Optimization of Calcium Fluoride Crystallization Process for Treatment of High-Concentration Fluoride-Containing Semiconductor Industry Wastewater.

This study utilized a fluidized bed reactor (FBR) for fluoride removal from high-concentration fluoride-ion-containing simulated semiconductor industry wastewater and recovered high-purity CaF2 crystals. The effects of hydraulic retention time (HRT), pH, Ca2+ to F- ratio, upflow velocity, seed size and seed bed height were investigated by performing lab-scale batch experiments. Considering fluoride removal and CaF2 crystallization efficiency, 5 h HRT, pH 6, seed height of 50 cm and [Ca2+]/[F-] ratio of 0.55 (mol/mol) were found to be optimum. The effect of the interaction between the important process parameters on fluoride removal was further analyzed using response surface methodology (RSM) experimental design. The results showed that all the individual parameters have a significant impact (p = 0.0001) on fluoride removal. SEM-EDX and FTIR analysis showed the composition of the crystals formed inside FBR. HR-XRD analysis confirmed that the crystalline structure of samples was mainly CaF2. The results clearly demonstrated the feasibility of silica seed material containing FBR for efficient removal and recovery of fluoride as high-purity calcium fluoride crystals.

Novel pit and fissure sealant with nano-CaF2 and antibacterial monomer: Fluoride recharge, microleakage, sealing ability and cytotoxicity.

Conventional resin-based sealants release minimal fluoride ions (F) and lack antibacterial activity. The objectives of this study were to: (1) develop a novel bioactive sealant containing calcium fluoride nanoparticles (nCaF2) and antibacterial dimethylaminohexadecyl methacrylate (DMAHDM), and (2) investigate mechanical performance, F recharge and re-release, microleakage, sealing ability and cytotoxicity. Helioseal F served as commercial control. The initial F release from sealant containing 20% nCaF2 was 25-fold that of Helioseal F. After ion exhaustion and recharge, the F re-release from bioactive sealant did not decrease with increasing number of recharge and re-release cycles. Elastic modulus of new bioactive sealant was 44% higher than Helioseal F. The new sealant had excellent sealing, minimal microleakage, and good cytocompatibility. Hence, the nanostructured sealant had substantial and sustained F release and antibacterial activity, good sealing ability and biocompatibility. The novel bioactive nCaF2 sealant is promising to provide long-term F ions for caries prevention.

Microwave hydrothermal sulfuric acid leaching of spent cathode carbon from aluminum electrolysis for high efficiency removal of insoluble calcium fluoride.

Toxic substances, like fluoride salts present in spent cathode carbon (SCC), have been a great risk to the environment and public health. Our approach involves alkali leaching to eliminate soluble fluoride, followed by microwave hydrothermal acid leaching to efficiently remove insoluble CaF2 from SCC. The optimized conditions, including a temperature of 353 K, a solid-liquid ratio of 1:20, and a 60-minute reaction time, resulted in an impressive 95.6 % removal of fluoride from SCC. Various characterization techniques were employed to analyze the composition, micro-morphology, and elemental content of the materials before and after the leaching process. Furthermore, critical process parameters on the leaching separation of insoluble CaF2 during microwave hydrothermal acid leaching were systematically investigated. The study removal mechanism revealed the transformation of insoluble CaF2 in the process of microwave oxidation insertion-hydrothermal acid leaching for SCC. The kinetic characteristics of the two-stage leaching process of CaF2 at different temperatures were analyzed according to the shrinkage kernel model. The results indicate that the two-stage leaching process of CaF2 is affected by mixing control and by diffusion control, severally. The expansion of the graphite flake layer of SCC through oxidative intercalation was identified as a critical process for the thorough removal of CaF2. Microwave hydrothermal acid leaching demonstrated a 17 % improvement over traditional hydrothermal acid leaching within the same reaction time, showcasing a noteworthy enhancement in fluoride removal. Consequently, the microwave oxidizing intercalation-hydrothermal acid leaching treatment of SCC, as explored in this study, offers an effective approach for achieving deep defluoridation of SCC.

Sulfate Doping Promotes Agglomeration of Calcium Fluoride Crystals.

