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Types of Fillings

There are many options for filling materials to repair teeth that have been damaged by a cavity or through trauma or attrition. Fillings can be made out of metal such as gold or dental amalgam or tooth-colored materials such as glass ionomers or composites. Some fillings are placed directly into the tooth, while others are fabricated with an impression and sent to a laboratory for fabrication. Fillings fabricated with an impression can be made of cast gold, ceramic such as porcelain, or a tooth-colored composite. Computer assisted impressions are also utilized for the fabrication of ceramic tooth-colored restorations. This technique is known as the CAD (Computer Aided Design)/CAM (Computer Aided Manufacturing) technique. A ceramic filling is cut from a block with the CAD/CAM technique and then custom fit into the tooth.


METAL

Amalgam

Made of: A mixture of silver, tin, zinc, copper and mercury. Mercury is nearly 50% of the mixture.

Types: Traditional (non-bonded)

Used for: Fillings in back teeth

Lasts: At least 10 years, usually longer

Costs: The least expensive type of restorative material

Advantages

  • Amalgam fillings are strong. They can withstand the forces of chewing.
  • They are less costly than the alternatives.
  • Amalgam fillings can be completed in one dental visit.
  • They are less sensitive to moisture during the filling process than composite resin.

Disadvantages

  • Amalgam doesn't match the color of your teeth.
  • Amalgam fillings can corrode or tarnish over time. This can cause discoloration where the filling meets the tooth.
  • A traditional (non-bonded) amalgam filling does not bond (hold together) with your tooth.
  • The cavity preparation (the "pocket" in your tooth) developed by your dentist requires undercuts or ledges to keep the filling in place. Your dentist may have to remove more of the tooth to create a secure pocket.
  • Some people may be allergic to mercury or be concerned about its effects. Research shows that the small amount of mercury exposure from fillings is similar to what people get from other sources in the environment.

Cast Gold

Made of: Gold alloy (gold mixed with other metals)

Used for: Inlays and onlays, crowns

Lasts: At least 15 years, usually longer

Costs: More than most other materials; 6 to 10 times more expensive than amalgam

Advantages

  • Gold doesn't corrode.
  • Some people like the gold color better than the silver color of amalgam.
  • Gold fillings are durable enough to withstand chewing forces. They last longer than all other filling materials.

Disadvantages

  • You must visit the dentist at least twice to receive a gold filling. At the first visit, the dentist makes an impression of your tooth and places a temporary filling. The gold filling is made from the impression. It is placed at a second visit.
  • The cost is high because of the high cost of gold and the work involved.
  • If gold and amalgam fillings are right next to each other in your mouth, an electric current can result from interactions between the metals and your saliva. This can cause discomfort, called "galvanic shock."
  • Gold fillings are not tooth-colored.

TOOTH COLORED

Tooth colored fillings have several advantages:

  • They match the tooth color and shading. They therefore blend in with the rest of the tooth and other teeth.
  • They are bonded to the tooth. This helps seal the filling and prevent decay around it.
  • Glass ionomer and resin/modified glass ionomer fillings release fluoride and also absorb fluoride from saliva, or from fluoride containing toothpastes and rinses. The fluoride mineral helps strengthen the tooth and prevent more decay.
  • Usually, the dentist can make a smaller opening in the tooth for a plastic filling than for an amalgam filling. That's because chemical bonding helps to hold the filling in place.
  • A type of plastic filling is the dental sealant. Sealants are typically placed over the pits and grooves of a tooth in areas where food gets caught and cavities can develop. A well-placed dental sealant can cover a groove or pit that has questionable or a minimal cavity. Sealants should be checked by your dental hygienist or dentist to make sure that they are effective.
  • A new approach to slow the progression of cavities between the teeth is called resin infiltration. The material used flows into the “pores” that have been made in the tooth by the cavity and fills these areas preventing growth of the cavity.

However:

  • Some plastic fillings contain Bisphenol A (BPA). BPAs can present health risks because they have some properties similar to estrogen, a human hormone. The amount of BPA that is present is reduced by your dentist when they clean the filling surface after placement.
  • Placing a tooth-colored filling involves a few more steps than placing a metal filling. This means your child may spend more time in the dentist's chair.

Composite Resin

Made of: A mixture of plastic and fine glass particles.

Types: Direct and indirect. Direct fillings are placed by your dentist using a bright blue light that hardens the soft material. For indirect fillings, your dentist prepares the tooth and takes an impression of it. A laboratory or the dentist then will make the filling from the mold. During a second visit, your dentist cements this filling into place.

