Cosmetic Post in Root Canals
Why would root-canal treated teeth need a cosmetic
(white) post?
All-porcelain restorations allow direct light
to penetrate. The amount of scattering versus
transmission of light depends on the chemical
composition of the porcelain1s glass matrix, the
size and structure of the crystalline phase, and
the processing technique. Light penetration adds
a translucency to the restorations that is comparable
to natural teeth even under compromised light conditions.
The transillumination quality also improves the natural
pale-pink appearance of the adjacent marginal
gingiva. The remaining tooth structure should
be observed more critically in light of the high
translucency of all-porcelain crown systems. Dark
and non-pleasing stumps can spoil the appearance
of very translucent restorations. The drawback
of any light-inhibiting core material is a shadow
effect at the gumline. Even all-porcelain crowns
can cause a dark gumline if their cores are too opaque
and inhibit light transmission. Bleaching, opaquers,
and cosmetic endodontic posts should therefore be considered.
What is a cosmetic post?
Cosmetic posts are white and consist of glass fibers
or zirconia, which is a dioxide of zirconium. The same
material is used for the production of imitation diamonds.
The zirconia used for endodontic posts is stabilized
with yttrium oxide and exhibits superior fracture toughness
and strength. Since the late eighties, the yttrium-oxide
stabilized zirconia has been used in orthopaedics for
total hip replacement. It has since been improved for
dental implants and endodontic posts. Cosmetic posts
allow the placement of tooth-colored, metal-free, and
translucent restorations. However, zirconium posts require
a special surface treatment in order to achieve a strong
and permanent bond to the tooth. They are sandblasted
with aluminum oxide, silanated, and cemented with a
phosphate-monomer modified resin composite. Only this
surface treatment allows a durable bond of the post
to the tooth. If the wrong cement is utilized, the initial
bond between the tooth and the post will eventually
decrease an
This patient came with extensive marginal decay of her
pre-existing porcelain-fused-to-metal crowns (Figure 1).
After complete removal of the decay, the teeth were restored
with cosmetic fiber posts and composite build-ups (Figure
2). This was necessary to allow a natural translucency
of the all-porcelain crowns of the restored teeth. The
patient also needed extensive cosmetic gum adjustments
to allow for proper proportions of the final 6 Empress
restorations (Figure 3).
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