Take nothing for granted
There hs been some discussion lately on clearance and how to plan accordingly. Many great items we can add to our armenatarium to help with clearance. Router bur from Meisinger is a huge help, as can be the lowly 330 bur ( please check the length of the bur yourself since manufacturers vary).
Now you may think that when you are replacing a crown with recurrent decay, and it looks like nice porcelain work you can cut corners and just prep away. Unfortunately these are the cases where you to be very careful with clearance
Here the Porcelain looks adequate when we get down to metal
But as we sink the 330 to depth we have gone down past the cement into tooth structure.
And with the removal of the crown we see the depth grooves and the sharp line angles of the prep.
Ceramic does not like a cast metal prep, it will not survive long term if we follow the tenets beat in our heads in dental school. Don't take anything for granted, prep the restored tooth as you would a virgin tooth delivering the adequate clearance, smooth transition and smooth margins that out Cerec produced restorations like
Wonderful advice Pete! Beautiful dentistry and presentation. I am always leery of these older PFMs with a worn occlusal surface. I tell my self that these teeth are going to be under reduced and possible have previous retention (ferrule) issues. Great case!
Thanks for sharing
John. I am traveling so if I don’t have a prep picture on my laptop I will update when I return
Great example to show depth cuts through that crown, Pete! I’ve found the 330 from trihawk to be great for these. You’re right about having to measure them; I’ve found a range of 1.4-2.5 mm. Another benefit of the 330 as a depth cutter is you can use it to open the interproximal contacts and not have to change burs.
On 3/9/2018 at 7:46 am, Jeremy Bewley said... Great example to show depth cuts through that crown, Pete! I’ve found the 330 from trihawk to be great for these. You’re right about having to measure them; I’ve found a range of 1.4-2.5 mm. Another benefit of the 330 as a depth cutter is you can use it to open the interproximal contacts and not have to change burs.
Nice clinical tip!!
