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

Background

As silver diamine fluoride (SDF) gains popularity for caries arrest, the authors aimed to investigate the content of fluoride and silver in 38% SDF produced for the US market and its short-term stability.

Parental perceptions and acceptance of silver diamine fluoride staining

Background

The caries arrest that can be achieved by using silver diamine fluoride (SDF) offers a minimally invasive and inexpensive alternative to traditional restorative caries treatment. The authors evaluated how the dentinal staining that is associated with SDF influences the acceptance of this treatment among parents of young children in the New York City metropolitan area.

Remineralisation of enamel with silver diamine fluoride and sodium fluoride

Objective

To evaluate the remineralising effect of the adjunctive application of 38% silver diamine fluoride (SDF) solution and 5% sodium fluoride (NaF) varnish on artificial enamel caries lesions.

Reaction of silver diamine [corrected] fluoride with hydroxyapatite and protein

Silver diammine fluoride (SDF) is used as an anticaries agent; however, its mode of action is uncertain, whether chemical, physical, mechanical or antibacterial. As a preliminary study, the effect of SDF on hydroxyapatite (HAp) and gelatin (as a chemically-representative protein) was examined.

Methods

2.5 mg HAp powder specimens and 0.5 mL 10% gelatin (Riedel-de Haën) (initially as a sol at ∼37 °C), were mixed with 0.5 mL of 38% SDF (J. Morita), 4% NaF (Sigma) or 40% AgNO₃ (Sigma) and tumbled in 1.5 mL polypropylene tubes (Sarstedt) for 48 h at ∼23 °C, in two series: exposed to laboratory lighting, and kept dark at all times. The HAp specimens were separated by centrifugation and decanting, then these and one set of gelatin specimens were dried at 60 °C in situ; a second parallel set of gelatin specimens were dried at ∼23 °C. Each was washed with 1 mL deionized water for 1 min, 3 times. Treated materials were observed, before and after washing, with scanning and transmission electron microscopy (SEM, TEM); energy-dispersive X-ray analysis (EDX), and electron diffraction (ED).

Results

SDF appeared to produce globular particles of CaF₂ on the surface of the HAp, but these disappeared on washing, whilst with AgNO₃ yellow cubic crystals of Ag₃PO₄ formed which were not dissolved on washing, but which darkened, converting gradually to metallic silver, on exposure to light. NaF had no effect on gelatin, whilst with SDF and AgNO₃, particles of silver were produced which were resistant to washing.

Conclusions

Both principal components of tooth tissue react with SDF; the solubility of the putative CaF₂ formed weakens the case for it exerting a caries-protective effect. The importance of the persistent silver needs further study.     

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氟化氨银（silver diamine fluoride,SDF）溶液是一种局部应用的含氟、银和氨离子的溶液,通过作用于龋损部位的牙体组织和细菌防治龋病,国际上正在深入开展相关的研究,一些国家已将其应用于临床和社区工作中。然而,国内相关工作开展很少。本文就SDF的防龋机制及其临床应用与研究做一简要介绍。     

An ex vivo study of arrested primary teeth caries with silver diamine fluoride therapy

Objectives

This ex vivo study compared the physico-chemical structural differences between primary carious teeth biannually treated with silver diamine fluoride (SDF) and carious teeth without such treatment.

Method

Twelve carious primary upper-central incisors were collected from 6-year-old children. Six teeth had arrested caries after 24-month biannual SDF applications and 6 had active caries when there was no topical fluoride treatment. The mineral density, elemental contents, surface morphology, and crystal characteristics were assessed by micro-computed tomography (micro-CT), energy-dispersive X-ray spectrometry (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

Results

Micro-CT examination revealed a superficial opaque band approximately 150 μm on the arrested cavitated dentinal lesion. This band was limited in the active carious lesion. EDX examination detected a higher intensity of calcium and phosphate of 150 μm in the surface zone than in the inner zone, but this zone was restricted in the active cavitated dentinal lesion. SEM examination indicated that the collagens were protected from being exposed in the arrested cavitated dentinal lesion, but were exposed in the active cavitated dentinal lesion. TEM examination suggested that remineralised hydroxyapatites were well aligned in the arrested cavitated dentinal lesion, while those in the active cavitated dentinal lesion indicated a random apatite arrangement.

