Abstract
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.
Key words: Silver diamine fluoride, Stability, Silver, Fluoride, Caries
Introduction
Amongst fluoride agents used in dentistry, silver diamine fluoride (SDF) has the highest fluoride content. It can be used to manage early childhood caries, control root caries in older adults, prevent secondary caries, treat dentine hypersensitivity, and remineralise hypomineralised teeth.1 Some clinicians have suggested SDF in preventing dental erosion, detecting carious tissue during excavation, and disinfecting infected root canals. A systematic review noted the effectivity, efficiency, and equitability of the SDF agent for controlling dental caries.2 Moreover, SDF therapy is safe, simple, painless, and inexpensive.3,4 Thus, it is currently the standard of care for dental caries in the US and other countries.1,5 SDF treatments can be provided in outreach settings without complicated or expensive equipment.5,6 In the US, paediatric dentistry residency programmes in all universities have adopted SDF for the management of early childhood caries.7 Furthermore, the World Health Organization (WHO) added SDF to its model list of essential medicines for adults and children in 2021.8 In particular, WHO asserts that SDF should be accessible to everyone, and all governments should ensure the availability and affordability of SDF to their populations.
SDF is manufactured in several countries, including Australia (Riva Star), India (e-SDF), Japan (Saforide), Thailand (Topamine), and the US (Advantage Arrest). Although manufacturers have not disclosed the details of their ingredients, SDF products mainly contain silver, fluoride, and ammonia.9 Silver inhibits the growth of bacteria, whereas fluoride promotes the remineralisation of teeth.9,10,11 The most commonly available SDF concentration is 38%, which contains approximately 25% silver (253,900 ppm), 5% fluoride (44,800 ppm), 8% ammonia, and 62% water. However, studies reported the considerable variations in the silver and fluoride ion concentrations of SDF products.9,12 Patel et al13 noted the large difference between the reported and measured concentrations of silver and fluoride ions in several 38% SDF solutions. Crystal et al14 reported the variations in the silver and fluoride contents in different bottles of 38% SDF solution.
As SDF is a colourless alkaline solution with a pH of 9–10, manufacturers (Elevate Oral Care Company and DentaLife Company) use a blue dye for easy identification.10 Because silver fluoride solution is unstable, manufacturers dissolve silver fluoride in ammonia solution to form diamine silver fluoride, which has higher stability. Further, SDF is light-sensitive and decompose into silver, which is easily oxidised to form silver oxides under light irradiation. Therefore, SDF is stored in a light-proof bottle. Manufacturers have suggested that SDF should be used immediately after delivered from the bottle. The manufacturers of SDF claim that SDF products generally have a shelf life of 2 to 3 years. In clinical practice, we noted that clinicians often use up or discard a bottle of SDF solution within 6 months from its opening. Only 2 studies have reported the short-term stability of silver and fluoride ion concentrations in two 38% SDF products for 28 days.12,14 The current study aims to determine the stability of the alkalinity and fluoride and silver ion concentrations of 5 commercially available 38% SDF solutions over 180 days. In addition, the stability of 5 freshly opened 38% SDF solutions under room light and temperature was determined.
Materials and methods
This study investigated 5 commercially available 38% SDF solutions: Advantage Arrest, e-SDF, Riva Star, Saforide, and Topamine (Table 1). We assessed 6 bottles of each brand of 38% SDF solution with the same lot number in April 2022. This sample size allowed us to detect a difference of 10% of the fluoride concentration from the standard 38% SDF (44,800 ppm) with a common standard deviation of 6% (2688 ppm). The 6 bottles of each brand of 38% SDF solution products were examined on days 0 (freshly opened), 30, 60, 90, and 180. The alkalinity, fluoride ion concentration, and silver ion concentration measurements were performed in triplicate of each SDF bottle. All analyses were performed in an air-conditioned laboratory at a temperature of 25 °C and humidity of 40%.
Table 1.
