DETERMINATION OF ROOT CANAL LENGTH
The exact apical termination of the root canal preparation has always been a subject of contention. The pedantic answer is that the root canal should be prepared to that point where the inside of the tooth becomes the outside . Some authors suggest this is the apical constriction, some the cemento-dentinal junction, some suggest that the apical foramen should be enlarged, some suggest that the preparation be taken to an arbitrary point 1 mm from the radiographic apex. As described in Part 4, the apical anatomy may be complex, and the term apical delta may be more appropriate. This author considers that the preparation should be taken as close as possible to the cemento-dentinal junction, and that wherever possible the foramen of the major canal should be kept patent. (This technique is described later.) The other minor canals forming the apical delta will only be cleaned by antibacterial irrigation flushing through the entire canal system.
An estimate of the root length is made from the pre-operative radiograph taken with a parallel technique. However, confirmation of the actual working length is not carried out until the coronal preparation of the canal has been completed, as this may straighten a curved canal which would change a measurement that had been taken too early. Most operators now confirm the
actual working length when the crowndown preparation has progressed to within 3 or 4 mm of the estimated working length. There are three accepted methods for this determination. The exact apical termination of the root canal preparation has always been a subject of contention. The pedantic answer is that the root canal should be prepared to that point where the inside of the tooth becomes the outside . Some authors suggest this is the apical constriction, some the cemento-dentinal junction, some suggest that the apical foramen should be enlarged, some suggest that the preparation be taken to an arbitrary point 1 mm from the radiographic apex. As described in Part 4, the apical anatomy may be complex, and the term apical delta may be more appropriate. This author considers that the preparation should be taken as close as possible to the cemento-dentinal junction, and that wherever possible the foramen of the major canal should be kept patent. (This technique is described later.) The other minor canals forming the apical delta will only be cleaned by antibacterial irrigation flushing through the entire canal system.
An estimate of the root length is made from the pre-operative radiograph taken with a parallel technique. However, confirmation of the actual working length is not carried out until the coronal preparation of the canal has been completed, as this may straighten a curved canal which would change a measurement that had been taken too early. Most operators now confirm the