DENTAL CROWNS..................
What
are dental crowns?
Crowns are a type
of dental restoration which, when cemented into place, fully
cup over the portion of a tooth which lies at and above
the gum line. In comparison, fillings are dental restorations
that are used to fill in or cover over just a portion of
a tooth. Since dental crowns encase the entire visible aspect
of a tooth, a dental crown in effect becomes the tooth's
new outer surface.
Crowns can be made
out of porcelain (or some other ceramic material), gold
(or metal alloys), or a combination of both. Dental crowns
are often referred to as "dental caps" or "tooth
caps".
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Why
do teeth need dental crowns?
A dentist might recommend
placing a dental crown for a variety of reasons but, in
general, most of these reasons will usually fall within
one of the following basic categories:
dental crowns & dental "caps"
- To restore a tooth
to its original shape.
- To strengthen a
tooth.
- To improve the
cosmetic appearance of a tooth.
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How
do dental crowns strengthen teeth?
The strengthening
capability of dental crowns is related to the fact that
they cup over and encase the tooth on which they are placed,
thus serving as a splint which binds the tooth together.
Dental crowns are a very important means by which a dentist
can strengthen a tooth.
In contrast, dental
fillings, especially large ones, often have a weakening
effect on the teeth in which they are placed. Dental fillings
rely on a tooth's remaining structure to hold and support
them. Fillings, in general, don't strengthen a tooth and
don't protect a tooth from the forces generated by biting
and chewing.
If a small amount
of tooth decay is present then it's usually no problem to
make a repair by way of placing a dental filling. In these
cases there will still be a substantial amount of healthy
tooth structure remaining after the decay has been removed
and the filling has been put in place.
On the other hand,
repairing a large cavity often requires removing so much
tooth structure that the overall strength of the tooth is
greatly reduced. This is simply because the tooth is no
longer as intact as it once was, its structural integrity
has been compromised.
Of course it's not
exactly the same thing but... the structural integrity aspect
of a tooth is a little like an egg. If you take a raw egg
and want to break it open, well it really takes a pretty
firm rap. That's because an egg shell, in that specific
shape, is really a surprisingly strong object.
Now, in comparison,
say you have broken the egg open and the two halves of the
empty shell are lying on their sides. It's pretty simple
to crush each piece of the shell now. Its structural integrity
has been compromised. The shell is no longer in the shape
it was meant to be so to withstand forces. Teeth are somewhat
the same in the sense that once a large portion of the tooth
is missing (because it has broken, decayed, or has been
drilled away) it is simply no longer as sound.
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What
are the consequences of not protecting a tooth with a dental
crown?
It's impossible to
know precisely what the future holds for a tooth that seems
to be a candidate for a dental crown. Here are some of the
possible scenarios that might develop for a tooth, ranging
from benign to somewhat painful.
A)
The tooth will experience no problems.
When a dentist suggests that a dental filling should not
be placed but instead the tooth should have the protection
of a dental crown they are no doubt basing their recommendation
on their years of dental training and clinical experience.
As you might guess,
some teeth that very much seem to be in need of the protection
of a crown never produce pain or become problematic. No
dentist can know precisely what set of occurrences will
transpire with a tooth. They are simply advising you as
to what they consider to be the most predictable treatment
in regards to the long-term health of your tooth.
B)The
tooth will crack.
One possible outcome for a tooth that is in need of the
protection of a dental crown is that it will crack. Unlike
cracks in bones, the cracks in teeth do not repair themselves
or heal over. Once a crack has formed it often will, with
time, increase in size due to the cumulative effects of
repeated exposure to biting forces.
Those teeth that
do crack can do so in the following fashions:
1)
Teeth that have cracked but no piece has broken off or has
become mobile. The tooth produces no pain or discomfort.
In many cases unless a portion of your tooth has broken
off you may not be aware that a crack has formed. This is
because many cracks are difficult, if not impossible, to
visualize and not all cracks in teeth are significant enough
to produce symptoms.
