Optimized 3D printed zirconia-reinforced leucite with antibacterial coating for dental applications

OBJECTIVES

This study aims to produce by robocasting leucite/zirconia pieces with suitable mechanical and tribological performance, convenient aesthetics, and antibacterial properties to be used in dental crown replacement.

METHODS

Leucite pastes reinforced with 12.5%, 25%, and 37.5% wt. ZrO2 nanoparticles were prepared and used to print samples that after sintering were characterized in terms of density, shrinkage, morphology, porosity, mechanical and tribological properties and translucency. A coating of silver diamine fluoride (SDF) and potassium iodide (KI) was applied over the most promising material. The material's antibacterial activity and cytotoxicity were assessed.

RESULTS

It was found that the increase of ZrO2 reinforcement up to 25% enhanced both microhardness and fracture toughness of the sintered composite. However, for a superior content of ZrO2, the increase of the porosity negatively affected the mechanical behaviour of the composite. Moreover, the composite with 25% ZrO2 exhibited neglectable wear in chewing simulator tests and induced the lowest wear on the antagonist dental cusps. Although this composite exhibited lower translucency than human teeth, it was three times higher than the ZrO2 glazed material. Coating this composite material with SDF+KI conferred antibacterial properties without inducing cytotoxicity.

SIGNIFICANCE

Robocasting of leucite reinforced with 25% ZrO2 led to best results. The obtained material revealed superior optical properties and tribomechanical behaviour compared to glazed ZrO2 (that is a common option in dental practice). Moreover, the application of SDF+KI coating impaired S. aureus proliferation, which anticipates its potential benefit for preventing pathogenic bacterial complications associated with prosthetic crown placement.

Comparative Evaluation of the Remineralizing Potential of Silver Diamine Fluoride, Casein Phosphopeptide-amorphous Calcium Phosphate, and Fluoride Varnish on the Enamel Surface of Primary and Permanent Teeth: An In Vitro Study

Introduction

With the paradigm shift in the management of dental caries, the focus is now laid on remineralization therapies that can arrest the progression of the disease and remineralize the subsurface lesions.

Objectives

The purpose of this study was to determine and compare the remineralizing potential of silver diamine fluoride (SDF), casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), and fluoride varnish (FV) on enamel surfaces in primary and permanent teeth.

Materials and methods

A total of 120 primary anterior teeth and 120 premolars were used to prepare enamel blocks in acrylic resin. The mean baseline surface microhardness (SMH) for each sample was determined using a microvickers hardness testing machine. Thereafter, the samples were randomly and equally distributed into groups and subgroups based on the materials used, that is, SDF, CPP-ACP, FV, and distilled water (control). After subjecting the samples to a pH cycling regime, SMH was determined again and the percentage change in SMH was calculated.

Results

The data were tabulated and subjected to statistical analysis using an independent t-test and one-way analysis of variance (ANOVA). In primary teeth, the least mean percentage reduction in SMH was observed after the application of FV followed by SDF, CPP-ACP, and control. In permanent teeth, both SDF and FV showed the least percentage reduction of enamel SMH followed by CPP-ACP and control.

Conclusion

Silver diamine fluoride (SDF), FV, and CPP-ACP showed remineralizing potential in both primary and permanent teeth.

How to cite this article

Kaur S, Bhola M, Bajaj N, et al. Comparative Evaluation of the Remineralizing Potential of Silver Diamine Fluoride, Casein Phosphopeptide-amorphous Calcium Phosphate, and Fluoride Varnish on the Enamel Surface of Primary and Permanent Teeth: An In Vitro Study. Int J Clin Pediatr Dent 2023;16(S-1):S91-S96.

Evaluation of the remineralizing capacity of silver diamine fluoride on demineralized dentin under pH-cycling conditions

OBJECTIVE

(1) to determine the effects of the silver diamine fluoride (SDF) and sodium fluoride (NaF) in demineralized dentin exposed to an acid challenge by pH-cycling, (2) to evaluate the remineralizing capacity of SDF/NaF products based on the physicochemical and mechanical properties of the treated dentin surfaces.

