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.     

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.     

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。     

The inhibitory effect of proanthocyanidin on soluble and collagen-bound proteases

Objective

This study evaluated the inhibitory effect of proanthocyanidin (PA), a natural collagen cross-linker, on soluble and matrix-bound proteases, which are responsible for progressive degradation of exposed collagen fibrils within the hybrid layer and resin–dentine bond failure over time.

Methods

The inhibitory effects of PA (1%, 2%, 3%, 4.5% and 6%) on soluble recombinant matrix metalloproteinases (MMP-2, -8 and -9) and cysteine cathepsins (cathepsin B and K) were evaluated using MMP and cysteine cathepsins fluorometric assay kits. Chlorhexidine (CHX) was used as an inhibitor control. The effect of PA on endogenous matrix-bound proteases was examined by determining the change in dry mass of demineralized dentine beams and solubilized collagen peptides over 30 days. Two-way ANOVA and Tukey multiple comparison tests were used to analyze the effect of PA and proteases on the percentage inhibition of soluble proteases (α = 0.05). Kruskal–Wallis one-way ANOVA and Dunn's multiple comparison tests were used to analyse the effect of PA on loss of dry mass and hydroxyproline content over time (α = 0.05).

Results

Proanthocyanidin inactivated more than 90% of soluble recombinant MMP-2, -8 and -9 and around 75–90% of cysteine cathepsin B and K, which was significantly higher than CHX (P < 0.05). The inhibition of endogenous proteases by PA increased in a dose-dependent manner. The loss of dry mass and hydroxyproline release in the medium over time was the lowest in dentine beams pretreated with PA < CHX < control (P < 0.05).

Conclusion

Proanthocyanidin exhibited both dentine MMP and cysteine cathepsins inhibition, which was higher than chlorhexidine.     

Co-distribution of cysteine cathepsins and matrix metalloproteases in human dentin

It has been hypothesized that cysteine cathepsins (CTs) along with matrix metalloproteases (MMPs) may work in conjunction in the proteolysis of mature dentin matrix. The aim of this study was to verify simultaneously the distribution and presence of cathepsins B (CT-B) and K (CT-K) in partially demineralized dentin; and further to evaluate the activity of CTs and MMPs in the same tissue. The distribution of CT-B and CT-K in sound human dentin was assessed by immunohistochemistry. A double-immunolabeling technique was used to identify, at once, the occurrence of those enzymes in dentin. Activities of CTs and MMPs in dentin extracts were evaluated spectrofluorometrically. In addition, in situ gelatinolytic activity of dentin was assayed by zymography. The results revealed the distribution of CT-B and CT-K along the dentin organic matrix and also indicated co-occurrence of MMPs and CTs in that tissue. The enzyme kinetics studies showed proteolytic activity in dentin extracts for both classes of proteases. Furthermore, it was observed that, at least for sound human dentin matrices, the activity of MMPs seems to be predominant over the CTs one.     

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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。     

Pharmacokinetics of 38% topical silver diamine fluoride in healthy adult volunteers

Background

Silver diamine fluoride (SDF) is used topically to prevent or arrest caries. The authors' aim was to characterize the kinetics of silver and fluoride after topical application of SDF.

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.     

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.

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.     

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.

Effect of topically applied silver compounds on the demineralisation of hydroxyapatite

ObjectivesThis study investigates the demineralization inhibitory mechanisms of AgNO₃, AgF and silver diamine fluoride (SDF) using a previously used hydroxyapatite (HAP) caries demineralization model system.MethodsHAP discs were allocated into three groups (n = 3) and immersed in demineralization solution (buffered pH 4.0, 0.1 mol/L acetic acid) for 4 h. Each disc was treated topically with either 3.16 M AgNO₃, 3.16 M AgF or 3.16 M SDF using a micro-brush. The discs were then demineralized for a further 4 h. Calcium, silver, and fluoride ion selective electrodes (ISEs) were used to monitor the changes in each ion concentration at 1 min intervals throughout. Demineralization inhibition was calculated as the percentage reduction in the rate of calcium ion loss from HAP (PRCL_HAP). Characterization of similarly treated HAP powder was carried out with Magic Angle Spinning-Nuclear Magnetic ResonanceResultsThe mean PRCL_HAP for each treatment group was; AgF (72.3 + 4.8%), SDF (69.7 + 5.3%) and AgNO₃ (14.9 + 2.7%). Ag₃PO₄ was detected in all HAP powders. CaF₂ and fluorohydroxyapatite (FHA) were detected only in powders treated with either AgF or SDF.The demineralization inhibitory efficacy of topically applied AgNO₃ results from the formation of a Ag₃PO₄ barrier. Whereas, the demineralization inhibitory efficacy of topically applied AgF, and SDF, results from the formation of a barrier composed of Ag₃PO₄, CaF₂, and FHA.SignificanceIn addition to their anti-microbial properties, clinical topical application of silver compounds for caries preventative treatment is due to their ability to form acid-resistant barriers composed of silver phosphate. When fluoride is present, this barrier also contains CaF₂ and FHA, additionally protecting the mineral.     

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.

Clinical evaluation of diamine silver fluoride/potassium iodide as a dentine desensitizing agent. A pilot study

Background: The aim of the present study was to compare the efficacy of an experimental diamine silver fluoride/potassium iodide product with an oxalic acid‐based preparation in reducing dentine hypersensitivity. Methods: The study was conducted as a double‐blind, randomized clinical trial. A total of 19 subjects with dentine hypersensitivity on both sides of their upper arch were selected. The most sensitive tooth in each quadrant was identified and received a cold stimulus. The response was recorded on a visual analogue scale (VAS). The tooth thus selected was treated with one of the treatment agents. One week later the level of dentine sensitivity was assessed. Participants were also asked for their subjective assessment of treatment effects. Results: The mean difference between VAS at baseline and seven days for teeth treated with diamine silver fluoride/potassium iodide was greater than that for teeth treated with the oxalic acid‐based preparation (p = 0.0134). The subjects’ subjective assessment of changes in dentine hypersensitivity indicated that more obtained relief with the diamine silver fluoride/potassium iodide treatment (p = 0.0129). Conclusions: It was concluded that an experimental diamine silver fluoride/potassium iodide product has potential as a treatment for dentine hypersensitivity.