Calcium salt precipitation is an effective solution to wastewater fluoride pollution. The purity and precipitation efficiency of calcium fluoride is critical for its removal and recovery. This study aimed to reveal the role of coexisting sulfates in the precipitation of calcium fluoride. A low sulfate concentration promoted calcium fluoride precipitation. The size of calcium fluoride-aggregated particle clusters increased from 750 to 2000 nm when the molar ratio of sulfate to fluoride was increased from 0 to 3:100. Sulfate doped in the calcium fluoride crystals neutralized the positive charge of the calcium fluoride. Online atomic force microscopy measurements showed that sulfate reduced the repulsive force between calcium fluoride crystals and increased the adhesion force from 1.62 to 2.46 nN, promoting the agglomeration of calcium fluoride crystals. Sulfate improved the precipitation efficiency of calcium fluoride by promoting agglomeration; however, the purity of calcium fluoride was reduced by doping. Sulfate reduced the induction time of calcium fluoride crystallization and improved the nucleation rate of calcium fluoride. Sulfate should be retained to improve the precipitation of calcium fluoride and to avoid its loss from the effluents. However, it is necessary to separate sulfate from fluoride to obtain high-purity calcium fluoride. Therefore, sulfate concentration regulation in high-fluoride wastewater is key to achieving the efficient removal and recovery of fluoride ions.

Novel Remineralizing and Antibiofilm Low-Shrinkage-Stress Nanocomposites to Inhibit Salivary Biofilms and Protect Tooth Structures.

Recurrent caries remain a persistent concern, often linked to microleakage and a lack of bioactivity in contemporary dental composites. Our study aims to address this issue by developing a low-shrinkage-stress nanocomposite with antibiofilm and remineralization capabilities, thus countering the progression of recurrent caries. In the present study, we formulated low-shrinkage-stress nanocomposites by combining triethylene glycol divinylbenzyl ether and urethane dimethacrylate, incorporating dimethylaminododecyl methacrylate (DMADDM), along with nanoparticles of calcium fluoride (nCaF2) and nanoparticles of amorphous calcium phosphate (NACP). The biofilm viability, biofilm metabolic activity, lactic acid production, and ion release were evaluated. The novel formulations containing 3% DMADDM exhibited a potent antibiofilm activity, exhibiting a 4-log reduction in the human salivary biofilm CFUs compared to controls (p < 0.001). Additionally, significant reductions were observed in biofilm biomass and lactic acid (p < 0.05). By integrating both 10% NACP and 10% nCaF2 into one formulation, efficient ion release was achieved, yielding concentrations of 3.02 ± 0.21 mmol/L for Ca, 0.5 ± 0.05 mmol/L for P, and 0.37 ± 0.01 mmol/L for F ions. The innovative mixture of DMADDM, NACP, and nCaF2 displayed strong antibiofilm effects on salivary biofilm while concomitantly releasing a significant amount of remineralizing ions. This nanocomposite is a promising dental material with antibiofilm and remineralization capacities, with the potential to reduce polymerization-related microleakage and recurrent caries.

The beneficial effects of simultaneous supplementation of Lactobacillus reuteri and calcium fluoride nanoparticles on ovariectomy-induced osteoporosis.

BACKGROUND: The development of new strategies to inhibit and/or treat osteoporosis as a chronic systemic disease is one of the most crucial topics. The present study aimed to investigate the simultaneous effects of calcium fluoride nanoparticles (CaF2 NPs) and lactobacillus reuteri ATCC PTA 6475 (L. reuteri) against osteoporosis in an ovariectomized rat model (OVX). METHODS: In this study, 18 matured Wistar female rats were randomly assigned into 6 groups, including control, OVX, sham, OVX + L. reuteri, OVX + CaF2 NPs, and OVX + L. reuteri + CaF2 NPs. We used OVX rats to simulate post-menopausal osteoporosis, and the treatments were begun two weeks before OVX and continued for four weeks. All groups' blood samples were collected, and serum biomarkers (estrogen, calcium, vitamin D3, and alkaline phosphatase (ALP)) were measured. The tibia and Femur lengths of all groups were measured. Histopathological slides of tibia, kidney, and liver tissues were analyzed using the Hematoxylin and Eosin staining method. RESULTS: Our results revealed that dietary supplementation of L. reuteri and CaF2 NPs in low doses for 6 weeks did not show adverse effects in kidney and liver tissues. The tibial and femoral lengths of OVX rats as well as the population of osteoblasts and osteocytes and newly generated osteoid in the tibia remarkably increased in the combination therapy group. Moreover, there was a significant increase in serum estrogen levels and a significant decrease in serum calcium and alkaline phosphatase levels in combination treatment groups compared to the OVX groups not receiving the diet. CONCLUSIONS: Our results suggest the favorable effects of the simultaneous supplementation of L. reuteri and CaF2 NP to reduce post-menopausal bone loss.

