Cervical extension for crown prep

One of the trickiest aspects of crown preps is cervical extension. Dentists are scared to extend the prep sub-gingivally for fear of invading the biologic width but end up short more often than not like in this case:

The crown was cemented by another dentist 2 years ago but the patient came to see me as an emergency because the crown had come off 3 times and the patient was not happy with that.

I recommended replacing the crown, and also the one on #14, and the patient agreed. I like to make sure that the refined prep has addressed the issue for re-doing the crown and hence I like to take a bitewing of the temp before I cement it.

The mesial margin was slightly open and so I was able to seal it but you can appreciate the adequate cervical extension of the prep on the distal.

Bottom Line: Ensure adequate extension of the crown prep cervically. Take BW when in doubt to ensure same!

You need a root canal-Post/core or Core build up-Crown!

How frustrating is it for us to do a wonderful root canal only for the patient not to get it restored and need extraction!

I had more of these when I started my dental career than I do today and it is not that the dental IQ of my patients is any different from back in the day. It is the way I approach the case from the very beginning.

When a patient presents with pulpal pain, the conversation is usually like this:

Pt: I am in a lot of pain. It hurts when I drink something hot and cold OR it hurts when I bite down!
Dr: Looks like you need a root canal. This will be the cost to you out of pocket!
Pt: Ok let's do it.

Note that nowhere was there a mention of a coronal restoration, leave aside a crown. So one of two things happen when the endo is completed:

1) The patient is then informed about the need for a post-core/build up and crown and given the financial estimate. Patient's normal and expected reaction is "I never knew I had to get that done! That's too much. I can't get that done."

2) The patient is given an apt for a full exam and never shows up.

Either way, it's a lose-lose situation.

What we do now is make the coronal seal and crown part of the root canal therapy. So instead of just saying "You need a root canal", we say "You need a root canal and then some sort of a permanent filling and possibly a crown over it to save the tooth. Failure to do any of the subsequent steps will render the root canal susceptible to infection and fracture and will most likely need extraction!"

Bottom Line: Don't separate the coronal restoration from the root canal therapy!

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