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Objective: This study aimed to assess the remineralization efficacy of casein phosphopeptide‐amorphous calcium phosphate (CPP‐ACP), silver diamine fluoride/potassium iodide (SDF/KI), and sodium fluoride with functionalized tricalcium phosphate (NaF/fTCP) on artificial early enamel lesion using laser fluorescence and micro‐CT analysis. Methodology: On extracted impacted third molars, artificial enamel lesions were prepared. Twenty‐eight specimens were randomly assigned to four groups (n = 7 per group): a control group (artificial saliva), CPP‐ACP (GC Tooth Mousse), SDF/KI (Riva Star), and NaF/fTCP (Clinpro White varnish). Following the manufacturer's instructions, the remineralization agents were applied to demineralized surfaces. Laser fluorescence and micro‐CT were used to evaluate the remineralization efficacy of the agents and analyzes were performed during four stages: before demineralization, after demineralization, 1st day of remineralization and 30th day of remineralization. Shapiro–Wilk test, repeated measures two‐way ANOVA, and Spearman correlation tests were used for statistical analysis. A significant level of p < 0.05 was established. Results: SDF/KI significantly reduced the lesion area and lesion volume on the demineralized enamel surface after 30 days of remineralization. In the T3 period, SDF/KI increased the mineral density statistically significantly compared to the T1 period. The laser fluorescence values for all three remineralizing agents exhibited a linear decrease. A significant correlation between the fluorescence values and the mineral density was found (p = 0.01). Conclusion: All three investigated agents were showed positive remineralization efficacy on artificial enamel lesion. However, SDF/KI, containing silver diamine fluoride and potassium iodide exhibited superior than other agents in promoting remineralization. Clinical Significance: Although all three remineralization agents showed positive remineralization efficacy on artificial enamel lesions, SDF had higher remineralization performance over the other two agents. SDF has potential to prevent progression of demineralization in treating children with high caries risk in the long‐term. [ABSTRACT FROM AUTHOR]

The purpose of the study was to compare the fluoride release in two conventional glass ionomer cements (Ionobond, Ketac Molar) and two resin-modified glass ionomer cements (Vitrebond, Fuji II LC) adapted with halloysite nanotubes preloaded with sodium fluoride at different concentrations. In total, 96 samples were prepared and distributed into four control groups and eight experimental groups (5 % and 10 %). Totals of 10 % and 5 % of the total weight of ionomer powder needed to prepare the samples were replaced with nanotubes, preloaded at 2,000 parts per million, respectively. The experimental groups were followed for 120 days at seven time intervals. All the samples were stored at 37 °C. All the experimental groups showed significant differences compared with the control groups; likewise, differences were observed between the concentrations of 5% and 10%. The experimental groups (conventional and resin-modified glass ionomer cements adapted with preloaded nanotubes) released a higher and more constant amount of fluoride compared to the control groups. [ABSTRACT FROM AUTHOR]

Objective To explore the role of autophagy in improving fluoride-induced SH-SY5Y cytotoxicity by grape seed proanthocyanidins (GSPE) in human neuroblastoma. Methods SH-SY5Y cells were treated with sodium fluoride (60 mg/L) for 24 h to establish a fluoride-infected cell model, and then were randomly divided into the control group, sodium fluoride-infected group, sodium fluoride+low dose GSPE group. sodium fluoride + middle dose GSPE group and sodium fluoride + high dose GSPE group. The cell viability values of each group were detected by CCK-8 assay. Hoechst33342 staining was used to analyze the apoptosis level of each group. Immunofluorescence method was used to analyze the expression of LC3 in each group. The expressions of cleaved-caspase 3, cleaved-PARP, LC3, and p62 were detected by Western blot. Subsequently. Rapamycin was included in the regrouping and the expressions of cleaved-PARP, LC3, p62 and other proteins in each group were detected, and the changes of apoptosis level in each group were analyzed by Hoechst33342 staining. Results Compared with the control group, the apoptosis level of SH-SY5Y cells in the sodium fluoride group was significantly increased (P<0.05), while the cell viability and autophagy level of SH-SY5Y cells were increased after GSPE intervention (P<0.05). Compared with the sodium fluoride group, Rapamycin intervention could effectively inhibit apoptosis, and the autophagy level was further enhanced in the combination of rapamycin and GSPE together (P<0.05). Conclusion GSPE can inhibit SH-SY5Y cell apoptosis induced by NaF, and this role may be related to the activation of autophagy. [ABSTRACT FROM AUTHOR]

