Oral Health Topics
Amalgam (Dental Filling Options)
- Overview
- Restoring Your Smile: Dental Filling Choices
- Frequently Asked Questions (FAQ)
- Additional Resources
Overview
Thanks to advances in modern dental materials and techniques, dentists have more ways to create pleasing, natural-looking smiles. Dental researchers are continuing their often decades-long work developing materials, such as ceramics and polymer compounds that look more like natural teeth. As a result, dentists and patients today have several choices when it comes to selecting materials to repair missing, worn, damaged or decayed teeth.
These new materials have not eliminated the usefulness of more traditional dental materials, such as gold, base metal alloys and dental amalgam. That’s because the strength and durability of traditional dental materials continue to make them useful for situations, such as fillings in the back teeth where chewing forces are greatest.
Restoring Your Smile: Dental Filling Choices
- What's Right for Me?
- Types of Dental Restorations
- Amalgam Fillings
- Composite Fillings
- Ionomers
- Indirect Restorative Dental Materials (Two or more visits)
- All-Porcelain (Ceramic) Dental Materials
- Porcelain-fused-to-Metal
- Gold Alloys
- Base Metal Alloys
- Indirect Composites
What's Right for Me?
Several factors influence the performance, durability, longevity and cost of dental restorations. These factors include: the patient's oral and general health, the components used in the filling material; where and how the filling is placed; the chewing load that the tooth will have to bear; and the length and number of visits needed to prepare and adjust the restored tooth.
With so many choices, how do you know what's right for you? To help you better understand what's available, here are the advantages and disadvantages of commonly used dental restorations.
The ultimate decision about what to use is best determined by the patient in consultation with the dentist. Before your treatment begins, discuss the options with your dentist.
Types of Dental Restorations
There are two types of dental restorations: direct and indirect.
Direct restorations are fillings placed immediately into a prepared cavity in a single visit. They include dental amalgam, glass ionomers, resin ionomers and some resin composite fillings. The dentist prepares the tooth, places the filling and adjusts it during one appointment.
Indirect restorations generally require two or more visits. They include inlays, onlays, veneers, crowns and bridges fabricated with gold, base metal alloys, ceramics or composites. During the first visit, the dentist prepares the tooth and makes an impression of the area to be restored. The impression is sent to a dental laboratory, which creates the dental restoration. At the next appointment, the dentist cements the restoration into the prepared cavity and adjusts it as needed.
Return to Restoring Your Smile
Amalgam Fillings
Used by dentists for more than a century, dental amalgam is the most thoroughly researched and tested restorative material among all those in use. It is durable, easy to use, highly resistant to wear and relatively inexpensive in comparison to other materials. For those reasons, it remains a valued treatment option for dentists and their patients.
Dental amalgam is a stable alloy made by combining elemental mercury, silver, tin, copper and possibly other metallic elements. Although dental amalgam continues to be a safe, commonly used restorative material, some concern has been raised because of its mercury content. However, the mercury in amalgam combines with other metals to render it stable and safe for use in filling teeth.
While questions have arisen about the safety of dental amalgam relating to its mercury content, the major U.S. and international scientific and health bodies, including the National Institutes of Health, the U.S. Public Health Service, the Centers for Disease Control and Prevention, the Food and Drug Administration and the World Health Organization, among others have been satisfied that dental amalgam is a safe, reliable and effective restorative material.
Because amalgam fillings can withstand very high chewing loads, they are particularly useful for restoring molars in the back of the mouth where chewing load is greatest. They are also useful in areas where a cavity preparation is difficult to keep dry during the filling replacement, such as in deep fillings below the gum line. Amalgam fillings, like other filling materials, are considered biocompatible—they are well tolerated by patients with only rare occurrences of allergic response.
Disadvantages of amalgam include possible short-term sensitivity to hot or cold after the filling is placed. The silver-colored filling is not as natural looking as one that is tooth-colored, especially when the restoration is near the front of the mouth, and shows when the patient laughs or speaks. And to prepare the tooth, the dentist may need to remove more tooth structure to accommodate an amalgam filling than for other types of fillings.
