3/4 and 7/8 crown

[Teru78]

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I have a question about these crowns. What's the difference with onlays?
I know the prep is diferent, but can you do an onlay instead of 3/4 or 7/8?
When I was in school I never heard or learn about these crowns.
Are dentist en US still doing this kind of crowns?
Thanks 🙂

 

[ilovegoldens]

I have a question about these crowns. What's the difference with onlays?
I know the prep is diferent, but can you do an onlay instead of 3/4 or 7/8?
When I was in school I never heard or learn about these crowns.
Are dentist en US still doing this kind of crowns?
Thanks 🙂

In practice it is rare to use these preps. First because of the difficulty of the prep, and secondly because nowadays a lot of people think about aesthetics a lot more.
However it is a great way for a school to text your manual dexterity.

Onlays are any type of crows that cover the cusps area.
The idea of the 7/8 and 3/4 is to combine tooth preservation and cosmetics. In the case of the 7/8 you leave the mesio-vestibular cusp of a 1st sup molar for example, which is the most visible part of the tooth in the mouth.
the 3/4 you have the vestibular face exposed instead of covering the entire tooth with metal, in the case of a pre molar for example. So it is obvious that in practice most patients would prefer an aesthetic material. So in practice these crowns turn out to be PFM or porcelain MOD onlays.

 

[Teru78]

Thanks you so much ilovegolden 🙂
More than 100 person read this post but you are the only one who reply...
I practice 3/4 and 7/8 crown in the typodont, but its pretty hard, so I think I will try to do PFM, onlay or inlay for USC interview since they dont tell you exactly what they want, you have to think what restoration to do in the case scenario they give.
I read that you got accepted in San Antonio. Congratulations 👍
I still waiting for a reply for an interview in San Antonio, I dont think I have much chance, the interview for 2010 is almost over.