Crowns can become broken by a fracture, non-retentive preparation, secondary caries, weak cement, excessive occlusal forces, decementation or loosening of the crown.
The consequences of a crown becoming loose include the risk of ingestion and less likely, inhalation. The management of the loose crown includes immediate recementation or a replacement crown, depending on the assessment conducted by the dentist.
The factors that are taken into consideration in making this decision include the strength of the temporary crown to be placed and occlusal forces. Thus, a thorough occlusal examination is of paramount importance, strength of the cement, a strong alternative of cement should be considered. The occlusion assessment should also include the static and functional occlusion as well as the possible presence of Para functional habits, such as clenching or bruxism.
Management includes cleaning all the cement and residues, to carefully inspect for any underlying caries or fractures. Details that need to be assessed include margins, gingivae and contact points; occlusion needs to be checked in both ICP and in lateral and protrusive excursions, before the crown can be re-cemented. Stronger cement should be used than the original such as resin cements, especially in cases of heavy occlusal forces.
In some cases, immediate reconstruction of the abutment may be deemed inappropriate, if the underlying structure is deemed deficient due to caries or a fracture then this issue needs to be addressed. The treatment plan may vary with the addition of a root canal treatment or a temporary crown for the reconstruction of a new crown.