Evaluation of Dentin Remineralization with Zinc Oxide and Calcium Fluoride Nanoparticles - An In vitro Study.

Background: Partially demineralized dentin is remineralizable when mineral ions are made available in the near vicinity. Nanoparticles (NPs) have wide applications in remineralization process. Zinc promotes remineralization and has a synergistic effect when combined with fluoride. Hence, zinc oxide and calcium fluoride NPs were considered for dentin remineralization. Aim: The aim of this study was to evaluate the remineralizing ability of zinc oxide and calcium fluoride NPs on demineralized dentin individually and in combined form. Settings and Design: This was an in vitro study. Materials and Methods: Forty-eight dentin disks were prepared from the crowns of 12 extracted human molars and were allocated into four groups of 12 each, i.e., Group I - nano zinc oxide (nZnO), Group II - nano calcium fluoride (nCaF2), Group III - combined group (nZnO + nCaF2), and Group IV - artificial saliva (AS, control group). The specimens were demineralized with 37% phosphoric acid and placed in the respective remineralizing solutions for 24 h and 1 month. Calcium (Ca) and phosphorous (P) uptake was measured using energy-dispersive X-ray spectrometry, and structural changes were analyzed using scanning electron microscopy (SEM). Statistical Analysis: One-way analysis of variance, Student's t-test, and post hoc Tukey's test were used for statistical analysis. Results: At 1-month interval, all the groups showed an increase in Ca/P ratio, with highest being the combined group (4.24), followed by nCaF2 (3.30), nZnO (1.71), and AS (1.31) groups, and these differences were statistically significant (P = 0.000). On SEM analysis of dentinal samples at 1 month, depositions were evident in intertubular regions, wherein the highest deposits were observed in the nZnO group, followed by nZnO + nCaF2 and nCaF2 groups. Conclusion: Dentin samples subjected to remineralization with aqueous solutions of nZnO and nCaF2 showed an increase in calcium and phosphorous uptake and also dense granular depositions were evident in intertubular regions of dentin.

Anticaries potential of a fluoride foam

Abstract Foam has been used worldwide as a vehicle for the professional application of fluoride and hypothetically should have the same anticaries potential as conventional fluoride gel (F-gel) in terms of the formation of reaction products with enamel. Thus, the ability of Flúor Care® foam (FGM, Joinville, SC, Brazil, 12,300 ppm F, acidulated) to react with enamel was evaluated in comparison with Flúor gel® (DFL, Rio de Janeiro, RJ, Brazil, 12,300 ppm F, acidulated). Slabs (n=10/group) of sound enamel and with caries lesion were used, in which the concentrations of total fluoride (TF), and loosely (CaF2-like) and firmly (FAp) bound types were determined. The importance of agitation during application was previously tested. The determinations were made with fluoride ion-specific electrode and the results were expressed in μg F/cm² of the treated enamel area. ANOVA and Tukey tests were used to analyze the difference among treatments, independently for sound and carious enamel. The agitation of the products during application significantly increased the reactivity of the foam (p<0.05), but not that of the gel (p>0.05). The foam did not differ from F-gel (p>0.05) concerning the formation of TF and CaF2-like in sound or carious enamel. Regarding FAp, the foam did not differ from F-gel (p>0.05) in the carious enamel, but the concentration in the sound was lower (p<0.05). The results show that this commercial fluoride foam tested needs to be agitated during application to improve its reactivity with enamel, which raises a question about other brands.

