Anyone having blending issues at the incisal half? My crowns are ending up with diagonal lines where it looks like the body shade and translucent incisal shades are coming together. I have the sprues along the facial as directed but still having issues.
It definitely sounds like an issue with sprue placement. There are a couple things to keep in mind when sprueing:
1. make sure you are aiming the sprue so that the material does not press into the prep. The sprue should be positioned so that the material actually flows around the facial of the restoration. This prevents turbulence in the material when it presses (which causes blending issues) and prevents the material from breaking the prep.
2. The crown and the pattern should always be centered on each other and long axis should be parallel. Do not move the restoration up or down on the sprue pattern to control translucency, move the entire sprue/pattern assembly down on the sprue base. This ensures that you have unrestricted flow into the restoration, but blocks some of the cervical material from entering the pattern.
3. When attaching the sprue, DO NOT flare the attachment point, only add enough wax to close any gaps and ensure that the attachment points are very smooth. Again, flared or rough attachment points will cause turbulence when the material presses, causing blending issues.
I hope these tips help.