Teeth are remarkably strong, but they are not immune to damage. There are many ways you might crack or break a tooth, including:
Impact or Injury Whether due to a fall, a blow to the mouth, or another type of accident, an impact to your face or jaw may result in a cracked or broken tooth.
Biting Down on Something Hard
Biting down on hard food (like nuts) at just the wrong angle, or even chewing on a pen or your nails, can cause damage, chips, and cracks to the teeth.
Having a Weakness in the Structure of the Tooth Teeth can become structurally weak as a result of tooth decay, a filling, other previous dental work, and a variety of other reasons. A tooth that is already weak is more prone to cracks and breaks.