Determining If You Need a Filling
Your dentist may use several methods to
determine if you have tooth decay,
Observation — Some discolored spots
on your teeth may indicate decay, but not
all of them. Your dentist will use an
explorer, a metal instrument with a sharp
tip, for a more thorough examination of
possible decay. Healthy tooth enamel is hard
and will resist pressure by the explorer.
Decayed enamel is softer and the instrument
will stick in it slightly. Explorers should
be used with caution. A healthy tooth can be
damaged if an explorer is used with too much
Cavity-detecting dye — This can be
rinsed over your tooth. It will stick to
decayed areas and rinse cleanly from healthy
X-rays — X-rays can help your dentist
see decay that doesn't show on the surface.
However, X-rays are often not accurate in
detecting smaller cavities, and existing
fillings or other restorations can block the
view of decay.
Decay is not the only reason you may need a
filling. Cracked or broken teeth, or teeth
that are worn from unusual use — such as
nail-biting, tooth grinding (bruxism), or
using your teeth to open things — may also
Steps to a
When you visit your dentist to get a
filling, you will be given local anesthesia
to numb the area if necessary. Next, your
dentist will remove decay from the tooth,
using hand instruments or a drill. Air
abrasion and lasers can also be used to
A drill, which dentists call a handpiece,
uses metal cones called burs to cut through
the enamel and remove the decay. Burs come
in many shapes and sizes, and your dentist
will choose the ones that are right for the
size and location of your decay.
At first, your dentist will use a high speed
drill (the one with the familiar whining
sound) to cut through the hard enamel. He or
she will precisely outline the cavity with
the drill, removing only enough tooth
material so the filling material can be
placed properly. Once the drill reaches the
dentin, or second layer of the tooth, the
dentist may use a lower speed drill because
dentin is softer than enamel.
To clean out the decay, your dentist may use
a round bur. Throughout the removal process,
your dentist will test the area with the
explorer to see if all the decay has been
removed. A cavity-detecting dye may also be
used. Dentists do not use color to judge
whether all the decay has been removed. Not
all cavities are discolored, and discolored
enamel can be healthy.
Once all the decay is removed, your dentist
will shape the space to prepare it for the
filling. Different types of fillings require
different shaping procedures to make sure
they will stay in place. Your dentist may
put in a base or a liner to protect the
tooth's pulp (where the nerves are). The
base or liner can be made of composite
resin, glass ionomer, zinc oxide and eugenol
or another material.
Some of these materials release fluoride to
protect the tooth from further decay.
If your dentist is placing a bonded filling,
he or she will etch (prepare) the tooth with
an acid gel before placing the filling.
Etching makes tiny holes in the tooth's
enamel surface, which allows the filling
material to bond tightly to the tooth.
Bonded fillings can reduce sensitivity and
reduce the risk of leakage or decay under
the filling because the etched surface of
the tooth and the filling material form a
mechanical bond. Bonding is generally done
with composite fillings. It can also be done
with amalgam materials.
If you are getting a light-set,
composite-resin filling or a resin-bonded
glass ionomer filling, your dentist will
stop several times to shine a bright blue
light on the resin. This cures (hardens) the
material and makes it strong.
Finally, after the filling is placed, your
dentist will use burs to finish and polish
After a Filling
Many people experience some sensitivity
after they receive a filling. The tooth may
be sensitive to pressure, air, sweet foods
or temperature. Composite fillings often
cause sensitivity, but other types of
filling material can, too.
In most cases, the sensitivity will subside
over one to two weeks. Until then, try to
avoid anything that causes it. If your tooth
is extremely sensitive or your sensitivity
does not decrease over about a two-week
period, you should contact your dentist's
It's important to let your dentist know
about any sensitivity you are experiencing.
The next time you need a filling, he or she
may be able to use a different material and
make modifications to minimize sensitivity.
People vary in their response to different
materials, and your dentist has no way of
predicting if your tooth will react to a
When you talk to your dentist about the
sensitivity, try to describe it as precisely
as possible. The information you give will
help decide what should be done next. Your
dentist may take out the filling and put in
a new one, possibly adding a base, liner or
desensitizing agent on the tooth as well. If
the filling was very deep, you could need a
root canal treatment to solve the problem.
Besides sensitivity, some people experience
discomfort when they bite down. There are
two types of pain, each with a different
The first type occurs when you bite, and
worsens over time. This is caused by a
filling that interferes with your bite. Once
your anesthetic wears off, you would notice
this right away and should contact your
dentist. You will need to return to the
office to have the filling reshaped.
The second type of discomfort is a very
sharp shock that appears only when your
teeth touch. This is called galvanic shock
and is caused by two metals (one in the
newly filled tooth and one in the tooth it's
touching) producing an electric current in
your mouth. This would happen, for example,
if you had a new amalgam filling in a bottom
tooth and had a gold crown in the tooth
Your dentist polishes the filling after it
is placed, but occasionally sharp edges may
remain. If you find one, contact your
dentist and arrange to have it smoothed as
soon as possible to avoid injury to your
tongue or mouth.
You may receive a temporary filling
(usually white, off-white or gray) if:
▪ Your treatment requires more than one
▪ Your dentist wants to wait for a short
period of time for the tooth to heal.
▪ You have a deep cavity and the pulp (nerve
and blood vessels) becomes
exposed during treatment.
▪ You need emergency dental treatment.