Resumo A espuma tem sido utilizada mundialmente como veículo para aplicação profissional de fluoreto e hipoteticamente deveria ter o mesmo potencial anticárie que o gel fluoretado convencional (F-gel) em termos de formação de produtos de reação com o esmalte. Assim, a capacidade da espuma Flúor Care® (FGM, Joinville, SC, Brasil, 12.300 ppm F, acidulada) de reagir com o esmalte foi avaliada em comparação com o Flúor gel® (DFL, Rio de Janeiro, RJ, Brasil 12.300 ppm F, acidulado). Foram utilizados blocos (n=10/grupo) de esmalte hígido e com lesão de cárie, nos quais foram determinadas as concentrações de flúor total (FT), e os tipos de flúor fracamente (tipo-CaF2) e firmemente (FAp) ligados ao esmalte. A importância da agitação durante a aplicação foi previamente testada. As determinações foram feitas com eletrodo íon específico para fluoreto e os resultados foram expressos em μg F/cm² da área tratada do esmalte. A diferença entre os tratamentos foi analisada por ANOVA e Tukey (α=5%), independentemente para esmalte hígido e cariado. A agitação dos produtos durante a aplicação aumentou significativamente a reatividade da espuma (p<0,05), mas não a do gel (p>0,05). A espuma não diferiu do F-gel (p>0,05) quanto à formação de FT e tipo-CaF2 no esmalte hígido ou cariado. Em relação à FAp, a espuma não diferiu do F-gel (p>0,05) no esmalte cariado, mas a concentração no hígido foi menor (p<0,05). Os resultados mostram que esta espuma fluoretada comercial testada precisa ser agitada durante a aplicação para melhorar sua reatividade com o esmalte, o que levanta questão sobre outras marcas.

Solid Features Modification by the Reactor Selection and US Support during Reactive Crystallization.

The use of materials requires adjusting their features to current applications/needs. In crystallization, the production methods leading directly to the product with pre-determined characteristics are being sought. The research focuses on the abilities of "shaping" the solid product (CSD, shape, form, etc.) and is based on experimental work carried out in the ultrasound (US)-assisted Koflo static mixer (STM). As the model reaction calcium fluoride precipitation has been used as a "common denominator" that complements the previous authors' studies, providing comprehensive knowledge and a more general look at the mentioned problem. It has been shown that it is possible to obtain crystals with the desired characteristics; however, one should be aware of the used reactors' limitations. The conscious selection of operating conditions, as well as US parameters (if they are used), is also essential. It has been revealed that the introduction of US to the STM only affects the turbulence intensity, but it doesn't change the mixing profile. The kinetics of crystallization remain unchanged, but crystals are subjected to greater attrition. In the stirred tank reactors, one might significantly improve the homogeneity of the unit mixing distribution by the selection of the relative input power εrel and, thus, affect the kinetics of crystallization.

Characterization of Wear Properties of Pure Nickel Modified by Ni-Cr Composite and CaF2 Solid Lubricant Addition.

Nickel composites doped by chromium and calcium fluoride were produced by powder metallurgy. The friction coefficient of the samples containing 20% of the CaF2 was lower at elevated temperatures (600 °C) than the friction coefficient for the Ni-50%NiCr(80/20) composite (0.14 vs. 0.20). Sample surfaces were analyzed by the scanning electron microscope (SEM). EDS analysis proved tribofilm formation on the surface of the sample with CaF2 addition. A laser confocal microscope (LCM) was used to investigate the surface condition of the counter-sample after wear tests. The presence of the tribofilm reduced the wear of the frictional pair, and because of that the wear tracks were smooth. Tribofilm limited the abrasive wear and ploughing. Therefore, the tribofilm protected the sample and counter-sample from wear.

The Influence of Alkali-Free Shotcrete Accelerators on Early Age Hydration and Property Development within Cement Systems.

Fluoride-containing alkali-free setting accelerators are a common type of admixture used in tunnel shotcrete but few studies in the literature focus on the effect of their fluoride compounds on the setting and hardening properties of accelerated cement paste under low environment temperatures. Tunnel shotcrete in cold regions or winter construction periods would be obviously influenced by low environment temperatures, especially for its fast setting and quick support applications. The objective of this work is to evaluate the early age hydration behavior of different accelerated cement pastes under 20 °C and 5 °C environment temperatures. In this study, setting time measurement, early age strength development, hydration ion leaching concentration, isothermal calorimetry, X-ray diffraction, and ESEM were performed on cement systems prepared with a non-fluoride alkali-free accelerator (aluminum sulfate solution with over 60% solid content) and a designed fluoride-containing alkali-free setting accelerator (aluminum sulfate and fluoride compound). The results showed that the fluorides obtained in alkali-free accelerators promote C3S dissolution and massive ettringite needles together with monosulfoaluminate (AFm) hydrate formation, thus leading to a quicker setting effect and low sensitivity to low environment temperatures than in non- fluoride groups. However, the rate of mechanical strength development of cement pastes hydrated within 24 h was decreased obviously when fluorine-containing alkali-free accelerator was used. This phenomenon is mainly related to the crystallization of thin-plate shape calcium fluoride (CaF2) formations and promoted conversion of ettringite to monosulfoaluminate hydrate in the accelerating period, thus weakening the denseness of C-S-H gel and inhibiting alite further hydration.