Probably the greatest
threat associated with this status is that this condition
may be the prelude to a more serious situation. While clearly
not all cracks will unequivocally lead to problems, the
presence of a crack can suggest that a fracture, cracked
tooth symptoms, or a problem with the tooth's nerve may
be more likely to develop with this tooth than if the crack
was not present.
2)*Teeth
that have cracked and no piece has broken off or has become
mobile. The tooth does produce some pain or discomfort.
Cracked teeth can be sensitive. Biting pressure can separate
the portions of the tooth associated with the crack and
therefore trigger a painful response.
The classic sign
of a cracked tooth is that there is a sudden sharp pain
from the tooth when you bite down. The pain then subsides
once you have released your biting pressure. The pain may
not be produced every time you close, sometimes it takes
biting (or biting on something) at just the right angle
to trigger the response.
While cracks in teeth
do not heal, cracked tooth symptoms can subside. If you
anticipate that you do have a tooth which has cracked you
should let your dentist evaluate it and make a treatment
recommendation. They may determine that your tooth requires
little or no treatment, or at the other extreme, that a
dental crown should be placed so to splint the tooth together.
3) Teeth which crack and as a result have a portion
that breaks off or becomes mobile.
Teeth can crack and as a result have a piece that fractures
off. The piece that has separated can break away cleanly
or, if the fractured portion is still attached to the gums,
the piece will be mobile yet stay in place somewhat.
As you might expect,
the amount of pain or discomfort associated with a tooth
that has broken can vary widely depending on the specifics
of the situation. Sometimes these teeth:
- are totally asymptomatic.
- are sharp or rough and therefore irritating to the person's
tongue or cheek.
- have an increased sensitivity to hot and cold stimuli.
- are painful to biting pressure.
- are spontaneously painful.
Here are
some of the scenarios which often present themselves as
a result of a tooth fracture:
a) The tooth
breaks in a fashion that is easily repaired.
It's not always a catastrophic event when a tooth breaks
and, in fact, in most cases it usually it isn't. Any tooth
that has broken should however be inspected by your dentist
so they can make a treatment recommendation. A stitch in
time really can save nine when it comes to teeth.
It is conceivable
that such a small portion of the tooth has fractured off
that it only requires some minor smoothing. At the other
extreme you may find that your dentist recommends the placement
of a dental crown. Especially in those cases where a large
portion of your tooth is missing, take the obvious suggestion
that both your tooth and dentist are trying to give you,
have the crown made.
b)*The tooth
breaks, but it requires other types of dental work before
the dental crown can be made.
More serious tooth fractures will require more involved
dental treatment to repair them.
The tooth fractures,
periodontal surgery (gum surgery) is required.
If that segment of the tooth that has broken off comprises
a portion of the tooth's root a type of gum surgery called
"crown lengthening" may be needed before a dental
crown can be placed. This is because the edge of a dental
crown cannot extend too far underneath the gum line or else
it will impair the health of the gums around the tooth.
The tooth fractures,
root canal treatment is required.
Deep tooth cracks and tooth breakage can damage or compromise
the health of a tooth's nerve. In these cases your dentist
cannot simply place a dental crown on the tooth. They must
first perform root canal treatment so to remedy the problem
with the tooth's nerve.
c)*The
tooth breaks in a fashion in which it cannot be repaired.
Surprisingly, even teeth that have broken off flat with
the gum line can usually be rebuilt. If a crack or break
involves a large portion of the root portion of the tooth
however (the portion way down underneath the gum line),
your dentist may find that no dental treatment will be able
to adequately repair the tooth and it must be extracted.
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What
steps are involved when dental crowns are made?
It
typically takes two separate appointments for a dentist
to make a dental crown for a tooth:
I) The initial
dental crown appointment.
A) Your dentist
will numb your tooth.
Before the process of making your dental crown is begun
your dentist will anesthetize (numb) your tooth and the
gum tissue which lies around it.
B) Your dentist
will shape your tooth.