The randomized study aimed to evaluate the comparability of in situ (iS) and in vitro (iV) study protocols regarding remineralization of artificial enamel lesions. Two toothpastes (group A: 1450 ppm sodium fluoride, group B: placebo 0 ppm F-), were investigated. IV, a pH-cycling model with toothpaste slurry treatment was applied for 10d. IS, remineralization was performed in 9 participants wearing splints with embedded enamel samples for 10 and 21d, randomly allocated to groups A and B. Samples were scanned by X-ray micro-computed tomography (μCT) and grayscale value line profiles corresponding to mineral density (rel.ΔZ) were analyzed. Statistical analyses were performed using MedCalc Statistical Software, v22.021. T-Test for dependent and independent data and analysis of variance (ANOVA) were used for further analyses (α = 0.05). Rel.ΔZ of fluoride treated samples (A) were iV = 40.2%, iS 10d = 11.5% and iS 21d = 46.1% (p > 0.05). Rel.ΔZ of placebo treated samples (B) were: iV = − 6.2%, iS 10d = 25.2% and iS 21d = 11.0% (p > 0.05). Remineralization potential of both toothpastes was significantly different regarding iV (p < 0.001) and iS after 21d (p = 0.034), while in case of iS 10d no significant difference was detected (p = 0.4). Despite different study protocols the μCT results after remineralization were comparable between iV and iS. The results suggest that selected studies can be carried out in faster, simplified iV studies using pH-cycling instead of iS studies. [ABSTRACT FROM AUTHOR]

Background: Dentin hypersensitivity (DH) is a common oral condition that is associated with severe dental pain. Pain relief is a key focus of the treatment of DH. The purpose of this study was to evaluate the blocking and antacid effects of gallic acid (GA) combined with sodium fluoride (NaF) on dentinal tubules in vitro. Methods: Ninety dentin discs from human third molars were treated with 6% citric acid for 2 min. Then, the surface morphologies of ten dentin discs were observed by scanning electron microscopy (SEM). The remaining samples were randomly divided into four groups: the NaF group, which was treated with 1000 ppm NaF; the GA group, which was treated with 4000 ppm GA; the GA + NaF group, which was treated with 1000 ppm NaF + 4000 ppm GA; and the blank group, which was treated with deionized water. The dentin permeability of each sample was measured with a water-filled system before processing and after 7 days of treatment. Dentin morphology and surface deposits were observed by SEM. Then, samples from the NaF, GA + NaF and blank groups were subjected to an acid challenge by incubation with 0.02% citric acid for 2 min. SEM and a water-filled system were used to evaluate the blocking and antacid effects of NaF and GA + NaF. Results: 1. NaF and GA + NaF significantly decreased dentin permeability. The effect of the GA + NaF treatment was more significant. After acid challenge, both groups still exhibited decreased dentin permeability compared with the initial assessment. 2. Compared with the NaF group, the GA + NaF group had more mineral deposits on the dentin surface and dentin tubules. After acid challenge, the deposits in the GA + NaF group were still clearly visible. Conclusion: The combined effect of GA and NaF on reducing dentin permeability by blocking open dentin tubules is better than that of NaF alone. After acid challenge, the GA + NaF treatment still had a better effect. [ABSTRACT FROM AUTHOR]

Purpose: Due to the critical threat of antibiotic-resistant K. pneumoniae, there is an urgent need for novel therapeutic strategies. This study aimed to evaluate the antibacterial efficacy of sodium fluoride (NaF) against K. pneumoniae by investigating changes in both morphology and biochemical profiles. Methods: The study investigated the antibacterial and antibiofilm effects of different concentrations of NaF against the K. pneumoniae strain. Additionally, it examined alterations in morphology using scanning electron microscopy (SEM), metabolic changes through Fourier Transform Infrared (FTIR) Spectroscopy, biochemical responses, and antioxidant defense mechanisms by assessing stress markers in NaF-exposed K. pneumoniae cells. Results: K.pneumoniae strains exhibited sensitivity, with inhibition zones of 13±1.0 mm, 20±1.5 mm, and 25±1.0 mm for NaF concentrations of 10%, 20%, and 30%, respectively. Remarkable morphological and biochemical alterations were noted in NaF-treated cells in a dose-dependent manner. NaF-exposed K. pneumoniae cells demonstrated elevated levels of oxidative markers such as lipid peroxidation and ascorbic acid, and a decrease in both enzymatic and nonenzymatic antioxidants, particularly reduced glutathione (GSH) and glutathione- S-transferase (GST) Conclusions: NaF induces oxidative stress and causes morphological changes in antibiotic-resistant K. pneumoniae strains. [ABSTRACT FROM AUTHOR]

