Latest generation patented apex location technique replacing the age old multi-frequency measurement method
The precise electronic length determination of the root canal works with a new impulse measuring method. For these impulse method company Schlumbohm has the patent. Thanks to the newest microprocessor technology the exact determination of the preparation length is done with 10-Bit-resolution in real time up to 1024 bits. In comparison with the old impedance difference – or impedance quotient – method, the measuring time is significant shorter and the interpret ability is improved.
The old frequency measurement method
The 2-frequency method uses two voltages with different frequencies, which will be applied to the tooth – time after time. Therefore, no real-time measurement is possible. As a result, there are only two individual time-shifted impedance values. The manufacturers of these devices use subtraction- and division-processes. Of course the possibilities of calculation with only two values are limited. Ultimately you obtain only one result which cannot be verified.
|Measurement 1||Measurement 2|
The new impulse measuring method
The current flow behaves differently on the way to the apex. By using an impulse signal for measuring, the influence of the current flow results a deformation of the input signal. A variety of information can be used from the determined curve.
Input signal square wave
The degree of deformation of the signal can be considered as a measure of the approach to the apex.
- A single measurement is sufficient. The measurement is performed in real time which makes the process faster and therefore safer.
- There are evaluated a large number of individual values within the measurement. This makes the process more flexible and more accurate.
- The Impulse-curve offers more possibilities for interpretation. Special curve forms may indicate disturbances of the measurement. A compensation of interferences are not always possible, but the detection brings decisive advantages. A typical problem is the so called “semblance-apex“:
Many devices indicate “apex” just by contact of the instrument with liquid in the root canal (especially in the coronal area). These measuring failure can mostly be avoided by the impulse measuring method.
- These kind of measurement was especially developed for measuring through a contra-angle, which is fast moving up and down in the root-canal.