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

Temporisation of inlay preparations
In most cases inlay preparations are relatively small and simply
require the preparation to be filled with a material that can be
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Chapter 6
removed easily. Proprietary materials specifically intended for this
purpose are available, consisting of a resin-based material that is 
simply placed in the preparation and polymerised with a light-curing
unit. These materials do not need to be cemented and are easily
removed when needed. Although very convenient, these have dis-
advantages of needing adequate bulk and also occlusal stability is
difficult to achieve – occlusal contacts must be present on the un-
prepared tooth as the materials are hard to shape and relatively soft.
When these materials cannot be used, a custom-made temporary
inlay may be constructed from direct resin composite (placed in the
preparation with a separating medium, polymerised, removed and
then cemented), although the presence of any undercuts in the prepa-
ration will prove disastrous as the composite will then need to be
removed with a bur with subsequent risk of further loss of tooth struc-
ture and damage to the preparation. An alternative is simply to fill 
the preparation with a traditional cement (e.g. zinc polycarboxylate).
Great care is required to remove these cements without damage to the
tooth/preparation.
Types of temporary crown
Temporary crowns may be made using a prefabricated crown or may
be custom made; the latter can be constructed chairside or indirectly.
The choice of material is largely determined by the aesthetic and
mechanical properties.
Prefabricated crowns
A wide variety of prefabricated crowns is available and these vary 
in quality and anatomic form – some being so poorly shaped that 
they would not be able to fulfil the roles of a temporary restoration.
Prefabricated crowns may be made from metal (typically aluminium
or stainless steel) for use posteriorly or from plastic (typically from
polycarbonate) for use when aesthetics are more important. A pre-
fabricated crown is essentially a shell that can be trimmed to follow
the contours of the margin and further adjusted to achieve adequate
occlusal contacts. Although these types of temporary crown may be
trimmed to fit and filled with a bulk of cement, a much better result 
is obtained if the shell is relined with a resin material. This will 
result in better stability of the temporary restoration as well as vastly
improved marginal fit. Both metal and plastic shells may be relined in
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this way, although some roughening of the internal surface is often
required to allow the relining resin to be retained within the shell.