help tooth prep

[doddares]

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Hi,

I had a little question about tooth preeration, I hope someone answers this.
I know that theoreticaly it is generally considered to make a chamfer margin for pocelain fuse to metal bridges or crowns. Im a student and personally i consider it more comfortable to make shoulder margins.

If a patient came in and i needed to make fixed bridge would to be wrong to make a shoulder preperation instead using a tapered fland end bure rather then the chamber bur ? I mean what are the consequences of doing this.

I spoke to colleague and was told that her father in general makes shoulder preps for all his fixed work. I observed another dentist use shoulder in his fixed metal to poreclain too.

So it is such a bad thing ? is it a bad thing to use to to use a different finishing line for a recommeded prosthesis. For example in this case im repreparing the margins for a new full house bridge ? The dentist who performed the job before me seems to have not placed any margins at all ? How was this possible ?? i assume thats why Im changing it due to all those caries underneath !

Also if your repreparing a tooth what margin do u use then, do you change the previous line, for example move it from a supre gingival position to a paragingival ?

My teacher says im doing a decent job so far but i want to be sure, colleagues say i try to make finishing preperations too perfectly and theory is different to practice its just not the same thing.

I know these are alot of questions but I hope someone can enlighten me a little.

Thanks

 

[HupHolland]

A shoulder margin for a PFM isn't ideal but it is done all the time in practice, usually for aesthetic areas so you don't show a metal collar.

As far as a "marginless" fixed prosthesis...those can't really be done. Some crown preps can be done with a feather edged chamfer, but there is still a definitive margin.

Your friends in private practice probably rarely do preps exactly the way they're taught at the dental school. The dental school expects perfection for both projects and practicals because they are setting the bar high. If they only expected average, then most likely you would be doing below average work when you start working without supervision. No dental school wants to turn out sub-par dentists.

Hup