Operative dentistry aje qualtrough, jd satterthwaite la morrow, pa brunton

Choice of core material
The choice of core material depends on several clinical variables. The
role of the core material with regard to a space-filling or functional
role is critical and the degree to which the core will be subjected to
stress and the amount of bracing provided by remaining coronal 
dentine should be considered when selecting the material. Amalgam
alloy should not be used beneath anterior full-veneer crown restora-
tions as corrosion products from the amalgam core may stain the 
dentine peripheral to the restoration and result in poor aesthetics.
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Similarly, an amalgam core underneath a three-quarter crown may
shine through the remaining tooth and be unaesthetic.
Restoration of the endodontically treated tooth is covered in detail
in Chapter 4, though points of particular relevance are repeated here.
In most situations the general principles above apply. When little
tooth structure remains it is usual to place a post-retained core,
although molar teeth may successfully be restored with an amalgam
dowel core (Nayyar core). If a direct intra-radicular post has been
placed in order to retain a core, then care should be taken to ensure
that the properties of the core material are not mismatched to those of
the post (e.g. avoid glass-ionomer cement or resin-composite cores
with metal intra-radicular posts), although some studies suggest that
fibre posts (with a relatively low modulus of elasticity) perform better
with a rigid metal core
9
.
In general terms, when there is sufficient coronal dentine remaining
to provide some support to the core material, then resin-based
restorative materials are the core materials of choice. However, for a
tooth that has lost much coronal tooth structure then a stronger core
material (amalgam or cast metal if root treated) should be placed.