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

Broken down and worn teeth
When there has been extensive loss of tooth structure due to caries,
tooth or restoration fracture or due to other non-carious tooth tissue
loss, it is often necessary to provide an indirect restoration.
In addition to the major examples described above, indirect restora-
tions may also be used in a number of other situations:
• To restore teeth with structural defects, e.g. hypoplastic teeth.
• As part of a larger restoration/reconstruction, e.g. part of fixed
bridge-work.
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• For splinting, e.g. periodontally compromised teeth.
• For aesthetic improvement, to alter colour, shape, size or inclina-
tion of teeth.
• To alter occlusal relationships.
When deciding whether to provide an indirect restoration for 
a patient, the individual tooth should not be considered in isolation,
but it is also essential to consider other factors that have a bearing on
treatment:
• Patient motivation
• Oral hygiene status
• Periodontal condition
• The restorative state of the mouth
• Occlusal relationships
• Age of patient (size of pulp-space)
Once it has been decided that an indication exists for an indirect
restoration, and that such an approach to treatment is suitable for that
patient, then the type of core restoration and indirect restoration to be
provided should be decided.
CORE RESTORATIONS
A core is the term used to describe the restoration that is placed in
order to build up a broken down tooth before receiving an indirect
restoration. In some cases it may not be necessary to place a separate
core, but an indirect restoration may be constructed to replace all 
of the missing tooth structure. Typical examples of this include 
root-filled teeth in which an integral corono-radicular restoration and
core may be placed
5
, or for teeth that have suffered cusp fracture
where placement of a traditional restoration would leave very little
tooth structure (e.g. premolars with a previous mesio-occluso-
distal restoration and one lost cusp, a ‘one-piece’ onlay may be the 
treatment of choice). However, for most teeth requiring an indirect
restoration, a core restoration will need to be provided.
The exact nature of any particular core will depend on the degree to
which the tooth in question is broken down and how much coronal
dentine remains. When attempting to understand the rationale for
choice of core restoration, it is helpful to consider the concept of
extremes, from a simple space-filling core to a structural core (Fig. 5.3)
and relate the different functions to the materials available.
Principles of indirect restoration