Caries Management Using Silver Diamine Flouride

Learning Outcomes

• Understand the benefits, limitations, and challenges associated with the application of Silver Diamine Fluoride (SDF).
• Recognize adult applications of SDF.
• Review the global history of SDF utilization for caries management.
• Be aware of the informed consent considerations relevant to SDF usage.
• Examine the effectiveness of SDF in comparison to fluoride varnishes for caries control.
• Gain insight into the human clinical trials conducted on SDF for halting caries progression.
• Familiarize with the delivery protocol for SDF established by UCSF.
• Review the current approval status from the Federal Drug Administration concerning SDF.
• Understand the recommendations and guidance statement on SDF use from the 2017 American Academy of Pediatric Dentistry.

Overview

Dental caries is the most prevalent infectious disease impacting the global population. The primary bacterial strains implicated in this condition are Streptococcus mutans and Streptococcus sobrinus. Unfortunately, most dental interventions focus on restorative treatments, which only address the consequences of caries without eliminating the underlying causes. In pediatric patients, the repercussions of caries can be severe, often necessitating extensive restorative work accompanied by behavioral management strategies, including sedation and general anesthesia, to facilitate treatment.

The U.S. Food and Drug Administration (FDA) has acknowledged the potential severe side effects of these management methods. They issued a cautionary statement warning that “repeated or lengthy use of general anesthetic and sedation drugs during surgery or procedures in children younger than three may affect the development of children’s brains.”

Additionally, the financial burden of hospitalization, anesthesia, and sedation poses significant obstacles for families with low income, making it common for children in the U.S. to require treatment in hospital settings or under sedation.‘

Consequently, there is an ongoing quest for less invasive and more affordable treatment options. Recently, the use of silver diamine fluoride (SDF) for caries arrest has gained considerable media attention in the United States. A notable article published by The New York Times, titled “A Cavity-Fighting Liquid Lets Kids Avoid Dentists’ Drills,” highlighted this new treatment option, capturing public interest.

Historically, the concept of arresting caries in children dates back to 1900, when Dr. G. V. Black, often referred to as the “father of modern dentistry,” explored silver nitrate solutions. This approach was further developed in the 1920s by Dr. Percy Howe, the director of the Forsythe Dental Institute in Boston, who successfully employed silver nitrate to treat caries in children and adolescents. His findings were later published by the American Dental Association (ADA). However, the use of silver nitrate diminished as dental schools and pediatric specialty programs shifted their focus toward restorative methods, facilitated by the advent of effective local anesthetics.

Direct treatment for eliminating cariogenic bacteria resurfaced in the 1960s when dentists in Japan began to use a more stabilized ammoniated silver solution. Over the past 80 years, more than 2 million containers of SDF have been utilized. The 38% silver diamine fluoride formulation represents a more effective version of these solutions, having been used internationally for many years, although it became available in the United States only recently.

SDF's silver content provides a direct antimicrobial effect, while the fluoride component aids in remineralization, and ammonia serves to stabilize the compound. The FDA approved the use of SDF 38% in 2014, but initially only for treating dentinal hypersensitivity, a designation also applied to fluoride varnishes. Similar to fluoride varnishes, which are widely used off-label for caries management, SDF is increasingly being employed to arrest and control caries. In 2016, the FDA awarded SDF 38% the Breakthrough Therapy designation for its use in halting caries in both adults and children. This designation followed a review of global clinical trial outcomes involving children aged 3 to 9 and adults aged 60 to 89. The FDA grants this status to therapies that address serious conditions and show significant improvement over existing treatments. This designation aims to expedite the development and review of novel drugs and devices with potential breakthrough effects, indicating that the procedure is both permissible and appropriate for use.

SDF 38% Overview

The FDA's approval is specifically limited to a 38% concentration of silver diamine fluoride (SDF). In the United States, two commercially available products meet this criterion: Advantage Arrest, manufactured and marketed by Elevate Oral Care (www.elevateoralcare.com), and SilverSense SDF, produced by Centrix (www.centrixdental.com). These solutions come in 8 mL bulk dropper bottles or unit-dose ampules. A single drop (25 micro-liters) is estimated to effectively treat up to five teeth, with each 8 mL bottle containing roughly 250 drops.

