When I was 15 years old, I was riding my bike going down hill and tried to do a sharp turn.  Sure enough flipped over and hit my teeth on the bike handle and chipped my tooth.

The chip was not significant, but I always felt it being sharp when I would rub my tongue on it.  At first my dentist just smoothed it down.  Finally, after a year or so, got it filled. Unfortunately, I had it fall it couple times until finally I got it capped.