Man, think about it - how bad is this really? Teeth break. Don't worry about why - just get it fixed when you can. Don't dwell on the past - it is over and you can't change it.
The best thing to do now is research the interview company, do some contingency planning, think about the GOOD things you are, have, or can do.
Contingency planning - think about all the really dumb things interviewers can ask, and come up with a slick answer for these slick interviewers.
If the interviewer is a pro, you should have nothing to worry about. That interviewer will ask about your experiences, and ask you describe actual events such as a time you had to fire somebody; they may ask what you have done to develop yourself, or others; they may ask about a succesful project; or whatever. But a pro will want to review actual experiences.
If you end up with a dud, like one that asks what would you do if you found a bag of money, millions, in the middle of a deserted road in the middle of nowhere. (I had this asked of me - I burned a bridge and asked him does such a stoopid question have to do with being a senior member of mgt., told the interviewer he needed to learn something about effective interviewing, and I got up and walked out.) Try to answer a question similar to what the interviewer is asking, but a question you wished they had asked (like politicians do!)
Say the question is - what would you do if a coworker tried to undermine you. Don't answer hypothetical questions. EVER. You have no idea what is in the interviewer' mind. Answer the question with something you actually experienced, like, as an example, the time that biotch redhead tried to hijack yor project. Turned out that after you approached her about it, you found out that her boss inadvertently gave her the same project you were working on (don't tell them you later got jiggy with her!). Takes away all the doubt.
Kinda hard to get this all down so you don't blow the interview. Don't lie, don't answer dumb questions, turn the questions around so you can tell real-world experiences, make sure you've taken stock of your successes, and what you research shows that you can do to help them, don't over or under dress, if this is a higher level job, prepare a powerpoint, on CD and paper, all about yourself, if the job has anything to do with numbers - wow them with your numbers, if it is task based job, bring in something similar to what they do so they can see your work, and on and on.
Would you like us all to interview you on line? It may be revealing, but you may get a taste of what will be asked of you. It might be fun!