臨床向け歯の動揺度テスタ(T-Mテスタ)の開発

抄録

The examination of tooth mobility is very important to estimate the condition of the periodontium in prosthodontics, orthodontics, periodontics, etc. A manual examination of tooth mobility, which is done by moving the tooth with fingers or dental hand instruments, is carried out regularly in dental clinics. In conjunction with the radiograph, the mobility examination is useful in determining whether there is sufficient alveolar attachment to warrant endodontic treatment or not. The readings, M0-M3, of trained dentists may correspond to the degree of tooth movement, but their interpretation requires skill and experience. We have previously reported on the automatic diagnosis system of tooth mobility for objectively determining the tooth mobility in clinical practice, by applying a small random vibration (30-1000Hz) to the labial crown of a tooth. The system is composed of a measuring probe, with a vibrator and an impedance-head, and a data analysis unit using a personal computer. The biomechanical mobility spectrum of the periodontium is obtained, and the viscoelasticity of the periodontal ligament correlates closely with the tooth mobility. The system is on a fairly large scale, because of the use of a personal computer. In a previous study, the authors developed a new tooth movement transducer. The transducer utilizes bi-morph piezoelectric ceramics, and is therefore small, light, and convenient. Measuring frequency is the resonance frequency of the transducer, and the measurement is made at a constant preload. Hence, the transducer is highly accurate and reliable. The authors applied this transducer to a sensor system for measuring tooth mobility. The tooth movement transducer is located on the Tooth Mobility (T-M) tester. In this tester, a sinusoidal vibration is applied to the tooth crown, and acceleration response is detected. The measured value is proposed as the index of the tooth mobility, Mobility Index (MI) score, corresponding to the tooth movement. The tester is characterized by portability and rapid measurement. The clinical practicality of the tester is examined by using artificial tooth models, and the tooth mobility of maxillary and mandibular teeth is measured.