Manufacturer details of the 38% SDF solutions.
| Advantage Arrest | e-SDF | Riva Star | Saforide | Topamine | |
|---|---|---|---|---|---|
| Ingredients (provided by the manufacturer) | 38%–43% diamine silver fluoride, water, triarylmethane dye | 5% fluoride, 25% silver, 8% ammonia, 62% water | 6% fluoride, 32% silver | 38% diamine silver fluoride | 36%–40% diamine silver fluoride, ammonium fluoride, triarylmethane dye |
| Manufacturer | Elevate Oral Care | Kids-e-Dental | SDI Limited | Toyo Seiyaku Kasei | DentaLife |
| Country | United States | India | Australia | Japan | Thailand |
| Lot number | 21109 | ESDF JK121 | 1190365 | 910 RA | B0553 |
| Manufacture date | Mar 2021 | Oct 2020 | Jan 2022 | Oct 2019 | Oct 2020 |
| Expiration date | Mar 2024 | Oct 2022 | Jan 2024 | Oct 2022 | Oct 2022 |
| Shelf life | 3 years | 2 years | 2 years | 2 years | 2 years |
| Fluoride ion (ppm) | 44,800–50,694 | 44,800 | 53,760 | 44,800 | 42,442–47,157 |
| Silver ion (ppm) | 253,900–287,307 | 253,900 | 324,922 | 253,900 | 240,536–267,263 |
SDF, silver diamine fluoride.
Alkalinity measurement
The alkalinity (pH) of the SDF products was determined using a pH electrode with pH accessories. The electrode was thoroughly rinsed with deionised water prior to measurement and stored with potassium chloride after measurement. The pH meter was calibrated using 3 standard calibration solutions (pH 4.01, 7.01, and 10.00) before each assessment. An electrical potential difference was produced when the electrode was placed in the test solution. The pH was determined using 0.2 mL of the original solution without dilution.
Measurement of fluoride concentration
Before the assessment, each SDF solution was diluted with deionised water at a factor of 1:100. A fluoride-ion-selective electrode (ISE) was used to determine the free-fluoride ion concentration of the SDF solutions using the direct reading method.9 Prior to the measurement, ISE was calibrated using 5 standardised fluoride solutions with concentrations of 0.1, 1, 10, 100, and 1000 µg g−1. The electric potential of each sample was measured using an electrode on a potentiometer. A standard curve was plotted against the standard with an auto-determined potential (mV), which was used to derive the fluoride concentration of the 38% SDF solutions. The electrode was rinsed and dried after each measurement and recalibrated after every 10 assessments to prevent potential drift. The coefficient of determination for all calibrations is 0.99.
Measurement of silver concentration
The silver ion concentrations were determined using a charge-coupled device detector inductively coupled plasma optical emission spectrometer (ICP-OES). The solution was diluted with deionised water (1:1000). A standard curve for silver was developed using a standard silver solution, which was analysed before measuring the silver ion concentration. ICP-OES was operated at a radio frequency power of 1 kW with a plasma flow rate of 15 L min−1. In particular, 4 mL diluted test solution was converted to a fine spray using a nebuliser and mixed with argon in the spray chamber. The sample was added to the plasma and instantly excited by high temperature to measure the silver content of the solution with an emission line of 328 nm.
Time for precipitation
The time taken in hours for each freshly opened product to form a precipitate under room light (500 lx) and temperature (25 °C) was recorded. From a freshly opened SDF solution, 50 µL 38% SDF solution was added into a 24-well cell culture plate. Six bottles for each product were assessed. Visual examination was performed to measure the minimal time (in hours) required for the SDF products to form a precipitate.
Statistical analyses
Based on the intraclass correlation coefficient (ICC) estimate, the reliability index in test-retest (first measurement-duplicated measurement) of 38% SDF ion concentrations and alkalinity was graded as poor (<0.50), moderate (0.50–0.75), good (0.75–0.90), and excellent (>0.90).15 A generalised estimating equation (GEE) model for repeated measurements at different time points with an unstructured correlation matrix and identity link function was used to study the time effect on the measurement results (pH, silver concentration, and fluoride concentration). Bonferroni-adjusted pairwise comparisons between 2 time points were also performed. The cutoff significance was 5% for all tests.
Results
Alkalinity
Alkalinity obtained an ICC with excellent agreement (0.948). The pH of the freshly opened Riva Star was 13.06, which was the highest value amongst the tested products (Table 2). Meanwhile, freshly opened Topamine had the lowest pH of 9.42. The results exhibit a decreasing trend of pH over 180 days for all samples, as indicated by the significant time effect on the pH (P = .002) based on the GEE model with adjustment for the effect of the product on pH. Time and pH did not exhibit a significant interaction effect (P = .077). No significant pairwise comparison was noted between the 2 time points after Bonferroni adjustment. Moreover, the pH variations within 0.1 over 180 days were not considered clinically significant.
Table 2.
