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March 2004 – System S Technique for a Molar
For the past 2 years I have been mostly using a "Squirt" technique for canal filling that uses the Obtura Gun for the entire filling. I was introduced to this technique by Dr. John Stropko and Dr. Joe Dovgan of Scottsdale Az.
We know that classic warm vertical compaction technique requires Gutta Percha MASS. This Gutta Percha mass is what accepts the heat and allows for the deformation at the apex that gives us the great anatomy. Classically trained Warm Gutta Percha advocates were used to preparing canals that had larger shapes. This occurred because of the emphasis on deeper irrigation and the use of hand reamers in the body of the canal during the preparation technique as taught by Schilder.
In comparison, the canals that are now being prepared by Ni-Ti Rotary files and much thinner because the Ni-Ti metal is much more flexible than stainless steel. The problem with this is that as these more conservative shapes are achieved, the mass of gutta percha available for obturation is much less. Therefore, less heat is accepted by the material and is available for deformation. This is with one or two passes of an F2/F3 (insert your favorite Ni-Ti file to the apex/gauging tool -here-) I'm seeing a lot more cases produced with LESS bulk, skinnier canals.
When I started using Ni-Tis my shapes also got thinner, no doubt. BUT I also noticed that although the corresponding AutoFit GP Cones fit the preps well, I would occasionally pull a cone out during the pack when doing classic vertical Compaction Technique.. That was probably my mistake in that I let the heat carrier freeze momentarily on the cone while it was at the midroot. But what was alarming was that the amount of deformation at the apex (even though I was heating maybe 5-8 mms from the apex), was virtually nil. These skinnier shapes were more likely to leave you cold down there unless you ARE 3 mm from the apex. 3 mm is too close to the apex for my liking and again, it leaves so little GP that you don't get the hydraulics you need. Not to mention how difficult that can be in curved canals.
I see the System S ( and Jerry's Avillion's Pac Mac System A) as a reasonable compromise. It allows for the use of rotary Ni-Ti instruments and preservation of dentin. If puffs and occasional minimal excess don't bother you, System S is a great technique. But it too is shape dependent. (John Stropko likes to finish with a ProFile 29 around size #21 instrument, as I recall.) I prefer to finish with a ProTaper F2 or F3 slightly short in most cases. That may be too small for clinicians who need to open canals up to a size 40 or so, in order to get them as clean as they would like. You're definitely not going to want to use a Lightspeed close to the apex with this injectible technique.
However, I submit the case below as an example of System S Obturation. It is a wonderful technique when done properly.
Fig. 1 - Pre Op
Fig. 2 - Working Length
Fig. 3 - Downpack System S ( Obtura )
Fig. 4 - Final Fill - Bonded Orifices and Post Space
Note: Bifid Distal Apex
Fig. 5 - Final Fill Mesial shift shot