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

Custom-made temporary crowns
Rather than relying on the shape of prefabricated crowns, a tempor-
ary crown may be custom-made for each patient. When a temporary
crown is to be used as a provisional restoration or when multiple 
units are being restored, then this is the method of choice. Custom
temporary crowns may be made at the chairside or indirectly.
Chairside custom temporary crowns are made using a pattern 
or matrix of the required tooth shape. When only a few crowns are
required and the tooth shape before preparation is an acceptable
form, then this matrix may be made from the teeth at the start of 
treatment. When the existing teeth are not of acceptable form or when
a provisional restoration is required, this matrix should be con-
structed from a diagnostic wax-up of the intended result. Alginate or
silicone putty may be used to form the matrix (Fig. 6.2), or a vacuum-
formed stent may be constructed from a stone duplicate of the diag-
nostic wax-up. A variety of resin materials may be used to construct
the temporary crown. Polymethylmethacrylate or higher molecular
weight methacrylates may be used and can be easily modified to
result in very well-fitting restorations; however these materials are
Fig. 6.2
Matrix being filled for custom temporary.
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Chapter 6
difficult to handle and have an exothermic setting reaction and a 
large amount of excess monomer, both of which may be injurious to
the health of the tooth when in contact with freshly cut dentine
4
.
Proprietary materials containing bis-acrylates are also available for con-
struction of temporary restorations. These materials have low shrink-
age, so result in a good marginal fit, have a low exothermic reaction on
setting and have less potential for pulpal irritation
5,6
. Additions to these
materials are possible with resin composite (due to similar chemistry)
though this is not as easy or reliable as additions to methacrylates.
When using these materials, care should be taken to ensure that the
resin does not flow into undercuts (or is removed before set) so that
the temporary restoration may be removed. The temporary restora-
tion is then trimmed and polished before cementation.
When time allows, custom temporary restorations may be made
indirectly. An impression is taken of the prepared teeth, and is poured
in a quick-setting stone. The temporary restorations are then con-
structed as above using a matrix. The main advantage of this method
is that acrylic resins may be used without the worry of irritant effects
of heat and monomer. The acrylic can be cured under heat and 
pressure to give a strong restoration. This method is useful when 
multiple indirect restorations are required, and these can be more 
reliably made in this way, although the length of the patient’s
appointment is increased and on-site laboratory support is required.
As well as the relatively quick procedures outlined above, pro-
visional restorations that are intricate, that need to be placed for a long
time or may be subjected to large stresses (e.g. extensive temporary
restoration in a bruxist), may be made indirectly in a similar manner
to definitive restorations. These may be made from heat-cured acrylic,
resin composite or one of these materials in combination with a metal
substructure (e.g. cast gold or silver). These methods require much
more time for construction and in such cases it would be usual to 
provide a short-term temporary restoration, while the provisional
restoration is constructed.