Silver and fluoride content and short-term stability of 38% silver diamine fluoride

The effect of silver diammine fluoride on In Vitro Enamel caries lesion remineralization and staining as a function of lesion baseline mineral distribution

OBJECTIVES

to investigate whether baseline mineral distribution modulates the ability of silver diammine fluoride (SDF) to remineralize and stain enamel caries lesions.

METHODS

This laboratory study followed a 3 [treatment: SDF/fluoride varnish (FV)/deionized water (DIW)] ×3 [lesion protocol: methylcellulose (MeC)/hydroxyethylcellulose (HEC)/Carbopol 907 (C907)] factorial design. Lesions were created in bovine enamel specimens (n = 20). Treatments were applied and lesions remineralized in artificial saliva. Digital transverse microradiography (TMR-D) was used to analyze lesions. Lesion color was monitored spectrophotometrically. The effects of lesion protocol and treatment on changes in lesion depth (ΔLD), mineral loss (ΔΔZ), maximum mineral density at the surface zone (ΔSZmax), and color changes related to remineralization (ΔL*remin) were analyzed using two-way ANOVA.

RESULTS

The treatment×lesion protocol interaction was significant for ΔΔZ (p < 0.01) and ΔL*remin (p < 0.01), however not for ΔLD (p = 0.23) or ΔSZmax (p = 0.91). There were no differences in ΔΔZ between treatments in HEC and C907 lesions. However, DIW resulted in more remineralization than both SDF (p < 0.01) and FV (p = 0.01) in MeC lesions. Considering changes from lesion baseline after remineralization in MeC lesions, SDF treatment resulted in the highest mineral gain in the surface zone. However, DIW revealed the highest mineral gain after remineralization in the lesion body. SDF stained lesions with the intensity increasing after remineralization in C907 lesions, whereas staining decreased in MeC and HEC lesions.

CONCLUSION

High fluoride treatments can interfere with continuous remineralization of caries lesions due to partial arrest. Baseline lesion mineral distribution affects SDF's ability to enhance remineralization and the staining caused by SDF.

CLINICAL SIGNIFICANCE

SDF is being used to arrest active caries lesions extending into dentin and to treat dentin hypersensitivity. This study shed light on SDF's effect on an isolated process in dental caries only, remineralization. It achieved this by examining enamel caries lesions with differing mineral distributions and assessing their staining properties.

Synthesis of novel silver-loaded clay AgF@Hec for the prevention of dental cariesin vitro

Dental caries, a chronic infectious disease characterized by tooth mineral loss caused by plaque, is one of the major global public health problems. Silver diamine fluoride (SDF) has been proven to be a highly effective anti-caries drug due to its high bacterial inhibition and remineralization ability. However, the SDF solution is unstable, which immensely limits its clinical application. Therefore, new silver-load clay named AgF@Hec was designed by replacing the NH3with hectorite in this study. Fourier transform infrared spectroscopy and x-ray diffraction spectroscopy were employed to confirm the structure of AgF@Hec. Dynamic light scattering analysis was used to reveal the effect of different hectorite concentrations on the stability of AgF@Hec. Moreover, AgF@Hec exhibits significant remineralization and hardness recovery of the initial carious lesions. Bacteriostatic experiments also proved that it has a significant inhibitory effect onA. Viscosus, S. mutans, S. sanguinis, S. salivarius, Lactobacillus sp.and both gram-positive and gram-negative bacteria. We therefore believed that AgF@Hec should be a promising biomaterial that can be applied in the prevention of dental caries.

Explorations of the chemical constitution and aqueous solution status of caries-arresting silver(I)-diammine fluoride and silver(I)-fluoride products using high-resolution 19F NMR analysis. Spectroscopic and SEM investigations of their interactions with human saliva: evidence for the in vivo salivary-catalysed autoconstruction of Ag/AgCl-based nanoparticles (IV-SCAN)-part I

Introduction

Silver(I)-diammine fluoride (SDF) and silver(I)-fluoride (SF) complexes have been successfully employed for the arrest of dental caries for many years. However, to date there are very few studies available reporting on the molecular structural compositional and solution status of these agents [typically applied as highly-concentrated 38% (w/v) solutions]. Here, we explored the solution status and chemical constitution of commercially-available SDF and SF products, and secondly investigated the multicomponent interplay of these products with biomolecules present in intact human whole-mouth salivary supernatants (WMSSs) in vitro.

