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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Why do I need to replace this crown-Overhang!

One of the most challenging aspects of clinical practice is convincing patients to go through with elective asymptomatic treatment. One such area is crown and bridge.

 This X-ray will appear repeatedly on this blog. Right now let's focus on #19-there is a clear overhang on the distal aspect!

This is how we explain the need to replace this crown to the patient:






 


" A crown needs to fit the tooth like a skull-cap fits the head-tightly around the seam. This crown is sitting on the tooth like an oversized hat-sticking out! This will eventually lead to food impaction leading to a cavity on the tooth and/or bone loss which will eventually lead to the tooth needing to be extracted."

It helps to have a comparative bitewing to show a well sealed margin like the one on the right.

Inferior Alveolar Block:

The most common complaint I get from patients regarding Local Anesthesia on the lower arch is that their lip felt numb but they still felt the pain when the dentist drilled on the teeth!

This happens because the operator administered the Long Buccal Nerve Block before verifying that the Inferior Alveolar Nerve Block has kicked in. There are 2 essential steps to do so:

1) Always use a long needle.
2) Don't start injecting till 90% of the needle is in the Pterygomandibular Space and you have hit bone.
3) Ensure that the side of the lower lip is numb EXACTLY to the middle. I also verify with an explorer in the canine area.
4) Do not adminster the Long Buccal Nerve Block till #1,2 and 3 have been completed!