Welcome to Justanswer.I will do my best to answer your question.I am not a great typist,be patient and feel free to ask if anything is unclear.There are a few causes for teeth chipping or fracturing.The most common cause is underlying decay.The decay may have entered through the side of the tooth undermining the enamel structure and when you bite down on something,the enamel crumbles because it is unsupported by decayed dentin.We also see alot of chipped teeth with patients that wear tongue bars .They get in the way sometimes when you are chewing and will fracture even healthy teeth.Grinding your teeth excessively can cause tooth fracture.Having missing teeth that have not been replaced can also cause teeth to shift.When the teeth shift..they hit the opposing tooth at an incorrect angle and will cause the tooth to fracture.Teeth with large fillings also have a tendency to break and chip.The larger the filling the greater tendency to break.If you have a small fracture ,many times these teeth can be buffed off and smoothed and do not need to be filled.Your dentist can do this in a matter of seconds and you will feel better instantly,your tongue will thank you for it.If you have any further questions please ask.