The active ingredients in the SDF 38% solution, expressed in weight/volume, include:

• Fluoride 5% (for remineralization)
• Silver 25% (providing antibacterial properties)
• Ammonia 8% (acting as a stabilizing agent)

Microscopic examinations have shown that SDF can penetrate dentin to a depth of 250 microns and enamel to 25 microns. Photographs taken under a microscope reveal long, tendril-like extensions of precipitated silver that can be seen occluding dentinal tubules.
The mechanisms by which SDF operates include:

• Interactions of silver ions with sulfhydryl groups in proteins, altering hydrogen bonding
• Inhibition of bacterial respiration
• Prevention of bacterial cell wall formation
• Interference with bacterial DNA replication
• Denaturation of bacterial proteins
• Hardening of tooth structure through the formation of fluorapatite
• Suppression of biofilm development

This solution is typically odorless, although a slight ammonia scent may be present. It has a metallic taste that is often deemed unpleasant and maintains a pH of 10. The solution can appear clear, resembling water, or may have a slight tint to enhance visibility during application. Notably, the amount of fluoride ion absorbed from a single drop of SDF when ingested is less than half of that obtained from a standard topical application of 0.25 mL fluoride varnish.

In published clinical trials, over 4,000 children have received the recommended dosage of SDF without any reported adverse systemic reactions, indicating a safety margin of 400-fold. However, SDF should not be used in patients with a known allergy to silver compounds.

Overview of Clinical Research

Numerous international studies have explored the application of SDF 38% in pediatric patients, yielding favorable outcomes. According to the American Dental Association (ADA), seven completed clinical trials have shown that SDF is effective in “caries control and management, and lowers caries risk in both treated teeth and adjacent surfaces.” Additionally, the ADA indicates that SDF proves beneficial in managing root caries among elderly patients and may serve as an interim solution for individuals undergoing extensive treatment plans or those who cannot complete complex cases immediately.

In pediatric dental environments, many young patients struggle to endure prolonged treatments without sedation or general anesthesia. Moreover, parents may feel hesitant or unable to afford comprehensive treatment plans. Unfortunately, neglecting treatment can exacerbate the condition, leading to painful experiences and negatively impacting both oral and systemic health. SDF presents a viable alternative to costly or extensive treatment strategies, particularly for patients facing barriers to accessing care.

Even with extensive restorative procedures, patients at high risk for caries often experience a recurrence of decay due to the underlying bacterial infection that remains untreated. SDF targets this issue by providing a dual approach—effectively eliminating bacteria while remineralizing and strengthening tooth structure. Treated lesions display the formation of hydroxyapatite and fluorapatite, leading to a reduction in the depth of demineralized areas. Furthermore, these lesions experience increased mineral density and hardness, making them more resistant to future decay. An additional benefit is the sustained antibacterial action from silver residues within dead bacteria, a phenomenon referred to as the “zombie effect.”

One of the largest studies involving SDF was conducted in China, where the prevalence of caries among young children is alarmingly high. Due to high costs and a shortage of available treatment facilities, most children in China face significant barriers to receiving restorative dental care. The government is actively seeking innovative solutions to improve children’s oral health. In a study by Chu, Lo, and Lin (2002), researchers compared the effectiveness of applying sodium fluoride (NaF) varnishes every three months with annual applications of SDF 38% to the anterior teeth of 375 preschoolers in the Guangzhou area, where fluoride levels in the water supply are less than 0.2 ppm. The children were evaluated every six months for signs of arrested dentinal caries. Results indicated that the group receiving annual SDF applications showed significantly greater rates of caries arrest compared to those receiving quarterly fluoride varnish applications, with SDF proving to be twice as effective in halting dentinal caries. The control group, which received only water applications, exhibited significant increases in diagnosed caries. Notably, the SDF-treated group achieved a 70% reduction in caries within anterior teeth, and prior excavation of lesions did not significantly impact the effectiveness of caries arrest, representing a clear advantage in community health settings by minimizing costs and chair time.

Supporting evidence for SDF efficacy comes from earlier studies conducted in China (Li, 1984), Japan (Moritani, 1970), and Australia (Gotjamanos, 1996). In another notable trial in Cuba, reported by Llodra et al. (2005), 452 young schoolchildren were followed over a 36-month period in Santiago de Cuba, a region with fluoride concentrations below 0.09 ppm and high caries rates. In this trial, SDF 38% (Fluoroplat, Laboratories Naf, Argentina) was applied biannually to primary canines, molars, and first permanent molars. Children in the SDF group demonstrated a 79.7% reduction in caries compared to the control group. The choice of Santiago de Cuba was particularly relevant, as there were no resources available for alternative preventive measures (such as sealants) or restorative treatments for the first permanent molars. Data indicated an 80% reduction in caries for deciduous teeth and a 65% reduction in first permanent molars. Impressively, 77% of active caries at the study's commencement were arrested after 36 months, highlighting SDF's significant ability to halt caries progression without restorative intervention.

