Only when this is achieved can the clinician and patient rest assured that microorganisms will be prevented from re-entering the root canal system, and that any bacteria that may remain within the tooth from nutrients in tissue fluids will stay isolated.
One method that has proved its worth over the years is the Continuous Wave technique of obturation, which was introduced by Steven Buchanan in 1994, as a result of his modifications in instruments and techniques on the original technique of warm vertical condensation.
Steven Buchanan wrote at the time: “The technique differs from warm vertical condensation in that it requires a System B plugger instrument as well as modifications in the method that the condensation is completed. As with any method of obturation its success is completely dependent upon the cleaning and shaping of the root canal system”
The Continuous Wave technique
Since then technology has moved on, allowing the endodontist to use ever more effective tools, such as the Elements and Elements Free obturation systems from Kerr, with which the Continuous Wave technique works as follows:
1. Fit the master cone (in a wet canal) to full length. Grip it at a right angle to the reference point with cotton pliers and trim the tip to be 0.5mm short of full working length.
2. Pre-fit a Buchanan heat plugger in the canal and adjust the rubber stop to the reference point. Compare the fit plugger to the fit cone to determine the depth of the plugger in the canal; the ideal is 4-6mm from the terminus.
3. Coat the apical third of the cone with sealer and slowly place it to length in the canal, pumping it up and down two to three times.
4. The downpack device can be used with both gutta-percha and synthetic material.
5. Sear the cone off at the orifice level.
6. Select the appropriate size Buchanan hand plugger and, using the stainless steel end, firmly condense the gutta-percha at the orifice.
7. Set the heat plugger on the cone: activate the heat and downpack, releasing your finger from the operating switch shy of the binding point and maintaining apical pressure for 10 seconds.
8. Activate the heat switch for a one second separation burst, pause for one second and remove the heat plugger.
9. Select the appropriate Buchanan hand plugger and, using the nickel titanium (NiTi) end, condense the apical mass while removing any material from the canal walls.
10. Lightly place more sealer in the backfill space with the tip of a paper point.
11. Extrude a small amount of material to heat the needle.
12. Place the backfill device needle in the canal short of the condensed fill and wait five seconds for the needle to reheat. Backfill the canal halfway. Using the NiTi end of the Buchanan hand plugger, condense the fill.
13. Re-insert the needle, wait five seconds for it to reheat and then backfill to the canal orifice.
14. Select the appropriate Buchanan hand plugger and, using the stainless steel end, condense the coronal fill. Finally, if using synthetic material, light cure for the appropriate amount of time.
A cordless system for easier obturation
One of the challenges faced by clinicians during obturation is caused by the cord attached to their backfilling syringe of choice, as it can get in the way. Overcoming this problem, the Elements Free system from Kerr is cordless and designed for use with the Continuous Wave technique.
As Steven Buchanan once commented: “The Elements Free's primary difference from previous cordless heat sources is that it heats to 200°C in 0.5 seconds. All previous units heated over a two to three second period, increasing the amount of heat transmitted to the outside surface of the root during the downpack. Elements free has a downpacking heat source that is analogous to the System B handpiece in every way, except it is unplugged.”
If you would like more information about the difference a cordless backfilling syringe can make to your obturation techniques, please visit www.kerrdental.co.uk, call 01733 892292 or email kerruk@kerrdental.com
References available on request.