Temporary Crown and Bridge Resins
Temporary crown and bridge resins are used to provide immediate temporary coverage following tooth preparation for crowns or bridges.
The usual technique is to record an initial impression in an alginate material prior to tooth preparation. The major impression may be recorded then or subsequently using an elastomeric impression material. The mixed temporary crown or bridge resin is applied to the prepared areas by placing it into the desired area of the alginate impression which is reseated in the patient’s mouth. After initial setting, the impression and the resin are removed and final hardening occurs outside the mouth. Temporary crowns can also be fabricated by placing the resins on to prepared teeth in clear plastic crown formers. In addition, the fit of prefabricated crowns can be improved by relining them with one of the temporary crown and bridge resins.
The temporary crowns and bridges are cemented into place with temporary cements, normally of a zinc oxide – eugenol composition.
The product should ideally be non-injurious to oral tissues since it comes into direct contact with freshly cut dentine and the oral mucosa. During setting, it should not give an unduly large temperature rise whilst in contact with dentine, as this could damage the pulp. It should not undergo a large setting contraction which could make removal of the temporary crown or bridge difficult, particularly if the set material is rigid.
The material should also have convenient setting characteristics, including the following.
It should be strong and tough enough to resist fracture and wear in use and should, ideally, be />