When most people think of a
"filling", they imagine an item made out of some sort
of material, either metal or plastic that is placed directly
in a hole in a tooth, carved to resemble the original shape
of the tooth, and then allowed to harden inside the hole to
restore the form and function of the tooth. Of course, it also
must relieve the pain associated with the cavity. In fact, these
"direct" restorations, though far and away the most
common types due to their lower cost are only one half of the
Another type of restoration,
less common due to their much higher cost, are called "indirect"
restorations. These "fillings" justify their expense
by being more durable (in other words, properly cared for, they
should last longer than regular indirect restorations), and
also more esthetic (better looking because they are actually
built by a laboratory technician on a lab bench without the
difficulties imposed by the time constraint and the poor access
the dentist faces working in a patient's mouth). Indirect fillings,
made in a dental laboratory, are known as inlays and onlays.
Indirect fillings used to be
more common when gold and ivory were the principal dental materials.
With the advent of porcelain laboratory produced restorations,
most dentists today prefer the superior strength and esthetics
of "full coverage" of the tooth in the form of crowns
or veneers rather than simply filling cavities with laboratory
processed gold or porcelain fillings.
The types of direct fillings
There are three major types
of direct filling materials; silver amalgam, composite (combination
of glass/porcelain particles in a plastic matrix) and temporary
filling materials. (There are also three major types of indirect
filling material; gold, fused porcelain and composite.) (There
is an indirect form of composite which some dentists use.)
Composite fillings (sometimes called "porcelain" fillings)
are what people think of when they say "white fillings"
or "porcelain fillings". We call them tooth colored
fillings to distinguish them from amalgam, gold and temporary
filling materials. There are a number of different formulations
of composite filling, but the type most commonly used today
is made of microscopic glass, or porcelain particles of varying
shapes and sizes (depending on the intended use) embedded in
a matrix of acrylic. The glass particles account for between
60% and 80% of the bulk of these materials, so these restorations
could more properly be called porcelain fillings.
The glass particles
give the composite restoration their color (and their stiffness
in the unset state). The acrylic is the plastic matrix that
holds the glass particles together. Most composite restorations
today are "light cured" which means that the acrylic
remains fluid until a very bright light is shined on it causing
it to harden.
allows the dentist time to work with the material, building
and shaping it correctly, and when ready, to harden it immediately
with the light. The light curing also makes for a more color
stable restoration. The new tooth colored composite restorations
do not get yellow or brown with age as the older ones did.
The before and
after images of the tooth above are impressive, but do not tell
the whole story. In fact, a tooth that is built in more than
50% restorative material is inherently weak and should be prepared
for a crown. This does not mean that all badly damaged teeth
should be crowned immediately. In fact the decay in this one
was quite deep. Deep decay places the nerve in jeopardy, so
a plain filling may serve as a good intermediate restoration
to test whether the nerve will die before a final crown is placed
on the tooth.
particles also give the restoration a great deal of resistance
to wear. Amalgam fillings will probably always wear less than
composite restorations, however the recent advances in particle
formulation and shape have made the newest posterior composites
quite competitive for filling back teeth. Five to seven years
is average. Composites are even stronger than amalgams in shear
strength which makes them better for overlaying large biting
Composite fillings have been
used in front teeth for years, but only recently has the technology
in composite formulation improved enough to allow their common
use in back teeth. Prior to acrylic/glass composites, other
types of composites were used in areas where esthetics was important.
This is why even in the early twentieth century people were
not forced to have silver amalgam fillings in their front teeth.
However, even in the 1980's the technology had not yet advanced
enough to allow the routine use of composite to restore chewing
areas of the back teeth.
are still not as popular with dentists for repairing back teeth
as old-fashioned amalgam. In fact, only about 25% of dentists
currently use them routinely for restoring posterior teeth.
for this are that they are not as wear resistant as amalgam
restorations, they are more technique sensitive than amalgam,
and there is a tendency for more prolonged tooth sensitivity
to cold after the restoration is done. On the other hand, as
the materials continue to improve, they have become tougher
and more wear resistant while improvements in placement technique
have reduced cold sensitivity. However, the greater difficulty
in placing these restorations remains a deterrent for many dentists,
and continues to keep the cost of the service higher than for
an a comparable amalgam restoration.
