Scientific Research Fund of Japanese MEXT (Basic Research B2 of No.14380404) and Osaka Dental University Joint Research Funds (B03-01).