Novel rechargeable nano-calcium phosphate and nano-calcium fluoride resin cements.

OBJECTIVE: In most clinical circumstances, secondary caries at the margin of fixed dental restorations leads to restoration failure and replacement. Accordingly, the objectives of this study were to: (1) develop a novel rechargeable nano-calcium phosphate (NACP) and nano-calcium fluoride (nCaF2) resin-based cement; and (2) investigate their mechanical properties and calcium (Ca), phosphate (P), and fluoride (F) ion release, recharge, and re-release for the first time. METHODS: The cement matrix consisted of pyromellitic glycerol dimethacrylate (PMGDM), ethoxylated bisphenol-A-dimethacrylate (EBPADMA) was denoted PEHB. Four cements were fabricated: (1) PEHB+0%NACP+0%nCaF2 (experimental control); (2) PEHB+25%NACP+0%nCaF2, (3) PEHB+0%NACP+25%nCaF2; (4) PEHB+12.5%NACP+12.5% nCaF2. RelyX luting cement was used as a commercial control. Mechanical properties and long-term Ca, P, and F ion release, recharge, and re-release were evaluated. RESULTS: Adding 25% NACP, 25% nCaF2 and adding both 12.5% NACP and 12.5% nCaF2 to the cement matrix presented a significantly higher shear bond strength, flexural strength compared to the commercial control (p < 0.05) with a comparable outcome with no significant different (p > 0.05) compared to experimental control. The film thickness results of all cement groups met the ISO requirement (<50 µm). The resin cement group with both 12.5% NACP and 12.5% nCaF2 successfully released Ca, P, and F ions at 3.1 ± 0.01, 1.1 ± 0.05, and 0.51±0.01 mmol/L respectively. Moreover, it showed the ability to re-release Ca, P, and F ions at 0.62±0.01, 0.12±0.01, and 0.42±0.01 mmol/L respectively. CONCLUSIONS: The resin cement group with both 12.5% NACP and 12.5% nCaF2 demonstrated the advantages of both types of bio-interactive fillers as it could release a higher level of ions than the resin cement with 25%nCAF2 and exhibited a better rechargeability compared to the resin cement with 25%NACP. CLINICAL SIGNIFICANCE: The ability of this novel resin-based cement to release, recharge, and re-release Ca, P, and F ions could be one of the keys to lengthening the survivability of fixed dental restorations. These features could help to reduce the onset of secondary caries by enhancing the remineralization and preventing the demineralization of tooth structures.

The Mechanism of Wear Reduction in the Ni-CaF2 Composite Material: Raman and Confocal Microscopy Insights.

A powder metallurgy process was used to produce high temperature self-lubricating composites based on Ni, with varying content of calcium fluoride (10 wt.% and 20 wt.%). The wear properties of the samples were investigated by a pin-on-disc test at elevated temperature, up to 600 °C. Aside from standard techniques for the sample characterization, confocal microscopy and micro-Raman spectroscopy were used for the first time for this type of sample. These methods were used to examine the changes in topography and to detect the distribution of the tribofilm on sample surfaces. The addition of solid lubricant particles decreased the coefficient of friction and improved the tribological properties, because of the tribofilm which formed on sample surfaces.

The antibacterial activity of mineral trioxide aggregate containing calcium fluoride.

