What is silver diamine fluoride?
At AdVance Dental we have recently added a new treatment option for tooth decay. Silver diamine fluoride (SDF) is a high concentration fluoride solution that can be used to treat cavities and in some situations can be used to keep from drilling on a tooth and doing a filling.
SDF has been used as a therapeutic agent in Japan since the 1960’s. It has also been used for many years to treat dental cavities in Argentine, Australia, Brazil, and China. It was approved by the US Food and Drug Administration (FDA) for use in the USA in 2014. In addition to being used to treat existing cavities, it has been used to treat tooth sensitivity, and has been placed on cavity-free teeth for prevention of future cavities1.
How does silver diamine fluoride work?
SDF is effective at killing various types of bacteria that cause cavities, and has been shown to be more effective at this than fluoride alone. Both the silver and fluoride have different ways of killing bacteria (silver breaks bacterial membranes, while fluoride blocks their metabolism)2.
SDF at the commercially available concentration of 38% contains 44,800 parts per million (p.p.m.) of fluoride, which is higher than any other fluoride agent available for dental use. Fluoride, in addition to its antibacterial properties, can be absorbed into broken down tooth structure, re-hardening it and making it stronger than it was before.
Is silver diamine fluoride safe?
SDF is a liquid that is applied to affected areas of the teeth with a small brush or special spongy floss, then dried/rinsed. Patients may have a momentary metallic taste and the gums may be temporarily irritated. Vaseline is usually placed around the gums of the teeth that are being treated. It can also stain bare skin, so great care is taken to be careful in its application.
In terms of toxicity, a lethal dose (LD) of oral administration of SDF is approximately 520 mg/kg of body weight, while an LD of subcutaneous (under the skin) administration is 380 mg/kg of body weight. One drop of SDF contains about 11.88mg of SDF. The max amount of recommended teeth that the manufacturer the brand of SDF that we use recommends no more than 5 sites at a time. One drop will often treat multiple teeth, but even if I used 5 drops in one sitting, that would be 59.4 mg of SDF. I weigh 94 kg, using the more conservative LD of 380 mg/kg, it would take 35,720 mg of SDF to be lethally toxic for me. This is a 600 fold safety margin (it would take 600 times what I would receive in one sitting to be lethally toxic)2.
The Environmental Protection Agency (EPA) has set the long term exposure limit at 1 gram of silver to avoid argyria (a condition in which the skin turns purple or purple-gray due to excessive exposure to compounds containing silver)5. This condition has been reported after consumption of colloidal silver (products marketed as dietary supplements or immune system boosters). One study6 found this to be 400 times the amount of silver applied while treating 3 teeth at at time with SDF. One case report of argyria7 happened after a patient consumed a cumulative dose of 200g of silver (an estimated 648 mg every day for 10 months). This daily dose of 648mg of silver is 275 times higher than the maximum amount applied in the study treating 3 teeth. A study testing blood and urine levels of silver after SDF application also saw no adverse events3.
SDF is not for every situation. One key drawback is that it will stain any part of a tooth that is decayed dark brown or black. So any cavities treated in areas that can be seen when smiling/talking will likely need additional treatment such as fillings to cover up the staining. It also needs to be avoided in patients with a silver allergy or very sensitive gums/mouth sores due the potential irritation of the soft tissue surrounding the teeth4.
Why would I need silver diamine fluoride?
If you have cavities on back teeth that can’t been seen visually and you’d like them treated without being numbed or drilled, SDF might be for you. It also can be useful when many large cavities exist and we are trying to slow the progression of cavities in order to keep teeth from hurting or having to be removed. They can also be used on younger patients and/or patients with anxiety that want to avoid being numbed and having their teeth drilled on (provided they are open to the cosmetic compromise of the teeth being darkened, at least for some period of time.) If a tooth is already hurting, SDF probably can’t be used as the cavity is too deep already. An in-office examination is required to determine if SDF is an option for any particular situation.
I hope this has been an informative read.
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References:
1.) https://onlinelibrary.wiley.com/doi/full/10.1111/idj.12320
2.) https://c.ymcdn.com/sites/www.ohiochc.org/resource/collection/844C898D-52EB-4349-97E0-9311C1B316EB/T10_Vinod_Flouride%20(1).pdf
3.) https://jada.ada.org/article/S0002-8177(18)30758-X/abstract
4.) https://www.ada.org/~/media/ADA/Public%20Programs/Files/MPRG_SDF_Presentation_Crystal.pdf?la=en
5.) https://en.wikipedia.org/wiki/Argyria
6.) https://bmcoralhealth.biomedcentral.com/track/pdf/10.1186/1472-6831-12-60
7.) Wadhera A, Fung M: Systemic argyria associated with ingestion of
colloidal silver. Dermatol Online J 2005, 11(1):12.