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

particularly useful for managing cases involving tooth wear.
Increasing the occlusal vertical dimension
Increasing the occlusal vertical dimension (OVD) and providing
restorations without occlusal reduction will allow restorations to 
be placed with less need for tooth substance removal. However, 
this approach is more clinically demanding, is complex and requires 
a very compliant patient. The dentition will normally need to be
restored at the retruded axis position (RAP), hence a period of stabil-
isation splint wear will be required (which will also aid in treatment 
by providing stability). In addition, a major disadvantage of this
approach is that multiple restorations will be required in order to 
re-establish occlusal contact between all teeth.
In many cases in which multiple teeth require restoration and space
is at a premium, for example tooth wear, a combination of approaches
is required. Also, when there are very short clinical crowns, sur-
gical crown lengthening may be performed to increase clinical crown
height and increase retention, as described previously.
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Chapter 6
LIMITATIONS OF INDIRECT RESTORATIONS
Indirect restorations typically have a longer lifespan than similar
direct restorations
27
. However, it is a common misconception that
once an indirect restoration is placed then the tooth does not require
any care. In fact, the opposite is true. Any indirect restoration will
have a ‘long’ margin that is essentially its weak point with respect 
to caries. It is not uncommon for caries to progress rapidly along 
the margins of a restoration such as a crown and for this caries to go
unnoticed for some time. Caries at the margins of indirect restorations
is often not detected until it has progressed so far as to make further
restoration of the tooth questionable at best, and often impossible. It 
is essential that follow-up and maintenance are provided for any
restoration and especially for indirect restorations.
Provision of indirect restorations entails a significant increase in
costs due to the extra time and need for multiple appointments and
also the cost involved in production of the restoration. Although 
it would appear that indirect restorations are more expensive to pro-
vide than direct restorations, over a lifetime, this may not be the case
as there will be fewer interventions due to the increased longevity of
the restoration
28,29
.
Without judicious application of the correct technique, indirect
restorations may be harmful to the tooth. For example, an inlay that spans
from one proximal surface to the other (i.e. mesio-occluso-distal) will
inherently predispose the tooth to fracture owing to its wedging
effect. It should also be remembered that many indirect restorations
entail a ‘cost’ to the tooth due to the need for the removal of (often 
substantial) amounts of tooth structure and possible pulpal injury.