Alkalinity (mean pH ± standard deviation) of the SDF products over 180 days (n = 6 bottles).
| Day | Advantage Arrest | e-SDF | Riva Star | Saforide | Topamine |
|---|---|---|---|---|---|
| 0 (freshly opened) | 9.83 ± 0.05 | 10.55 ± 0.07 | 13.06 ± 0.09 | 9.84 ± 0.12 | 9.42 ± 0.39 |
| 30 | 9.81 ± 0.03 | 10.55 ± 0.09 | 13.06 ± 0.07 | 9.83 ± 0.13 | 9.39 ± 0.35 |
| 60 | 9.81 ± 0.03 | 10.53 ± 0.12 | 13.05 ± 0.11 | 9.83 ± 0.12 | 9.35 ± 0.35 |
| 90 | 9.80 ± 0.04 | 10.52 ± 0.11 | 13.01 ± 0.10 | 9.83 ± 0.12 | 9.33 ± 0.31 |
| 180 | 9.80 ± 0.03 | 10.50 ± 0.10 | 13.00 ± 0.16 | 9.83 ± 0.12 | 9.32 ± 0.17 |
SDF, silver diamine fluoride.
Fluoride concentration
Fluoride concentration obtained an ICC with excellent agreement (0.996). The highest measured mean fluoride concentration was 53,394 ppm (Topamine), whereas the lowest mean fluoride concentration was 39,004 ppm (Riva Star). The mean fluoride concentration of freshly opened Topamine was 53,394 ppm, which was 13.2% higher than that of the manufacturer information (42,442–47,157 ppm or 36%–40% SDF; Table 3). From the GEE model, the fluoride concentration of the products decreased over 180 days (P < .001) and varied amongst the 5 products, as suggested by the significant interaction effect between time and products (P < .001). In the pairwise comparison, the fluoride concentrations of e-SDF, Saforide, and Topamine were different between days 0 (freshly open) and 90 (P < .05) and between days 90 and 180 (P < .001). In addition, the fluoride concentrations of Advantage Arrest and Riva Star were different between days 0 (freshly open) and 180 (P < .01). In this study, the largest difference between the measured and manufacturers’ reported fluoride concentration was of 13.2%. In contrast, the lowest difference in the measured and reported differences in the fluoride concentration was observed for Saforide (2% higher than the manufacturers’ expected fluoride concentration). Figure 1 shows the change in fluoride concentration over 180 days. Advantage Arrest obtained a more stable fluoride concentration for over 180 days, whereas a marked decrease was noted in Saforide after 90 days. Deviation of the mean fluoride ion concentration at day 60 from the freshly opened fluoride ion concentrations for Saforide was 6.6%.
Table 3.
Fluoride and silver ion concentrations of the SDF products over 180 days (n = 6 bottles).
| Day | Advantage Arrest | e-SDF | Riva Star | Saforide | Topamine |
|---|---|---|---|---|---|
| Mean fluoride ion concentration in ppm ± standard deviation (% reduction from Day 0–freshly opened) | |||||
| 0 | 42,396 ± 476 | 50,863 ± 2587 | 39,004 ± 1705 | 45,753 ± 528 | 53,394 ± 1242 |
| 30 | 42,337 ± 526 (0%) | 50,308 ± 1359 (1%) | 38,791 ± 3249 (1%) | 43,410 ± 757 (5%) | 52,371 ± 1853 (2%) |
| 60 | 42,061 ± 1150 (1%) | 49,282 ± 1865 (3%) | 38,359 ± 3880 (2%) | 42,721 ± 2324 (7%) | 51,699 ± 935 (3%) |
| 90 | 41,697 ± 664 (2%) | 49,216 ± 1496 (3%) | 37,571 ± 1839 (4%) | 42,648 ± 906 (7%) | 47,746 ± 2060 (11%) |
| 180 | 40,933 ± 907 (4%) | 46,655 ± 905 (8%) | 36,955 ± 1804 (5%) | 37,064 ± 545 (18%) | 47,685 ± 2200 (11%) |
| Mean silver ion concentration in ppm ± standard deviation (% reduction from Day 0–freshly opened) | |||||
| 0 | 306,967 ± 18,164 | 315,380 ± 11,391 | 435,748 ± 19,416 | 281,040 ± 26,233 | 456,134 ± 29,080 |
| 30 | 306,651 ± 34,843 (0%) | 311,728 ± 9783 (1%) | 429,967 ± 35,871 (1%) | 269,238 ± 5330 (4%) | 446,178 ± 46,203 (2%) |
| 60 | 290,880 ± 17,030 (5%) | 310,631 ± 13,439 (2%) | 427,411 ± 28,060 (2%) | 267,509 ± 6614 (5%) | 442,707 ± 21,547 (3%) |
| 90 | 287,632 ± 10,500 (6%) | 308,507 ± 9772 (2%) | 421,084 ± 9383 (4%) | 267,058 ± 12,825 (5%) | 438,279 ± 34,828 (4%) |
| 180 | 283,417 ± 7152 (8%) | 307,309 ± 7981 (3%) | 418,631 ± 10,846 (4%) | 266,343 ± 8056 (5%) | 416,222 ± 20,342 (9%) |
SDF, silver diamine fluoride.
Fig. 1.
Fluoride concentrations of the silver diamine fluoride products over 180 days.
Silver concentration
The silver concentration achieved an ICC with excellent agreement (0.946). The silver concentration of the products decreased over 180 days because of the significant effect of time on the silver concentration (P < .001) based on the GEE model with adjustment for the effect of the product on the silver concentration. No significant interaction effect was noted between time and product on the silver concentration (P = .079). In the pairwise comparison, the silver concentration of the products was significantly different at days 0 (freshly open) and 90 (P = .014) and between days 0 (freshly open) and 180 (P < .001). The highest measured mean silver concentration was 456,134 ppm (Topamine), whereas the lowest mean silver concentration was 281,040 ppm (Saforide; Table 3). The mean silver concentration of freshly opened Topamine was 456,134 ppm, which was 70.7% higher than the manufacturer information (240,536–267,263 ppm or 36%–40% SDF; Table 1). This difference of 70.7% in the measured and manufacturers’ reported silver concentration was the highest amongst all products. Meanwhile, the smallest difference in the measured and manufacturers’ reported silver concentration was that of Advantage Arrest (6.8% higher). Figure 2 shows the changes in the silver concentration of the 5 products over 180 days. e-SDF had a more stable silver concentration for over 180 days. Meanwhile, a marked decrease in the silver concentration after 90 days was observed in Topamine. Deviation of the mean silver ion concentration at day 60 from the freshly opened fluoride ion concentrations for Advantage Arrest was 5.24%.
Fig. 2.
Silver concentrations of the silver diamine fluoride products over 180 days.
Time for precipitation
We tested 6 bottles of each SDF product on the minimum time to form a black precipitate. Riva Star required the shortest minimum time (6 hours) to form a black precipitate. Saforide and Topamine took a minimum of 7 hours, whereas e-SDF took 12 hours to form a black precipitate. Advantage Arrest had the longest minimum time of 17 hours to form a black precipitate.
Discussion
Studies have reported the considerable variations in the silver and fluoride ion concentrations of SDF products, which should be addressed to ensure their effective application SDF.9,12, 13, 14 To address this aforementioned research gap, this study investigated the stability of the alkalinity, fluoride ion concentration, and silver ion concentration of 5 commercially available 38% SDF solutions over 180 days.
We chose a high-accuracy pH metre and used a conventional method to evaluate the silver and fluoride concentrations in the SDF solutions.12 ISE is a common, accurate, fast, economical, and sensitive analytical technique used to determine the activity of fluoride ions in an aqueous SDF solution by measuring the electrical potential.9 We used a total ionic strength adjustment buffer to maintain the accuracy by eliminating potential interference and maintaining a constant ionic strength. ICP-OES, which is a reliable, sensitive, and fast method, was used to measure the silver concentration9.
