Feather Margins?

[Baker]

Can someone explain what a feather margin is and how to do one.

Thanx guys..

 

[TheLabGuy]

Feather margin as I know it, is just a margin that the Dentist has done very little to prep it. Under a microscope you will see the bur marks, it's very faint. Usually straight up and down with the axial wall. It doesn't flare out like a chamfer and isn't noticeable like a beveled margin and no where near a shoulder margin. Hope this helps, I'll find ya prep description and post it for ya.

 

[TheLabGuy]

Here is a picture for you, the first one is a feather edge margin, second is a chamfer, third is a shoulder. Hope this helps.
Picture>>>>> http://www.prestige-dental.co.uk/product_images/398.jpg

 

[sixonice]

I can also throw in the feather (also called "slice" margins by some) margins are unacceptable for pretty much ANY all-ceramic restoration including zirconia. The computers have a very tough time reading feather preps & they are not strong enough. Any pressed all-ceramic is also difficult because during the divesting process the margins can get chipped or blasted off.

 

[Baker]

thank you Lab guy / Sixonice. I will share this with my father. The picture will help for he is more hands on/visual, than a read and learn kind of guy.
Thanx again for your knowledge on this subject of feather margins.

 

[aidihra]

I would just like to add that PFM crowns with metal margins or full gold crowns are usually made for a tooth with feathered margins.

 

[JohnWilson]

A feather margin is a margin that has no definitive stop. Generally any restoration that is fabricated will be over-contoured at the margin. A metal margin is best suited for this type of prep. Wedging of the crown and porc fractures are common as this prep often resembles a wedge used to split fire wood.

 

[Clear Precision Dental]

Traditionally, feathered margins are the oldest form of margin in dentistry. In the era of the belt driven handpiece, the preparations were made with a large rotating disk that would pass through the interproximal, opening the contact point and removing interproximal undercut. This was literally, the "slice" preparation. These preparations had the intent of removing undercut... thats about it.

Impression materials that could capture accurate margin detail and tissue contour were not available. Also, the bone-heads of the time, (and up to currently for those that neglect learning),believed in sinking the margin deep below the gingival tissue would place the margin in an area that bacteria could not have access. In combination with the poor impression technique, this allowed the lab technician to extrapolate the tooth contour, one or two millimeters subgingivally, and pick for themselves where the margin would go.

I, frustratingly, worked (only about two months) with a newly graduated dentist from the country of Turkey. She was recruited to a clinic because she was one of the best and brightest (she also did a one year geriatric fellowship in Pittsburg, PA). After my discussing her poor technique, she told me that is what she was taught in dental school. She added that she was also taught to prepare the occlusal reduction "flat-as-a-tabletop." She thought our "morphological tooth reduction" took too long, and took control away from the technician.

To this day, I continue to see variations of this technique done by old dentists, dentists from foreign countries, and sloppy dentists.

This margin type has uses, however, only in situations where there is not a better choice.