Methods

High-resolution 19F NMR analysis was employed to explore SDF and SF product solutions, and to determine WMSS fluoride (F-) concentrations, whereas ammonia (NH3) release form SDF was tracked by 1H NMR spectroscopy. SEM and thin-film FTIR-ATR analyses were employed to explore the atomic and molecular compositions of sequentially-generated AgCl deposits and chromophoric Ag/AgCl nanoparticles (CSNPs); the time-dependent generation of the latter was followed spectrophotometrically.

Results

19F NMR spectra of aqueous SF solutions contained a very broad F- signal (Δv1/2 70 Hz), demonstrating that much of its solvated F- content was rapidly exchanging with Ag(I) on the NMR timescale, but those of SDF had a much sharper resonance, similar to that of "free" F- (4 Hz). Moreover, further NMR results revealed that a popular SDF product contained high molar excesses of both F- and NH3. Treatment of WMSSs with SDF and SF generated an off-white precipitate, which slowly developed into CSNPs at 23°C; SEM demonstrated high contents of both silver and chloride in this material (ca.1:1 atomic content ratio). FTIR-ATR analysis found that the CSNPs formed contained a range of salivary biomolecules, which appear to encapsulate the Ag/AgCl core (significant thiocyanate contents were also found). In conclusion, NMR results acquired demonstrated that SF, but not SDF, product solutions feature rapidly-exchanging F - between its "free" and Ag(I)-bound forms, and that SDF contains large excesses of both F- and its NH3 ligands. Characterised AgCl deposits and CSNPs were sequentially produced from the interactions of these complexes with WMSS biomolecules.

Discussion

In view of their well-known microbicidal and cariostatic properties, the observed autobioconstruction of CSNPs involving salivary catalysis is of much therapeutic significance.

Silver Diamine Fluoride in Pediatric Dentistry: Effectiveness in Preventing and Arresting Dental Caries-A Systematic Review

BACKGROUND

Tooth decay is considered a global scourge by the World Health Organization (WHO) starting at an early age. In recent years, silver diamine fluoride (SDF) has regained interest, particularly in pediatric dentistry, used to prevent the development of carious lesions or arrest their progression.

OBJECTIVE

The aim of this study was to assess, through a systematic review of the literature, the effectiveness of SDF, used in pedodontics, in temporary teeth, in preventing or arresting dental caries.

MATERIAL AND METHODS

An electronic search was conducted on PubMed, Web of Science and Scopus. The effect of SDF on both temporary and permanent teeth has been considered.

RESULTS

The inclusion criteria identified 16 randomized controlled trials involving patients aged 18 months to 13 years and followed over a period of 12-30 months.

CONCLUSIONS

SDF is a practical, accessible and effective non-invasive way to prevent and arrest caries in temporary and permanent teeth. Its application requires regular monitoring. The resulting black spot is diminished by immediate application of potassium iodide but this may affect its effectiveness.

The pharmacokinetics of 38% silver diamine fluoride in healthy children with dental caries: a quasi-experimental study

PURPOSE

Silver diamine fluoride (SDF) is a medication used for the arrestment of dental caries. This study aims to determine the pharmacokinetics (PK) of silver and fluoride following SDF application in healthy children with dental caries.

METHODS

A total of 15 subjects, aged 4 to 10 years, with at least one cavity on a primary tooth, were recruited for this study. Urine samples were collected at baseline, first 24 h (F1) and second 24 h (F2) after SDF treatment for analysis of silver and fluoride content. Hair samples were also collected at baseline and at 7, 14, 30, 60, 75, and 90 days after SDF treatment to analyze silver content.

RESULTS

Participants with under or over-collection of urine, or failure to provide urine collection were excluded for fluoride analysis. As a result, eight subjects' urine samples were eligible for fluoride analysis. Significant correlations were observed between baseline urinary fluoride levels and F1/F2 levels. Pairwise comparisons from Friedman's test showed significant differences between baseline and F1 fluoride levels. For silver analysis, 15 subjects were studied. F1 urinary silver levels were higher than baseline and F2 levels. Subsequent to SDF treatment, hair silver levels displayed fluctuations around the baseline. None of the participants reported adverse effects, and all caries teeth ceased progression within 30 days.

CONCLUSIONS

The urinary fluoride levels after SDF treatment, although higher, were not clinically significant. Urinary and hair silver levels were negligible. Therefore, SDF appears safe to be used among children.

Stability of Silver and Fluoride Contents in Silver Diamine Fluoride Solutions

OBJECTIVE

This study aims to determine the stability, alkalinity, and fluoride and silver ion concentrations of 5 commercially available 38% silver diamine fluoride (SDF) solutions-namely Advantage Arrest, e-SDF, Riva Star, Saforide, and Topamine-in 180 days.

