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Improvement of the mechanical, tribological and antibacterial properties of glass ionomer cements by fluorinated graphene.
Sun, L, Yan, Z, Duan, Y, Zhang, J, Liu, B
Dental materials : official publication of the Academy of Dental Materials. 2018;(6):e115-e127
Abstract
OBJECTIVE The aim of this study was to improve the mechanical properties, wear resistance and antibacterial properties of conventional glass ionomer cements (GICs) by fluorinated graphene (FG), under the premise of not influencing their solubility and fluoride ion releasing property. MATERIALS AND METHODS FG with bright white color was prepared using graphene oxide by a hydrothermal reaction. Experimental modified GICs was prepared by adding FG to the traditional GICs powder with four different weight ratios (0.5wt%, 1wt%, 2wt% and 4wt%) using mechanical blending. Compressive and flexural strength of each experimental and control group materials were investigated using a universal testing machine. The Vickers microhardness of all the specimens was measured by a Vicker microhardness tester. For tribological properties of the composites, specimens of each group were investigated by high-speed reciprocating friction tester. Fluoride ion releasing was measured by fluoride ion selective electrode methods. The antibacterial effect of GICs/FG composites on selected bacteria (Staphylococci aureus and Streptococcus mutans) was tested with pellicle sticking method. RESULTS The prepared GICs/FG composites with white color were successfully fabricated. Increase of Vickers microhardness and compressive strength and decrease of friction coefficient of the GICs/FG composites were achieved compared to unreinforced materials. The colony count against S. aureus and S. mutans decreased with the increase of the content of FG. And the antibacterial rate of S. mutans can be up to 85.27% when the FG content was 4wt%. Additionally, fluoride ion releasing property and solubility did not show significant differences between unreinforced and FG reinforced GICs. SIGNIFICANCE Adding FG to traditional GICs could not only improve mechanical and tribological properties of the composites, but also improve their antibacterial properties. In addition, the GICs/FG composites had no negative effect on the color, solubility and fluoride ion releasing properties, which will open up new roads for the application of dental materials.
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Silver nanoparticle modulates gene expressions, glyoxalase system and oxidative stress markers in fluoride stressed Cajanus cajan L.
Yadu, B, Chandrakar, V, Korram, J, Satnami, ML, Kumar, M, S, K
Journal of hazardous materials. 2018;:44-52
Abstract
Application of engineered nanomaterials has increased these days due to their beneficial impacts on several sectors of the economy, including agriculture. Silver nanoparticles (AgNP) are commonly used to improve rate of seed germination, and growth and development of plants. The present study was aimed to monitor the role of engineered AgNP (non-dialysed) in the amelioration of fluoride (F)-induced oxidative injuries in Cajanus cajan L. Experimental results revealed that F-exposure inhibited growth and membrane stability index, while were enhanced with the augmentation of AgNP. The results also demonstrated that F treatment enhanced the accumulations of reactive oxygen species, malondialdehyde and oxidized glutathione, gene expression of NADPH oxidase, and activity of lipoxygenase, but were decreased by the addition of AgNP. The results indicated that exogenous application of AgNP provided tolerance against F-toxicity via enhancing the levels of proline, total and reduced glutathione, glyoxalase I and II activities, and expression of pyrroline-5-carboxylate synthetase gene. Conducted study uniquely suggested potential role of AgNP in the remediation of F-toxicity, at least in the Cajanus cajan L. radicles. Further research would be intended to unravel the molecular mechanism(s) involved precisely in the AgNP mediated alleviation of F-toxicity.
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A review of emerging adsorbents and current demand for defluoridation of water: Bright future in water sustainability.
Yadav, KK, Gupta, N, Kumar, V, Khan, SA, Kumar, A
Environment international. 2018;:80-108
Abstract
Fluoride contamination of groundwater is a serious problem in several countries of the world because of the intake of excessive fluoride caused by the drinking of the contaminated groundwater. Geological and anthropogenic factors are responsible for the contamination of groundwater with fluoride. Excess amounts of fluoride in potable water may cause irreversible demineralisation of bone and tooth tissues, a condition called fluorosis, and long-term damage to the brain, liver, thyroid, and kidney. There has long been a need for fluoride removal from potable water to make it safe for human use. From among several defluoridation technologies, adsorption is the technology most commonly used due to its cost-effectiveness, ease of operation, and simple physical process. In this paper, the adsorption capacities and fluoride removal efficiencies of different types of adsorbents are compiled from relevant published data available in the literature and represented graphically. The most promising adsorbents tested so far from each category of adsorbents are also highlighted. There is still a need to discover the actual feasibility of usage of adsorbents in the field on a commercial scale and to define the reusability of adsorbents to reduce cost and the waste produced from the adsorption process. The present paper reviews the currently available methods and emerging approaches for defluoridation of water.