The ADA has also reported promising outcomes in the arrest of cervical lesions in elderly patients, though further research is necessary to establish a professional consensus regarding clinical applications in geriatric care. The recent designation of SDF as a Breakthrough Therapy by the FDA is expected to accelerate research efforts, particularly concerning the substantial population of elderly individuals with untreated cervical caries.

Advantages and Disadvantages

While numerous studies underscore the effectiveness and cost-efficiency of SDF in clinical applications, it is not a comprehensive solution for dental caries and has its own advantages and disadvantages. To evaluate the suitability of SDF, researchers and policymakers have assessed its clinical outcomes against established treatment standards. One set of criteria analyzed pertains to the three goals outlined by the U.S. Affordable Care Act (ACA), which states that an ideal treatment should:

• Enhance access to care
• Improve health outcomes
• Lower costs

SDF satisfies all three ACA criteria by:

• Requiring no specialized equipment or additional behavioral interventions
• Being easy to administer without extensive training
• Demonstrating efficacy in reducing caries by 60-80% and arresting active caries in both primary and permanent teeth
• Having no significant adverse systemic health effects
• Allowing treatment of multiple teeth in a matter of minutes
• Reducing or eliminating the need for restorative interventions
• Minimizing the equipment needed for administration
• Diminishing or eliminating the need for sedation, anesthesia, or hospitalization

Additionally, the U.S. Institute of Medicine has identified six quality aims for healthcare:

• Safety
• Effectiveness
• Efficiency
• Timeliness
• Patient-centeredness
• Equity

SDF meets these six quality aims as it:

• Shows no significant adverse systemic side effects
• Reduces caries incidence and halts progression in both primary and permanent teeth
• Can be delivered without specialized facilities
• Takes only minutes to treat multiple teeth without anesthesia, sedation, or hospitalization
• Addresses immediate patient needs promptly during a single visit without causing fluorosis
• Is accessible to all socio-economic demographics, irrespective of race, ethnicity, location, or culture

However, several drawbacks exist in SDF usage:

• The most significant drawback is the dark staining of teeth with carious lesions, which many consider unsightly. This cosmetic concern deters SDF use, particularly in the United States, where aesthetic considerations hold greater cultural significance compared to other countries. Notably, the staining is permanent and does not fade over time, presenting ongoing challenges throughout the treatment period.
• Saturated Solution of Potassium Iodide (SSKI): Although SSKI can be applied immediately after SDF to reduce staining, its effectiveness is limited. Additionally, it is contraindicated for pregnant women and those breastfeeding within the first six months due to concerns about excessive iodide potentially overloading the thyroid gland. SSKI is approved for other uses, such as a mucus release agent and as a thyroid protective agent in radiation emergencies, but its application here is considered “off-label.”
• Staining Risks: SDF severely stains various materials, including lab coats, patient clothing, and hard surfaces such as dental counters and carts. Any spills should be promptly cleaned using copious amounts of water, ethanol, or bleach.
• Skin Discoloration: If SDF contacts the skin outside the oral cavity, it can leave a temporary henna-like tattoo that lasts approximately two weeks.
• Taste and Sensation: Patients may experience an unpleasant bitter metallic taste upon application, along with a burning sensation if SDF contacts the oral mucosa.
• Contraindications: SDF should not be applied in the presence of oral ulcers or stomatitis.
• Odor: There may be an unpleasant ammonia smell associated with the solution.
• Application Challenges: Applying SDF to interproximal lesions can be difficult, and a single application is often insufficient; reapplication every six months is necessary for optimal effectiveness.
• Liability Concerns: Using SDF off-label for caries management poses potential liability issues, as its FDA approval is primarily for use as a desensitizing agent.
• Informed Consent: The need for comprehensive informed consent is heightened due to the off-label use and associated risks.
• Lack of Consensus: There is currently no widely accepted standard of care for SDF application, creating variability in practice.
• Economic Considerations: Dentists may face economic pressures, as patients and parents might prefer less expensive SDF treatments over more extensive restorative treatment plans.
• Insurance Coverage: The reimbursement and coverage for SDF treatment by dental insurers are not well-established, which can further complicate its usage in clinical practice.