METHODS

Alkalinity was determined using a pH electrode. The fluoride and silver ion concentrations were obtained using a calibrated ion-selective electrode and optical emission spectrometer, respectively. Six bottles of each product were examined on days 0 (freshly opened), 30, 60, 90, and 180. The time taken for each freshly opened product to form a black silver precipitate under room light (500 lx) and 25 °C was also recorded.

RESULTS

For 180 days, Advantage Arrest, e-SDF, Riva Star, Saforide, and Topamine had the pH range of 9.8-9.8, 10.5-10.6, 13.0-13.1, 9.8-9.8, and 9.3-9.4; fluoride ion concentration range (nearest 1000 ppm) of 40.9%-42.4%, 46.7%-50.9%, 37.0%-39.0%, 37.0%-45.7%, and 47.7%-53.4%; silver ion concentration range (nearest 1000 ppm) of 283.4-307.0, 307.3-315.4, 418.6-435.7, 266.3-281.0, and 416.2-456.1 ppm; and precipitation time (nearest hour) of 17, 12, 6, 7, and 7 hours, respectively. The percentage change of fluoride and silver could be more than 5% after 60 days.

CONCLUSIONS

The alkalinity of the 5 SDF solutions remained stable after 180 days. In addition, their fluoride and silver concentrations decreased substantially after 60 days. The freshly opened SDF solutions did not precipitate within 5 hours under ambient room conditions. The alkalinity and fluoride and silver concentrations of the 38% SDF solutions could be less stable after 60 days; thereafter, the fluoride and silver concentrations decreased. Thus, the SDF solution should be used within 60 days after opening.

Antibacterial effect and impact on caries activity of nanosilver fluoride and silver diamine fluoride in dentin caries of primary teeth: a randomized controlled clinical trial

BACKGROUND

The use of silver diamine fluoride (SDF) in caries treatment in children has increased despite the disadvantage of causing tooth discoloration. Nanosilver fluoride (NSF) is a possible alternative. This study aimed to assess the antibacterial effect of NSF and SDF and their impact on the activity of dentin caries in primary teeth.

METHODS

Synthesis and characterization of the physical and biological properties of NSF were conducted. Fifty children aged 4-6 years with dentin caries (active caries corresponding to ICDAS code 5) in deciduous teeth were randomly assigned to treatment by NSF or SDF. Baseline assessment of Streptococcus mutans (S. mutans) and lactobacilli counts as CFU/mL in caries lesions was done, followed by the application of the agents. After one month, microbiological samples were recollected, and lesion activity was reassessed. Groups were compared using Mann-Whitney and Chi-Square tests, while intragroup comparisons were done using Wilcoxon and McNemar tests. Multilevel logistic regression analysis was used to assess the effect of different variables on the outcomes.

RESULTS

There were 130 teeth in 50 children; mean ± SD age = 4.75 ± 0.76 years, 63% were posterior teeth. At the one-month follow-up appointment, both groups showed a significant decrease from baseline bacterial counts. There was a significant difference in the reduction of S. mutans between NSF and SDF (21.3% and 10.5%, respectively, p = 0.002), while not in lactobacilli (13.9% and 6.0%, respectively, p = 0.094). In both groups, there was a significant reduction in the number of active caries from baseline (p < 0.0001) with no significant difference between groups (percentage inactive = 64.4% and 63.4%, p = 0.903). Multilevel regression revealed non-significant differences in S. mutans and lactobacilli counts (AOR 1.281, p = 0.737 and 1.888, p = 0.341, respectively), and in the number of inactive lesions (AOR 1.355, p = 0.731) between groups.

CONCLUSION

The short-term antibacterial efficacy of NSF was similar to that of SDF. In both groups there was a significant reduction of S. mutans and lactobacilli counts in active dentin caries, and two-thirds of the lesions became inactive with no differences between the two interventions. Further research is needed to investigate the long-term efficacy of NSF and its suitability for clinical use in caries management.

TRIAL REGISTRATION

This trial was prospectively registered on the clinicaltrials.gov registry with ID: NCT05221749 on 03/02/2022.

