What is a tooth filling?
To treat a cavity your dentist will remove the decayed portion of the tooth and then "fill" the area on the tooth where the decayed material once lived.
Fillings are also used to repair cracked or broken teeth and teeth that have been worn down from misuse (such as from nail-biting or tooth grinding).
What steps are involved in filling a tooth?
First, the dentist will numb the area around the tooth with a local anesthetic. Next, a drill, air abrasion instrument or laser will be used to remove the decayed area. The choice of instrument depends on the individual dentist's comfort level, training, and investment in the particular piece of equipment as well as location and extent of the decay.
Next, your dentist will probe or test the area during the decay removal process to determine if all the decay has been removed. Once the decay has been removed, your dentist will prepare the space for the filling by cleaning the cavity of bacteria and debris. If the decay is near the root, your dentist may first put in a liner made of glass ionomer, composite resin, or other material to protect the nerve. Generally, after the filling is in, your dentist will finish and polish it.
Several additional steps are required for tooth-colored fillings and are as follows. After your dentist has removed the decay and cleaned the area, the tooth-colored material is applied in layers. Next, a special light that "cures" or hardens each layer is applied. When the multilayering process is completed, your dentist will shape the composite material to the desired result, trim off any excess material and polish the final restoration.
What types of filling materials are available?
Today, several dental filling materials are available. Teeth can be filled with gold; porcelain; silver amalgam (which consists of mercury mixed with silver, tin, zinc, and copper); or tooth-colored, plastic and glass materials called composite resin fillings. The location and extent of the decay, cost of filling material, patients' insurance coverage and your dentist's recommendation assist in determining the type of filling that will best address your needs.
- Durability -- lasts at least 10 to 15 years, usually longer; doesn't corrode
- Strength -- can withstand chewing forces
- Aesthetics -- some patients find gold more pleasing to the eye than silver, amalgam fillings
- Expense -- more than other materials; up to 10 times higher than cost of amalgam filings
- Additional office visits -- requires at least two office visits to place
- Galvanic shock -- a gold filling placed immediately next to a silver, amalgam filling can cause a sharp pain (galvanic shock) to occur. The interaction between the metals and saliva causes an electric current to occur -- it's a rare occurrence, however
- Aesthetics -- most patients don't find any "colored" fillings to be an "eye-pleasing" advantage
- Durability -- lasts at least 10 to 15 years and usually outlasts composite fillings
- Strength -- can withstand chewing forces
- Expense -- is less expensive than composite fillings
- Poor aesthetics -- fillings don't match the color of your natural teeth
- Destruction of more tooth structure -- healthy parts of the tooth must often be removed to make a space large enough to hold the amalgam filling
- Discoloration -- amalgam fillings can create a grayish hue to the surrounding tooth structure
- Cracks and fractures -- although all teeth expand and contract in the presence of hot and cold liquids, which ultimately can cause the tooth to crack or fracture, amalgam material -- in comparison with other filling materials -- may experience a wider degree of expansion and contraction and lead to a higher incidence of cracks and fractures
- Allergic reactions -- a small percentage of people, approximately 1%, are allergic to the mercury present in amalgam restorations
Tooth-colored composite fillings
- Aesthetics -- the shade/color of the composites can be closely matched to the color of existing teeth; is particularly well suited for use in front teeth or visible parts of teeth
- Bonding to tooth structure -- composite fillings actually chemically bond to tooth structure, providing further support to the tooth
- Versatility in uses -- in addition to use as a filling material for decay, composite fillings can also be used to repair chipped, broken or worn teeth
- Tooth-sparing preparation -- sometimes less tooth structure needs to be removed compared with amalgams when removing decay and preparing for the filling
- Lack of durability -- composite fillings wear out sooner than amalgams (lasting at least 5 years compared with at least 10 to 15 for amalgams); in addition, they may not last as long as amalgams under the pressure of chewing and particularly if used as the filling material for large cavities
- Increased chair time -- because of the process to apply the composite material, these fillings can take up to 20 minutes longer than amalgams to place
- Additional visits -- if composites are used for inlays or onlays, more than one office visit may be required
- Chipping -- depending on location, composite materials can chip off the tooth
- Expense -- composite fillings can cost up to twice the cost of amalgams
In addition to tooth-colored, composite resin fillings, two other tooth-colored fillings exist -- ceramics and glass ionomer.
- Ceramics, which are made most often of porcelain, are more resistant to staining than composite resin material but are also more abrasive. This material generally lasts more than 15 years and can cost as much as gold.