Return to Restoring Your Smile
Composite Fillings
Composite fillings are a mixture of glass or quartz filler in a resin medium that produces a tooth-colored filling. They are sometimes referred to as composites or filled resins. Composite fillings provide good durability and resistance to fracture in small-to-mid size restorations that need to withstand moderate chewing pressure. Less tooth structure is removed when the dentist prepares the tooth, and this may result in a smaller filling than that of an amalgam. Composites can also be "bonded" or adhesively held in a cavity, often allowing the dentist to make a more conservative repair to the tooth.
The cost is moderate and depends on the size of the filling and the technique used by the dentist to place it in the prepared tooth. It generally takes longer to place a composite filling than what is required for an amalgam filling. Composite fillings require a cavity that can be kept clean and dry during filling and they are subject to stain and discoloration over time.
Return to Restoring Your Smile
Ionomers
Glass ionomers are translucent, tooth-colored materials made of a mixture of acrylic acids and fine glass powders that are used to fill cavities, particularly those on the root surfaces of teeth. Glass ionomers can release a small amount of fluoride that may be beneficial for patients who are at high risk for decay. When the dentist prepares the tooth for a glass ionomer, less tooth structure can be removed; this may result in a smaller filling than that of an amalgam.
Glass ionomers are primarily used in areas not subject to heavy chewing pressure. Because they have a low resistance to fracture, glass ionomers are mostly used in small non-load bearing fillings (those between the teeth) or on the roots of teeth.
Resin ionomers also are made from glass filler with acrylic acids and acrylic resin. They also are used for very small, non-load bearing fillings (between the teeth), on the root surfaces of teeth, and they have low to moderate resistance to fracture.
Ionomers experience high wear when placed on chewing surfaces. Both glass and resin ionomers mimic natural tooth color but lack the natural translucency of enamel. Both types are well tolerated by patients with only rare occurrences of allergic response.
Return to Restoring Your Smile
Indirect Restorative Dental Materials (Two or more visits)
Sometimes the best dental treatment for a tooth is to use a restoration that is made in a laboratory from a mold. These custom-made restorations, which require two or more visits, can be a crown, an inlay or an onlay. A crown covers the entire chewing surface and sides of the tooth. An inlay is smaller and fits within the contours of the tooth.
An onlay is similar to an inlay, but it is larger and covers some or all chewing surfaces of the tooth. The cost of indirect restorations is generally higher due to the number and length of visits required, and the additional cost of having the restoration made in a dental laboratory. Materials used to fabricate these restorations are porcelain (ceramic), porcelain fused to a metal-supporting structure, gold alloys and base metal alloys.
Return to Restoring Your Smile
All-Porcelain (Ceramic) Dental Materials
All-porcelain (ceramic) dental materials include porcelain, ceramic or glasslike fillings and crowns. They are used as inlays, onlays, crowns and aesthetic veneers. A veneer is a very thin shell of porcelain that can replace or cover part of the enamel of the tooth. All-porcelain (ceramic) restorations are particularly desirable because their color and translucency mimic natural tooth enamel.
All-porcelain restorations require a minimum of two visits and possibly more. The restorations are prone to fracture when placed under tension or on impact. The strength of this type of restoration depends on an adequate thickness of porcelain and the ability to be bonded to the underlying tooth. They are highly resistant to wear but the porcelain can quickly wear opposing teeth if the porcelain surface becomes rough.
Return to Restoring Your Smile
Porcelain-fused-to-Metal
Another type of restoration is porcelain-fused-to-metal, which provides strength to a crown or bridge. These restorations are very strong and durable.
The combination of porcelain bonded to a supporting structure of metal creates a stronger restoration than porcelain used alone. More of the existing tooth must be removed to accommodate the restoration. Although they are highly resistant to wear, porcelain restorations can wear opposing natural teeth if the porcelain becomes rough. There may be some initial discomfort to hot and cold. While porcelain-fused-to-metal restorations are highly biocompatible, some patients may show an allergic sensitivity to some types of metals used in the restoration.
Return to Restoring Your Smile
Gold Alloys
Gold alloys contain gold, copper and other metals that result in a strong, effective filling, crown or a bridge. They are primarily used for inlays, onlays, crowns and fixed bridges. They are highly resistant to corrosion and tarnishing.