Silver diamine fluoride therapy for dental care

Silver diamine fluoride (SDF) was developed in Japan in the 1960s. It is used to control early childhood caries, arrest root caries, prevent fissure caries and secondary caries, desensitise hypersensitive teeth, remineralise hypomineralised teeth, prevent dental erosion, detect carious tissue during excavation and manage infected root canals. SDF is commonly available as a 38% solution containing 255,000 ppm silver and 44,800 ppm fluoride ions. Silver is an antimicrobial and inhibits cariogenic biofilm. Fluoride promotes remineralisation and inhibits the demineralisation of teeth. SDF also inactivates proteolytic peptidases and inhibits dentine collagen degradation. It arrests caries without affecting dental pulp or causing dental fluorosis. Indirect pulp capping with SDF causes no or mild inflammatory pulpal response. However, direct application of SDF to dental pulp causes pulp necrosis. Furthermore, SDF stains carious lesions black. Patients must be well informed before SDF treatment. SDF therapy is simple, painless, non-invasive, inexpensive, and requires a simple armamentarium and minimal support. Both clinicians and patients generally accept it well. In 2021, the World Health Organization included SDF as an essential medicine that is effective and safe for patients. Moreover, it can be used for caries control during the COVID-19 pandemic because it is non-aerosol-generating and has a low risk of cross-infection.

Fluoride and silver ion concentrations and pH in silver diamine fluoride solutions from Argentina

The aim of this study was to measure the fluoride (F) and silver (Ag) ion concentration and the pH, over time, of 2 solutions of 38% silver diamine fluoride (SDF) produced in Argentina. The brand Fluorsilver® was established as Group 1 (G1) (Densell), and the brand FAgamin® (Tedequim) as Group 2 (G2), each with two different lots. The following were determined at time 0 (t0) and 30 days after opening (t30): a) fluoride concentration (w/v) by visible spectrophotometry b) Ag content (w/v) by atomic absorption spectrophotometry c) pH. Results: The data in the freshly opened bottles were for G1 lot1/lot2: a) 0.96/1, b) 8.3/7.8, c).11.5/11.3; G2 lot1/lot2: a) 11.5/9.9, b) 39/39, c) 7/6,9; and after 30 days, G1 lot1/lot2: a) 0.85/0.81, b) 7.2/8.2, c) 11.3/11.6; G2 lot1/lot2: a) 9.35/8.43, b) 38/38, c) 7.6/7.6. Conclusion In relation to the expected values (5.0-5.9% fluoride and 24.4-28.8% silver), the average concentration of fluoride and silver ions was lower for G1, but higher for G2. The pH was alkaline for G1 and neutral for G2. Over the 30 days, the content of fluoride and silver tended to decrease.

Revisiting Fluoride in the Twenty-First Century: Safety and Efficacy Considerations

Over 100 years of scientific literature is available which describes the long relationship between dentistry and the many possible applications of fluoride anion (F−) as successful therapeutic strategies. To date, systemic introduction of fluoride via water, milk and salt fluoridation, and fluoride-containing tablets, has been employed. Post-eruption topical fluoride products have also been introduced, such as fluoridated toothpaste, along with fluoride-containing rinses and varnishes. Importantly, a recent addition to the available armamentarium of fluoride therapeutics now exists in the form of metal ion-fluorido adducts, most especially silver(I)-diammine fluoride (SDF). In view of its high level of therapeutic success, very recently this agent was added to the World Health Authority's (WHO's) list of essential medicines available for the treatment and prevention of tooth decay. Overall, this current state of affairs merits a major review of all these fluoride-containing therapeutic compounds, together with their risks and benefits, both individually and collectively. In this study, a simple graphical tool has been developed for the rapid “on-site” evaluation of fluoride intake with respect to a range of oral healthcare products and body mass index is presented as a gauge of safety for the risk of fluoride toxicity in individual patients. This exposition commences with (a) an account of the history and value of fluoride therapeutics in clinical dentistry, including applications of monofluorophosphate and stannous fluoride; (b) an evaluation of the toxicological activities of fluoride, together with a summary of any reports, albeit very rare ones, arising from its clinically-driven overuse; (c) a history of the development, molecular structure, mechanisms of action, and therapeutic applications of SDF, including a summary of any possible toxic activities and effects arising from silver(I) ion rather than fluoride itself; and (d) the establishment of a working relationship between fluoride exposure and toxicity, with special reference to the instigation of newly-developed tabular/graphical reference guidelines for use by dental clinicians who employ fluoride-rich products in their practices. Particular attention is given to the oral care and treatment options of pediatric patients. In conclusion, applications of this unique monitoring tool may serve as a valuable toxicity guide for dental practitioners.

