best core material receiving a crown on molar:
a- amalgam. ***
b- reinforced glass ionomer.
d- composite
Direct method Pre-formed posts are cemented into one or more canals. Amalgam may also be Packed into the coronal aspect of the root canals (Nayyar core technique) and an amalgam core Built up, which is the preferred technique. Resin modified GI or resin composite may also be used.
These materials have the advantage that the preparation can be completed at the same visit. A Dentine adhesive system should be used with resin composite to enhance retention.
- composite resin cores exhibit greater microleakage than do amalgam cores,29 and they are not as dimensionally stable as amalgam in an vitro study. crowns made for teeth with composite resin cores failed to seat by 226 um more than crowns made for teeth with amalgam cores after immersion in body-temperature normal saline solution for 1 week. The surface of a composite resin core is affected adversely by exposure to zinc oxide-eugenol temporary cement,31 although that does not seem to have a negative effect on the tensile strength of the final crown.
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Endodontics