Conclusions

A highly remineralised zone rich in calcium and phosphate was found on the arrested cavitated dentinal lesion of primary teeth with an SDF application. The collagens were protected from being exposed in the arrested cavitated dentinal lesion.

Clinical significance

Clinical SDF application positively influences dentine remineralisation.     

氟化氨银溶液对人工脱矿牙本质粘接强度的影响

目的：评价氟化氨银溶液（silver diammine fluoride,SDF）对人工龋牙本质和玻璃离子粘固剂（glass ionomer cement,GIC）之间的微拉伸粘接强度的影响。方法：将12颗人离体磨牙制备成脱矿牙本质和未脱矿牙本质2组标本,均分为对照组、氟化氨银组及氟化氨银与光固化联合处理组（n ＝20）,将处理完成的牙本质与 GIC 富士 IX 粘接,24 h 后对标本进行切割及微拉伸强度试验,最后用扫描电镜观察牙本质与 GIC 之间的超微结构,并进行数据统计分析。结果：脱矿后牙本质的粘接强度显著高于未脱矿的牙本质（P ＜0．01）。经过光固化 SDF 处理的人工龋牙本质的粘接强度数值显著高于只经 SDF 处理的人工龋牙本质的粘接强度（P ＜0．01）。结论：SDF 处理的人工脱矿牙本质与 GIC 之间的微拉伸粘接强度得到显著提高。     

Inhibitory effect of silver diamine fluoride on dentine demineralisation and collagen degradation

Objective

To investigate the inhibitory effects of 38% silver diamine fluoride (SDF) on demineralised dentine.

Methods

Human dentine blocks were demineralised and allocated to four groups: SF, F, S and W. The blocks in group SF received a topical application of 38% SDF solution (253,900 ppm Ag, 44,800 ppm F), group F received a 10% sodium fluoride solution (44,800 ppm F), group S received a 42% silver nitrate solution (253,900 ppm Ag) and group W received deionised water (control). They were subjected to pH cycling using demineralisation solution (pH 5) and remineralisation solution (pH 7) for 8 days. The surface morphology, crystal characteristics, lesion depth and collagen matrix degradation of the specimens were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-CT testing and spectrophotometry with a hydroxyproline assay.

Results

The surface morphology under SEM showed evident demineralisation with exposed collagen in groups S and W, but not in group SF. Clusters of granular spherical grains were observed in the cross-sections of specimens in groups SF and F. XRD revealed precipitates of silver chloride in groups SF and S. The mean lesion depths (±SD) of groups SF, F, S and W were 182 ± 32 μm, 204 ± 26 μm, 259 ± 42 μm and 265 ± 40 μm, respectively (SDF, F < S, W; p < 0.01). Groups SF and S had significantly less hydroxyproline liberated from the dentine matrix than groups F and W (p < 0.01).

Conclusion

The use of 38% SDF inhibited demineralisation and preserved collagen from degradation in demineralised dentine.

Clinical significance

SDF application positively influences dentine remineralization.     

Caries arrest using silver diamine fluoride: Knowledge,attitude, and perception of adult patients in Saudi Arabia

ObjectivesThe objective was to evaluate the current knowledge, attitude, and perception of adult patients toward SDF and identify related factors.Materials and methodsIn this cross-sectional study, data were obtained from adult participants of the Kingdom of Saudi Arabia. A simple random sampling method was used. An electronic questionnaire was designed to collect data regarding participants’ demographics and their knowledge, attitude, and perception toward the use of SDF.ResultsThe majority (86.6%) of the participants were females. Approximately 58% were ≤ 25 years of age. Overall, 77.1% of the participants had college/higher level education, and 34.2% had a monthly income of > 16000 Saudi Riyals (SAR). Approximately 75.8% of them did not suffer from medical conditions, 60.8% had tooth decay, 82.5% brushed their teeth daily, 77.7% flossed regularly, and 63% used fluoridated toothpaste. Dental pain or inflammation was reported by 87.7% of the participants (P-value < 0.001). A higher proportion of adult patients (47.8%) was strongly satisfied with the speed of treatment, 58.9% were strongly satisfied with advantages, and 24.5% were dissatisfied with disadvantages (P-value < 0.001). Disagreement (24.0%) toward SDF material use for anterior teeth was statistically high (P-value < 0.001). Females (64.5%) demonstrated strong satisfaction with the benefits of SDF material (P-value = 0.004). Participants of male sex (26.0%), education up to high school (33.0%), and income of > 16000 SAR (31.0%) showed statistically strong disagreement (P-value < 0.05) with use of SDF for anterior teeth.ConclusionThe present study demonstrates that SDF is acceptable among Saudi adults for the purpose of arresting dental caries. However, pigmentation of anterior teeth is a major concern, especially in male participants with high socioeconomic status.     

