Four Basic Margin Preparations

There are four basic types of margin preparations. The Full Shoulder (Butt) preparation is usually suggested for porcelain jackets. The other basic types are Bevel, Feather and Chamfer.

	The Full Shoulder or butt preparation is used in porcelain jacket work. There are to be no overextensions and care should be taken to cover the full shoulder of the preparation.
	The shoulder with Bevel is cut with a long tapered diamond instrument, or bur. This is done to create a taper which provides and permits the margin to be burnished.
	The Feather is one which has no shoulder and because of this, should be marked or ditched by the doctor to avoid errors.
	The Chamfer preparation is similar to the butt except it is more rounded and may also be burnished. This is usually done with a round ended bur or diamond instrument. This also requires a bevel at the margin