A question that comes up often regarding one cone Hydraulic Condensation is the folowing: Why is it that every once in a while, a matching EndoSequence BC cone that coresponds to the final matching Master File hangs up short after placemenet of the sealer.
The answer is the following:
When you have a tightly matching gutta percha cone to a canal shaped with a matching master file (a situation in which synchronicity of match is maximized,) placement of too much sealer creates a hydraulic lock that prevents the cone from seating all the way down (the matching cone trapps a little bit of the sealer apical to the cone which resists full seating of the cone. This hangs up the cone.
First, you have to make sure that you have a properly fitted your master cone and the cone actually goes to the full working length. Then you have to score the gutta percha at that working length (this ensures that you can detect a cone that’s hanging up high right away and you can remove it.)
Depending on the tightness of the canal, place an adequate amount of sealer (less for tight canals and more for looser fits) and then proceed to cement the cone. If the cone goes to full marked length then you have achieved working length. If you it’s short, then you should remove the cone immediately and proceed to palce the original Master File to full length. This removes the sealer plug ahead of the master cone and repeat the process. If the same problem occurs again you may fit one size smaller cone (e.g. if your master file is 35/.04 you can use a size 30/.04 master cone.) This provides a little space between the gutta percha and the mastercone that helps “venting” of the sealer back up coronally and allows seating of the cone.
Remember that BC Sealer is a final filler (non-resorbable and non-shrinkable.) Therefore, having a thin (or even thick) circumferential ring of sealer sandwitched between the canal wall and the gutta percha is not a problem. The sealer will bond chemically to the canal wall and the gutta percha surface.
Our priority, however, is making sure our cone goes all the way to the full working length and does not hang up short. Using a one size smaller cone to achieve that is not a problem.