In dealing with porcelain fused to metal crowns, one of the problems that is most often seen is about the how to do a perfect transition of the chamfer margins to shoulder. Sometimes, the transition is to abrupt or too soon, usually located more buccal than the usual. Remember that this is the location where the metal meets with the ceramic, therefore as much as possible we want this to be hidden away from view. Technically, the transition should start 1mm lingual to the contact area. Though some may find it difficult to locate this (especially if you have broken the contacts already), there are other ways to keep you on track:

1. Take the central groove of the adjacent tooth as your reference point. This will be an approximate point as to where your transition should start at.
2. After reducing all your axial walls, notice that your crown has a boxy shape when seen occlusally. The transition should be between the two line angles of your prep.

Remember that the transition has a gradual shift of the thickness, from shoulder to chamfer. To achieve this, first you may use 847kr to extend the shoulder margins and change to your chamfer bur just to have your chamfer margins to “blend” in with the shoulder margin.