One of the nice features of the Fine Cut Endo Handpiece is that it can be used for probing both initially and subsequently and because it uses a mechanical linkage instead of harmonic resonance it can be use to remove set cement.
If PCA sealer is too easy to remove you probably did it wrong in the first place. If you can simply push a file into it, it probably has too much eugenol in it.
PCA sealer when mixed properly sets hard.
It's intended to be.
But that still doesn't answer the question.
The answer to the question is that you remove it like other hard materials...like calculus.
Since it is hard and brittle it is amenable to an ultrasonic scaler.
The trick is how to apply the scaler to sealer which is down in a canal.
There is a scaler tip called a PHD( Post Hole Digger ) that is small and pointy.
But there is another way.
Take an endo file, preferably a Fine-Cut file, partly because it is pointy but partly because it can be embedded in cement and pulled out.
Hold the file in a hemostat and apply the scaler tip to the side of the file below the hemostat.
This will transmit the bulk of the vibratory energy to the file and help work it into the cement.
Once the file is embedded in the cement pull it out.
Do this repeatedly until the file starts to get stuck in dentin.
Once you have a guide channel for the file, you can use push-turn-pull filing to get the rest of it out.
As hard as cement is, it is softer than dentin.
If you push a Fine-Cut file or screw in a Fine-Cut file it will penetrate the cement without damaging the dentin.
Once you have a channel through the cement then simply file the rest of it out.
Will solvents work? I doubt it.
Don't even think of using a Gates or Peezo on it.
All you'll do is perforate.
Dr. Kent Powers has considerable experience removing PCA.
He starts removing the cement in the coronal portion of the canal with a TFI EWPP tip on a Cavitron, which gets him down to about 6 mm into the canal.
Then he screws a file into the cement and apples the Cavitron tip to the file and repeats until he's got it all out.
But now that the Fine-Cut Endo Contra-angle is available that is the preferred method. Since PCA sealer sets hard, it is also brittle, like most cements.
All it takes is to repeatedly poke at it with a sharp instrument. Since the handpiece makes over 200 "poking" movements per second, it isn't to hard to see how this could work. And it does.
But the trick is to frequently remove the file to allow the chunks of cement to bypass the file. All the while maintaining a flow of water.
My file of choice for this is usually a size 25 Fine-Cut SPeed file. This will usually get you down to within a few millimeters of the apex where you can continue the process with a smaller file OR simply use a Fine-Cut Hand File poking and pulling back until you reach the apex.
Just to prove it could be done, I took about 30 filled root canals that had been done over a few months period in my course and removed the cement from them. It took an average of about 45 seconds each.