Gold alloys exhibit high strength and toughness that resists fracture and wear. This allows the dentist to remove the least amount of healthy tooth structure when preparing the tooth for the restoration. Gold alloys are also gentle to opposing teeth and are well tolerated by patients. However, their metal colors do not look like natural teeth.
Return to Restoring Your Smile
Base Metal Alloys
Base metal alloys are non-noble metals with a silver appearance. They are used in crowns, fixed bridges and partial dentures. They can be resistant to corrosion and tarnishing. They also have high strength and toughness and are very resistant to fracture and wear.
Some patients may show allergic sensitivity to base metals and there may be some initial discomfort from hot and cold. However, due to their metal color, gold alloys do not look like natural teeth.
Return to Restoring Your Smile
Indirect Composites
Crowns, inlays and onlays can be made in the laboratory from dental composites. These materials are similar to those used in direct fillings and are tooth colored. One advantage to indirect composites is that they do not excessively wear opposing teeth. Their strength and durability is not as high as porcelain or metal restorations and they are more prone to wear and discoloration.
Frequently Asked Questions
- If my tooth doesn’t hurt and my filling is still in place, why would the filling need to be replaced?
- Are dental amalgams safe?
- Is it possible to have an allergic reaction to amalgam?
- Is there a filling material that matches tooth color?
If my tooth doesn’t hurt and my filling is still in place, why would the filling need to be replaced?
Constant pressure from chewing, grinding or clenching can cause dental fillings, or restorations, to wear away, chip or crack. Although you may not be able to tell that your filling is wearing down, your dentist can identify weaknesses in your restorations during a regular check-up.
If the seal between the tooth enamel and the restoration breaks down, food particles and decay-causing bacteria can work their way under the restoration. You then run the risk of developing additional decay in that tooth. Decay that is left untreated can progress to infect the dental pulp and may cause an abscess.
If the restoration is large or the recurrent decay is extensive, there may not be enough tooth structure remaining to support a replacement filling. In these cases, your dentist may need to replace the filling with a crown.
Are dental amalgams safe?
Yes. Dental amalgam has been used in tooth restorations worldwide for more than 100 years. Studies have failed to find any link between amalgam restorations and any medical disorder. Amalgam continues to be a safe restorative material for dental patients.
Is it possible to have an allergic reaction to amalgam?
Only a very small number of people are allergic to one or more of the metals used in amalgam fillings. In these rare instances, the filling may trigger a localized reaction that produces symptoms similar to a skin allergy. Often patients who have this reaction to amalgam have a medical or family history of allergy to metals. Another dental filling material will be used instead of amalgam in these situations.
Is there a filling material that matches tooth color?
Yes. Composite resins are tooth-colored, plastic materials (made of glass and resin) that are used both as fillings and to repair defects in the teeth. Because they are tooth-colored, it is difficult to distinguish them from natural teeth. Composites are often used on the front teeth where a natural appearance is important. They can be used on the back teeth as well depending on the location and extent of the tooth decay. Composite resins are usually more costly than amalgam fillings.
Additional Resources
Dental Filling Facts Brochure
Surfing for Substance: Evaluating Oral Health Information on the Internet
The Internet's vast resources offer many options for finding dental health information, but how can you determine if a Web site is trustworthy and accurate? Just because something is posted on the Internet does not mean the information is true or reliable.
Identifying credible health information can be a challenge. Here are some things to consider:
- Why is the person or organization writing about a particular topic?
- Is the information provided in the public interest?
- Is any advertising clearly separate from the health information?
- Does the site promote a particular cause or point of view?
- Is the person or organization trying to raise money?
- Does the Web site solicit personal information? Are they asking you to do something on their behalf?
- Is there a link describing the sponsor? Is there a way to verify the Web sites sponsor with a telephone number or postal address?
- Is the content presented as an opinion and clearly stated as such?
- How long ago was the site updated?
Be cautious about any individual or organization pushing you to immediate action without consulting your dentist.
Consider the content provider's qualifications. Ask yourself:
- Who wrote the material? Are the author's qualifications clearly stated?
- What type of scientific or health care expertise does the content provider have?
- Does this person have a dental or medical degree?
