It happens, just don't stress yourself out about it. You'll remember your mistakes and likely, learn from them. Dentistry is about practice, learning, moving on and getting better. Crap happens, as long as you strive to get better from it than you need to realize that's sometimes it's the best you can do.
As long as you didn't prep into the pulp, you're fine. Most labs want way more than the 1mm of facial reduction that they recommend in dental school, otherwise your crowns end up looking bulky in the anterior.
But that's a different post for a different time.
Contach above is dead on with this comment about how to handle the mistakes being more important. How did you/your TA handle the situation? Usually something that can be corrected by the lab isn't something you need to discuss with the patient.
For others like nicking an adjacent tooth (happens occasionally), I usually ask the patient "I don't like the shape of the tooth in front/behind the one I'm working on, can I reshape it to make the contact better on the crown?" Most patients don't care, but you've asked their permission.
Or a tooth you recently worked on needing a root canal, I look the patient in the eye and say, "sometimes these things happen. Anytime we take a bur to a tooth, there is always a chance that the nerve may never recover from the trauma. It sucks, but it happens a small percentage of the time. Here's what we need to do to fix it."
Patient management is the hardest and most important part of dentistry. Learn it early and you will be extremely successful.
Patients know that you're friends, they like you and you don't hurt them. They don't know that you've over-reduced tooth #18 when doing the crown, but they will know if it falls off. They don't know that your filling is perfect, they'll know if it's sensitive or the bite is off.
Learn how to talk to your patients, explain things without accepting/shifting blame and you'll go far with them.
Thanks again though!
