Would you like your preparations to be more efficient and predictable? As dentists we can have the tendency to under reduce when we cut our preparations. This is due to the fact that we have a great respect for tooth structure and want to preserve as much of it as we can. The unfortunate side effect of this is that it can lead to restorations that are too thin.

Whether you send your indirect restorations to a lab or fabricate them yourself using a system such as CEREC, proper reduction will not only make the fabrication of your restorations easier, it will result in higher quality restorations.

One thing I have found is if you know the dimensions of your burs and the reduction you need, it makes your preparations easier to achieve. It's really that simple.

While manufacturers list the diameters of their burs there can be some variance between grits. If you are using tapered burs it's critical to measure both the tip and base. Given these facts, if we want to be as predictable as we can, it's best to measure your burs with a set of digital calipers. While this takes a bit of work, if you don't change manufacturers or grits you only need to do this once.

It's important to evaluate your provisional and/or final restorations for proper thickness and contours. If your restoration is thick enough but over-contoured it means you under reduced. Just as important though, if your restoration is properly contoured and much thicker than needed, you are over reducing.

John R. Carson, DDS, PC, Spear Visiting Faculty. [ www.johnrcarsondds.com ]


Commenter's Profile Image Kevin D. Huff, DDS, MAGD
October 29th, 2013
Great post, John! I agree completely. I have found this especially true when using a 330 bur as an occlusal depth cutter, which should be a 1.8mm long cutting head. I have found these to vary from 1.6 to 2.0mm from manufacturer to manufacturer. Of course, a putty reduction guide is also very useful for determining appropriate axial reduction.
Commenter's Profile Image John R. Carson
October 29th, 2013
Thanks Kevin, excellent points yourself!
Commenter's Profile Image Doug McMaster
October 29th, 2013
Measuring the diameter and the shank is a great idea, for sure. As well, when removing an existing crown, for example, it is also smart to make guide cuts into it (the last doctor may have under reduced!)......or reduce it to better profile to before the guide cuts.
Commenter's Profile Image John R. Carson
October 30th, 2013
Excellent points Doug, thanks.