Used for: Small and large fillings, especially in front teeth or the visible parts of teeth; also, for inlays

Lasts: At least five years

Costs: More than amalgam, but less than gold

Advantages

  • Your fillings or inlay will match the color of your teeth.
  • A filling can be completed in one dental visit. An inlay may require two visits.
  • Composite fillings can bond directly to the tooth. This makes the tooth stronger than it would be with an amalgam filling.
  • Less drilling is involved than with amalgam fillings. That's because your dentist does not have to shape the space as much to hold the filling securely. The bonding process holds the composite resin in the tooth.
  • Indirect composite fillings and inlays are heat-cured. This step increases their strength.
  • Composite resin can be used in combination with other materials, such as glass ionomer, to provide the benefits of both materials.

Disadvantages

  • Composite resins cost more than amalgam fillings.
  • Although composite resins have become stronger and more resistant to wear, it's not clear whether they last as long as amalgam fillings under the pressure of chewing.
  • The composite may shrink when placed, producing gaps between the tooth and the filling. This can lead to more cavities in areas where the filling is not making good contact with your tooth. The shrinkage is reduced when your dentist places this type of filling in thin layers.
  • Some plastic fillings contain Bisphenol A (BPA). BPAs can present health risks because they have some properties similar to estrogen, a human hormone. The amount of BPA that is present is reduced by your dentist when they clean the filling surface after placement.
  • These fillings take more time to place. That's because they are usually placed in layers. The increased time and labor involved also contribute to the higher cost.
  • Indirect fillings and inlays take at least two visits to complete if your dentist is not prepared to make the inlay while you wait. Your dentist takes impressions at the first visit and places the filling or inlay at the second visit.

Ceramics

Made of: Porcelain, most commonly

Used for: Inlays and onlays, crowns, veneers, implants, and orthodontic brackets

Lasts: More than seven years

Costs: More than composite and as much as or more than gold, depending on the filling.

Advantages

  • Ceramics are tooth colored.
  • Ceramics are more resistant to staining and abrasion than composite resin.

Disadvantages

  • Ceramics are more brittle than composite resin and can break.
  • A ceramic inlay or onlay needs to be large enough to prevent it from breaking. This means that the tooth must be reduced in size to make room for the extra bulk.

Glass Ionomer

Made of: Acrylic and a component of glass called fluoroaluminosilicate

Types: In a traditional filling, the material sets without a bright light. Resin-modified or hybrid composite glass ionomer fillings are stronger than traditional ones. A bright blue light is used to set the material.

Used for: Glass ionomer is used most commonly as cement for inlay fillings. It also is used for fillings in front teeth, or around the necks of your teeth, or in roots. As filling material, glass ionomer is typically used in people with a lot of decay in the part of the tooth that extends below the gum (root caries). It is also used for filling baby teeth and as a liner for other types of fillings.

Lasts: Five years or more

Costs: Comparable to composite resin

Advantages

  • Glass ionomer matches the color of the teeth, but not always as well as composite resin. Resin-modified glass ionomer is usually a better match than traditional glass ionomer.
  • Glass ionomers release fluoride, which can help protect the tooth from further decay.
  • Glass ionomer restorations bond (stick) to the tooth. This helps to prevent leakage around the filling and further decay.

Disadvantages

  • Traditional glass ionomer is significantly weaker than composite resin. It is much more likely to wear or fracture.
  • Traditional glass ionomer does not match your tooth color as precisely as composite resin.
  • A resin-modified glass ionomer filling needs to be applied in thin layers. Each layer must be cured, or hardened, with a special bright blue light. Then the next layer can be added. This makes the tooth stronger but can lengthen the time of the dental appointment.

HYBRID FILLLINGS

Resin-modified glass ionomers are relatively new to dentistry and have eliminated many of the disadvantages present with traditional glass ionomers. They match tooth color much better and have many of the advantages of traditional glass ionomers, such as the release of fluorides to reduce the possibility of future tooth decay and filling failure. In addition, they have advantages that are similar to composite resins.

These fillings are gaining acceptance in dental practice, however more research is required to determine how they should be used and how long the restoration will last. The cost of these hybrid products is higher than glass ionomers or resin composites.

 

Updated- January 22, 2021

 

References:

  • Rasines Alcaraz MG, Veitz-Keenan A, Sahrmann P, Schmidlin PR, Davis D, Iheozor-Ejiofor Z. Direct composite resin fillings versus amalgam fillings for permanent or adult posterior teeth. Cochrane Database Syst Rev. 2014 Mar 31;(3):CD005620. doi: 10.1002/14651858.CD005620.pub2. PMID: 24683067.
  • Weldon JC, Yengopal V, Siegfried N, Gostemeyer G, Schwendicke F, Worthington HV. Dental filling materials for managing carious lesions in the primary dentition. Cochrane Database of Systematic Reviews 2016, Issue 9. Art. No.: CD012338. DOI: 10.1002/14651858.CD012338
  • Blatz MB, Conejo J. The Current State of Chairside Digital Dentistry and Materials. Dent Clin North Am. 2019 Apr;63(2):175-197. doi: 10.1016/j.cden.2018.11.002. PMID: 30825985.
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