Silver diamine fluoride (SDF) is a liquid substance used to help prevent tooth cavities (or caries) from forming, growing, or spreading to other teeth. SDF is made of:

  • silver: helps kill bacteria
  • water: provides a liquid base for the mixture
  • fluoride: helps your teeth rebuild the materials they’re made of (known as remineralization)
  • ammonia: helps the solution remain concentrated so that it’s maximally effective against cavity resonance

SDF was first approved for use in Japan more than 80 years ago. SDF was approved by the U.S. Food and Drug Administration (FDA) in 2014 for use in the United States.

SDF is considered a class II medical device. This means that it only carries slight risks (for reference, condoms and pregnancy tests are also class II medical devices). It’s sold in some stores for home use, but it’s most commonly and safely used in dental clinics.

Most dentists use a liquid form of SDF containing at least 38 percent of the SDF solution. It’s applied topically, meaning that it’s applied directly to the surface of your teeth. Many dentists use the following steps:

  1. Cotton or gauze is placed near the affected teeth to prevent saliva from moistening the teeth.
  2. Moisture is removed from the surface of the teeth using a vacuum suction tool.
  3. SDF is applied to the area affected by a cavity.

Your dentist may also use the following to mask the areas affected by cavities:

  • glass ionomer
  • opaquer
  • crowns

SDF is most commonly used on areas affected by cavities. Research shows that SDF can be just as helpful when used as a preventive measure by being applied to healthy tooth surfaces. Research also suggests that dentists don’t need to treat cavities with fillings or tooth surface modification before using SDF.

Traditionally, many dentists have used a fluoride varnish to help stop cavity development. SDF has proven to be much more successful at reducing cavity growth than varnish. SDF also requires fewer treatments over time.

There’s no set number of applications required for SDF to work. Most dentists only apply SDF once per year. Varnishes often need to be applied four or more times per year.

  • SDF has widely been shown to be effective in completely stopping cavity development after a cavity has formed. Dentists call this process caries resonance.
  • SDF helps kill the bacteria that break down tooth surfaces while also keeping them from spreading to other teeth.
  • SDF is often suggested as a more comfortable alternative to drilling cavities. This can be helpful for children or adults who have anxiety about the dentist or may not be able to fully engage in dental procedures, such as those with special health care needs.
  • SDF can be helpful as a cavity treatment if you’re overly sensitive to the instruments and substances used during cavity treatments.
  • SDF can help keep cavities to a minimum or prevent them entirely if you feel that it’s difficult to make time for regular dental check-ups or feel uncomfortable about cavity procedures. It’s quick, requires no special equipment, and generally only needs to be done once per year.

Few harmful or negative side effects have been found with use of SDF. SDF is widely considered by dentists to be safe, even on young children. You shouldn’t use SDF if you have a silver allergy, advanced gum disease, or major tooth decay that’s exposed the soft tissue of your tooth beneath the enamel. These conditions can have painful reactions with the acid or ammonia in SDF.

The only common side effect of SDF noted in hundreds of studies is black staining around the area where SDF is applied. SDF can also stain surfaces that it comes into contact with when being applied, such as clothing or nearby tissues in the mouth.

Some research recommends the use of potassium iodide along with SDF to keep staining to a minimum. This mixture may also turn black when exposed to light. One study found that a similar treatment using nano-silver fluoride (NSF) limits SDF’s black staining. But more research needs to be done to make sure that NSF is just as effective as SDF in stopping cavities over a longer period. NSF may need to be applied more often than SDF to have the same level of success.

The average cost of an SDF application is $75 for a single treatment. This cost usually equals about $20–$25 per tooth.

SDF may be covered by certain health insurance plans or be eligible for flexible spending accounts (FSAs) available from some health care providers because it’s a class II medical device.

Many states now offer Medicaid plans that cover SDF treatments. A growing number of state legislatures have either proposed or are currently considering adding SDF to Medicaid and other government-sponsored health care plans.

SDF is a safe, painless alternative to traditional cavity drilling procedures.

Your dentist may not recommend SDF in every case of cavities. It’s also not yet as widely available as similar treatments, such as fluoride varnish. But SDF has been proven to be highly successful in stopping the development and spread of cavities. Even more effective forms that leave fewer black stains continue to be tested.