As we age, many of us
find ourselves with teeth that are no longer structurally sound.
Root canals, lost fillings, decay below a filling, chipping
and cracking of the enamel are all things that can lead to large
scale defects in a tooth's surface. When the entire surface
of the tooth is a problem, but the root system is intact, a
crown might be just what the dentist orders.
Grinding your teeth,
an improper bite, age, fillings and tooth decay can all be contributing
factors in the wearing down, cracking or breakage of your teeth.
Dental crowns cover the entire visible surface of your affected
tooth and add strength, durability and tooth stability.
Grinding your teeth,
an improper bite, age, fillings and tooth decay can all be contributing
factors in the wearing down, cracking or breakage of your teeth.
Dental crowns cover the entire visible surface of your affected
tooth and add strength, durability and tooth stability.
Dr Phillip F. Ajaje will
usually be able to spot problem areas in your mouth that might
lead to tooth damage and a need for crowns. Chewing patterns
play a big role as well. By selectively grinding the tips of
your middle and back teeth (called cusps) will alter your bite
to reduce the stress on at-risk teeth.
In other instances, crowns
are used to replace a actual missing tooth. These crowns are
anchored to the teeth on either side, with a bridge section
connecting the two crowns. Instead of bridges, single tooth
dental implants may be used that eliminate the need for supporting
the crowns.
Dr Phillip F. Ajaje will
make an impression of the tooth and a dental laboratory will
create the crown. You will typically leave the office with a
temporary crown to wear while the permanent crown is being made
- this takes about two weeks. The permanent crown is then cemented
onto your tooth. Typically, only two visits are required for
this part of the procedure. Often, a preliminary restoration
of your tooth may be needed before a crown can be placed. To
stabilize your tooth, a filling must first be put in place prior
to placing a crown due to the loss of original tooth structure.
Tooth crowns usually last ten to fifteen years.
Be sure to discuss with
your cosmetic dentist that the cement colour used for your permanent
crown will be the same as used for your temporary crown. A try
in paste is used for this purpose. The colour of the cement
does affect the overall colour of a porcelain crown, so this
needs to be discussed long before your temporary crown is placed.
In some cases your cosmetic
dentist may choose to use a Flipper instead of a temporary crown.
A Flipper is a false tooth to temporarily take the place of
a missing tooth before the permanent crown is placed. A Flipper
can be attached via either a wire or a plastic piece that fits
in the roof of your mouth. Flippers are meant to be a temporary
solution while awaiting the permanent crown.
As the illustration above
indicates:
1) a tooth presents with
a large cavity or broken portion of tooth structure. This tooth
is vulnerable to further decay and fracture.
2) the dentist will 'prepare'
or shape the tooth for a crown. In preparing the tooth, the
dentist will incorporate resistance and retention features in
order for the crown to stay in place. These features vary in
every tooth and are determined by the type of bite you have.
An impression of the prepared tooth is taken and sent to a dental
laboratory for processing.
3) a crown is then fabricated
in the dental laboratory with instruction from the dentist such
as type of crown and shade or colour of the tooth. The crown
is then cemented in place by the dentist. A temporary crown
is placed while the laboratory is constructing the crown.
There are basically 2
types of crowns, those made of ceramic crowns and metal-ceramic
crowns. Metal-ceramic crowns are extremely durable and are normally
used in molars, where the forces from chewing and grinding are
most prevalent. Ceramic crowns are used primarily for front
teeth, since they can best resemble the natural tooth colour.
All Porcelain
Crowns
The new reinforced resin
or bonded all-porcelain type of crown has the nicest appearance.
This crown can be made from pure ceramic or a new reinforced
composite resin, and is almost indistinguishable from natural
teeth. The new bonding technology involved provides an exceptional
bond your tooth. It is metal-free, and thus satisfies the needs
of patients with metal sensitivities. When correcting your back
teeth with bonding, the cosmetic dentist will perform a tooth
coloured onlay. This type of procedure is used to correct only
those parts of the tooth that are in need. This is a metal-free
procedure.
Porcelain
fused to Metal Crowns
For a very natural appearance,
porcelain fused to metal crowns are the answer. However, they
have a metal substructure and require an opaque below the porcelain.
This can make the translucency of natural teeth difficult to
replicate. Occasionally a darker line will be visible at the
edge of the crown, near to your gum when it recedes with age.
There are basically two
types of porcelain you're likely to hear and read about most
- the felspathic and pressed
ceramic porcelains. The felspathic type is the
original method that has been around for 20 years. A Ceramist
in a dental lab bakes porcelain onto tin foil and then heats
it in an oven. The Ceramist is able to create tints and opaques
inside the porcelain to give the natural look we seek.
Pressed
ceramic is created from a single ingot.
The single ingot is milled in one piece to create the desired
shape. The stains and opaques are applied only to the surface
of the porcelain to give a natural look.
Zirconium
oxide - One of the most difficult areas
in dentistry today is the restoration of dental structures with
biocompatible materials that are strong enough to withstand
the forces of chewing (500-1000lbs pressure on molar teeth).
Recent technology from Germany now offers a material that has
overcome most of the pitfalls of present day products. Patients
now have a choice of a material that is esthetic, strong, pure,
biocompatible and capable of being used for single and long
span dental bridgework. That material is called Zirconium oxide.
Tooth crowns in general
add a good deal of strength to weakened or worn teeth. Depending
on your habits and the condition of your gums, there can be
some drawbacks. Your cosmetic dentist will advise which is best
for you given many factors, including how important appearance
is to you. The following are the advantages and disadvantages
of the most common crown types.
Porcelain
Crowns
Advantage:
Porcelain crowns or new reinforced resin are considered to be
the most aesthetically pleasing, as it is so easily matched
in colour to the surrounding teeth.
Disadvantage:
The thickness of the porcelain required for pleasing aesthetics
also requires that more tooth structure needs to be removed.
It is more difficult for your cosmetic dentist to get an ideal
fit where your gum meets the crown. Gingival inflammation appears
to be more common with porcelain crowns than gold crowns. All-porcelain
crowns require a higher skill level from your dentist and lab.
Porcelain
Fused-to-Metal Crowns
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