A cracked tooth means a crack extends from the chewing surface of your tooth vertically toward the root. The tooth is not yet separated into pieces, though the crack may gradually spread. Early diagnosis is important to save the tooth.
If the crack has extended into the pulp, the tooth can be treated with a root canal procedure and a crown to protect the crack from spreading. A cracked tooth that is not treated will progressively worsen. If the crack extends below the gum line, it is no longer treatable, and the tooth will need to be extracted. That's why early treatment is so important.
While cracked teeth are not completely preventable, you can take some steps to make your teeth less susceptible to cracks: