|Year : 2021 | Volume
| Issue : 4 | Page : 210-215
Role of silver diamine fluoride in caries prevention: A narrative review
Shivani Nagnath Bhadule, Ritesh Kalaskar
Department of Pedodontics and Preventive Dentistry, Government Dental College and Hospital, Nagpur, Maharashtra, India
|Date of Submission||03-Jun-2021|
|Date of Acceptance||08-Sep-2021|
|Date of Web Publication||20-Dec-2021|
Dr. Shivani Nagnath Bhadule
Department of Pediatric and Preventive Dentistry, Government Dental College and Hospital, Nagpur, Maharashtra
Source of Support: None, Conflict of Interest: None
Dental caries is one of the most common diseases affecting people across the globe. Unlike other infectious diseases, dental caries is not a self-limiting disorder. Preventive outlook to avoid tooth decay is hence very essential. Fortunately, there has been a rapid shift from surgical model, which emphasizes on the restorative aspect to the medical model that majorly focuses on disease prevention. The use of silver diamine fluoride (SDF) has recently been in limelight due to its ability to prevent as well as arrest dental caries. The purpose of this review is to compile and procure all related data regarding SDF, along with the inclusion of its various recent advancements and its efficiency in the current pandemic situation. The article further includes reviews from various clinical trials performed in the past as well as in recent times, regarding the efficacy of SDF when compared to other caries preventive agents.
Keywords: Caries inhibition, caries prevention, dental caries, silver diamine fluoride
|How to cite this article:|
Bhadule SN, Kalaskar R. Role of silver diamine fluoride in caries prevention: A narrative review. SRM J Res Dent Sci 2021;12:210-5
| Introduction|| |
Dental caries is defined as an infectious process that is associated with the disintegration of the structure of tooth. Treatment of dental caries involves restorative procedures, root canal treatments or extractions all of which can lead to a traumatic experience particularly in the younger age groups. To overcome these problems, preventive aspects such as fluoride application, pit and fissure sealant placement, noninvasive techniques and use of silver diamine fluoride (SDF) are hugely considered. SDF in particular is gaining popularity due to its role in caries prevention as well as inhibition. The aim of this article is to review the synthesis, mechanism of action, application, drawbacks, and scopes of SDF in dental field. Along with this, the review also includes newer treatment alternatives using SDF as well as results from clinical trials performed currently and their benefits in reducing caries incidence. Treatment options in case of staining due to SDF have also been elaborated adequately.
| Fluoride as a Boon in Dental Preventive Practice|| |
The remarkable discovery of fluoride as a caries preventive agent was marked as a pioneer event in the history of dentistry. It has been evident that extensive role of fluorides in various caries preventive programs has effectively minimized caries prevalence, especially in the developed countries. Fluoride has been accredited with its cariostatic action mainly due to its physiochemical ability, which enhances remineralization and impedes demineralization. It is usually witnessed that even low ion concentrations are ample to allow the dental hard tissues to maintain an equipoised state at a neutral pH of 7. Sometimes due to acid production by the plaque, the pH reduces to certain extent, and a higher ion concentration is now necessary to prevent dissolution. Thus, the process of undersaturation begins at a pH of 5.5, during which even the calcium and phosphate ions become inadequate to maintain the dental hard tissue in equilibrium state. This results in the dissolution of the enamel. In contrast, fluor hydroxyapatite crystals remain stable even at lower pH. As the pH increases, there is a beginning of supersaturation process with respect to fluor hydroxyapatite. It has been evident that, the enamel which had undergone demineralization first followed by subsequent remineralization is more resistant to acid than normal enamel. Fluoride ions are also known to effectively affect the critical mutans streptococci (MS) virulence factors, thereby notably minimizing the glucan formation as well as the acidogenicity.
Among most of the topical fluoride agents, SDF contains the maximum concentration of fluoride ions [Table 1].,,, The application of SDF thus is a perfect alternative treatment for dental caries for many circumstances. This procedure is painless, does not need local anesthesia, is accepted by children, and can be used without drilling the tooth. Furthermore, many studies reported that 38% SDF is proven to be useful in preventing and arresting dental caries. Recently, the FDA cleared SDF to be used as “off-label” to arrest carious lesions similar to using fluoride varnish.
| Silver Diamine Fluoride – an Introductory Briefing|| |
SDF (Ag [NH3] F2) is a colorless or blue alkaline topical fluoride solution consisting of silver (254,709 ppm) and fluoride (44,860 ppm) ions. SDF can be stored conveniently at a steady pH of 10.4 for a considerable amount of time and is also more stable than silver fluoride. Ammonia helps in reducing the oxidative potential of SDF, thus, increasing its stability and deionized water acts as a liquid base [Table 2]. The liquid has a specific gravity of 1.25 and presents with pungent ammonia odor.
It is a light sensitive liquid and thus is usually contained in an opaque bottle. Few of the commercially available SDF include advantage arrest (38% SDF), Bioride (30% SDF), Cariestop (12% and 38% SDF), Cariostatic (10% SDF), Dengen Caries arrest (38%), FAgamin 38%, FluoroplatV (38%), Riva Star (38% SDF), and Saforide (38% SDF).
| Mechanism of Action|| |
The phenomenal mechanics behind the success rate of SDF pertains to the dual activity portrayed by silver and fluoride. The anti-microbial effect of silver is due to the fact that, there is an interaction between the sulfhydryl groups of proteins and DNA of the bacteria with silver ions that leads to the inhibition of respiratory process, DNA-unwinding, cell-wall synthesis, and cell division.
Different theories proposing the mode by which SDF acts are as follows:
- After the application of SDF, there is the formation of silver phosphate which is more resistant to bacterial challenge. This also increases the resistance of peri-tubular and inter-tubular dentin to acid decalcification. Thus, there is an increase in the hardness of dentin due to the retardation of acid penetration into deeper layers of the dentin which prevents dental caries
- Obturation of dentinal tubules by SDF, prevents acid and cariogenic microorganisms to invade deeper, thus arresting the caries process. This also reduces dentin sensitivity
- The anti-enzymatic property of SDF inhibits bacterial enzyme activities by disrupting the metabolic process of the cariogenic bacteria. It also reduces the colonization of cariogenic bacteria by inhibiting the formation of dextrin induced agglutination of Streptococcus mutans.
Zombies effect is another proposed theory that signifies the action of silver component present in SDF, which is responsible for the solution's antibacterial property. It states that the bacteria killed by silver show biocidal activity and effectively kill the remaining living bacteria. The metal-induced biocidal action occurs wherein metallic species remain activated, and the dead bacteria act as a reservoir that releases metallic cations which are lethargic in nature and act against the viable bacteria.
| Effects of Silver Diamine Fluoride on Various Entities of Tooth Structure|| |
On cariogenic biofilm
SDF effectively works against the biofilms formed by cariogenic bacteria such as S. mutans and Actinomyces naeslundii. Silver ions being the bactericidal metal cations, inhibit biofilm formation by interfering with the bacterial synthesis of cellular polysaccharides.
On sound and carious enamel
Silver has the tendency to penetrate into the demineralized enamel as there is enlarged gaps between rods and inter-rods which provides path for silver penetration. The amount of enamel demineralization is directly proportional to the degree of silver penetration. The penetration however is not seen on sound enamel. Therefore, SDF application on a tooth surface free from caries do not produce staining.
On dentinal mineral content
In recent times, minimally invasive dentistry is approached towards the removal of infected dentin which comprises usually of the outer layer. The concept mainly focuses on arresting and re-mineralizing the carious dentin with its inner layer, in particular with solutions like SDF. In vitro study was carried out in which human molars affected with occlusal caries (n = 90) with no prior restoration were collected with the aim to investigate the functional repair and mineral content after using SDF. It was evident that there was a considerable amount of improvement in mechanical properties of the carious tooth after application of SDF. Also, it was found in the study that microhardness of remineralized dentin increased with SDF treatment. The report also confirmed that SDF was responsible for the formation of extrafibrillar and intrafibrillar minerals.
On lesion depth
A study was done to portray the effect of SDF, in which human dentin blocks were demineralized and allocated to four groups. Group 1, Group 2, Group 3, and Group 4 blocks were treated with 38% SDF solution, 10% sodium fluoride solution (44,800 ppm F), 42% silver nitrate solution (253,900 ppm Ag), and deionized water, respectively. All the blocks underwent pH cycling, which was performed using demineralization solution with pH 5 and remineralization solution with pH 7 for 8 days. Under SEM, the surface morphology portrayed exposed collagen along with demineralization in group 3 and group 4. However, this was not evident in Group 1. Although both Group 1 and Group 2 blocks showed clusters of granular spherical grains in their cross-sections. The depths of lesion in Group 1, Group 2, Group 3, and Group 4 were 182 ± 32 μm, 204 ± 26 μm, 259 ± 42 μm, and 265 ± 40 μm, respectively. Thus, it was evident that SDF, due to its superior properties, resulted in the least lesion depth.
A study showed that histological section of a lesion treated with SDF portrayed the dental pulp tissue being fibrous with inflammatory infiltrate. Furthermore, Gotjamanos reported that there was a penetration of silver ions into the coronal pulp after application of AgF in cavities with close affinity to pulp.
| Clinical Applications of Silver Diamine Fluoride|| |
Sedation free treatment particularly favoring the pediatric population
It is commonly witnessed in recent times that parents opt for minimally invasive treatment modalities for their children. The role of SDF becomes very significant in such cases as it can be applied easily and painlessly on a sound or carious tooth. It further more acts as a stop-gap treatment for the younger patients until they turn older or become more cooperative.
Caries prevention and arrest for special needs and medically compromised patients
Many people with special needs and other complex medical problems such as those undergoing chemotherapy, salivary dysfunction or are suffering from chronic diseases or immunocompromised or syndromic patients are extremely benefitted by SDF treatment due to its noninvasive and simpler application technique.
Prevention and arrest of root caries
Carious root surfaces are clinically challenging, particularly in the geriatric population. A study was done in which three random control trials were considered which stressed how effective SDF application was on root caries in older adults. It was observed that SDF had significant amount of higher caries arrest rate than placebo. Moreover, SDF showed 71% root caries prevented fraction as compared to placebo.
SDF produces favorable amount of fluor hydroxyapatite and increases the mineral density and hardness. Thus, it occludes the dentinal tubules and thereby plays the role of a powerful desensitizer. As SDF usually does not stain a sound tooth, it can be readily used in patients who suffer from hypersensitivity, particularly in those patients in whom potassium nitrate-containing toothpastes proved not to be effective.
Treatment of infected root canals and strengthening of endodontically treated teeth
It has been seen that SDF preferably 3.8% can effectively act as an interappointment dressing as well as an antibacterial root canal irrigant. According to Tanaka, aqueous solution of AgF acts as a strong disinfecting agent, it furthermore portrays protein-coagulating function and is also known to occlude the dentinal tubules of the walls of the canals. Okamoto et al. stated that the application of SDF reduced the number of required treatments. Mathew et al. furthermore stated that to treat infected root canals, SDF can be used successfully as an irrigant to confiscate the microbes present in the canals.
| Advantages of Silver Diamine Fluoride|| |
The advantages depicted by SDF are several such as its application procedure is simple and does not require injection or drilling, it is cost effective in most of the countries, it does not stain sound enamel and thus is used for treating hypersensitivity. It can be used easily in case of disobliging children, patients with special health care needs, and aged patients who are facing difficulties to adapt to the conventional dental care techniques. It is suggested for high-risk patients with salivary dysfunction and for patients with multiple carious lesions that may not all be treated in one visit. Dental hygienists and dental assistants can apply it without any supervision. It has no posttreatment limitations, is a time-saving procedure with quick application needing <5 min, requiring no sharp instruments or anesthesia.
| Limitations of Silver Diamine Fluoride|| |
One of the major drawbacks of SDF is that it stains the demineralized areas and soft tissues. Usually, the stains do not appear immediately, and it might take few hours for it to occur. They are however limited to areas of direct contact. This is because the silver precipitate that is formed is black in color. However, when we apply potassium iodide immediately after SDF application, silver iodide precipitate is formed instead, which is yellow in color and is also insoluble in water. Application of KI solution also removes the excess of silver ions. It is, however, witnessed that its application releases ammonium odor presumably due to the release of ammonia gas during the chemical reaction. Apart from this disadvantage, KI is very efficient in reducing the staining of the teeth after SDF application.
SDF can transiently stain skin like a henna tattoo which takes almost 7 days to disappear, and mucosa, which resolves in 2 days though it does not cause any pain or damage. SDF also causes pulpal inflammation in affected dentin connected to pulp or lesions with pulp involvement manifestations. Few others include permanent staining of clothes, staining of counters, floors and instruments, unpleasant metallic taste, and it can also cause severe burning or in some cases, blindness when is in contact with eyes. It can also be reactive to patients with silver allergy and can cause tissue irritation for patients with oral ulceration, stomatitis, or ulcerative gingivitis.