For the alkalinity, fluoride concentration, and silver concentration, this study obtained excellent results, as indicated by the ICC values, which is a widely used reliability index in test-retest, intra-rater, and inter-rater reliability analyses, of at least 0.95.15 In data analysis, we employed the GEE model to study the influence of time after opening and the product brand on the alkalinity, fluoride concentration, and silver concentration. The GEE model can robustly estimate the variances of the regression coefficient for the data, thereby achieving a high correlation between repeated measurements.16 Similar to other parametric models, the GEE parameter estimates are sensitive to outliers or contaminated data. Hence, it may fail to provide consistent estimators, which could lead to an incorrect conclusion.17
We used a high-precision laboratory bench pH meter to measure the alkalinity of the SDF products. Amongst these, the measured and reported fluoride and silver concentrations of Saforide and Advantage Arrest had the least variation. A previous study noted the substantial differences between the reported and measured fluoride ion concentrations amongst SDF products.12 Similarly, we found that SDF solutions of the same lot have different silver and fluoride concentrations. In addition, the ion concentrations and pH values in this study were different from those reported in a previous study12 because of the effects of temperature on the electric potential of fluoride ions.9 We investigated the SDF solution at 25 °C, whereas previous studies used 20 °C.9,12 The electric potential of fluoride increased by 1 mV when the temperature was increased by 5 °C.9 As the ion concentration was determined using the standard curve from the measured electric potential of the tested solution, the results in this study were higher than those of a previous study.9
The fluoride ions in SDF solution may react with water and other chemicals such as nitric oxide in the air. The reaction could reduce the fluoride content of the SDF solution over time. Crystal et al14 noted the slight increase in fluoride concentration 28 days after opening. However, similar to a previous study,12 the fluoride concentration decreased after 28 days. This difference can be ascribed to the inconsistencies in the surgical procedures. The SDF bottle caps were tightened and capped in this study. The SDF products were stored at 25 °C and 40% humidity, which minimised dehydration, thereby increasing the fluoride concentration after storage. This study exhibited the same results as that of previous studies, that is, a slight reduction in the silver concentration after 28 days.12,14
This study recorded the time required for each freshly opened 38% SDF product to form precipitate. We observed uniformly distributed round, dotlike black precipitate under room light and temperature. When silver comes into contact with hydrogen sulfide, which can be found in air, a chemical reaction takes place to form black precipitate. All 38% SDF products were stable without precipitation for at least 5 hours under ambient light and temperature conditions. Hence, the tested SDF solution could remain stable without precipitation in a morning or an afternoon session. Riva Star had the highest alkalinity when freshly opened, suggesting its high ammonia content, as demonstrated by its strong pungent smell when opened.
This study evaluated the baseline values and changes in pH, fluoride concentration, and silver concentration of 5 commonly used SDF solutions. The result found a difference between the baseline-measured and manufacturer's reported fluoride and silver ion concentration. The difference of certain products can be high and clinicians should take note in choosing the SDF products. The objective of this study is to determine the stability, alkalinity, and fluoride and silver ion concentrations of the 5 SDF solutions. It is not the aim of this study to make recommendations to clinicians in choosing an SDF product. However, they can choose their preferred product with reference to the results of this study. Moreover, this study found that the fluoride and silver concentrations could decrease more than 5% after 60 days. Hence, it is desirable to finish or discard the SDF solution within 60 days.
This study aimed to study as many commercially available 38% SDF products as possible. We, however, could not purchase all SDF products, particularly those made in South America. Therefore, we could not exhaustively investigate all 38% SDF solutions available in the market. However, this study investigated most of the 38% SDF products reported in the literature. The manufacturers have indicated that the shelf life of 38% SDF products is 2 to 3 years. They have suggested that SDF should be used immediately after opening the bottle. The SDF products assessed in this study were prepared at different dates. It is impossible to get all SDF products produced by different manufacturers on the same day. However, the SDF in a sealed bottle should be regarded as stable before opening. Once clinicians open an SDF product for use, they generally finish the solution within half a year. In clinical practice, dentists usually use a bottle of SDF solution within 6 months because the volume of the SDF products were 1.5 to 5 mL. In addition, some dentists do not use a bottle of SDF that has been opened for 6 months because of the potential undesirable changes in SDF solution. Thus, this study analysed the stability of SDF solutions within 180 days, which is deemed acceptable by the researchers. According to the results in this study, clinicians are advised to use the solution within 2 months and discard SDF products that have been opened for at least 6 months.
Conclusions
In this study, the alkalinity of the 5 commonly available SDF solutions remained stable over 180 days. The fluoride and silver concentrations of the products were stable within 60 days and decreased after 180 days. The freshly opened SDF solutions did not precipitate for at least 5 hours.
CRediT authorship contribution statement
Iliana Gehui Yan: Conceptualization, Methodology, Writing – original draft, Writing – review & editing. Faith Miaomiao Zheng: Data curation, Software. Iris Xiaoxue Yin: Software, Validation. Ivy Guofang Sun: Visualization, Investigation. Edward Chin Man Lo: Supervision. Chun Hung Chu: Supervision.
Conflict of interest
None disclosed.
Acknowledgments
Acknowledgements
The authors thank Mr Geoffrey Ng and Mr Yip Chui providing technical advice in ion concentration measurement and thank Ms Samantha Li providing statistical advice for assistance during the experiments.
