When delivering a single crown, probably the toughest tooth we can prep for is the second molar.
There are a couple things to be aware of when prepping second molars:
1. Limited Opening
One, usually, there's a limited opening in that area, so when you are prepping the tooth, you have to give the patient breaks because you're going to have to ask them to open quite a bit.
2. Wear and Tight Neutral Zone
The second thing, which is more of a concern, is the wear in that area and also the tight neutral zone.
Risk of Joint Seating Up
When you chew, the second molar is where you exert the most force; so often those teeth can get pretty worn out if they aren't in the right position.
If this patient hasn't been equilibrated, prepping the second molar becomes more complicated. Now you're dealing with a situation where if you do prep this tooth, put on a temp, and take away the interferences that were there, then there's a risk that the joint could actually seat up. Then when you go to place the crown you're going to have to adjust and re-adjust the crown because there's less space available.
The Neutral Zone
The neutral zone is also a major concern. It's very tight in that area. So if you're making a temp and you've over-contoured the buccal, for example, that tooth could potentially tip inwards. So again, when you place the crown on the second molar, you could be adjusting the occlusion for a long time.
So key points:
Recognize what you're dealing with in regards to that second molar.
Is there a lot of wear in that situation? If there is a lot of wear, consider possible crown lengthening. Consider a restoration which will involve minimal occlusal reduction. A great example is monolithic zirconia crowns.
And in some situations, you may even have to adjust the opposing occlusion when you do insert the crown just to make sure that you have enough space and you're not thinning out the crown that you're inserting.
Pay attention to these things:
- Neutral zone
- The limited opening when you are prepping these teeth