Same procedure will be done here as to how buccal reduction are made. Make orientation grooves, then connect them while forming the margins.

The bur used for this margin is a rounded end tapered bur (856-014, 856-016). There is actually no strict rule on which bur to use but take note that creating any margin will depend on the shape of the tip of the bur. The key point in here is HOW you effectively use that bur to create a certain shape of a margin.

For creating a nice chamfer, it is a very good habit if you do not fully engage the whole shape of the bur. Always make sure that half of the diameter of the bur is outside the margins. This is because:

1. Chamfer width is only at 0.5mm. Half of the diameter of the bur will just be enough to create that width.
2. High chance of creating enamel lips when you fully engage the whole diameter of the tip. This unsupported enamel is a very grave mistake in the bench test. Also, in this manner you are more likely doing a deep chamfer already.

Step by Step

This is a step by step demo on a lower first molar prep for full gold crowns, the occlusal and buccal reduction are already done, if you want to review, please check the following page:

LINK on Occlusal Reduction Lower Molars

LINK on Occlusal Reduction Lower Molars

Demo Video

Add video here

Step 1: Orientation Grooves

Orientation grooves are made to keep your bur upright and orient your bur properly as you reduce the wall.

You may bring your bur on the buccal side and simulate the angulation for the lingual orientation grooves

Step 2: Connecting the Grooves

Make sure to maintain the angulation of the depth grooves (that’s what they’re for).

Keep the bur angulation consistent with the buccal reduction, the tapered shape of the bur will give the preparation the appropriate taper it needs. It’s easy to up-right the handpiece while working on the lingual surface, so be ware not to do so!

Bring your bur in as far interproximally as you can, without nicking the adjacent tooth.

When completed, the taper and angulation should look like the pictures below.

Now that the Buccal and Lingual Reductions are done, it is now time to break the contact and make a beautiful margin without nicking the adjacent teeth.

LINK Proximal Reduction Full Gold Crowns