METHODOLOGY

In total, 57 human molars were evaluated in different stages of the experimental period: sound dentin - negative control (Stage 1), demineralized dentin - positive control (Stage 2), and dentin treated with SDF/NaF products + pH-c (Stage 3). Several commercial products were used for the SDF treatment: Saforide, RivaStar, and Cariestop. The mineral composition and crystalline and morphological characteristics of the dentin samples from each experimental stage were evaluated by infrared spectroscopy (ATR-FTIR), X-ray diffraction, and electron microscopy (SEM-EDX) analytical techniques. Moreover, the mechanical response of the samples was analyzed by means of the three-point bending test. Statistics were estimated for ATR-FTIR variables by Wilcoxon test, while the mechanical data analyses were performed using Kruskal-Wallis and Mann Whitney U tests.

RESULTS

Regarding the chemical composition, we observed a higher mineral/organic content in the SDF/NaF treated dentin + pH-c groups (Stage 3) than in the positive control groups (Saforide p=0.03; Cariestop p=0.008; RivaStar p=0.013; NaF p=0.04). The XRD results showed that the crystallite size of hydroxyapatite increased in the SDF/NaF treated dentin + pH-c groups (between +63% in RivaStar to +108% in Saforide), regarding the positive control. SEM images showed that after application of the SDF/NaF products a crystalline precipitate formed on the dentin surface and partially filled the dentin tubules. The flexural strength (MPa) values were higher in the dentin treated with SDF/NaF + pH-c (Stage 3) compared to the positive control groups (Saforide p=0.002; Cariestop p=0.04; RivaStar p=0.04; NaF p=0.02).

CONCLUSIONS

The application of SDF/NaF affected the physicochemical and mechanical properties of demineralized dentin. According to the results, the use of SFD/NaF had a remineralizing effect on the dentin surface even under acid challenge.

Evaluation of the Effect of the Loading Time on the Microtensile Bond Strength of Various Restorative Materials Bonded to Silver Diamine Fluoride-Treated Demineralized Dentin

The aim of this study was to evaluate the effect of immediate versus delayed loading times on the microtensile bond strength (μTBS) of restorative materials, including resin-based composite (RBC), resin-modified glass ionomer cement (RMGIC) and glass ionomer cement (GIC), that were bonded to silver diamine fluoride (SDF)-treated demineralized dentin. Ninety caries-free extracted premolar teeth were assigned to three groups (n = 30) loaded with RBC, RMGIC and GIC restorative materials. Each group was further divided into three subgroups (n = 10): subgroup A (control specimens), immediate loading of the restorative material on sound dentin; subgroup B, demineralized dentin, SDF treatment and immediate loading of the restorative material; and subgroup C, demineralized dentin, SDF treatment and restorative material loading a week later. One-way ANOVA and Tukey’s post-hoc tests were performed to compare the μTBS values. The RBC exhibited the highest µTBS, followed by RMGIC and GIC. Multiple comparisons showed an increase in the µTBS in the delayed loading groups irrespective of the restorative material used. The majority of the failure modes were adhesive. Delayed loading of RMGIC for 1 week after SDF application showed significantly higher µTBS than that of immediate loading.

Characterization of Physical and Biological Properties of a Caries-Arresting Liquid Containing Copper Doped Bioglass Nanoparticles

Silver diamine fluoride (SDF) is an outstanding dental material for arresting and preventing caries, but some drawbacks, such as high flowability due to low viscosity and cytotoxicity to the pulp, have been reported. To overcome these problems, copper-doped bioactive glass nanoparticles (CuBGns) were combined with SDF. After synthesis, CuBGns were examined by physical analysis and added in SDF at different weight/volume% (SDF@CuBGn). After assessing physical properties (viscosity and flowability) of SDF@CuBGn, physicochemical properties (morphology before and after simulated body fluid (SBF) immersion and ion release) of SDF@CuBGn-applied hydroxyapatite (HA) discs were evaluated. Biological properties were further evaluated by cytotoxicity test to pulp stem cells and antibacterial effect on cariogenic organisms (Streptococcus mutans and Staphylococcus aureus). Combining CuBGns in SDF increased the viscosity up to 3 times while lowering the flowability. More CuBGns and functional elements in SDF (Ag and F) were deposited on the HA substrate, even after SBF immersion test for 14 days, and they showed higher Cu, Ca, and Si release without changing F and Ag release. Cell viability test suggested lower cytotoxicity in SDF@CuBGn-applied HA, while CuBGns in SDF boosted antibacterial effect against S. aureus, ~27% in diameter of agar diffusion test. In conclusion, the addition of CuBGn to SDF enhances viscosity, Ag and F deposition, and antibacterial effects while reducing cell toxicity, highlighting the role of bioactive CuBGns for regulating physical and biological effects of dental materials.