Fluoride Delivered via a Topical Application of 38% SDF and 5% NaF

OBJECTIVES

The objectives of this study were to compare the amount of fluoride delivered via a topical application of 38% silver diamine fluoride (SDF) solution and 5% sodium fluoride (NaF) varnish as well as to determine the amount of 38% SDF solution delivered using various micro-applicators.

METHODS

The weights of 38% SDF (Saforide) and 5% NaF (Duraphat) applied to the occlusal surface of an extracted human upper first premolar with a regular-size (2.50-mm tip diameter) micro-applicator were measured using an electronic-analytical balance. Afterwards, the weight of 38% SDF applied to a premolar using the micro-applicators of 5 common brands (Premium Plus, 3M, Dentsply, Elevate Oral Care, and SDI) were studied. The tip diameter of each micro-applicator was measured under a microscope. The weights of the delivered fluoride and silver were also calculated.

RESULTS

The mean weights of the fluoride delivered via the SDF solution and NaF varnish were 0.25 ± 0.07 mg and 0.49 ± 0.08 mg, respectively (P < .001). In addition, the tip diameters of the micro-applicators ranged from 1.89 ± 0.03 mm to 2.76 ± 0.02 mm. The mean weights of the fluoride delivered per application of 38% SDF using different applicators ranged from 0.13 ± 0.06 mg to 0.30 ± 0.09 mg, whereas the mean weights of the silver ranged from 0.76 ± 0.32 mg to 1.68 ± 0.50 mg. The weights of the delivered 38% SDF solution varied with the brand and with the tip diameters of the dental micro-applicators (P < .001).

CONCLUSIONS

The fluoride of the 38% SDF solution delivered topically was significantly less than that of 5% NaF varnish. Moreover, the amount of SDF solution delivered depends on the brand and size of the micro-applicators.

Longitudinal In Vitro Effects of Silver Diamine Fluoride on Early Enamel Caries Lesions

This laboratory study evaluated the longitudinal surface microhardness changes in early, incipient, noncavitated, white-spot, enamel caries lesions treated with silver diamine fluoride (SDF). Five intervention groups (SDF, AgNO3, KF, 5% sodium fluoride varnish (FV), deionized water (DI)) × two-time intervals after intervention (immediate & delayed pH-cycling) resulted in 10 groups (n=18). Silver nitrate (AgNO3) and potassium fluoride (KF) groups served as controls to assist in evaluating if remineralization effects were due to the silver or fluoride component in SDF. Early, incipient, noncavitated, white-spot, enamel caries lesions were created in bovine enamel, the extent of demineralization was determined using Vickers surface microhardness (VHNlesion). Intervention treatments were applied. Half the specimens from each group underwent immediate 5-day pH-cycling, and half were stored in an incubator with artificial saliva for 2 weeks before undergoing 5-day pH-cycling. After pH-cycling, lesion hardness was evaluated using VHNpost. Specimens were then exposed to a second demineralization challenge, and lesion softening was evaluated (VHNsecdem). Hardness variables were calculated: ΔVHN = VHNpost - VHNlesion; ΔVHNsecdem = VHNsecdem - VHNpost. Data were analyzed using two-way ANOVA (α=0.05). Immediately cycled, SDF had significantly (p<0.0001) greater remineralization than DI, AgNO3, and FV. All delayed cycling groups had significantly greater remineralization than FV (p<0.0001). Significantly greater remineralization was noted in delayed AgNO3 (p≤0.0001), DI (p=0.0003), and FV (p=0.0006) compared to immediately cycled. After the second demineralization challenge, FV had significantly less surface softening than AgNO3 (p=0.0002), DI (p=0.0003), KF (p=0.0225), and SDF (p=0.0388) intervention groups. No significant difference was found between the pH-cycle timings (p=0.2710). Based the present findings, FV may be better suited than SDF to treat early, incipient, noncavitated, white-spot, enamel caries lesions.

Global Oral Health Policies and Guidelines: Using Silver Diamine Fluoride for Caries Control

