What's wrong with the preps dentists provide?

[ross75]

Hi All,

My first post!

As a dentist (in Australia) who has just taken on an iTero I have to say it has opened my eyes regarding my clinical skills. Those margins can look very different on a screen in magnification+++.

It got me curious about the opinion of technicians regarding tooth preparation in general, for both crowns and bridges.

What are the most common issues from a technician's viewpoint (underpreped, overcontoured, undercut etc...)?

If you could give dentists a 'Prep Wishlist', what would it be?

Regards
Ross

 

[doug]

Well, you opened a can of worms there. Not enough occlusal reduction. Trust the scanner when it tell you there's not enough room. More second angle cut on upper posteriors on the lingual. More second angle cut on lower posteriors on the buccal. Aim those functional cusp preparations towards the fossa. Move through function and look at the clearance on all preps. More "Scoop" on linguals of anteriors to accommodate long centric closure. allow "air space" on posterior preparations. There's a lot of open area on natural dentition in MIP, we need room to reproduce it in our crowns. Polish your preps. Thanks for being brave enough to ask.

 

[RileyS]

Thank you so much for caring!
To put it simply: smooth, chamfered, and minimum of 1.5 mm on occlusion. impression is also big deal. i don't know why a cord isn't used every single time, trimming a die should not involve so much guess work.
one last prep design: no steep axial walls.

 

[SiKBOY]

Welcome Ross, another Aussie here in Sydney.

All the above and shoulder prep on the buccal is ideal. Undercuts arnt that big a deal. We can manage most of them unless they are crazy but the number one thing is taking a good accurate impression.

You can have the best prep but if it can't be relayed to the tech, all your prep work is wasted with us guessing where margins are and easing drags etc.

 

[CoolHandLuke]

here is an example of a poorly done case. the kind we see nearly constantly.


here is the waxup, which the doctor provided, waxed by himself (rather poorly)


here are his preps. anyone see the margins? anyone tell me what kind of draw direction i'm supposed to have, or how these teeth are going to even stick for very long ?

 

[Mark Jackson]

I just had my teeth prepped the day before yesterday. Here is what I like to see:

 

[CoolHandLuke]

pretty wide interproxyz on those upper molars, mark, no ? wouldn't you like those sharp edges to be a bit chamfered ?

 

[actittle]

How do you plan on preventing food packing in between 12 & 13 where the margin is supa-gingival?

If it was dropped down a bit more you could develop a proper emergence profile.

 

[Mark Jackson]

That's a lot of preps and lot of retracted tissue for one day (20 units). All the margins are crystal clear and there is enough reduction that everything will be clean and hygienic. I'm plenty happy with the entire outcome.

 

[rkm rdt]

You're sure gonna have a pretty mouth!

 

[ed 3]

Welcome, WOW!!!! you are the first dentist who asking actually first in my practice to us- technicians. Kudos to ya.


1.Give us enough room
2. No undercuts
3.no sharp corners
4. make parallel axial walls between abutments especially for bridges
5.take an extra time to make a nice shoulder margins.
If there is not enough room can be done between upper and lower don't ask us [lab]. to make an Emax crowns or even all porcelain crowns. Remember we are not a magicians.
6. before sending out impressions make sure that margins are clear visible on it.
Regards,Ed

 

[Affinity]

All bruxzir? Then youre ready for the future!

 

[DMC]

I hate Dentists!

Quit working for them....ALL OF THEM! LOL

They can just blow-me!

I make more than 1/2 of them in my city anyway!

:thefinger:

 

[JohnWilson]

Who cut those preps Mark, I will send them some info on my lab. How does your jaw feel today?

 

[actittle]

Who is going to do the lab work?