電気的根管長測定法に関する基礎的研究

―6. Sono-Explorer MKⅡ Junior, Neosono MC. Justy の基礎的評価―

抄録

Abstract : The electric characteristics of the Sono-Explorer MKⅢ, Neosono MC, and Justy were evaluated in covalent circuits or extracted human tooth models. The results obtained were as follows :

 1. Sono-Explorer MKⅢ

 As the impedance of the load decreased, the frequency of the measuring current of the device increased. This device measures the impedance of the root canal as a change of the frequency of the measuring current. Since the rationale of this device is a single impedance method, it cannot overcome the electrical change in the root canal when an electro-conductive fluid is in the root canal.

 2. Neosono MC

 This device follows the measuring method of the Sono-Explorer MKⅢ. In this device, a change of the frequency is expressed as a distance from the apical foramen.

 3. Justy

 The measuring current of this device has two different frequency rectilinear waves which appear alternatively. These two waves detected from the root canal are separated with digital filters, and two electric potentials are obtained which correspond to two impedances of the root canal. Then, these two potentials are converted to the logarithmic values, and one is subtracted from the other. The result drives the meter.

 Since a subtraction of the logarithm is a logarithm of the quotient, the rationale of the Justy very much resembles that of the Root ZX.