Silver Diamine Fluoride in Preventing Caries: A Review of Current Trends

Aim and objective

Background

Review results

Conclusion

Clinical importance

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Efficacy of Silver Diamine Fluoride on Streptococcus mutans Count Present in Saliva

Aim and objective

Evaluate the efficacy and longevity of silver diamine fluoride (SDF) to inhibit the dental caries initiator bacteria; Streptococcus mutans count in saliva.

Study design

Twenty children having class I and II dental caries with no prior restorations were included in the study. Unstipulated saliva samples were collected before and immediately after application of SDF, 1, 3, and 6 months after application, and intergroup comparison was done.

Materials and methods

Silver diamine fluoride was applied on the cavitated surfaces with microbrush tip under isolation, then wait for 4 minutes and washed away all surfaces with water spray. Saliva was collected in a sterile saliva collection tube and sent for microbiological culture assessment. CFU/mL of S. mutans count was done with the Digital colony counter. For statistical analysis, paired T-test was performed.

Results

Silver diamine fluoride showed a significant drop in CFU/mL of S. mutans count at 1 month then 3 and 6 months accordingly.

Conclusion

Silver diamine fluoride can be used to prevent and arrest dental caries and the best result can be achieved by quarterly application.

How to cite this article

Chakraborty S, Gupta N, Gambhir N, et al. Efficacy of Silver Diamine Fluoride on Streptococcus mutans Count Present in Saliva. Int J Clin Pediatr Dent 2021;14(5):700–704.

Comparative evaluation of antimicrobial efficacy of silver diamine fluoride, chlorhexidine varnish with conventional fluoride varnish as a caries arresting agent. An in vivo sodium dodecyl sulfate-polyacrylamide gel electrophoresis study

INTRODUCTION

Silver diamine fluoride (SDF) is employed as an adjunct cariostatic agent in the management of dental caries in high-risk population. Other than fluorides, chlorhexidine (CHX) is the most potent antimicrobial and efficacious agent against Streptococcus mutans.

AIM

The aim of this study is to evaluate and differentiate the efficacy of 38% silver diamine fluoride, CHX varnish, and fluoride varnish on carious primary teeth.

MATERIALS AND METHODS

Ninety children having a count of ≥1 carious lesion were recruited. Thirty-eighty percent silver diamine fluoride or fluoride varnish and CHX varnish were topically applied on the lesion. The primary outcome measured was the arrest of carious lesion (lesion rendered inactive as per the Nyvad criteria) after a follow-up of 14-21 days. Dental biofilm sample was obtained from each child and subsequently assessed for microbial composition by colony-forming unit method before and after treatment followed by protein analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis method.

RESULTS

Average proportion of arrested caries lesions in the SDF group was higher followed by CHX and fluoride varnish groups. Decreased total protein amount was found in SDF group. This proves that there is decrease in microbial load posttreatment in SDF group.

CONCLUSION

Thirty-eight percent SDF is more effective than CHX varnish and fluoride varnish in arresting dentin carious lesions in young children.

