Some teeth that crack after crown restoration often appear at the root of the tooth, most likely due to excessive bite forces on the crown, or excessive cusp slope without timely adjustment of the bite, resulting in a concentration of stress on the root of this tooth and a cracked root.
If the patient has night grinding itself, or excessive wear, this may also cause the tooth to crack.
If the tooth has developed intracanal resorption, resulting in thin root walls or excessive pressure on the root canal filling, this may also cause the tooth to crack.