"Ribs" on walls of PFM crown prep

[MattBiggar80]

SDN "Ribs" on walls of PFM crown prep

Hi guys

You gave me amazing advice in the past for my class 2 amalgam preparation, so maybe you can help once again.

When I do a PFM crown prep, I am using "too much" pressure and i get these "ribs along the walls.I find it very difficult to smooth the walls as well as the finish line.
Do you guys have any tips?

again, at my school they severely restrict the number of burs we can use and make us use the same diamond bur for about every 10-15, even 20 teeth. I know some students who just dont switch out the diamond burs.

we have a chamfer skinny one that is 0.8 at the tip and another chamfer fat one that is 1.2 at the tip.


I recently got a free sample of a bur called a ultra great white (sswhiteburs). I used it and it cuts through the plastic teeth like butter. less "ribs" / divets in the wall but still not smooth the way it should be.

Please let me know if you can give me some advice.

thanks

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[jay47]

SDN "Ribs" on walls of PFM crown prep

Hi guys

You gave me amazing advice in the past for my class 2 amalgam preparation, so maybe you can help once again.

When I do a PFM crown prep, I am using "too much" pressure and i get these "ribs along the walls.I find it very difficult to smooth the walls as well as the finish line.
Do you guys have any tips?

again, at my school they severely restrict the number of burs we can use and make us use the same diamond bur for about every 10-15, even 20 teeth. I know some students who just dont switch out the diamond burs.

we have a chamfer skinny one that is 0.8 at the tip and another chamfer fat one that is 1.2 at the tip.


I recently got a free sample of a bur called a ultra great white (sswhiteburs). I used it and it cuts through the plastic teeth like butter. less "ribs" / divets in the wall but still not smooth the way it should be.

Please let me know if you can give me some advice.

thanks

I know I said this before, but you really just cant use the same bur for 15-20 teeth, ESPECIALLY for a crown prep. Think how much tooth you are cutting on a crown vs a class 2 prep. I'd say at the very least, change it out every 5 crown preps. There really is no excuse for not using the "right tools for the job".

As far as ribs, unless you use a new bur, I don't know that anything will fix the problem, but you could make sure that you use a good finger rest and focus "maco", not "micro" so that you get a good taper. try not to look directly at your margins when prepping and just focus on getting a good taper by looking at the handpiece and the angulation of the tooth.

 

[MattBiggar80]

i appreciate your help. its very difficult. at my school the manager of the dental equipment has orders that he is on a very tight budget. He severely restricts the number of plastic teeth distributed to students, and burs.

THere is really no exuse for using hte right tools for the job... but at my school the excuse is budget. Its like... we use windows 95 because we can't afford for EVERYBODY to upgrade to Windows 7. very frustrating..

 

[7 Iron]

i appreciate your help. its very difficult. at my school the manager of the dental equipment has orders that he is on a very tight budget. He severely restricts the number of plastic teeth distributed to students, and burs.

THere is really no exuse for using hte right tools for the job... but at my school the excuse is budget. Its like... we use windows 95 because we can't afford for EVERYBODY to upgrade to Windows 7. very frustrating..

Can you buy fresh burs with your own money? We can buy carbides for $1 each and diamonds are like $3 each.

 

[MattBiggar80]

hi
i bought burs. hopefully this will make the difference.

i bought burs for operative/restorative. It made a tremendous difference.
ill keep u guys updated!

Can you buy fresh burs with your own money? We can buy carbides for $1 each and diamonds are like $3 each.

 

[goffdent]

If you got ribs showing on your crown preps.. that means there not eating enough.. Feed them dang nabit!

 

[MattBiggar80]

Lol. But this is a serious problem and if someone could give me any more tips on how to
Make a better prep I would appreciate it. I am going to do some new preps with fresh burs today.

 

[goffdent]

do you not get finishing burs? fine diamond chamfers, shoulders, footballs etc? that's how you remove the "ribs"

 

[MattBiggar80]

I bought my own burs. I did not tell anybody about this.
The problem is solved.

Again. Having the right tools for the job makes a significant difference.

 

[7 Iron]

Glad it's working out for you

 

[mmasurf]

get a white stone and after each crown prep give it a run it will clean your bur, also dont be cheap make your life easier, go on ebay and buy the diamonds you need.