So a dental crown has adequate strength and, in the case
of porcelain type crowns, proper aesthetics, a crown must
possess a certain minimal thickness. Your tooth in turn
must be reduced by this same amount so once the crown is
cemented into place your tooth will not be oversized. The
minimal crown thickness that is usually needed lies on the
order of about two millimeters or so, which is just a little
more than a sixteenth of an inch.
In those areas where
a portion of your tooth has already broken off your dentist
may find that they have very little tooth reduction to accomplish.
As a part of the trimming process your dentist will ensure
that any and all decay has been removed from your tooth.
Besides reducing
your tooth so it is smaller in size your dentist must also
shape your tooth in a specific fashion. A tooth receiving
a dental crown must be slightly tapered in form so the crown
will slip over and seat on the tooth.
The more tooth structure
that extends up into the interior of a dental crown the
more stable the crown will be. There can be times when so
much of a tooth has broken off that a dentist will feel
that they must first "build up" a tooth with filling
material (make the tooth taller) before they do the final
shaping for the crown.
C)
Your dentist will make an impression of your tooth.
Once your tooth has been shaped appropriately your dentist
will need to make a copy of it (termed taking an "impression").
Your dental crown then in turn will be made from this impression.
There are two scenarios by which this process can occur:
1) Most dentists will take an impression
by way of making a dental mold of your tooth using impression
paste (a putty like material). This impression will then
be sent to a dental laboratory that will in turn use it
to create a plaster cast of your teeth. A dental technician
will fabricate your crown so it fits accurately on the plaster
cast. Since the cast is a precise representation of your
teeth the crown will fit on your tooth also.
Depending on the arrangements your dentist has made with
the dental technician, the amount of time required to fabricate
a dental crown is usually lies on the order of two weeks
or so.
2)
Your dentist might have a dental ceramic milling machine
in their office. These machines are attached to a camera
that can take an impression of your tooth optically. From
this image the machine can subsequently design your dental
crown and then create it by grinding down a block of dental
ceramic ("porcelain"), all in a matter of some
minutes. The obvious advantage of this technique is that
a tooth can be shaped and its dental crown cemented into
place, all in one visit.
If your dentist does not utilize a ceramic milling machine
it can be for good reason. Milling machines can only be
used to fabricate all ceramic ("porcelain") crowns.
Your dentist may feel that the physical properties and/or
the aesthetics of this type of crown are not appropriate
for your situation.
D) A temporary dental crown
will be made for your tooth.
In those cases where your dental crown will be created by
a dental laboratory you will have to wait the two to three
weeks while your crown is being fabricated. During this
time period your tooth will be covered over by a temporary
dental crown that your dentist has made. The temporary crown,
which is typically made from plastic or else a thin shell
of metal, will be cemented into place over your tooth. (Information
regarding temporary crowns.)
E)
Your dentist will select the proper shade of porcelain needed
for your dental crown.
If your crown will have a porcelain surface your dentist
will need to determine what shade of porcelain most closely
matches your tooth's neighboring teeth. Usually a dentist
will have a series of small tooth shaped pieces of dental
porcelain (each of a different color) which are collectively
called a "shade guide". Your dentist will select
various porcelain samples from the shade guide and hold
them in the area your new crown will occupy, until they
find the one which most closely matches the color of your
tooth's neighboring teeth.
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II)
Your second dental crown appointment.
Cementing your permanent crown in place.
At that point in time when the fabrication of your crown
has been completed your dentist will proceed with the process
of cementing it on your tooth. Your dentist will first make
sure your tooth is numb. Then, if a temporary crown has
been placed your dentist will remove it.
Before your dentist
can cement your new dental crown into place they will first
need to evaluate the way it fits on your tooth. To do so,
your dentist will place the crown on your tooth, inspect
its fit (possibly by way of using dental floss, feeling
it with a dental tool, or asking you to gently bite down),
remove the crown and adjust it, repeatedly, until they are
satisfied.
Especially in those
cases where the dental crown will hold a prominent position
in your smile, your dentist will also evaluate (and probably
ask your opinion about) the crown's overall shape and color.
Once you and your
dentist both agree that all seems right with your new crown
it can be cemented. Your dentist will first place dental
cement inside your crown and then seat it over your tooth.
