Tooth fillings are generally required when the tooth has decay. The infected and decayed parts of the tooth are removed and the prepared cavity is filled. There are a variety of materials available for this purpose.
Determining If You Need a Filling
Your dentist may use several methods to determine if you have tooth decay, including:
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 pressure.
Cavity-detecting dye ― This can be rinsed over your tooth. It will stick to decayed areas and rinse cleanly from healthy ones.
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 need fillings.
Steps to a Filling
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 remove decay.
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 the tooth.
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 office.
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 particular material.
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 cause.
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 above it.
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 appointment.
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 reducing sensitivity.
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 complications.
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 pressures. 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 or cracks.
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 found.
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 some time.