Silver diamine fluoride (SDF) was developed in Japan in the 1960s. It is a clear solution containing silver and fluoride ions. Because of its anti-bacterial and remineralizing effect, silver diamine fluoride has been used in managing dental caries for decades worldwide. This paper aims to summarize and discuss the global policies, guidelines, and relevant information on utilizing SDF for caries management. SDF can be used for treating dental caries in most countries. However, it is not permitted to be used in mainland China. Several manufacturers, mainly in Australia, Brazil, India, Japan, and the United States, produce SDF at different concentrations that are commercially available around the world. The prices differ between contents and brands. Different government organizations and dental associations have developed guidelines for clinical use of SDF. Dental professionals can refer to the specific guidelines in their own countries or territories. Training for using SDF is part of undergraduate and/or postgraduate curriculums in almost all countries. However, real utilization of SDF of dentists, especially in the private sector, remains unclear in most places because little research has been conducted. There are at least two ongoing regional-wide large-scale oral health programs, using SDF as one of the components to manage dental caries in young children (one in Hong Kong and one in Mongolia). Because SDF treatment does not require caries removal, and it is simple, non-invasive, and inexpensive, SDF is a valuable strategy for caries management in young children, elderly people, and patients with special needs. In addition, to reduce the risk of bacteria or virus transmission in dental settings, using SDF as a non-aerosol producing procedure should be emphasized under the COVID-19 outbreak.

Microbial population shift and metabolic characterization of silver diamine fluoride treatment failure on dental caries

The objective of this pilot study was to describe the microbial profiles present in the plaque and saliva of children who continued to develop new carious lesions following treatment with silver diamine fluoride ("nonresponders") compared to caries active, caries-free, and children immediately receiving SDF treatment for untreated caries in order to identify potential microbial differences that may relate to a re-incidence of caries. Saliva and plaque samples from infected and contralateral sites were obtained from twenty children who were either caries free, had active carious lesions, were caries active and received SDF treatment immediately before sampling, or had previously received SDF treatment and developed new caries. In total, 8,057,899 Illumina-generated sequence reads from 60 samples were obtained. Reads were processed using the Quantitative Insights Into Microbial Ecology pipeline. Group differences were assessed using Analysis of Variance Models and Tukey Honest Significant Differences. To identify significant taxa between treatment groups, Linear discriminant analysis Effect Size (LefSe) and Analysis of Differential Abundance Taking Sample Variation Into Account were used. Differential abundant analysis indicated that members of the Lachnospiraceae family were significantly enriched in non-responders and the genus Tannerella and species Granulicatella adiances were also highly abundant in this group. LefSe analysis between non-responders and SDF-treated groups revealed that genera Leptotrichia and Granulicatella were enriched in non-responders. We observed the highest abundance of phosphotransferase system and lowest abundance of lipopolysaccharide synthesis in non-responders. The microbiome in dental biofilms is responsible for initiation and progression of dental caries. SDF has been shown to be effective in arresting the progression carious lesions, in part due to its antimicrobial properties. Findings suggest that the differential abundance of select microbiota and specific pathway functioning in individuals that present with recurrent decay after SDF treatment may contribute to a potential failure of silver diamine fluoride to arrest dental caries. However, the short duration of sample collection following SDF application and the small sample size emphasize the need for further data and additional analysis.

Acidity, fluoride and silver ion concentrations in silver diamine fluoride solutions: a pilot study

BACKGROUND

There has been renewed interest in the use of silver diamine fluoride (SDF) for the management of carious lesions in high-risk groups. Previous studies have found a difference in clinical efficacy among different concentrations of SDF and discrepancies between ionic concentrations of fluoride (F) and silver (Ag) in SDF preparations. The aim of this study was to measure the free F, Ag ion concentrations and pH of a variety of commercially available SDF preparations.

METHODS

Seven SDF products used globally were evaluated for F and Ag ion concentrations using a calibrated ion-selective electrode and optical emission spectrometry respectively. Acidity was determined with a pH electrode.

RESULTS

The 30% SDF solution contained almost half the F concentration and a much higher Ag concentration than expected (16 343 ppmF and 246 000 ppmAg). Comparatively, the mean F concentration of the remaining six 38% solutions was 74 802 ppm (expected mean 44 800 ppm) ranging from 36 457 ppm to 120 760 ppm. The mean Ag concentration was 326 000 ppm (expected mean 253 870 ppm) and ranged from 246 000 ppm to 425 451 ppm. All solutions were found to be neutral or mildly alkaline in nature (pH 7-10.3).

CONCLUSIONS

Wide variations between claimed and measured F and Ag ion concentrations exist among the different brands of commercially available SDF products.

Effect of silver diammine fluoride and glass ionomer on remineralisation of natural dentine caries

OBJECTIVES

Silver diammine fluoride (SDF) is a caries-arresting agent for dentine lesions. This study investigated the effect of application frequency of SDF when used with glass ionomer cement (GI) for remineralising carious dentine.