Purpose: Excessive fluoride induces kidney injury by reducing the antioxidant capacity and causing oxidative stress. Our previous studies have shown that moderately forced treadmill running alleviates oxidative injury. However, the impact of voluntary wheel-running exercise on fluoride-intoxicated mice remains unclear. In this study, we investigated the effects of voluntary wheel-running exercise on oxidative stress-induced renal injury in fluoride-intoxicated mice. Methods: 80 Institute of Cancer Research (ICR) mice (half male and half female), were randomly divided into one of eight experimental groups: four receiving distilled water and the other four ingesting 100 mg/L sodium fluoride. Each group was subdivided to incorporate different exercise regimens--no wheelrunning, daytime, nighttime, and all-day wheel-running exercises. After 6 months, mice were euthanized for subsequent analyses. Results: HE staining revealed that 6 months of fluoride exposure caused structural damage in the kidneys of mice, elevated blood urea nitrogen (BUN), and uric acid (UA) levels in the serum. Levels of malondialdehyde (MDA), reactive oxygen species (ROS), hydrogen peroxide (H2O2), and catalase (CAT) enzyme activity significantly increased. In contrast, glutathione (GSH) content and total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-PX) enzyme activities obviously decreased. Interestingly, these above changes were reversed by free-wheel movement. Correlation analysis demonstrated that negative relationships exist between ROS, MDA, H2O2 levels, CAT enzyme activity, and movement distance. Additionally, T-SOD and GSH-PX enzyme activities were positively associated with exercise distance. Conclusions: Voluntary wheel-running exercise mitigated renal injury induced by sodium fluoride in mice, and the extent of renal recovery was positively correlated with the distance covered during voluntary wheel-running exercise. [ABSTRACT FROM AUTHOR]

Breast cancer commonly metastasises to the skeleton, and stereotactic ablative body radiation therapy (SABR) is an emerging treatment for oligometastatic disease. Accurately imaging bone metastases and their response to treatment is challenging. [18F]NaF-PET has a higher sensitivity and specificity than conventional bone scans for detecting breast cancer bone metastases. In this pre-defined secondary analysis of a prospective trial, we evaluated the change in [18F]NaF uptake after SABR. Patients with oligometastatic breast cancer received a single fraction of 20 Gy to up to three bone metastases. [18F]NaF-PET was acquired before and 12 months after SABR. Pre- and post-treatment [18F] NaF-PET images were registered to the treatment planning CT. The relative change in tumour SUVmax and SUVmean was quantified. The intersection of each of the radiation therapy isodose contours with a non-tumour bone was created. The change in SUVmean in sub-volumes of non-tumour bone receiving doses of 0-20 Gy was quantified. In total, 14 patients, with 17 bone metastases, were available for analysis. A total of 15 metastases exhibited a reduction in SUVmax; the median reduction was 42% and the maximum reduction 82%. An increased absolute reduction in SUVmax was observed with higher pre-treatment SUVmax. One patient exhibited increased SUVmax after treatment, which was attributed to normal peri-tumoural bone regeneration in the context of a bone metastasis. There was a median reduction of 15%-34% for non-tumour bone in each dose level. [ABSTRACT FROM AUTHOR]

ABSTRACT Objectives Materials and Methods Results Conclusions Clinical Relevance To evaluate the effects of dentifrices containing sodium fluoride (NaF) combined with NovaMin (Sensodyne Repair & Protect—SRP), NaF combined with stannous fluoride (SnF2, Oral‐B Pro‐Gengiva—OBP), and amine fluoride (AmF, Colgate Elmex—ELM) on enamel subjected to simulated erosive cycling.Bovine enamel‐dentin discs (n = 10/group) were subjected to erosive cycling with orange juice (pH = 3.29, 5 min, 3x/day), artificial saliva (SA–2 h, 3x/day and overnight) and treated with dentifrice (2 min, 2x/day) or without treatment (CONT). Surface microhardness (SMH) was evaluated at baseline (T0), on the first (T1) and fifth (T5) days. SMH loss (%SHL) was calculated. Surface roughness (Ra, μm) was determined at T0 and T5. Morphology and mineral content were evaluated under scanning electron microscopy and energy‐dispersive x‐ray spectroscopy. Data were analyzed using ANOVA/Tukey or Bonferroni (α = 5%).No differences in %SHL were detected among groups at T1. At T5, OBP promoted %SHL, Ra, and ΔRa significantly lower than all the other groups (p < 0.05). All groups exhibited morphological changes in topography and similar Ca/P means before and after treatments.Dentifrice containing SnF2 minimized the negative effects on the SMH and Ra caused by exposure to orange juice after 5 days of simulated cycling.Patients who are more exposed to risk factors for dental erosion could benefit from the use of dentifrice containing SnF2. [ABSTRACT FROM AUTHOR]