- Did the information come from an objective source, such as the U.S. Food and Drug Administration, a medical or academic institution, or a well-known scientific or medical publication?
How valid is the science?
Always question scientific results and try to determine if the facts support the conclusions. Do the findings sound too good (or too awful) to be true? Ask yourself:
- Do the author's credentials reflect expertise in the area?
- Is the argument or conclusion supported by sound scientific evidence or just an unsubstantiated theory? Is it myth or fact?
- Do objective organizations such as the World Health Organization, the U.S. Food and Drug Administration and the National Institutes of Health support these claims or conclusions?
- Are the study results current and does the research provide the most up-to-date facts available?
- Does any other credible health care organization support the findings?
Additional Web sites worth checking out:
- The U.S. Centers for Disease Control
- U.S. Department of Health and Human Services: www.healthfinder.gov and www.guideline.gov
- The U.S. Food and Drug Administration
- U.S. National Library of Medicine
- The National Oral Health Information Clearinghouse
Overview
Dental amalgam has an established record of safety and effectiveness. Amalgam has been used to restore the teeth of more than 100 million Americans. However, the fact that its formulation includes mercury content has raised safety concerns in the minds of some. Small amounts of mercury vapor can be released from amalgam during placement, mastication and brushing. The safety of dental amalgam has been studied and reviewed extensively and no correlation has been found between the small amounts of mercury released from amalgam restorations and any adverse health effect.
Resources
Life Sciences Research Office Literature Review
In 2004, an expert panel reviewed the peer-reviewed, scientific literature published from 1996 to December 2003 on potential adverse human health effects caused by dental amalgam and published a report. The review was conducted by the Life Sciences Research Office (LSRO) and funded by the National Institutes of Dental and Craniofacial Research, National Institutes of Health and the Centers for Devices and Radiological Health, U.S. Food and Drug Administration (FDA). The resulting report states that, “The current data are insufficient to support an association between mercury release from dental amalgam and the various complaints that have been attributed to this restoration material. These complaints are broad and nonspecific compared to the well-defined set of effects that have been documented for occupational and accidental elemental mercury exposures. Individuals with dental amalgam-attributed complaints had neither elevated urinary mercury nor increased prevalence of hypersensitivity to dental amalgam or mercury when compared with controls.”
- Executive Summary (PDF)
ADA Literature Review
Based on the results of a comprehensive literature review on amalgam safety, the ADA Council on Scientific Affairs (CSA) reaffirmed that the scientific evidence supports the ADA’s position that amalgam is a valuable, viable and safe choice for dental patients.
FDA Literature Review (White Paper)
In 1997, the U.S. Food and Drug Administration (FDA) and U.S. Public Health Service concluded from a review of nearly 60 peer-reviewed studies that the “data does not support claims that individuals with dental amalgam restorations will experience adverse effects, including neurologic, renal or developmental effects, except for rare allergic or hypersensitivity reactions.” Recently the FDA set out again to update its position on dental amalgam based upon the literature that has been published since the 1997 review. In 2009 they concluded “that there is insufficient evidence to support an association between exposure to mercury from dental amalgams and adverse health effects in humans, including sensitive subpopulations.”
The Journal of the American Dental Association
- Prenatal exposure to dental amalgam: Evidence from the Seychelles child development study, main cohort (2011)
- Neurological outcomes in children with and without amalgam-related mercury exposure (2008)
- Survival and reasons for failure of amalgam versus composite posterior restorations placed in a randomized clinical trial (2007)
- A Dose-Effect Analysis of Children’s Exposure to Dental Amalgam and Neuropsychological Function (2007)
Additional Resources
- Public Health Reports: Economic Impact of Regulating the Use of Amalgam Restorations (PDF)
- ADA Principles of Ethics and Code of Professional Conduct
- ADA Statement on Dental Amalgam
- ADA News Release: American Dental Association Statement: Food and Drug Administration Action on Dental Amalgam (Posted 07/28/09)
- Oral Health Topic: Amalgam Separators
- Oral Health Topic: Best Management Practices (BMPs) for Amalgam Waste
- Centers for Disease Control and Prevention (CDC): Dental Amalgam Use and Benefits
- FDA: Dental Amalgam