METHODS

Freshly extracted human posterior teeth with advanced caries were used. After superficial removal of infected dentine, single (G3), double (G4), triple (G5) applications of SDF (Advantage Arrest SDF 38 %) followed by a layer of GI (GC Fuji IX GP) were compared to no treatment (negative control-G2), and GI only (G1). All teeth were stored in artificial saliva between treatments and for 2-weeks after final treatment. Micro-computed X-ray tomography (NSI) scans were obtained at each stage and analysed to plot mineral density-depth profile, lesion depth (LD) and mineral loss (ΔZ). Data was statistically analysed at a significance level of 0.05.

RESULTS

Mean LD values were 837 μm, 735 μm, 841 μm, 1008 μm, 707 μm at baseline and 785 μm, 727 μm, 712 μm, 855 μm, 639 μm after treatment for groups G1 to G5, respectively. Mean ΔZ values were 6327 vol%μm, 5995 vol%μm, 10014 vol%μm, 7192 vol%μm, 5649 vol%μm at baseline and 3686 vol%μm, 5126 vol%μm, 5539 vol%μm, 2327 vol%μm, 3218 vol%μm after treatment for groups G1 to G5, respectively. Paired t-test showed that LD and ΔZ changed significantly within all groups from baseline to treatment weeks following storage (p < 0.05) except LD in the control (p > 0.05). ANCOVA showed significant difference among groups in net lesion depth recovery and net mineral gain (p < 0.05), and G3 and G4 showed the highest mineral gains.

CONCLUSION

One or two applications of SDF prior to placement of GI, were effective in remineralising advanced dentine lesions, while additional applications, when combined with GI, did not demonstrate additional benefit in this study.

CLINICAL SIGNIFICANCE

This short-term laboratory research study showed that one or two applications of SDF followed by GI coverage could remineralise advanced dentine caries in the presence of artificial saliva. This procedure carries potential in the treatment of difficult lesions where conventional restorations would require significant tooth structure removal through traumatic procedures.

The antibacterial efficacy of silver diamine fluoride (SDF) is not modulated by potassium iodide (KI) supplements: A study on in-situ plaque biofilms using viability real-time PCR with propidium monoazide

Silver diamine fluoride (SDF) is commonly used to arrest caries lesions, especially in early childhood caries. Recently, it was suggested that SDF can be combined with potassium iodide (KI) to minimize the discoloration of demineralized dentine associated with SDF application. However, the antibacterial efficacy of SDF alone or combined with KI on in-situ biofilm is unknown. Hence, we compared the anti-plaque biofilm efficacy of two different commercially available SDF solutions, with or without KI, using an in-situ biofilm, analysed using viability real-time PCR with propidium monoazide (PMA). Appliance-borne in-situ biofilm samples (n = 90) were grown for a period of 6 h in five healthy subjects who repeated the experiment on three separate occasions, using a validated, novel, intraoral device. The relative anti-biofilm efficacy of two SDF formulations; 38.0% Topamine (SDFT) and 31.3%, Riva Star (SDFR), KI alone, and KI in combination with SDFR (SDFR+KI) was compared. The experiments were performed by applying an optimized volume of the agents onto the biofilm for 1min, mimicking the standard clinical procedure. Afterwards the viability of the residual biofilm bacteria was quantified using viability real-time PCR with PMA, then the percentage of viable from total bacteria was calculated. Both SDF formulations (SDFT and SDFR) exhibited potent antibacterial activities against the in-situ biofilm; however, there was non-significant difference in their efficacy. KI alone did not demonstrate any antibacterial effect, and there was non-significant difference in the antibacterial efficacy of SDF alone compared to SDF with KI, (SDFT v SDFR/KI). Thus, we conclude that the antibacterial efficacy of SDF against plaque biofilms is not modulated by KI supplements. Viability real-time PCR with PMA was successfully used to analyze the viability of naturally grown oral biofilm; thus, the same method can be used to test the antimicrobial effect of other agents on oral biofilms in future research.

The effect of silver diamine fluoride in preventing in vitro primary coronal caries under pH-cycling conditions

OBJECTIVES

This study investigated the ability of SDF, and its individual components, silver (Ag⁺) and fluoride (F^-) ions, in preventing enamel demineralization under pH-cycling conditions in the presence or absence of twice-daily fluoride application.

DESIGN

Polished human enamel specimens were assigned to five treatment groups (n = 36 per group): SDF (38 %); SDF followed by application of a saturated solution of potassium iodide (SDF + KI); silver nitrate (AgNO₃; silver control, 253,900 ppm Ag); potassium fluoride (KF; fluoride control, 44,800 ppm F); deionized water. Treatments were applied once. Specimens in each treatment group were divided into two subgroups (n = 18). During the subsequent 7-day pH-cycling phase, specimens were treated twice daily with either 275 ppm fluoride as sodium fluoride or deionized water, immediately before and after a 3-h cariogenic challenge with exposure to artificial saliva at all other times. Changes in color, Vickers surface microhardness (SMH), transverse microradiography (TMR) was calculated. Data were analyzed using two-way ANOVA.

