There are two established methods of assessing the working length of a root canal: one by radiography and the other with the use of an electronic device apex locator (Fig. 16).
Once the working length has been confirmed, the individual preparation instruments must be accurately marked to length accordingly. There are many different gadgets available for transfer of the working length; the author prefers the device shown in Figure 17. There are also different stops for the instrument, the most popular being rubber or silicone stops. These should always be placed at right angles to the shank of the instrument. Ideally the stops should be either notched, or pear shaped, so that in curved canals the notch or point of the pear may be directed towards the curve placed in the instrument.
Once the working length has been confirmed, the individual preparation instruments must be accurately marked to length accordingly. There are many different gadgets available for transfer of the working length; the author prefers the device shown in Figure 17. There are also different stops for the instrument, the most popular being rubber or silicone stops. These should always be placed at right angles to the shank of the instrument. Ideally the stops should be either notched, or pear shaped, so that in curved canals the notch or point of the pear may be directed towards the curve placed in the instrument.
Both methods will be described in Part 7.
Once the working length has been confirmed, the individual preparation instruments must be accurately marked to length accordingly. There are many different gadgets available for transfer of the working length; the author prefers the device shown in Figure 17. There are also different stops for the instrument, the most popular being rubber or silicone stops. These should always be placed at right angles to the shank of the instrument. Ideally the stops should be either notched, or pear shaped, so that in curved canals the notch or point of the pear may be directed towards the curve placed in the instrument.
Once the working length has been confirmed, the individual preparation instruments must be accurately marked to length accordingly. There are many different gadgets available for transfer of the working length; the author prefers the device shown in Figure 17. There are also different stops for the instrument, the most popular being rubber or silicone stops. These should always be placed at right angles to the shank of the instrument. Ideally the stops should be either notched, or pear shaped, so that in curved canals the notch or point of the pear may be directed towards the curve placed in the instrument.