This study aimed to assess the antibiofilm effects of dentin desensitizers using a modified Robbins device flow cell system. The test desensitizers were Saforide, Caredyne Shield, and Clinpro White Varnish. Standardized dentin specimens were prepared from human single-rooted premolars, treated with one of the materials, and mounted on the modified Robbins device flow cell system. Streptococcus mutans biofilms were developed for 24 h at 37 °C under anaerobic conditions. Scanning electron microscopy, fluorescence confocal laser scanning microscopy, viable and total cell counts, acid production, and gene expression analyses were performed. A wavelength-dispersive X-ray spectroscopy electron probe microanalyzer was used to analyze the ion incorporations. Clinpro White Varnish showed the greatest inhibition, suggesting its suppression of bacterial adherence and transcription of genes related to biofilm formation. Saforide reduced only the number of viable bacteria, but other results showed no significant difference. The antibiofilm effects of Caredyne Shield were limited. The uptake of ions released from a material into dentin varies depending on the element. Clinpro White Varnish is effective for the short-term treatment of tooth sensitivity due to dentin demineralization. It prioritizes remineralization by supplying calcium and fluoride ions while resisting biofilm formation. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of solutions containing aminomethacrylate copolymer (AA) and sodium fluoride (F; 225 ppm F−) or fluoride plus stannous chloride (FSn; 225 ppm F−, 800 ppm Sn2+) against enamel and dentin erosion/abrasion. Solutions F, FSn, AA, F+AA, FSn+AA, and deionized water as negative control were tested. Bovine enamel and dentin specimens (n = 13/solution/substrate) underwent a set of erosion‐abrasion cycles (0.3% citric acid [5 min, 4×/day], human saliva [1 h, 4×/day], brushing [15 s, 2×/day], and treatments [2 min, 2×/day]) for each of five days. Initial enamel erosion was evaluated using Knoop microhardness after the first and second acid challenge on day 1, and surface loss with profilometry after day 5. KOH‐soluble fluoride was assessed. Data were analyzed with ANOVA/Tukey tests. The combination of fluoride and AA resulted in higher protection against enamel erosion, whereas this was not the case for the combination of AA and FSn. All treatments protected against enamel and dentin loss. The lowest surface loss values were observed with F+AA and FSn+AA. The polymer did not significantly influence the KOH‐soluble fluoride formation on enamel/dentin specimens. The aminomethacrylate copolymer effectively enhanced the efficacy of sodium fluoride against initial erosion and improved the control of enamel and dentin wear of F and FSn solutions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Distillation enables the settlement and recovery of Li 2 CO 3 from spent electrolyte. • The oil and solid phase can be separated at a low temperature pyrolysis. • Conversion path of electrolyte concentrate during the whole process is proposed. • Addition of alkali shows well performance on fixation of fluorine and phosphorus. • A viable method is proposed for disposing the residual electrolyte. Disposal of electrolytes from waste lithium-ion batteries (LIBs) has gained much more attention with the growing application of LIBs, yet handling spent electrolyte is challengeable due to its high toxicity and the lack of established methods. In this study, a novel two-stage thermal process was developed for treating residual electrolytes resulted from spent lithium-ion batteries. The conversion of fluorophosphate and organic matter in oily electrolyte during low-temperature rotation distillation was investigated. The distribution and migration of the concentrated electrolytes were studied and the corresponding reaction mechanisms were elucidated. Additionally, the influence of alkali on the fixation of fluorine and phosphate was further examined. The results indicated that hydrolyzed carbonate esters and lithium in the electrolyte could combine to form Li 2 CO 3 and the hydrolysable hexafluorophosphate was proven to be stable in the concentrated electrolyte (45 rpm/85 °C, 30 min). It was found that CO 2 , CO, CH 4 , and H 2 were the primary pyrolysis gases, while the pyrolysis oil consisted of extremely flammable substances formed by the dissociation and recombination of chemical bonds in the electrolyte solvent. After pyrolysis at 300 °C, fluorine and phosphate were present in the form of sodium fluoride and sodium phosphate. The stability of the residue was enhanced, and the environmental risk was reduced. By adding alkali (KOH/Ca(OH) 2 , 20 %), hexafluorophosphate in the electrolyte was transformed into fluoride and phosphate in the residue, thereby reducing the device's corrosion from fluorine-containing gas. This study provides a viable approach for managing the residual electrolyte in the waste lithium battery recovery process. [ABSTRACT FROM AUTHOR]