RESULTS

In both models, SDF, SDF + KI and KF were superior in inhibiting demineralization compared to AgNO₃ and deionized water (p < 0.0001). There was no statistically significant difference between SDF, SDF + KI and KF with twice daily fluoride treatments (p > 0.8). However, KF was more effective in preventing demineralization than SDF and SDF + KI in the absence of fluoride treatments (p = 0.0002). KI did not affect the ability of SDF to prevent demineralization (p > 0.4).

CONCLUSION

SDF and SDF + KI appears to be an effective option in preventing primary coronal caries.

Effectiveness of in vitro primary coronal caries prevention with silver diamine fluoride - Chemical vs biofilm models

OBJECTIVES

The main goal of this study was to investigate the effectiveness of SDF and its individual components, silver (Ag⁺) and fluoride (F^-) ions, in preventing enamel demineralization using biofilm and chemical models.

METHODES

Polished human enamel specimens were assigned to five treatment groups (n = 18 per group): SDF (38 %); SDF followed by application of a saturated solution of potassium iodide (SDF + KI); silver nitrate (AgNO₃; silver control, 253,900 ppm Ag⁺); potassium fluoride (KF; fluoride control, 44,800 ppm F); deionized water (DIW). Treatments were applied once to sound enamel. In the biofilm model, specimens were demineralized by aerobic overnight incubation using cariogenic bacteria isolated from human saliva in brain heart infusion supplemented with 0.2 % sucrose for three days. In the chemical model, enamel specimens were immersed in a demineralizing solution containing 0.1 M lactic acid, 4.1 mM CaCl₂, 8.0 mM KH₂PO₄, 0.2 % Carbopol 907, pH adjusted to 5.0 for five days. Vickers surface microhardness was used to determine the extent of enamel demineralization. Data were analyzed using one-way ANOVA.

RESULTS

In the chemical model, there was no statistically significant difference between SDF and SDF + KI in preventing coronal caries (p < 0.0001). In the biofilm model, SDF + KI was significantly less effective in preventing demineralization than SDF (p < 0.0001). In both models, SDF and SDF + KI were superior in their ability to prevent caries lesion formation than AgNO₃ and DIW.

CONCLUSION

KI application after SDF treatment appears to impair SDF's ability to prevent biofilm-mediated but not chemically induced demineralization.

CLINICAL SIGNIFICANCE

SDF may be a viable option in preventing primary coronal caries.

Fluoride Concentration in SDF Commercial Products and Their Bioavailability with Demineralized Dentine

Abstract The aim of this in vitro study was to determine the fluoride concentration in silver diamine fluoride (SDF) products and their bioavailability with demineralized dentine. The products evaluated (expected fluoride concentrations) were: I: Saforide 38% (45,283 ppm F); II: Advantage Arrest 38.3 to 43.2% (45,283 to 51,013 ppm F); III: Ancárie 12% (14,100 ppm F); IV: Ancárie 30% (35,400 ppm F), V: Cariestop 12% (14,100 ppm F) and VI: Cariestop 30% (35,400 ppm F). The fluoride concentration was evaluated using an ion-specific electrode (ISE) by direct technique, which was confirmed after microdiffusion. The pH of the products was determined with a pH test strip. For the bioavailability test, demineralized dentine slabs were treated with one of the products for 1 min. Loosely (CaF2-like) and firmly-bound fluoride (FAp) were determined. The fluoride concentration found in the products (mean±SD; ppm F) by the ISE direct technique was: I:53,491±554; II:57,249±1,851; III:4,814±268; IV:5,726±43; V:10,145±468; VI:11,858±575; these values were confirmed after microdiffusion (t-test; p>0.05) and disagree with the declared by the manufacturers. The pH of Ancárie 12 and 30% was 6.0 and 4.5, respectively, in disagreement with the alkaline pH expected for SDF solution and found in the other products evaluated. There was no correlation between either CaF2-like (r=0.221; p=0.337) or FAp (r=-0.144; p=0.830) formed in demineralized dentine and fluoride concentration found in the products. The problems of pH and fluoride concentration found in available professional commercial SDF products suggest that they are not under sanitary surveillance.