The inhibitory effects of silver diamine fluorides on cysteine cathepsins

Aim

The expression of cysteine cathepsins in human carious dentine suggests that this enzyme contributes to the collagen degradation in caries progress. This study investigated whether silver diamine fluoride (SDF) inhibited the activity of cysteine cathepsins.

Methods

Three commercial SDF solutions with concentrations at 38%, 30% and 12% were studied. Two fluoride solutions with the same fluoride ion (F^-) concentrations as the 38% and 12% SDF solutions, and 2 silver solutions with the same silver ion (Ag⁺) concentrations as the 38% and 12% SDF solutions were prepared. Five samples of each experimental solution were used to study their inhibitory effect on two cathepsins (B and K) using cathepsin assay kits. Positive control contained assay buffer and cathepsins dilution was used to calculate the percentage inhibition (difference between the mean readings of the test solution and control solution divided by that of the control group).

Results

The percentage inhibition of 38%, 30% and 12% SDF on cathepsin B were 92.0%, 91.5% and 90.3%, respectively (p < 0.001); on cathepsin K were 80.6%, 78.5% and 77.9%, respectively (p < 0.001). Ag⁺ exhibited the inhibitory effect against both cathepsin B and K with or without the presence of F^- (p < 0.01). The solutions containing Ag⁺ have significantly higher inhibitory effect than the solutions containing F^- only (p < 0.01).

Conclusion

According to this study, SDF solution at all 3 tested concentrations significantly inhibited the activity of cathepsin B and K.     

Influence of 38% silver diamine fluoride application on bond stability to enamel and dentin using universal adhesives in self-etch mode

In order to evaluate the influence of 38% silver diamine fluoride (SDF) application on enamel and dentin bond stability of universal adhesives in self-etch mode, a 38% SDF and three universal adhesives were used in this study. Initial shear bond strength (ISBS), fatigue bond strength (FBS), and shear bond strength of survivors (SBSS) to enamel and dentin of universal adhesives in self-etch mode, with and without SDF application, were determined. SDF was applied to the polished enamel or dentin surface for 1 min, water-rinsed and air-dried for comparison with controls. The universal adhesives were applied to the prepared samples and composite resin was bonded using a mold-enclosed method. Enamel bond stability of universal adhesives with SDF (ISBS: 14.7–20.4 MPa; FBS: 5.5–7.4 MPa and SBSS: 14.4–21.5 MPa) was significantly weaker than those without SDF (ISBS: 28.0–29.2 MPa; FBS: 12.1–15.6 MPa and SBSS: 28.4–34.4 MPa). Dentin bond stability with SDF (ISBS: 14.8–20.9 MPa; FBS: 7.1–8.2 MPa and SBSS: 17.3–21.8 MPa) was also significantly weaker than without SDF (ISBS: 19.3–36.1 MPa; FBS: 11.0–13.7 MPa and SBSS: 22.2–34.6 MPa). The results suggest that SDF application on enamel and dentin reduces the bond stability of universal adhesives in self-etch mode.     

Unacceptably high levels of fluoride in commercial preparations of silver fluoride

Instead of expected fluoride ion concentrations of around 60 000 ppm, commercial preparations of 40 per cent aqueous silver fluoride were found to contain 120 000–127 000 ppm. Information received from the Western Australian Chemistry Centre which provided independent confirmation of the higher than expected [F] indicates that the currently available commercial preparations contain silver difluoride rather than silver fluoride.
In view of the potential of fluoride-containing products such as dentifrices (1000–1500 ppm F) and topical fluoride gels and solutions (6000-12 000 ppm F) to cause adverse effects if excessive quantities are ingested, any product that contains 120 000 ppm [F] should be regarded as carrying a high risk of toxicity when used on young children.