The application of SDF on the teeth surfaces should follow a sequence of events as follows:
- It is mandatory to make the patient put on a protective eyewear and use a plastic-lined bib before starting the treatment
- The lips and peri-oral tissue should be coated with petroleum jelly to prevent staining or irritation to the tissues
- The tooth surface should be cleaned thoroughly to remove all the food debris
- In case of SDF application technique, it is not a compulsion to remove the caries
- Proper isolation protocol should be followed using dry-aides and cotton rolls
- Dry the tooth surface either with a gauze piece or with compressed air
- A drop of SDF should be taken onto a dappen dish, and using a microbrush or an applicator, apply the SDF solution on the tooth surface by completely saturating the lesion
- Leave it for a couple of minutes to allow the SDF to soak using capillary action
- Make sure the SDF does not come in contact with the tongue or adjacent tissue surfaces
- Blot the excess SDF once it is absorbed completely
- Usually, no restrictions on a diet posttreatment are necessary.
| Silver Diamine Fluoride - Application on the Horizon (Role as an Indirect Pulp Capping Dental Material)|| |
Studies reported that SDF can be successfully used as an indirect pulp capping agent pertaining to its remineralization ability and antimicrobial effect. It can also be used effectively as a restorative material used in cases of atraumatic restorative technique. Silver modified atraumatic restorative technique is one such technique which uses both SDF first, followed by restoration with glass ionomer cement (GIC) to seal the teeth thereby halting the caries in a single appointment. This technique was devised to promote both caries inhibitory action of SDF and sealing property of GIC to prevent the reach of any nutrients to the bacteria that somehow survived even after the use of SDF. It is an efficient preventive modality which successfully tackles the problem of caries in a single sitting and also aids in preserving the pulp as complete removal of caries is not performed. The GIC also efficiently masks the black stains in cases like these.
Few other ways to mask the black staining caused by SDF includes the application of KI as discussed earlier or restore the tooth with composite restorative material after SDF application thereby enhancing the aesthetics. Quock et al. furthermore stated that SDF does not affect the bond strength of resin composite to sound tooth in adverse way.
| How Safe is the use of Silver Diamine Fluoride?|| |
An investigation carried out by the Health Department of Western Australia proposed that SDF, when applied, does not cause fluorosis. It is estimated that 380 mg/kg LD50/0.95 mg/kg is the relative safety margin dose for a child weighing 10 kg. However, care should be taken while applying SDF in patients who are allergic to silver or suffer from oral ulcerations or canker sores and/or gum diseases. These conditions can have painful reactions with the acid or ammonia in SDF and thus require monitoring during application. Other than these effects, SDF is widely considered by dentists to be safe, even in young children.
In recent times, clinical trials have played a pivotal role in inventing newer treatment plans and introducing more advanced and sophisticated ways to explore novel materials or improving the characteristics of those already present. Similarly, many studies and systematic reviews concerning the effectiveness of SDF have been conducted due to its growing popularity. Few of such clinical trials and reviews depicting the efficacy of SDF when compared to other caries preventive agents are mentioned in [Table 3].
|Table 3: Studies and reviews depicting the rising popularity of silver diamine fluoride|
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| Importance of Silver Diamine Fluoride in the Recent COVID-19 Pandemic|| |
The use of SDF has been recently emphasized in the current pandemic situation pertaining to its ability to arrest the carious lesions particularly in children who are medically compromised or children with special needs. It is also very efficient in people who are at a high risk of developing caries or are not willing to undergo invasive treatments. Furthermore, SDF application being a nonaerosol generating procedure, has very high recommendation from dentists worldwide to prevent as well as halt caries.
| Conclusion|| |
“Once you know the results, it becomes a habit!” – It's now proven by several studies that SDF has very high potential when it comes to preventing as well as inhibiting dental caries. Treatment done by SDF is very economical, easy to perform, time-saving, and safe. Its further ability to disinfect and remineralize can inhibit the process of caries formation. Children by far are most benefitted due to the overtly advantageous properties of SDF. The role of SDF particularly in the pediatric dentistry thus holds a very significant place in caries prevention and management. Moreover, making it a regular practice material in the clinic would be a huge step in bringing about many transformational changes as it is truly a blessing in disguise!
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]