PDF Version - Glidewell Dental Labs
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Figure 24: Here I am using the 856-016 bur to do the occlusal<br />
reduction on the bicuspid. I use the bigger 856-025 bur on molars,<br />
but it is a little too big to use on bicuspids without accidentally<br />
nicking the adjacent teeth. You could also use a football bur to<br />
do this reduction (the convex shape of the bur will give you some<br />
“bonus” reduction).<br />
Figure 25: The 856-025 bur does a great job on the facial surface of<br />
anterior teeth as well. You can see that I already finished the facial<br />
reduction on tooth #10 as I reduce tooth #9 here. Notice how dark<br />
the staining is on tooth #10 compared to tooth #8. Tooth #9 is right<br />
in the middle in terms of shade because we have removed about<br />
half of the enamel. You can already see that the margin looks good<br />
on tooth #10 — that’s the beauty of the round bur.<br />
Figure 26: I use the 379-023 football bur (Axis <strong>Dental</strong>) to reduce<br />
the lingual surfaces of the anterior teeth. The convex shape of<br />
the bur helps to prepare a concave shape that will allow room<br />
for the incisal edges of the lower anteriors. Unlike other allceramic<br />
materials that require at least 1 mm of reduction, we<br />
can reduce just 0.6 mm on the lingual for a BruxZir crown.<br />
I have a 0.6 mm depth cutter in my bur kit to measure this precisely.<br />
Figure 27: Toward the end of the prep sequence, I like to start<br />
rounding things over, especially the junctions of the facial surfaces<br />
and the incisal edges. I also try to avoid leaving sharp corners on<br />
the mesial and distal corners of the incisal edges. While BruxZir<br />
crowns are strong enough to be placed on these sharp angles,<br />
CAD/CAM mills are not able to replicate those sharp angles with<br />
their round burs.<br />
30 www.chairsidemagazine.com