Funding
This work was supported by the General Research Fund (#17100421) of the Research Grant Council of Hong Kong. The funding source was not involved in in study design; in the collection, analysis and interpretation of data; in the writing of the report; or in the decision to submit the article for publication.
REFERENCES
- 1.Chu CH, Lo EC. Promoting caries arrest in children with silver diamine fluoride: a review. Oral Health Prev Dent. 2008;6(4):315–321. [PubMed] [Google Scholar]
- 2.Rosenblatt A, Stamford TC, Niederman R. Silver diamine fluoride: a caries “silver-fluoride bullet. J Dent Res. 2009;88(2):116–125. doi: 10.1177/0022034508329406. [DOI] [PubMed] [Google Scholar]
- 3.Milgrom P, Chi DL. Prevention-centered caries management strategies during critical periods in early childhood. J Calif Dent Assoc. 2011;39(10):735–741. [PubMed] [Google Scholar]
- 4.Yan IG, Zheng FM, Gao SS, et al. Effect of application time of 38% silver diamine fluoride solution on arresting early childhood caries in preschool children: a randomised double-blinded controlled trial protocol. Trials. 2022;23(1):215. doi: 10.1186/s13063-022-06130-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Milgrom P, Horst JA, Ludwig S, et al. Topical silver diamine fluoride for dental caries arrest in preschool children: a randomized controlled trial and microbiological analysis of caries associated microbes and resistance gene expression. J Dent. 2018;68:72–78. doi: 10.1016/j.jdent.2017.08.015. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Chai HH, Chen KJ, Duangthip D, et al. Parental perspectives on the use of silver diamine fluoride therapy to arrest early childhood caries in kindergarten outreach dental services: a qualitative study. J Dent. 2022;125 doi: 10.1016/j.jdent.2022.104250. [DOI] [PubMed] [Google Scholar]
- 7.Crystal YO, Janal MN, Yim S, et al. Teaching and utilization of silver diamine fluoride and Hall-style crowns in US pediatric dentistry residency programs. J Am Dent Assoc. 2020;151(10):755–763. doi: 10.1016/j.adaj.2020.06.022. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.World Health Organization. WHO model list of essential medicines - 22nd list. 2021. Available from: https://www.who.int/publications/i/item/WHO-MHP-HPS-EML-2021.02. Accessed 30 September 2021.
- 9.Yan IG, Zheng FM, Gao SS, et al. Ion concentration of silver diamine fluoride solutions. Int Dent J. 2022;72(6):779–784. doi: 10.1016/j.identj.2022.04.005. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Zheng FM, Yan IG, Duangthip D, et al. Silver diamine fluoride therapy for dental care. Jpn Dent Sci Rev. 2022;58:249–257. doi: 10.1016/j.jdsr.2022.08.001. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Yan IG, Zheng FM, Gao SS, et al. A review of the protocol of SDF therapy for arresting caries. Int Dent J. 2022;72(5):579–588. doi: 10.1016/j.identj.2022.06.006. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Mei ML, Chu CH, Lo EC, et al. Fluoride and silver concentrations of silver diammine fluoride solutions for dental use. Int J Paediatr Dent. 2013;23(4):279–285. doi: 10.1111/ipd.12005. [DOI] [PubMed] [Google Scholar]
- 13.Patel J, Foster D, Smirk M, Turton B, Anthonappa R. Acidity, fluoride and silver ion concentrations in silver diamine fluoride solutions: a pilot study. Aust Dent J. 2021;66(2):188–193. doi: 10.1111/adj.12822. [DOI] [PubMed] [Google Scholar]
- 14.Crystal YO, Rabieh S, Janal MN, et al. Silver and fluoride content and short-term stability of 38% silver diamine fluoride. J Am Dent Assoc. 2019;150(2):140–146. doi: 10.1016/j.adaj.2018.10.016. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Koo TK, Li MY. A guideline of selecting and reporting intraclass correlation coefficients for reliability research. J Chiropr Med. 2016;15(2):155–163. doi: 10.1016/j.jcm.2016.02.012. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Khajeh-Kazemi R, Golestan B, Mohammad K, et al. Comparison of generalized estimating equations and quadratic inference functions in superior versus inferior Ahmed glaucoma valve implantation. J Res Med Sci. 2011;16(3):235–244. [PMC free article] [PubMed] [Google Scholar]
- 17.Qu A, Song PXK. Assessing robustness of generalised estimating equations and quadratic inference functions. Biometrika. 2004;91(2):447–459. [Google Scholar]