- Glass ionomer is made of acrylic and a specific type of glass material. This material is most commonly used for fillings below the gum line and for fillings in young children (drilling is still required). Glass ionomers release fluoride, which can help protect the tooth from further decay. However, this material is weaker than composite resin and is more susceptible to wear and prone to fracture. Glass ionomer generally lasts 5 years or less with costs comparable to composite resin.
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Does dental insurance cover the cost of composites?
Most dental insurance plans cover the cost of the composites up to the price of the silver filling, then the patient must pay the difference.
What are indirect fillings?
Indirect fillings are similar to composite or tooth-colored fillings except that they are made in a dental laboratory and require two visits before being placed. Indirect fillings are considered when not enough tooth structure remains to support a filling but the tooth is not so severely damaged that it needs a crown.
During the first visit, decay or an old filling is removed. An impression is taken to record the shape of the tooth being repaired and the teeth around it. The impression is sent to a dental laboratory that will make the indirect filling. A temporary filling (described below) is placed to protect the tooth while your restoration is being made. During the second visit, the temporary filling is removed, and the dentist will check the fit of the indirect restoration. Provided the fit is acceptable, it will be permanently cemented into place.
There are two types of indirect fillings -- inlays and onlays.
- Inlays are similar to fillings but the entire work lies within the cusps (bumps) on the chewing surface of the tooth.
- Onlays are more extensive than inlays, covering one or more cusps. Onlays are sometimes called partial crowns.
Inlays and onlays are more durable and last much longer than traditional fillings -- up to 30 years. They can be made of tooth-colored composite resin, porcelain or gold. Inlays and onlays weaken the tooth structure, but do so to a much lower extent than traditional fillings.
Another type of inlay and onlay -- direct inlays and onlays -- follow the same processes and procedures as the indirect; the difference is that direct inlays and onlays are made in the dental office and can be placed in one visit. The type of inlay or onlay used depends on how much sound tooth structure remains and consideration of any cosmetic concerns.
What is a temporary filling and why would I need one?
Temporary fillings are used under the following circumstances:
- For fillings that require more than one appointment -- for example, before placement of gold fillings and for certain filling procedures (called indirect fillings) that use composite materials
- Following a root canal
- To allow a tooth's nerve to "settle down" if the pulp became irritated
- If emergency dental treatment is needed (such as to address a toothache)
Temporary fillings are just that; they are not meant to last. They usually fall out, fracture, or wear out within 1 month. Be sure to contact your dentist to have your temporary filling replaced with a permanent one. If you don't, your tooth could become infected or you could have other complications.
Are amalgam-type fillings safe?
Over the past several years, concerns have been raised about silver-colored fillings, otherwise called amalgams. Because amalgams contain the toxic substance mercury, some people think that amalgams are responsible for causing a number of diseases, including autism, Alzheimer's disease, and multiple sclerosis.
The American Dental Association (ADA), the FDA, and numerous public health agencies say amalgams are safe, and that any link between mercury-based fillings and disease is unfounded. The causes of autism, Alzheimer's disease, and multiple sclerosis remain unknown. Additionally, there is no solid, scientific evidence to back up the claim that if a person has amalgam fillings removed, he or she will be cured of these or any other diseases.
In March of 2002, the FDA reconfirmed the safety of amalgams. Although amalgams do contain mercury, when they are mixed with other metals, such as silver, copper, tin, and zinc, they form a stable alloy that dentists have used for more than 100 years to fill and preserve hundreds of millions of decayed teeth. The National Institutes of Health published several large-scale studies to answer many of the questions raised about silver-colored amalgams. Results of these studies were released in 2006.
In addition, there has been concern over the release of a small amount of mercury vapor from these fillings, but according to the ADA, there is no scientific evidence that this small amount results in adverse health effects.
What causes tooth decay?
How should I care for my teeth with fillings?
To maintain your fillings, you should follow good oral hygiene practices -- visiting your dentist regularly for cleanings, brushing with a fluoride-containing toothpaste, and flossing at least once daily. If your dentist suspects that a filling might be cracked or is "leaking" (when the sides of the filling don't fit tightly against the tooth, this allows debris and saliva to seep down between the filling and the tooth, which can lead to decay), he or she will take X-rays to assess the situation. If your tooth is extremely sensitive, if you feel a sharp edge, if you notice a crack in the filling, or if a piece of the filling is missing, call your dentist for an appointment.
Reviewed by the doctors at The Cleveland Clinic Department of Dentistry.
Edited by Charlotte E. Grayson, MD, February 2003, WebMD.
Portions of this page © The Cleveland Clinic 2000-2003
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Medically Reviewed on 10/22/2019
Medically reviewed by Kenneth Rotskoff, MD, DDS; Board Certified Dentistry, Oral/Maxillofacial Surgery
"Dental Filling Facts"
American Dental Association