After a few moments your dentist will use a dental tool
and scrape away any excess cement that has extruded from
underneath the edges of your crown. The placement of the
crown is now complete.
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What
precautions should be taken with a temporary dental crown?
Here are some things to know about temporary dental crowns,
including some of the types of precautions dentists often
recommend their patients take during that time when their
temporary crown is in place.
Temporary
dental crowns are held in place by "temporary"
cement.
Temporary dental crowns are usually cemented into place
using "temporary" cement so they can be removed
easily at the time of your next dental appointment. Because
this cement is not as strong as other types of dental cement,
your dentist will probably suggest that you take some precautions
so not to dislodge your temporary crown. Some of the types
of precautions your dentist might suggest are listed below.
You will simply need to ask your dentist if any of these
precautions (or any other precautions not listed here) are
important and relevant to your specific situation.
Minimize the usage of the side that has the temporary
crown.
There's no need to look for trouble, give the temporary
dental crown some consideration when eating. As much as
possible, shift the bulk of your chewing activities to other
areas.
Keep
sticky foods away from the temporary dental crown.
Anything sticky (caramel, chewing gum, etc...) has the potential
to grab onto the temporary crown and pull it off its tooth.
Avoid
chewing hard foods with the temporary dental crown.
Chewing exceptionally hard foods, such as raw vegetables
(carrots), can dislodge or break a temporary dental crown.
Suggestions
related to brushing and flossing a temporary dental crown.
A tooth with a temporary dental crown can usually be brushed
and flossed in normal fashion, with the following consideration.
After flossing it may be best to remove the dental floss
by way of letting go of one end and then pulling it out
to the side. Pulling the floss back out in normal fashion
might snag the temporary crown and pull it off its tooth.
What
to do if a temporary dental crown comes off.
If your temporary
dental crown does happen to come off contact your dentist's
office so they can provide you with specific instructions
and also make arrangements for you to come in and have it
recemented.
In regards to that
time period before you get back to your dentist's office
to have the temporary crown recemented, your dentist might
suggest that you simply place the temporary crown right
back on your tooth. Doing so can protect the tooth somewhat
from irritating stimuli such as hot or cold liquids. Wearing
the temporary crown will also hold the tooth in place and
keep it from shifting position (an important factor in how
well or how easily your permanent dental crown can be fitted).
Report to your dentist if you have found that the bite on
your temporary crown seems incorrect when it is placed back
on your tooth. In this situation your dentist will probably
prefer that you leave the temporary crown off.
If your uncemented
temporary dental crown doesn't seem to stay in place very
well your dentist might suggest that you fill it with toothpaste,
vaseline, or else denture adhesive before you place it over
your tooth (this technique should only be used for a few
days). Of course your dentist will no doubt advise you that
you will need to be careful with your temporary crown until
it can be recemented. So you don't end up swallowing or
biting on it unexpectedly, your dentist will probably state
that your temporary crown should be removed when you sleep
and eat. Anytime your temporary crown is not in your mouth
you should keep it wet. Put it in a glass of water or close
it up in a baggie containing a moist paper towel.
Pain and discomfort while your temporary dental crown is
in place.
If you notice any pain or discomfort with your tooth it's
best that you let your dentist know so they can evaluate
your symptoms. Here are some of the types of problems that
can occur:
A) The tooth has increased thermal sensitivity.
It is fairly common that a person will notice some increased
sensitivity to both hot and cold foods and beverages during
that time during which their temporary dental crown is in
place. This can often be related to the fact that the edges
of the temporary dental crown cover over the tooth less
fully and precisely than a permanent dental crown's edges
will, thus providing a space by the gum line where these
thermal irritants can get at your tooth. Just to play it
safe however, in this situation go ahead and contact your
dentist's office, report your symptoms, and let them make
a determination.
B) The gums around your tooth hurt.