The permanganate–H2SO4 redox reaction, useful in oxidative treatments under aqueous conditions, was studied spectrophotometrically in the absence and presence of cetyltrimethylammonium bromide (CTAB). The decolorization reactions were influenced by the [MnO4−], [H2SO4], and temperature. Permanganate reduction follows first‐, and complex–order kinetics with permanganate, and H2SO4 concentrations, respectively. The reduction of permanganate (Mn(VII)) proceeds through a complex formation between MnO4− and H2SO4. The characteristic absorption peaks for MnO42− (λmax = 439 and 606 nm), MnO43− (λmax = 667 nm), and MnO2 (λmax = 400–418 nm) were not appeared during the redox reaction. The KMnO4 degradation efficiency remains unaffected with sodium pyrophosphate and sodium fluoride. The results of this study demonstrated the formation of Mn(II) as the stable product in acidic reaction media. The degradation efficiency increases drastically from 15 to 100% with 2.0 × 10−4 to 16.0 × 10−4 mol/L CTAB concentration under sub‐, and post‐micellar reaction conditions, respectively. The thermodynamic parameters (activation energy = 98.8 and 43.2 kJ/mol), activation of enthalpy (96.3, and 39.0 kJ/mol), activation of entropy (16.2 and −149.5 J/K/mol), free energy of activation (93.1 and 83.5 kJ/mol) were calculated without and with CTAB, respectively. Hence, CTAB can be exploited for its multifunctional applications, and specifically for the catalytic role in the permanganate‐assisted redox reactions in future. [ABSTRACT FROM AUTHOR]

Purpose: To compare charcoal-containing dentifrices (CDs) to non-charcoal containing dentifrices (NCDs) through the following experiments: potentially available fluoride, 1-minute fluoride release, pH, cytotoxicity, heavy metals, enamel fluoride uptake (EFU) and relative dentin abrasivity (RDA). Methods: Nine fluoride dentifrices; six CDs and three NCDs were tested (n= 3) for available fluoride, the amount of fluoride released within 1 minute, pH cytotoxicity, heavy metals, EFU and RDA. Four CDs and 1 NCD contained sodium fluoride (NaF) as the active ingredient whereas two dentifrices contained stannous fluoride (SnF2; 1 CD and 1 NCD), and two dentifrices contained disodium monofluorophosphate (Na2FPO3, Or Na2MFP; 1 CD and 1 NCD). Available samples were homogenized and diluted to l-in-100 in deionized water (DIW). Release samples were prepared as l-in-4 homogenized dilutions by mass in DIW. Available and release samples were measured in triplicate (n= 3) via fluoride ion-selective electrode (F-ISE) and ion chromatography (IC). ANSI/ADA 130 was followed for pH. L929 cells were cultured using the lactate dehydrogenase (LDH) assay and ISO 10993-5 Annex C MTT cytotoxicity test. Heavy metals testing was performed using a hydrofluoric acid digestion sample preparation method followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. EFU was performed on enamel specimens that underwent treatment with a CD slurry (l-in-4 dilution) following Test Method #40 of FDA Monograph 21. RDA was performed following ISO 11609 Annex A and the Hefferren method. Data was analyzed using one-way ANOVA followed by post-hoc tests (α= 0.05). Results: Available fluoride for all nine dentifrices was between ~93-102% of the labeled amount. The amount of fluoride released after 1 minute of homogenous mixing ranged between 75-107% of the labeled amount. The pH values of the nine dentifrices ranged from 6.5 to 7.7. Charcoal did not significantly contribute to cytotoxicity in L929 cells. The concentrations of each heavy metal (Hg, Cd, As and Pb) present in each of the nine dentifrices were < 1 ppm, indicating trace amounts. The CDs were not significantly more abrasive than the NCDs. The SnFi CD had the highest EFU value (644.2 ±131.7 ppm) followed by the NaF CD and the NaoMFP CD at 492.2± 69.5 ppm and 140.1± 28.1 ppm, respectively. [ABSTRACT FROM AUTHOR]