Temporary fillings may have a sedative
effect on the tooth. The tooth may feel
better after a temporary filling is placed.
This is because the filling seals the tooth,
protecting the pulp from bacteria and
Temporary fillings often contain eugenol, an
ingredient in over-the-counter toothache
remedies that is known to have light
anesthetic properties. Eugenol is also a
component of oil of cloves, which people use
for toothache pain.
Temporary fillings are just that. They are
not meant to last. Usually, they fall out,
fracture or wear out within a month or two.
If you get a temporary filling, make sure
you visit your dentist to get a permanent
one. If you don't, your tooth could become
infected or you could have other
Why Replace a Filling?
Fillings don't last forever. They
can become discolored. For example, amalgam
or silver fillings corrode and tarnish,
while composite, tooth-colored fillings pick
up stains, and yellow or darken over time.
When you chew, your teeth and any fillings
in them are subjected to tremendous
Even if no other problems develop, some
fillings will wear out over time and will
need to be replaced. A filling will need to
be replaced earlier if it falls out, leaks
A filling that is cracked or leaking can
allow food debris and bacteria in your mouth
to seep down under the filling. Since you
can't clean there, the bacteria feed on the
food debris and form the acid that causes
tooth decay. Decay under a filling can
become extensive before you notice it or it
causes you pain. This can be prevented by
having your fillings checked regularly and
getting them replaced when problems are
Fillings That Fall Out
Fillings can fall out for several reasons:
▪ You chew too hard on a large filling, and
fracture the filling or the tooth that is
holding the filling.
▪ A filling material was used that cannot
restore the tooth to its proper form and
function. For example, if you have fractured
a large piece of your front tooth, a
porcelain (tooth-colored) crown is probably
the best treatment choice. In some cases, a
dentist may place a composite filling
instead. The appearance may be good or
acceptable. However, if the composite iss
too large, a strong biting motion may
fracture the plastic material.
▪ The cavity is contaminated with saliva
when the filling is placed, For composite
resins, this will disrupt the bonding of the
material. If the bond is not strong enough,
the filling can fall out. As a result, the
bond will not adhere well to the tooth and
it may fall out.
Both amalgam and composite fillings can
crack, either soon after they are placed or
after the filling have been in place for
Cracks can occur soon after a filling is
placed if the filling is higher than the
rest of the tooth surface, and most of the
force of biting is concentrated on the
Cracks can also occur over time, as the
forces from chewing and biting affect the
Small cracks also can occur at the edges of
a filling. These usually are caused by wear
over time. These cracks can often be
A filling is said to be leaking when the
side of the filling doesn't fit tightly
against the tooth. This can allow debris and
saliva to seep down between the filling and
the tooth, which can lead to decay,
discoloration or sensitivity.
Both amalgam and composite fillings can
leak. An amalgam filling sometimes leaks
slightly after it is placed. You would
notice this as sensitivity to cold. This
sensitivity decreases over a period of two
or three weeks before disappearing
altogether. Over that period, the amalgam
filling naturally corrodes, sealing the
edges of the filling and stopping any leaks.
A composite filling could be contaminated
with saliva, which would weaken the bond
between the filling and the tooth and allow
for leaks. Other times, there may be small
gaps where the tooth and filling meet. These
gaps are caused by shrinkage when your
dentist places the filling. Sensitivity
after receiving a composite filling may
disappear over time. If it doesn't, the
filling may need to be replaced.
Fillings also can leak as a result of wear
over time. These fillings should be
Some fillings can last for 15 years or
longer. Others, however, will have to be
replaced as soon as five years after they
are placed. Your dentist can determine if
your fillings are worn enough that they need
to be replaced.
Clenching and Grinding
If you clench or grind your teeth, you may
have more problems with your fillings. The
forces placed on your teeth can lead to
tooth sensitivity, and can cause fillings to
wear faster than they normally would.
Clenching or grinding also can cause your
teeth and fillings to crack or develop small
craze lines, which are fine cracks you can
see if you shine a lifht on your tooth.
Keeping Your Fillings
Although some fillings can last for many
years, the average life of an amalgam
filling is five to seven years. Some can
last 15 years. Composite fillings may not
last this long.
Your dentist will examine your fillings at
your checkup visits. You may need X-rays if
your dentist thinks a filling might be
cracked or leaking, or if decay is occurring
under the filling. If a tooth is sensitive,
if you see a crack or if a piece of a
filling appears to be missing, make an
appointment with your dentist for an
To help your fillings last, you should visit
your dentist regularly for cleanings, brush
with a fluoride toothpaste, and floss at
least once a day. For people with many
fillings or very large fillings, your
dentist may prescribe a fluoride gel you can
use at home. The fluoride will help
strengthen your teeth and prevent future
cavities. Your dentist or hygienist can also
place a fluoride varnish around the edges of
these teeth at your checkup visits.
Replacing a Filling
Before removing your old filling, your
dentist will discuss treatment options with
you. It is often possible to repair an old
filling instead of removing ir and replacing
it completely. However, if the entire
filling has to be replaced, the dentist may
have to reevaluate the tooth to determine
the best filling material to use. You should
talk with your dentist about your
preferences for appearance, form and
function so he or she can select the
material that is best for you.
American Dental Association
211 E. Chicago Ave.
Chicago, IL 60611
Phone: (312) 440-2500
Fax: (312) 440-2800
back to top