Post operative discomfort after
fillings (why they sometimes cause prolonged sensitivity to
cold or pressure)
When any type of filling is
done on a tooth, some sensitivity to cold and pressure is normal.
This often lasts for as much as a month after the filling is
done. The amount of post operative discomfort associated with
any given filling depends on the depth and extent of the cavity
preparation which in turn depends upon the depth and extent
of the original area of decay or of the old filling which is
to be replaced.
In many instances the living
nerve in the tooth is not especially healthy at the time the
filling is done, and the trauma caused by removal of the decay
or the old filling can push the nerve over the edge causing
an irreversible pulpitis (inflammation of the nerve) which will
lead to the eventual death of the nerve. Situations in which
the nerve of the tooth remains exquisitely sensitive to cold,
or hurts spontaneously without an external stimulus may have
a dieing nerve, and the only solution to this problem is either
to perform a root canal treatment or extraction on the tooth.
A second problem
that can cause prolonged sensitivity to cold or pressure on
a recently filled tooth is hyperocclusion. This is a technical
term that means that the filling is simply too "high"
and strikes the opposing teeth with too much force when the
patient closes his mouth. This can cause very severe sensitivity
to cold and sensitivity to pressure, especially pressure applied
to the side of the tooth.
This is a very
common problem because the patient is generally numb when the
dentist carves the top of the tooth. The patient may not be
closing into his normal bite and the dentist may miss a high
spot. The solution to this problem is to return to the dentist
for an occlusal adjustment, which means that the dentist determines
what spots on the tooth are high and grinds them down.
of an old filling or decay may reveal a crack in the floor of
the cavity preparation. This can lead to cracked tooth syndrome
which means that the tooth hurts whenever pressure is applied
to one or more cusps (points) of the tooth. Cracked teeth happen
all the time in dentistry, and they are one of our most challenging
appearance of cracked tooth syndrome does not mean that the
dentist did something wrong. It is generally due to a pre existing
crack which suddenly allowed the tooth segments to spring apart
when the old filling was removed, or when the dentist cut a
new surface in order to remove decay. The management and prognosis
for cracked teeth is complex and I urge you to read the page
I have provided to explain it.
When a patient
presents at my office with pain attributable to a cavity, we
sometimes place a temporary filling in the tooth and reappoint
the patient for a final permanent filling at another visit.
Sometimes, this is done in order to save time, especially if
we have slipped the emergency patient between two regularly
scheduled patients. Sometimes it is done in order to save money.
are the least expensive (and most temporary) way to fill a tooth.
Temporary fillings can be done quickly, because they are usually
inserted without any of the time consuming rituals associated
with a permanent filling. The patient is anesthetized, the decay
removed and the temporary filling is mixed and inserted, generally
simply by pushing it into the cavity preparation with a gloved
finger. The patient bites into it while it is still soft in
order to adjust the height, and the patient leaves the office
without even waiting for a final set on the material. In a phrase,
a temporary is "fast and cheap'.
But there is
another reason that may indicate that a temporary is the best
way to treat the patient, even if time or money is not an issue.
Temporary fillings are different from permanent amalgam or composite
fillings because they are "sedative" fillings. This
means that they tend to soothe an inflamed nerve in a tooth,
and may make the difference between the tooth needing a root
canal (or an extraction), or simply filling the tooth later
on, after the nerve has calmed down. Sometimes a temporary filling
is the best course to relieve pain.
are made of two major components: Oil of clove (eugenol), which
has been used for centuries to relieve toothaches, and Zinc
Oxide which is an excellent disinfectant. The oil and oxide
mix together to make a stiff paste that eventually hardens into
a waterproof substance which soothes the nerve of the tooth
and kills germs while protecting the cavity like a hard band
Zinc Oxide and
Eugenol is not very durable, and it wears away after just a
few weeks, but it works to relieve pain, calm the nerve and
protect the tooth until an appointment can be made to get it
Never plan to keep a temporary filling more than 6 months. They
are not meant to last that long, and while the eugenol lulls
the patient into a false sense of security, the restoration
wears rapidly and begins to leak. If you wait too long, the
nerve could die, the temporary filling will wear away, the tooth
will decay further, and then you will need a root canal or extraction.