Endodontics: Part 7 Preparing the root canal

Success in endodontic treatment depends almost completely on how well the root canal is shaped and cleaned. This part will cover the principles of root canal preparation, irrigation, root length determination, intracanal medication, and temporary fillings.
There have been more developments in recent years in this aspect of endodontic practice than any other. New instruments have been developed, employing different metals and different engineering philosophies. There has been a significant move away from the ISO standard 2% taper instrumentation.

Rubber dam forceps

The rubber dam forceps are used to carry the clamp to the tooth. The most frequently reported problem with rubber dam is that when the clamp has been expanded and placed on the tooth, the forceps are stuck in the clamp and cannot be removed! This is because the grooves in the tips of the forceps are too deep. These should be modified with a stone or sandpaper disc so that they just engage the clamp, but slide off easily. Most forceps have a second groove slightly distant from the tip, which may be used to remove the rubber dam clamp without re-engaging the holes (Figs 4 and 5).

Split dam

Occasionally, a broken down tooth may be isolated using a slit cut between the holes made for the two adjacent teeth, as shown in Figure 16. It is essential that the caulking material illustrated in Figure 9 is applied to prevent leakage and contamination.

Finally, if an operator decides to proceed with root canal treatment without the use of rubber dam, each hand file must be protected with either floss tied around the handle or an appropriate safety device. The excess saliva must be controlled with cotton wool rolls and aspiration, and great care must be taken with medicaments. It would be advisable to inform the patient of the risks involved, and the reduced prognosis for the treatment if