Biomineralization of Dental Tissues Treated with Silver Diamine Fluoride

Silver diamine fluoride (SDF) is a dental biomaterial used to arrest dental caries. To better understand SDF's mechanism of action, we examined the localization of silver within the tissues of SDF-treated teeth. Carious primary teeth fixed within 2 min of SDF application (SDF-minutes, n = 3), at 3 wk after SDF application in vivo (SDF-weeks, n = 4), and at 2 y after multiple SDF applications in vivo (SDF-multiple, n = 1) were investigated in this study. Carious primary teeth without SDF application (no-SDF, n = 3) served as controls. Mineral density and structural analyses were performed via micro-X-ray computed tomography and scanning electron microscopy. Elemental analyses were performed through X-ray fluorescence microprobe and energy-dispersive X-ray spectroscopic techniques. SDF-treated teeth revealed higher X-ray-attenuated surface and subsurface regions within carious lesions, and similar regions were not present in no-SDF teeth. Regions of higher mineral density correlated with regions of silver abundance in SDF-treated teeth. The SDF penetration depth was approximated to 0.5 ± 0.02 mm and 0.6 ± 0.05 mm (mean ± SD) for SDF-minutes and SDF-weeks specimens, respectively. A higher percentage of dentin tubular occlusion by silver or calcium phosphate particles was observed in primary teeth treated with SDF-weeks as compared with SDF-minutes. Elemental analysis also revealed zinc abundance in carious lesions and around the pulp chamber. SDF-weeks teeth had significantly increased tertiary dentin than SDF-minutes and no-SDF teeth. These results suggest that SDF treatment on primary teeth affected by caries promotes pathologic biomineralization by altering their physicochemical properties, occluding dentin tubules, and increasing tertiary dentin volume. These seemingly serendipitous effects collectively contribute to the cariostatic activity of SDF.

Can silver diamine fluoride or silver nanoparticle-based anticaries agents to affect enamel bond strength?

Objectives

The aim of the current study is to investigate the effect of different anticaries agents, such as experimental agents based on silver nanoparticles (SNPs) and silver diamine fluoride (SDF), on the micro-shear bond strength (μ-SBS) of composite resin applied to intact enamel (IE) or demineralized enamel (DE).

Materials and Methods

Sixty dental enamel fragments were collected from human third molars and categorized into 6 groups (n = 10): positive control (IE), negative control (DE), IE + SDF, DE + SDF, IE + SNP and DE + SNP. Samples from DE, DE + SDF and DE + SNP groups were subjected to pH cycling; superficial microhardness test was performed to confirm demineralization. Resin composite build-ups were applied to the samples (0.75-mm diameter and 1-mm height) after the treatments (except for IE and DE groups); μ-SBS was also evaluated. Samples were analyzed under a stereomicroscope at 40× magnification to identify failure patterns. Data were subjected to one-way analysis of variance, followed by Tukey's and Dunnett's tests (p < 0.05).

Results

There was no significant difference among the IE, IE + SNP, DE + SDF, and DE + SNP groups. The IE + SDF and DE groups recorded the highest and the lowest μ-SBS values, respectively. Adhesive-type failures were the most frequent for all treatments.

Conclusions

Anticaries agents did not have a negative effect on the μ-SBS of composite resin when it was used on IE or DE.

Effectiveness and Parental Perception of Silver Diamine Fluoride toward Treatment of Dental Caries in Primary Teeth

Aim

Materials and methods

Results

Clinical significance

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Comparative Evaluation of Effect of Potassium Iodide and Glutathione on Tooth Discoloration after Application of 38% Silver Diamine Fluoride in Primary Molars: An In Vitro Study

Aim

To evaluate and compare the effect of potassium iodide (KI) and glutathione (GSH) on tooth discoloration after application of 38% silver diamine fluoride (SDF) in primary molars.Method: Total of 30 primary molars were randomly divided into three groups of 10 each. Teeth were prepared and divided into: Group A—SDF only, Group B—SDF followed immediately by application of KI, and Group C—SDF was mixed with 25 mg of GSH. Final restoration was done using glass ionomer cement. Visual examination and color assessments using spectrophotometer were recorded at three time interval points, that is, day 1, 1 week, and 4 weeks.

Results

Statistical analysis was done using a repeated measures analysis of variances (ANOVA) test. The spectrophotometer results showed that Group A (SDF) exhibited the greatest amount of discoloration at all time intervals, while Group C (SDF + GSH) group was effective in decreasing the discoloration. Whereas, Group B (SDF + KI) significantly reduced the discoloration over the period of time. (p = 0.008).

Conclusion

KI can effectively reduce discoloration after application of 38% SDF. GSH can also be used as an alternative.

Clinical Significance

This two-step treatment for arresting caries can be a practical and low-cost option in areas with limited access to comprehensive dental care.

