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

partial-coverage, three-quarter gold crown. However, the visibility 
of gold is not very aesthetic and is often unacceptable to patients. The
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Indirect restorations – further considerations


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traditional aesthetic alternative would be to place a full-coverage 
metallo-ceramic crown with ceramic on the visible parts of the tooth;
however this would require removal of a significant amount of tooth
structure. The use of an adhesive restoration would allow for an 
aesthetic onlay/inlay to be directly bonded to the remaining tooth
structure with little additional preparation.
Increasing crown height
The height of a preparation may be simply increased by placing the
margin more gingivally, perhaps subgingivally. However, this may
predispose to periodontal problems. Increasing periodontal problems
may present when margins move from being supragingival to crestal
to subgingival. With deeper margins, there is likely to be more
inflammation, increased pocket depth and possibly loss of attach-
ment
20
. Margins should ideally be no more than 0.5 mm subgingivally
in order to keep clear of the attachment complex. If margins impinge
on the epithelial attachment or connective tissue, then inflammation
and potential periodontal problems result.
If margins are subgingival, or when there is a need to increase the
clinical crown height, then surgical crown lengthening may be con-
sidered. In healthy tissues there is a consistent relationship between
the crest of alveolar bone, the length of epithelial attachment and 
sulcus depth. This relationship has been termed ‘biological width’
and is the minimum width at the gingival sulcus required to maintain
a normal gingival attachment
21
. Removal of soft tissue alone would
not result in this relationship and thus apical movement of the entire
attachment apparatus is necessary, requiring removal of bone in
order to maintain health.
When aesthetics are critical, for example in the anterior segment 
of a patient with a high smile line, a contralateral procedure may be
necessary to retain symmetry. Also, if a single tooth requires crown
lengthening and supporting bone is removed from that tooth only, the
gingivae may not rest more apically but may ‘bridge’ the gap: thus 
a procedure on a single tooth may involve bone removal around 
adjacent teeth.