It's not unusual that the gums around a tooth that has been
prepared for a dental crown will be tender for a day or
so. Since the edge of most crowns end at or below the gum
line your dentist will have to perform dental work in this
area. It is very easy for a person's gums to get roughed
up during the crown making process. As a solution a dentist
will often suggest that rinsing with warm salt water up
to three times a day may speed up the healing of this gum
tissue. However, in all cases, if something seems amiss
you should feel free to report to your dentist and let them
evaluate your situation.
C) The bite on your temporary dental
crown seems incorrect.
After your numbness wears off you may find that when you
bite down your temporary crown touches first or hits harder
than its neighboring teeth. In these instances your dentist
will probably be very eager to adjust your temporary crown
so your bite is more even. Don't expect this situation to
take care of itself or improve with time. Allowing this
condition to persist can seriously aggravate the tooth's
nerve or even compromise its health.
D) Discomfort with your tooth.
It is not out of the ordinary that a tooth might feel a
little aggravated after having been drilled on. If you do
notice discomfort go ahead and let your dentist know so
they can evaluate your symptoms. As a solution for minor
reversible conditions, a dentist will often suggest that
their patients take an anti-inflammatory analgesic (such
as ibuprofen or aspirin) so to help their tooth settle down.
(You will need to read and evaluate the directions and precautions
that accompany these products so that you know that their
usage is appropriate for you.)
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What
problems might be experienced with a permanent dental crown?
People can and do experience problems with those teeth on
which a dental crown has been placed. No doubt it is both
your and your dentist's hope that once your dental crown
has been completed that your tooth will be just fine. Unfortunately,
life sometimes runs contrary to our wishes.
Here are some of
the types of complications people can experience, they can
range from very minor and common place in nature to serious
and disappointing. In all cases, if you experience a problem
you should let your dentist know, sooner rather than later,
so they can evaluate your symptoms and make a treatment
recommendation.
A) The tooth has sensitivity
to both hot and cold stimuli.
It's not uncommon that, after a dental crown has been cemented
into place, a person will notice that their tooth has sensitivity
to both hot and cold foods and beverages. Typically the
location of this sensitivity is at the edge of the crown,
by the gum line.
In some cases a dentist
might have a very simple solution for this problem. The
solution might be as easy as using a tube of one of those
toothpastes marketed as being a treatment for "sensitive
teeth" (the active ingredient in these products is
usually potassium nitrate). However, rather than make an
incorrect treatment decision yourself, let your dentist
know you are having a problem so they can evaluate your
situation and make a recommendation.
B) The bite of the dental crown seems off.
Your dentist will have evaluated the way your dental crown
touches against your other teeth when you bite down during
that visit when they cemented your dental crown in place.
Even so, you may find, especially after your numbness has
worn off, that some aspect of your crown's shape is not
quite right. Possibly when you bite down you feel your crowned
tooth makes contact first, or maybe as you slide your teeth
from side to side you can feel some aspect of the crown
which seems too prominent.
This type of problem
is usually an easy fix for your dentist, they simply need
to buff your dental crown down so its shape is more in harmony
with your bite. Don't expect this type of problem to take
care of itself because it won't. In fact, if this condition
is not remedied promptly it can lead to serious consequences
related to the health of the nerve in your tooth.
C) Other difficulties with
dental crowns.
The same events and circumstances that have led to the need
for your dental crown (a broken or cracked tooth, a large
cavity, etc...) can have a detrimental effect on other aspects
of your tooth's health. Possibly your tooth was asymptomatic
initially and now that the crowning process has been begun
(or completed) problems seem to have popped up. While this
set of circumstances is disappointing, it is not an indication
that all was well with your tooth initially. It simply suggests
that the full extent of the tooth's problems could not be
identified beforehand.
Sometimes after dental
crown treatment has been begun or completed a problem with
the tooth's nerve becomes apparent and subsequently root
canal treatment is needed. Some teeth are cracked seriously
enough that even a crown cannot hold the tooth together
sufficiently. These are not circumstances your dentist can
predict with certainty, they can't see the future and know
all outcomes. Your dentist is simply trying to rebuild your
tooth in that fashion that their experience and training
suggests to them is best and most reasonable.