How to cite this article

Kamble AN, Chimata VK, Katge F A, et al. Comparative Evaluation of Effect of Potassium Iodide and Glutathione on Tooth Discoloration after Application of 38% Silver Diamine Fluoride in Primary Molars: An In Vitro Study. Int J Clin Pediatr Dent 2021;14(6):752–756.

Evaluation of antibacterial and cytocompatible properties of multiple-ion releasing zinc-fluoride glass nanoparticles

Zinc-fluoride glass nanoparticles (Zinc-F) release several ions, such as fluoride, zinc and calcium ions, through acid-base reactions. The aim of this study was to evaluate the antibacterial and cytotoxic properties of Zinc-F. Antibacterial tests showed that a Zinc-F eluting solution significantly reduced the turbidity and colony-forming units of Streptococcus mutans and Actinomyces naeslundii, compared to that of calcium-fluoroaluminosilicate glass nanoparticles without zinc ions. In live/dead staining, Zinc-F eluate significantly decreased green-stained bacterial cells, indicating live cells, compared with the control (no application). Human dentin coated with Zinc-F showed suppressed S. mutans and A. naeslundii biofilm formation. Additionally, Zinc-F eluate showed low cytotoxic effects in osteoblastic and fibroblastic cells. Therefore, our findings suggested that Zinc-F exhibits antibacterial and biocompatible properties through multiple-ion release.

Effect of Silver Diamine Fluoride Treatment on Microbial Profiles of Plaque Biofilms from Root/Cervical Caries Lesions

Purpose: To assess the effect of silver diamine fluoride (SDF) on microbial profiles present in plaque from root/cervical carious lesions, and its association with caries lesion arrest. Materials and Methods: Twenty patients with at least one soft cavitated root/cervical carious lesion were included. One lesion/patient was randomly selected and treated with 38% SDF. Supragingival plaque samples were harvested at preintervention and 1 month postintervention. Using an MiSeq platform, 16S rDNA sequencing of the V3-V4 regions was used to determine bacterial profiles. Clinical evaluation of lesion hardness was used to evaluate arrest. t tests, principal component analysis (PCA), multidimensional scaling (MDS), and generalized linear models (GLMs) tests were used for statistical comparisons. Results: From a total of 40 plaque samples, 468 probe targets were observed. Although 60% of lesions became hard postintervention, PCA and MDS tests showed no distinct pre- and postintervention groups. In addition, pre- and postintervention differences in diversity (Shannon index) of microbial profiles between patients with and without lesion arrest were not statistically different. A likelihood ratio test for pre- versus postintervention differences within patients, i.e., adjusting for differences between patients using negative binomial GLMs, showed 17 bacterial taxa with significant differences (FDR <0.05). Conclusion: Although 60% of lesions hardened after SDF treatment, this was not directly due to either overall statistically significant differences in microbial profiles or differences in microbial diversity. Nevertheless, there was a trend with some acid-producing species in that their relative abundance was reduced postintervention. The negative binomial GLMs showed 17 bacterial taxa that were significantly different after SDF treatment.

Human Primary Tooth Histology Six Months after Treatment with Silver Diamine Fluoride

OBJECTIVE

To describe the histological characteristics of a human primary tooth with deep caries next to the dental pulp 6 months after being treated with silver diamine fluoride (SDF).

STUDY DESIGN

A tooth that was considered to be not restorable 6 months after being treated with SDF was examined with light microscopy.

RESULTS

the histologic examination revealed no carious pulp exposure, tertiary dentin, a flattened odontoblastic layer adjacent to irregular tertiary dentin, dentinal tubules with silver deposits to a depth of 1 mm and no bacteria, and a pulp with no significant inflammation.

CONCLUSIONS

The use of silver diamine fluoride as an interim treatment of deep caries on vital carious primary teeth of children, leads to histologic changes that prevent pain and pulp deterioration, and most likely facilitate pulp healing. These unique findings expand the knowledge about the effect of SDF on the human dental tissues.