Background/purpose: Because complete microbial elimination of the infected root canal system is nearly impossible to achieve, the use of root canal fillings with antibacterial effects may help to minimize intracanal infections. Our previous study, MTA modified by CaF2 addition, improved the biocompatibility and mineralization potential of human dental pulp cells without adverse effect on the physical properties. In this study, the antibacterial effect of MTA after CaF2 addition was evaluated for use as a root canal sealer. The objective of this study was to evaluate the antibacterial activity of MTA after the addition of CaF2. Materials and methods: The antibacterial activities of MTA and MTA-CaF2 mixture against Enterococcus faecalis (E. faecalis), Porphyromonas endodontalis (P. endodontalis), and Porphyromonas gingivalis (P. gingivalis) were investigated with MTA-CaF2 powder and eluates. The bacterial growth was measured by optical density using a spectrophotometer and the bacterial colony counting. Results: MTA inhibited the growth of E. faecalis, P. endodontalis, and P. gingivalis, and the addition of CaF2 improved this antibacterial effect in a concentration dependent manner (p < 0.05). E. faecalis was more resistant to MTA-CaF2 than the other groups of bacteria. Conclusion: The addition of more than 5% CaF2 to MTA can increase the antibacterial activity.

Atomic-resolution STEM image denoising by total variation regularization.

Atomic-resolution electron microscopy imaging of solid-state material is a powerful method for structural analysis. Scanning transmission electron microscopy (STEM) is one of the actively used techniques to directly observe atoms in materials. However, some materials are easily damaged by the electron beam irradiation, and only noisy images are available when we decrease the electron dose to avoid beam damages. Therefore, a denoising process is necessary for precise structural analysis in low-dose STEM. In this study, we propose total variation (TV) denoising algorithm to remove quantum noise in an STEM image. We defined an entropy of STEM image that corresponds to the image contrast to determine a hyperparameter and we found that there is a hyperparameter that maximizes the entropy. We acquired atomic-resolution STEM image of CaF2 viewed along the [001] direction and executed TV denoising. The atomic columns of Ca and F are clearly visualized by the TV denoising, and atomic positions of Ca and F are determined with the error of ±1 pm and ±4 pm, respectively.

Solid-state NMR spectroscopy measurement of fluoride reaction by bovine enamel and dentin treated with silver diammine fluoride.

OBJECTIVES: The aim of this study was to investigate the formation of fluoride compounds in bovine enamel and dentin treated with silver diammine fluoride (SDF) using 19F and 31P solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. METHODS: Enamel and dentin powder, obtained from bovine teeth, were treated with 38% SDF for four minutes and then washed thoroughly with Milli-Q water. The dehydrated SDF-treated samples were then examined. 19F solid-state MAS NMR spectra were acquired and 1H-31P cross-polarization (CP) experiments were performed on SDF-treated enamel and dentin powder. The surfaces of SDF-treated enamel and dentin blocks were observed by Scanning Electron Microscope (SEM). RESULTS: 19F MAS NMR detected a more pronounced signal intensity for the dentin sample than the enamel, indicating an increased reactivity of SDF for dentin, compared with enamel. 19F NMR spectra for the SDF-treated samples showed fluorhydroxyapatite (FHAp), and other fluoride compounds such as CaF2 and the fluoride-substituted carbonate. The 1H-31P CP intensities of prominent peaks were lower for the SDF-treated samples than the non-treated sample, indicating that the F- ion replaced the OH- ion in the lattice tunnel. SEM observations on the SDF-treated samples showed pronounced multiple precipitation and particles in dentin compared with enamel. SIGNIFICANCE: The solid-state MAS NMR revealed the reaction of fluoride on enamel and dentin and the identification of fluoride compounds. In particular, the formation of FHAp indicates that SDF is effective in reducing the risk of tooth decay.

Effect of casein phosphopeptide amorphous calcium fluoride phosphate and calcium glycerophosphate on incisors with molar-incisor hypomineralization: A cross-over, randomized clinical trial.

BACKGROUND: Within the scope of minimally invasive dentistry, the use of different biocompatible remineralization agents on incisors affected by molar-incisor hypomineralization (MIH) gains importance. OBJECTIVE: To evaluate the effect of casein phosphopeptide amorphous calcium fluoride phosphate (CPP-ACFP) and calcium glycerophosphate (CaGP) in mineral density (MD) of white/creamy and yellow/brown demarcated opacities on incisors affected by MIH by means laser fluorescence (LF). METHODS: As a cross-over, randomized trial, twenty-two children with 167 incisors affected by MIH were recruited and randomly assigned to one of the two different agents and crossed over to other agents with two weeks washout in between. Incisors were examined by using LF at all before and after three months periods. RESULTS: The results of the paired t-tests for determining the period effect between the baseline findings showed significant difference in white/creamy and yellow/brown demarcated opacities of LF values for both groups (p < 0.05). The difference between both groups according to after categorization of 20% increasing in MD in the percent of change before and after application on LF values; was not found statistically significant in white/creamy (p = 0.970) and yellow/brown (p = 0.948) opacities. CONCLUSIONS: The primary outcome was CPP-ACFP and CaGP had a positive effect in decreasing hypomineralization on MIH-affected enamel for three months period.