UCSF Protocol for SDF Application

Recognizing that the use of Silver Diamine Fluoride (SDF) marks a significant shift in conventional treatment strategies in the United States, the University of California, San Francisco (UCSF) School of Dentistry developed a clinical protocol to facilitate the effective delivery of this treatment. The “UCSF Protocol for Caries Arrest using SDF” was established by the Paradigm Shift Committee, resulting in the integration of SDF treatment into the dental school curriculum and its successful implementation in UCSF student dental clinics.

UCSF assessed SDF usage for specific patient populations, considering various conditions that might make them suitable candidates for this treatment:

• Patients with Extreme Caries Risk:
  • Salivary dysfunction
  • Cancer treatment
  • Sjögren’s syndrome
  • Elderly individuals with salivary atrophy
  • Methamphetamine abuse
• Patients Unable to Tolerate Standard Treatment:
  • Pre-cooperative children
  • Frail elderly individuals
  • Those with severe physical or cognitive disabilities
  • Dental phobic patients
  • Individuals with medical complications
  • Residents in nursing homes and hospice care
• Patients with Multiple Carious Lesions:
  • SDF can be applied during the initial diagnostic visit to stabilize caries and prevent further progression.
  • SDF application can occur between visits for quadrants not yet treated.
  • SDF can be utilized between phases of complex cases.
• Patients with Carious Lesions in Difficult-to-Treat Areas:
  • Lesions located in hard-to-access interproximal crown margins
  • Carious lesions in furcations
  • Occlusal caries in partially erupted third molars

Based on these considerations, the UCSF Paradigm Shift Committee established the following criteria for triaging potential candidates for SDF treatment:

1. Individuals at extreme caries risk (xerostomia or severe early childhood caries)
2. Treatment challenges due to medical or behavioral management issues
3. Multiple carious lesions that cannot be addressed in a single visit
4. Difficult-to-treat carious lesions
5. Patients lacking access to dental care

Clinical Application Procedure for SDF

The UCSF protocol for the application of Silver Diamine Fluoride (SDF) includes the following steps:

1. Cover countertops with plastic and provide the patient with a plastic-lined bib.
2. Ensure the provider and patient wear standard personal protective equipment (PPE).
3. Place one drop of SDF in a deep plastic dappen dish (avoid using glass dishes).
4. Use a saliva ejector to remove bulk saliva.
5. Isolate the tongue and cheek using cotton gauze or rolls.
6. If the application is near the gingiva, consider applying petroleum jelly with a cotton applicator.
7. Dry the affected tooth surfaces with an air syringe.
8. Use a microsponge to absorb SDF from the dappen dish, removing any excess on the dish's side.
9. Directly apply SDF onto the affected tooth surface.
10. Allow SDF to absorb for up to one minute, then remove any excess with a cotton roll.
11. Rinse the treated area with water.
12. Dispose of gloves, cotton products, microsponges, and the dappen dish in plastic waste bags.
13. Schedule patient recall appointments every six months for SDF retreatment.

Clinical studies suggest that extending the SDF absorption time to up to three minutes may enhance treatment efficacy. However, even with young patients who may have limited cooperation, applications lasting just a few seconds can still achieve caries arrest. Microscopic investigations reveal that longer contact durations allow SDF to penetrate deeper into dentinal tubules, reducing the necessity for rinsing residual SDF to prevent systemic absorption.

According to the California Business and Professions Code, registered dental assistants and hygienists are permitted to apply “topical fluorides” for caries control, which includes SDF. The Oregon Dental Board has also established a precedent, allowing dental assistants and hygienists to apply SDF based on existing statutes related to topical fluoride application. Supporting these decisions, the Code Maintenance Commission of the Code on Dental Procedures and Nomenclature (CDT) has introduced a new code (D1354) specifically for SDF application: “interim caries arresting medication application.” This code refers to the conservative treatment of active, nonsymptomatic carious lesions through the topical application of a caries-arresting medicament, without mechanically removing sound tooth structure.

However, it is important to note that the FDA has not yet approved SDF specifically for caries control. In 2017, the American Academy of Pediatric Dentistry (AAPD) issued a statement recommending the use of 38 percent SDF for the arrest of cavitated caries lesions in primary teeth as part of a comprehensive caries management program. The panel, considering the low cost and high prevalence of dental caries, expressed confidence that the benefits of SDF application in target populations outweigh potential adverse effects.