If you have found
that a problem has developed, or has persisted, after your
dental crown has been placed simply report to your dentist,
sooner rather than later, so they can evaluate your current
situation and suggest a treatment solution.
D)
What to do if a dental crown comes off.
If your dental crown comes off let your dentist's office
know promptly so they can provide you with specific instructions
and make an appointment for you where they will evaluate
your situation and then, if possible (and it very often
is), recement the crown on your tooth.
During that time
which exists before your dental appointment your dentist
may suggest that you simply place the crown back on your
tooth. The idea here is that wearing the crown will protect
your tooth from irritating stimuli such as hot or cold liquids.
Placing the crown on your tooth will also keep the tooth
from shifting. (A tooth without its crown can shift in position
so much that a dentist will not be able to recement the
crown but instead will have to make you a new one.)
Sometimes when a
person places a dislodged crown back on their tooth they
will find that the crown's bite seems to be off. This condition
must be reported to their dentist so a revised recommendation
can be made. Usually in this instance a dentist will feel
that is best just to leave the crown off, but that is for
them to decide.
If your dental crown
doesn't seem to stay in place very well your dentist might
suggest that you fill it with toothpaste, vaseline, or else
denture adhesive before you place it over your tooth (this
technique should only be used for a few days). Of course
your dentist will probably also tell you you will need to
be careful with your crown until it can be recemented. So
you don't end up swallowing or biting on your crown unexpectedly,
your dentist will probably suggest that you remove your
temporary crown when you sleep and eat.
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What
type of dental crown ("cap") should you have made?
Dental crowns (also
known as "dental caps" or "tooth caps")
can be made from metal, ceramic materials (porcelain), or
a combination of both (porcelain fused to metal). The information
on this page discusses the pros and cons of each of these
various types of dental crowns, but in general you should
rely on your dentist's judgment and advice as to which of
these types of crowns would be most appropriate for your
situation.
All metal dental
crowns. / Gold dental crowns.
Some dental crowns are made entirely of metal. The classic
metal dental crown is one made of gold, or more precisely
gold alloy. Over the decades a variety of different metal
alloys have been put to use in making dental crowns. Some
of these metals are silver in color rather than yellow like
gold.
Having a gold dental
crown made can be an excellent choice. Here are some reasons
why:
Because of its physical characteristics dentists find gold
to be a very workable metal and one which lends itself to
their being able to achieve a very precise crown fit.
Since they are metal
through and through, gold crowns withstand biting and chewing
forces well. They will not chip. It would be uncharacteristic
for a gold crown to break. Of all of the types of dental
crowns, gold crowns probably have the greatest potential
for lasting the longest.
Although they are
very strong the wear rate of a gold crown is about the same
as a person's own tooth enamel. This means that a gold dental
crown won't promote excessive wearing of the teeth it opposes
(the teeth with which it bites against).
Metal dental crowns
are usually placed on those teeth that are not overly visible
when a person smiles (i.e. molars). If you are considering
having a gold crown made take our advice on this point.
Before you give your dentist the go ahead on making a gold
crown, check with your spouse first. They're the one who
will be looking at your smile and your new dental crown
the most.
Dental crowns that
will show prominently when you smile are usually either
made of porcelain or else have a veneer of porcelain on
their surface (porcelain fused to metal crowns), so that
the crown's color is white like the rest of your teeth.
All
porcelain dental crowns.
Some dental crowns are constructed in a manner where their
full thickness is porcelain (or some other ceramic material).
These crowns can possess a translucency that makes them
the most cosmetically pleasing of all of the different types
of dental crowns.
Although they can
be very life like in appearance, the overall strength of
all porcelain dental crowns is less than the other types
of crowns. While they can be a good choice for front teeth,
due to the large chewing and biting forces which humans
can generate an all porcelain dental crown may not be the
best choice for back teeth.
Porcelain
fused to metal dental crowns.
Porcelain fused to metal dental crowns are somewhat of a
hybrid between all metal crowns and all porcelain crowns.
