May 09, 2012

Die Trimming

     This is part 3 of my dental tech tutorials. After the impression has been poured, and the model made you need to trim the dies so you can start making the restoration.

When trimming dies it is always a good idea to use a well lit station and to have some sort of magnification. I use a simple loop.

To trim the dies first reduce the bulk of the stone cervical to the preparation using a carbide bur. Always trim from below the margin coming up towards the margin with the round end of the bur. This will help to prevent chipping.

Once you have done as much as you can with the carbide move onto a smaller round or egg shaped bur to finish the trimming around the margin.

Remove any draws, pulls or other imperfections which may have been present in the impression with a small pointed bur. These are some examples from other models.

Fill any bubbles or undercuts on the die/margin with undercut wax.

Mark the margin of the preparation with a sharpened red pencil. When marking the margin make sure to rotate the pencil as you draw the line. A sharp margin will score a pencil crayon and create a groove which will straddle a margin rather than mark it. To smooth out the pencil again simply rub and spin the point on a piece of paper.

Apply die hardener to the margin as well as round 2mm above and below the margin. Use 2 coats.

Apply die spacer to the rest of the die about 1.5-2mm occlusal to the margin. To apply the spacer shake the spacer bottle vigorously to mix the die spacer within then when it is ready you can work from the spacer that will be in the lid of the bottle. Dip your brush in the spacer then apply as a bead along the the base of the die then pull the bead upwards towards the occlusal. If the spacer is thick one coat will do. If it is thin two coats may be necessary.

The dies are now ready to be waxed up.

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