The last twenty years has seen a revolution in
restorative dentistry. Instead of using gold and silver fillings, dentists
are increasingly using
tooth
colored materials for restorative procedures. These materials are also
being used in new ways, for example, to change the color and shape of teeth
to enhance one’s appearance.
There are three main classes of cosmetic
materials:
Resin composites
Resin composites are plastic materials filled with
ceramics. They can be “bonded” to
the surface of teeth. These materials are placed directly in the mouth
and are made to set
by shining a very intense beam of light on the surface of the material.
While
marvelous in many situations, they can tend to fracture under heavy loads
and one has to be careful about the seal of the restorations to make
sure that there is no leakage that can cause sensitivity and recurrent
decay.
Resin composites led to the development of a whole new field of dentistry, “Bonding”.
It is now possible to bond these materials to the surface of teeth to
change their appearance. Many people have deformed, irregular teeth that
can be improved by direct bonding. The tooth surface is conditioned by
a mild acid and a thin layer of bonding agent is placed. The bonding
material is then built up in layers to produce the color and appearance
that is desired. A dramatic change of appearance can be produced in a
single session.
Glass ionomers
Glass ionomers are materials which bond naturally to
tooth structure and which release fluoride to prevent recurrent decay.
They are not as
strong
as resin composites, nor are they as aesthetic, however they are very
useful in high caries situations, under composite and ceramic restorations
and
as cements to secure crowns. Dr Hunt has pioneered the use of these materials
in “internal” or minimally invasive cavity preparation principles.
Glass ionomers are often best used inside a tooth to prevent decay and
to help the healing of the dentin. Dr Hunt was the originator of the
concept of “internal” cavity preparation. In conventional
cavity preparations the whole side of the tooth is removed to get the
decay out. In internal cavity preparations a very small access to a carious
lesion is made in the hard outer enamel, and then the dentin softened
by decay is hollowed out.
No matter the particular design of restoration being placed, Dr Hunt
invariably places glass ionomer materials down on the dentin layer, rather
than directly applying resin composites. This reduces post-operative
sensitivity, the chance of recurrent decay and the incidence of root
canal problems.
Ceramics
Ceramics are very hard and durable glass based materials that
can only be formed outside the mouth. Great strides have been made
over the
last few years to speed the fabrication process and to reduce their
brittleness.
Ceramics of one form or another are used for almost all of our crown
restorative procedures.
Classically, ceramics can be very beautiful but rather brittle. The
most common way of using them in the mouth has been where they are enameled
to a cast metal substructure. In this way one gets the strength of a
metal framework with the esthetics of ceramic. However, it can sometimes
be tough to mask the metal framework, particularly at the margin.
The primary weakness of ceramics comes from porosities and inclusions
that get included as the ceramic is built up in layers. Although, it
is possible to find ceramics with have higher strength, the fabrication
process has always been the weak link. That is until now. With the CEREC
computerized scanning, design and milling technology it is now possible
to take a high resolution picture of the tooth, to design the restoration
on the computer and to mill the final shape of the restoration right
in the office from a high strength block of ceramic. This way there are
no inclusions or porosities in the ceramic and the restorations are much
stronger.
Dr Hunt uses this system in two ways. First to produce ceramic fillings
and restorations that can be fitted in the same session that the tooth
is prepared. This is great for the replacement of old silver amalgam
restorations. These ceramic restorations are stronger and much more durable
than plastic or composite fillings. Second, for larger cases, it allows
for the production of strong ceramic frameworks which replace the metal
substructures traditionally used.
On these high strength ceramic frameworks additional layers of ceramic
are fused to gain optimal esthetics.
There are limitations to this system. For example, it is not very easy
to splint teeth together or to construct bridgework. However, fewer and
fewer bridges are being placed these days because more and more missing
teeth are being replaced by implants.
Case Reports
 
 
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