When they are made the dental technician first makes a shell
of metal that fits precisely over the tooth. A veneer of
porcelain is then fused over this metal, giving the crown
a white tooth-like appearance. Depending on the requirements
of your situation, these crowns are sometimes made where
the porcelain veneer only covers those aspects of the crown
that are readily visible (the other portions of the crown
have a metal surface), in other cases these crowns are pretty
much fully surfaced by porcelain.
Porcelain fused to
metal dental crowns can be a good choice for either front
or back teeth. These crowns are strong enough to withstand
heavy biting pressures and at the same time can have an
excellent cosmetic appearance. There are some disadvantages
associated with porcelain fused to metal crowns however
(which no doubt your dentist will try to minimize as much
as is possible). They are:
1. While the cosmetic appearance of these crowns can be
excellent, they often are not as pleasing aesthetically
as all porcelain dental crowns.
2. The crown's porcelain
can chip or break off.
3. The porcelain
surface of the crown can significantly wear those teeth
that bite against it.
4. The metal underlying
the crown's porcelain can sometimes be visualized as a dark
line found right at the crown's edge. A dentist will usually
try to position this dark edge just underneath the tooth's
gum line but if a person's gums recede this dark line can
show, thus spoiling the crown's appearance.
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How
long can dental crowns last?
It would be reasonable
to expect that a dental crown could last between five and
fifteen years. Most likely a crown which did only last five
years would be somewhat of a disappointment to your dentist.
It's probably their hope that any crown they make for you
will last ten years or longer. Depending on what wear and
tear the dental crown is exposed to, and how well you keep
the tooth to which it is cemented free of dental plaque,
a crown can last somewhat indefinitely. Especially one found
in a location where its cosmetic appearance is not much
of a concern.
Why do dental crowns
need to be replaced?
There can be a variety of reasons why a dental crown might
need to be replaced. Some of them are:
A)
The formation of tooth decay.
While a dental crown cannot decay the tooth on which the
crown is cemented certainly can. If dental plaque is allowed
to accumulate on a tooth in the region where the crown and
tooth meet, a cavity can start.
While there can be
a lot of variables with this type of situation, the worst
case scenario for your dental crown is that in order for
your dentist to be able to get at the decay, and subsequently
restore your tooth properly, the crown will need to be removed
and replaced with a new one.
B) The dental crown becomes
excessively worn.
Dental restorations are not necessarily more wear resistant
than your own natural teeth, nor is it in your best interest
that they should be. The ideal dental crown would be one
made out of a material which has the same wear characteristics
as your own teeth. This way neither the dental crown nor
your teeth would wear each other excessively.
Dental crowns can
wear out, especially in those cases where a person clenches
and grinds their teeth excessively. A dentist will sometimes
detect a small hole on the chewing surface of a dental crown
in that area where it makes contact with an opposing tooth
(meaning a tooth which touches on the crown when you bite).
In these cases, since the crown no longer seals over your
tooth your dentist will probably recommend that a new crown
be made, before that point in time when dental plaque has
seeped under the crown and has been able to start a cavity.
C) The dental crown has broken.
Dental crowns can break, or more precisely the porcelain
component of a dental crown can fracture. Some dental crowns
are made in a fashion where their full thickness is porcelain.
In these cases if the crown breaks it will most likely break
through and through. Even if the broken piece of the crown
doesn't come off either the esthetics, function, or the
seal of the crown will most likely have been compromised
and the crown will need to be replaced.
Other ceramic dental
crowns are of the "porcelain fused to metal" variety.
When this type of crown is fabricated the dental technician
first makes a thin metal shell that fully covers over the
tooth, a layer of porcelain is then fused to this metal
so to give the crown a tooth-like color. In cases where
this type of crown has broken it is the layer of porcelain
that has fractured off, usually revealing the metal tooth
covering underneath (which is often grey in appearance).
While the function and esthetics of the crown may have been
compromised, the crown's seal over the tooth may not have
been affected.
Since the seriousness
of a dental crown fracture can vary greatly, any crown which
has broken should be evaluated by your dentist. Some minor
damage might not be of much concern, and possibly ameliorated
by a little smoothing with a dental drill, but only your
dentist should determine this and only after they have had
an opportunity to examine your precise situation.
