This can be done with an air chisel or a saw and a knife. It is easy to cut into or crack the denture at this point.

If you are using a saw, be careful of the palate, and the lingual borders of the mandibular.

Don't thin out the model (with the model trimmer) to make it easier to chip the stone off. You are sure to cut the denture.

18. Palatal acrylic has been sliced with model trimmer		18. Buccal borders of the mandibular denture have been shortened.

You want to divide the model into small sections so there will be a controlled breakage. With the maxillary draw a line down the middle (anterior-posterior). Then you can draw another parallel line on each side of that. Then draw perpendicular lines making somewhat of a checkerboard. Cut off the posterior segments first because there is no posterior wall. You know where the undercuts are. First remove the stone from the non-undercut areas.

I have seen students use the air chisel anteriorly and cause a crack between the centrals. If you force the stone apart and it has no place to go it will put pressure on the acrylic and crack it. Use hand pressure with a knife if worried about breakage.

©1999 by Julius Rosen, D.D.S.