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Figure 20: On posterior teeth, this depth cutter is also used to
establish reduction, which is typically 2 mm for bilayered restorations
such as PFMs or Lava crowns (3M ESPE; St. Paul, Minn.).
For lithium disilicate crowns, I prefer 1.5 mm of occlusal reduction.
I prefer 1 mm for BruxZir crowns, but this material can be prepped
as thin as 0.6 mm. On this cuspid, we are reducing the incisal edge
1.5 mm, like we did for the other anterior teeth.
Figure 21: I am now placing a 1 mm depth cut on the facial surface
of the teeth to be prepped. I prefer to do this at the height
of contour, or incisal to the height of contour, to ensure that I reduce
enough in that area. One of the most frequent mistakes I used
to make was under-reducing in this area, which leads to bulky,
opaque, ugly crowns.
Figure 22: This image shows the payoff of spending a little extra
time up front to make these depth cuts. Now we can grab our 856-
025 bur again and go to town, secure in the knowledge that we
know exactly where we are going. These depth cuts are a road map
that keeps us from under-prepping or over-prepping these teeth,
allowing us to fly through this part of the prep sequence.
Figure 23: Typically, I start this part of the prep sequence by reducing
the incisal edges. I intentionally use the middle third of the bur
to do this reduction because I want to save the tip of the bur for
finishing the gingival margin. There is little chance that the tip will
be dulled by then, but I’m prepping multiple teeth and I want it as
new and as sharp as possible.
Another Use for Anterior BruxZir Solid Zirconia Restorations29