D) The esthetics of the crown have become objectionable.
Some dental crowns are replaced because, from a cosmetic
standpoint, their appearance is no longer pleasing. Two
situations where the cosmetic aspects of a dental crown
can change with time are:
1) The dental crown's edge has become visible and appears
grey.
Often as time passes the gum line of a tooth on which a
dental crown has been placed will recede. This is especially
likely in those cases where diligent brushing and flossing
have not been practiced. If enough recession occurs the
edge of the dental crown, which was originally tucked out
of sight just under the gum line, will become visible and
appear as a grey line.
Inherent to porcelain
fused to metal dental crowns (related to their construction)
is the fact that the very edge of these crowns will show
some darkness (a hint of the grey metal that lies underneath
the porcelain). If enough gum recession occurs this dark
edge will become visible, thus spoiling the cosmetic appearance
of the crown.
All porcelain dental
crowns do not have the same inherent edge darkness as porcelain
fused to metal crowns. Gum recession can, however, expose
the portion of the tooth that lies beyond the edge of the
crown (the tooth's root surface). Usually the color of this
part of the tooth is significantly darker than the color
of the dental crown, thus spoiling the cosmetic appearance
of the tooth.
2) The color of the dental
crown no longer matches its neighboring teeth.
Also related to the cosmetic appearance of a dental crown,
there can be times when, as years have elapsed, the color
of the crown no longer closely matches the shade of its
neighboring teeth. In these cases it is not the color of
the porcelain used to make the dental crown that has changed
but instead the neighboring teeth have stained and darkened.
There can be two
solutions to this situation. The dental crown can be replaced
with a new one that more closely matches the current color
of its neighboring teeth. Another solution might be to use
a teeth whitening process to return the neighboring teeth
closer to the color they were when the dental crown was
originally placed.
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Are
there alternatives to dental crowns?
Alternatives to having
a dental crown made for a tooth.
There is no other
dental restoration that covers over a tooth in the same
fashion that a dental crown does *, and for that reason
there really is no perfectly equivalent alternative treatment
to the placement of a crown. There are however, depending
on your specific circumstances, other choices that might
be made. Since none of them are precisely identical to the
placement of a dental crown you may run some risk when choosing
one of them. It is your dentist's obligation to provide
you with an intelligent discussion regarding all of the
various options that dentistry has to offer.
[*There are variations
on the technique of dental crowns, they are termed onlays
and 3/4 crowns. The premise behind these types of dental
restorations is identical to that of a crown, they just
cover over a tooth less fully. For the purposes of our discussion
here, we have considered these restorations to be the same
as a dental crown.]
Alternatives to the
placement of dental crowns.
Here are some of the types of options that might be suitable
alternatives to the immediate placement of a dental crown.
It would seem that any thorough discussion your dentist
provides would need to include most of these topics.
You should never make a treatment decision unilaterally.
Both you and your dentist together need to determine which
of these alternatives might be a suitable approach for your
specific situation.
A)
Delay the placement of the dental crown.
This can be an appropriate solution in some circumstances,
in other situations it could be the absolute worst decision.
You should never elect this option without the advice and
concurring opinion of your dentist. Especially in those
cases where decay is already present, or the tooth has broken
in a fashion where it traps food and plaque and decay is
likely to form easily, delaying dental treatment could very
well lead to more serious dental complications and even
tooth loss.
B) Seek another dentist's
opinion.
Different dentists have different skills and have had different
clinical experiences. A second dentist may have varying
views or insights regarding what they feel can be an appropriate
treatment for your tooth. No one can predict the future,
there isn't always one right solution to every problem.
Hear each dentist out and see which approach makes the most
sense to you.
C) Ask what financial arrangements
can be made.
Dental crowns can be expensive and your dentist is probably
asked about this possibility with some frequency. They may
have a solution to offer.
D) Temporize the tooth, delay
the placement of the dental crown.
This quite possibly could be a good solution. Once again,
you will simply need to see