A New Simple Analytical Method for a Highly Accurate Determination of the Optical Parameters of a Slab from Transmittance Data.

To date, determining with high accuracy the optical parameters (extinction coefficient k and refractive index n) of a slab from the sole transmittance data requires an inverse method based on numerical iteration procedures. In this paper, we propose a new inverse analytical method of extracting (k, n) without numerical iterative processes. The high accuracy of this new inverse method is assessed, and as an application example, the optical parameters of CaF2 and Si substrates are determined in the IR spectral range of 4-8 µm.

Novel rechargeable calcium fluoride dental nanocomposites.

OBJECTIVES: Composite restorations with calcium fluoride nanoparticles (nCaF2) can remineralize tooth structure through F and Ca ion release. However, the persistence of ion release is limited. The objectives for this study were to achieve long-term remineralization by developing a rechargeable nCaF2 nanocomposite and investigating the F and Ca recharge and re-release capabilities. METHODS: Three nCaF2 nanocomposites were formulated: (1) BT-nCaF2:Bisphenol A glycidyl dimethacrylate (BisGMA) and triethylene glycol dimethacrylate (TEGDMA); (2) PE-nCaF2:Pyromellitic glycerol dimethacrylate (PMGDM) and ethoxylated bisphenol A dimethacrylate (EBPADMA); (3) BTM-nCaF2:BisGMA, TEGDMA, and Bis[2-(methacryloyloxy)ethyl] phosphate (Bis-MEP). All formulations contained 15% nCaF2 and 55% glass particles. Initial flexural strength and elastic modulus, F and Ca ion release, recharge and re-release were tested and compared to three commercial fluoride-containing materials. RESULTS: BT and BTM nCaF2 composites were 3-4 times stronger and had elastic modulus 2 times that of resin-modified glass ionomer controls. PE-nCaF2 had comparable strength to RMGIs. All nCaF2 composites had significant F and Ca ion release and ion rechargeability. In F and Ca recharging cycles, PE-nCaF2 had the highest ion recharging capability among nCaF2 groups, followed by BT-nCaF2 and BTM-nCaF2 (p < 0.05). For all recharge cycles, ion release maintained similar levels, demonstrating long-term ion release was possible. Furthermore, after the final recharge cycle, nCaF2 nanocomposites provided continuous ion release for 42 days without further recharge. SIGNIFICANCE: Novel nCaF2 rechargeable nanocomposites exhibited significant F and Ca ion release over multiple recharge cycles, demonstrating continuous long-term ion release. These nanocomposites are promising restorations with lasting remineralization potential.

Mineral Nanomedicine to Enhance the Efficacy of Adjuvant Radiotherapy for Treating Osteosarcoma.

It is vital to remove residual tumor cells after resection to avoid the recurrence and metastasis of osteosarcoma. In this study, a mineral nanomedicine, europium-doped calcium fluoride (CaF2:Eu) nanoparticles (NPs), is developed to enhance the efficacy of adjuvant radiotherapy (i.e., surgical resection followed by radiotherapy) for tumor cell growth and metastasis of osteosarcoma. In vitro studies show that CaF2:Eu NPs (200 µg/mL) exert osteosarcoma cell (143B)-selective toxicity and migration-inhibiting effects at a Eu dopant amount of 2.95 atomic weight percentage. These effects are further enhanced under X-ray irradiation (6 MeV, 4 Gy). Furthermore, in vivo tests show that intraosseous injection of CaF2:Eu NPs and X-ray irradiation have satisfactory therapeutic efficacy in controlling primary tumor size and inhibiting primary tumor metastasis. Overall, our results suggest that CaF2:Eu NPs with their osteosarcoma cell (143B)-selective toxicity and migration-inhibiting effects combined with radiotherapy might be nanomedicines for treating osteosarcoma after tumor resection.