As SDF application is a new procedure in the U.S. and is considered “off label,” obtaining informed consent prior to treatment is crucial. UCSF has developed a specific informed consent protocol for SDF application, which includes the following key points:

• SDF applications are necessary every six months.
• While SDF arrests caries, it does not eliminate the need for dental fillings or crowns to restore functionality or aesthetics.
• Treated areas will stain black permanently, and tooth-colored fillings may also discolor, leaving a stained edge between the tooth and filling.
• UCSF provides before-and-after photos of teeth treated with SDF to illustrate the permanent black stains resulting from the application.
• If SDF accidentally contacts the skin or gums, it may cause a brown stain that is harmless but cannot be washed off; it typically fades within one to three weeks.
• Depending on the extent and location of tooth decay, additional treatments may include fluoride varnish, fillings or crowns, extraction, or other advanced procedures.

Adult Treatment Considerations

While the use of Silver Diamine Fluoride (SDF) is well-established in pediatric populations, its application among adults is gaining traction. Many adults experience dentinal sensitivity, and in 2014, the FDA approved SDF as a dentinal desensitizing agent. This approval allows practitioners in the United States to use SDF without the liability associated with off-label applications. Although its use as a caries-arresting agent remains off-label in the U.S., it is regularly employed for this purpose in various countries worldwide.

In the context of caries prevention, the fluoride component of SDF primarily acts on tooth enamel, whereas the silver component mainly targets dentin. Fluoride facilitates remineralization, while silver effectively occludes dentinal tubules, reducing dentinal sensitivity. Together, they decrease the solubility of tooth structure and combat caries formation due to acidic challenges in the oral environment. Furthermore, the silver ions in SDF exhibit specific antimicrobial properties against cariogenic bacteria, such as Streptococcus mutans, and selectively bind to denatured proteins found in carious tooth structure rather than healthy enamel.

However, similar to pediatric applications, the most frequently reported adverse effect of SDF in adults is unsightly staining of the dentition. This occurs when silver ions reduce to form silver oxides, which must be considered when using SDF in adult cases.

Major Uses of SDF in Adult Treatment

• Dentinal Hypersensitivity: As an FDA-approved treatment, SDF can be applied in areas of gingival recession where exposed dentin is susceptible to sensitizing stimuli. This use is typically limited to the lower posterior teeth, where visibility is restricted, and is clinically effective with minimal aesthetic impact. Its application on the facial surfaces of maxillary teeth is extremely limited; however, some SDF formulations include potassium iodide to reduce staining.
• Caries Arrest: SDF can be utilized in non-visible areas as a cost-effective alternative to traditional restorations, especially for teeth that may otherwise require extraction. In such cases, SDF application can be combined with an interim restoration, such as a glass ionomer buildup, if a crown is not financially feasible.
• Anti-Caries Support for Restorative Procedures: For patients with a high risk of caries, applying SDF before placing restorations can enhance the longevity of those restorations. SDF provides antibacterial protection and seals out bacterial nutrients. Research indicates that SDF application does not compromise bond strength to composite restorations on non-carious dentin. It can also help prevent the formation of secondary caries, provided that the darkening of tooth structure beneath tooth-colored restorations is not a concern.
• Interim Stabilization: In complex restorative cases that require multiple phases or need to be extended over time due to financial constraints, SDF can stabilize teeth while awaiting definitive treatment. This application helps prevent the progression of caries, especially when patients are waiting for the renewal of insurance benefits after exhausting their yearly limits. Studies show that SDF application does not affect the bond strength of glass ionomer interim restorations.

Summary

Silver diamine fluoride (SDF) is a significant advancement in the ongoing battle against dental caries. Research indicates that SDF is considerably more effective than fluoride varnishes and demonstrates effectiveness comparable to that of sealants, all at a cost that is 10 to 20 times lower. Utilized successfully around the globe for decades, the primary drawback of SDF in the United States appears to be the aesthetic issue of dental staining.

Nevertheless, SDF represents a notable improvement in care for underserved populations and individuals who cannot safely undergo or afford extensive restorative treatments. As acknowledged by the FDA and conditionally recommended by the American Academy of Pediatric Dentistry (AAPD), SDF is a groundbreaking treatment that is expected to play a crucial role in the toolkit of dentists across the United States.

The impact of SDF on the standard of care for treating caries in both children and adults is yet to be fully determined, along with the financial implications of its use for dental practices, insurers, and governmental policies.

Quiz For Caries Management Using Silver Diamine Flouride