Randomized Clinical Trial on Preventing Root Caries among Community-Dwelling Elders

Dental root caries is a common disease among elders. More efforts on preventing this disease are needed. Silver diammine fluoride (SDF) is known to prevent dental caries in primary teeth. However, clinical evidence of its efficacy in preventing root surface caries is limited. This clinical trial aimed to compare the effectiveness of SDF in preventing root caries among elders in a water fluoridated area. A total of 323 elders who had at least 5 teeth with exposed root surfaces and who had self-care ability were randomly allocated into 3 intervention groups: group 1 (placebo control), annual application of tonic water; group 2, annual application of SDF solution; group 3, annual application of SDF solution, immediately followed by potassium iodide (KI) solution. Oral hygiene instructions and fluoride toothpaste were provided to all subjects. Status of dental root surface was assessed every 6 mo by the same independent examiner. After 30 mo, 257 (79.6%) elders were reviewed. The mean numbers of root surface with new caries experience in the control, SDF, and SDF/KI groups were 1.1, 0.4, and 0.5, respectively (analysis of variance, P < 0.001). Scheffe’s multiple comparison showed that elders who received placebo developed more new root caries lesions ( P < 0.05), while the difference between the SDF and SDF/KI groups was not statistically significant ( P > 0.05). Moreover, elders who had higher visible plaque index scores at 30-mo examination (analysis of covariance, P < 0.001) and those who had higher baseline DMFT scores (analysis of covariance, P = 0.005) developed more new root caries. It is concluded that annual application of SDF or SDF/KI solution is effective in preventing root caries among community-dwelling elders in a fluoridated area ( ClinicalTrials.gov NCT02360124).

Knowledge Transfer Statement: Annual topical application of silver diammine fluoride or silver diammine fluoride / potassium iodide solution is effective in preventing dental root surface caries among community-dwelling elders in a fluoridated area.

Effect of silver diamine fluoride and ammonium hexafluorosilicate applications with and without Er:YAG laser irradiation on the microtensile bond strength in sound and caries-affected dentin

BACKGROUND AND OBJECTIVE

Cariostatic and preventive agents are applied to create caries-resistant dentin surfaces and may affect subsequent resin bonding. The aim of this study was to investigate the effect of different agents with and without Er:YAG laser irradiation on the microtensile bond strength (µTBS) of resin composite to sound dentin (SD) and caries-affected dentin (CAD), and to assess the morphological and chemical changes in the specimens.

MATERIALS AND METHODS

Ninety-six extracted molar teeth were divided into a control group (deionized water) and two experimental groups (ammonium hexafluorosilicate [SiF], silver diamine fluoride [SDF]), that subdivided according to different conditions (SD, CAD, SD+laser irradiation, CAD+laser irradiation). After treatment procedures, the teeth were restored and the µTBS was tested with a universal testing machine. Morover, 144 teeth were prepared and after treatment modalities; morphological changes of the surface were investigated and elemental analyses were performed using scanning electron microscope/energy dispersive spectroscopy (SEM-EDS). The data were analyzed using Kruskal-Wallis and Mann-Whitney U tests.

RESULTS

SDF and SiF applications reduced the µTBS values in both the SD and CAD subgroups (P < 0.05). Laser irradiation increased the µTBS values in the SiF group and the values were adversely affected in the SDF group (P < 0.05). Fluoride content of the specimens increased in all of the treatment groups, compared with the control group. Silver content was detected only in the SDF group, and silicon was detected only in the SiF group.

CONCLUSIONS

The µTBS values of resin composite, surface morphology and chemical characteristics of dentin were affected by the material type, dentin condition and laser irradiation and the use of SiF and SDF solutions under the resin restorations do not seem appropriate.

Recent advancements in fluoride: A systematic review

To review advancements of fluoride in dentistry, a search of 21 electronic databases and World Wide Web was conducted. Relevant journals were hand searched and further information was requested from authors. Inclusion criteria were a predefined hierarchy of evidence and objectives. Study validity was assessed with checklists. Two reviewers independently screened sources, extracted data, and assessed validity. Fluoride has become an important tool in preventive dentistry. Current research is focused on the development of strategies to improve fluoride efficacy. Fluoride therapy in the form of varnish, gel, mouth rinse, or toothpaste has been used extensively as a caries-preventive intervention for over three decades. The purpose of this review is to inform the reader about new research related to the use of fluoride for the prevention of dental caries.