Background: The oral cavity is an important but often overlooked reservoir for Staphylococcus aureus. The effective control and prevention of S. aureus colonization and infection in the oral and maxillofacial regions are crucial for public health. Fluoride is widely used in dental care for its remineralization and antibacterial properties. However, its effectiveness against S. aureus has not been thoroughly investigated. Objectives: This study aimed to evaluate the potential of combining sodium fluoride (NaF) with compounds to enhance its antibacterial and antibiofilm effects against S. aureus. Method: We found that a urea derivative significantly enhances the efficacy of fluoride by promoting the retention of fluoride ions within the cells. The synergistic antibacterial and antibiofilm effects of BPU with NaF were confirmed through various assays, including checkerboard assays, time-kill assays, and growth curve analysis. These findings were further supported by additional methods, including transmission electron microscopy (TEM), in silico simulations, and gene overexpression studies. Results: These findings suggest that targeting fluoride ion membrane exporters could enhance antibacterial efficacy. When combined with fluoride, 1,3-Bis [3,5-bis(trifluoromethyl)phenyl]urea (BPU) showed increased effectiveness in inhibiting S. aureus growth and reducing established biofilms. Conclusions: This novel combination represents a promising therapeutic strategy for treating biofilm-associated S. aureus infections, offering a new strategy in oral healthcare. To fully evaluate the clinical potential of this synergistic therapy, further in vivo studies are essential. [ABSTRACT FROM AUTHOR]

Drawing inspiration from recent advances in microwave ablation (MWA) induced in situ tumor vaccination, a colloidal hydrogel comprising amphoteric gelatin nanoparticles and poly (acrylic acid) (PAA)‐calcium carbonate nanorods (PAA‐CaCO3 NRs) is developed to deliver the microwave‐sensitive agent sodium fluoride (NaF) which can also act as a glycolysis inhibitor in conjunction with the blockade of the T‐cell Ig and ITIM domain (TIGIT), a coinhibitory receptor expressed by both natural killer (NK) cells and T cells. The combination of NaF with microwave (MW) thermal‐dynamic sensitization effectively reversed the acidic and immunosuppressive tumor microenvironment (TME). Moreover, the incorporation of anti‐TIGIT monoclonal antibody (aTIGIT) molecules amplified both the innate and adaptive immune responses by counteracting the exhaustion of NK and effective CD8+ T cells. This augmentation resulted in enhanced tumor elimination and suppression of tumor metastasis and recurrence. Thus, this study underscores the potential of colloidal hydrogel‐sensitized MWA therapy, in conjunction with aTIGIT treatments, as a promising clinical strategy for in situ cancer vaccination. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate chitosan (CS)-based formulations loaded with 5% sodium fluoride (NaF) and/or 10% nanohydroxyapatite (nHA) to remineralize the demineralized primary tooth enamel surface. Ninety enamel blocks were demineralized and were divided into six groups (n = 15): (1) CS-based hydrogel, (2) CS-based hydrogel loaded with NaF, (3) CS-based hydrogel loaded with nHA, (4) CS-based hydrogel loaded with NaF and nHA, (5) 5% NaF varnish, and (6) negative control with no intervention. After intervention, the specimens were pH cycled by 2 h immersion in demineralizing solution and 22 h immersion in remineralizing solution for 8 days. The remineralization effects were evaluated by Vickers microhardness measurements and field emission scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (FESEM-EDS). The best mean ± SD percentage microhardness recovery in remineralized enamel (%REMH) was found in group 4 (56.90 ± 5.49). The %REMH of groups 2 (30.74 ± 3.51) and 5 (29.23 ± 5.65) were statistically the same (p = 0.943). FESEM images confirmed partial coverage of the porous demineralized enamel with a newly formed mineralized layer. Based on EDS findings, the Ca/P ratio values of the treated enamel surfaces with CS-based hydrogels ranged between 1.71 and 1.87, and the highest F content was noticed in group 2 (1.02 ± 0.03). Although, all tested CS-based hydrogels demonstrated the potential to repair demineralized enamel, nHA- and NaF-containing CS-based hydrogel showed the highest remineralization effect. We infer that this new hybrid hydrogel is a potentially useful dental material for tooth biomineralization. [ABSTRACT FROM AUTHOR]