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Evaluation of the Effects of Fluoride Prophylactic Agents on Mechanical Properties of Nickel Titanium Wires using Scanning Electron Microscope.
Gupta, AK, Shukla, G, Sharma, P, Gupta, AK, Kumar, A, Gupta, D
The journal of contemporary dental practice. 2018;(3):283-286
Abstract
INTRODUCTION Orthodontic treatment these days is increasing in demand, and therefore, it is relatively imperative for the orthodontist to prescribe the use of fluoride-containing products, such as mouthwashes and gels, to help prevent dental caries and maintain healthy oral health. The aim of the study was to assess and evaluate the effects of fluoride prophylactic agents on mechanical properties of nickel titanium (NiTi) wires during orthodontic treatment using scanning electron microscope (SEM). MATERIALS AND METHODS We used the commercially available round preformed NiTi orthodontic archwire (3M company) and three different mouthwash solutions, i.e., Phos-Flur gel (1.1% sodium acidulated phosphate fluoride, APF, 0.5% w/v fluoride, pH = 5.1; Colgate Oral Pharmaceuticals) and Prevident 5000 (1.1% sodium fluoride neutral agent, 0.5% w/v fluoride, pH = 7; Colgate Oral Pharmaceuticals). All the specimens were subjected to a three-point bending test on a universal testing machine. To observe the surface morphological changes, one wire from each group was randomly selected and observed under a SEM. RESULTS It was observed that there was not much difference in the values of both modulus of elasticity and yield strength obtained after loading of stress on the wires in all the three experimental conditions. A significant difference in both modulus of elasticity and yield strength was observed during unloading of stress. Further, when the surface characteristics were observed for all the specimens using SEM images, it was observed that NiTi wires treated with Phos-Flur showed large surface defects which appeared as round, pitted areas depicting corrosion, numerous white inclusions, and overall damaged surface structure of the wire as compared with the control. CONCLUSION Thus, fluoridated mouthwashes are essential to maintain good oral hygiene and decrease instance of caries in patients undergoing orthodontic treatment. The prophylactic usage of topical fluoride agents on NiTi wire seems to diminish the mechanical properties of the orthodontic wire that could significantly affect future treatment outcomes. CLINICAL SIGNIFICANCE It has been proved that fluoride mouthwashes/gels do affect the structural surface qualities and strength of wires used during the orthodontic treatment irrespective of the composition of the wires. Therefore, it is the responsibility of the clinician to prescribe these prophylactic agents carefully while keeping in mind their pH so that the overall result of the treatment may not be hampered and delayed due to change in properties of the wires used.
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Efficacy of fluorides and CPP-ACP vs fluorides monotherapy on early caries lesions: A systematic review and meta-analysis.
Tao, S, Zhu, Y, Yuan, H, Tao, S, Cheng, Y, Li, J, He, L
PloS one. 2018;(4):e0196660
Abstract
The study aimed to evaluate the efficacy of the combination of CPP-ACP and fluorides compared with fluorides monotherapy on patients with early caries lesions. The Medline, Embase and Cochrane databases up to August 2017 were scanned, with no restrictions. Studies satisfied the guideline of randomised controlled trials (RCTs), the patients with early caries lesions and data considering the efficacy of fluorides and CPP-ACP versus fluorides alone were selected. There was no language restriction during the literature search process, however, only papers in English or Chinese were included during the selection process. Outcome variables include laser fluorescence, quantitative light-induced fluorescence, lesion area and visual inspection scores. Mean differences were calculated during the data extraction process. Ten studies including 559 patients were selected in the meta-analysis. Fluorides combined with CPP-ACP achieved the same efficacy for early caries lesions on smooth surfaces compared with fluorides monotherapy (mean difference: -13.90, 95% confidence interval: [-39.25, 11.46], P = 0.28), and the combination treatment showed significantly better efficacy than fluorides monotherapy for occlusal early caries lesions (mean difference: -21.02, 95% confidence interval: [-27.94, -14.10], P<0.01). However, further well-designed studies are still needed.
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Potential Co-exposure to Arsenic and Fluoride and Biomonitoring Equivalents for Mexican Children.
Limón-Pacheco, JH, Jiménez-Córdova, MI, Cárdenas-González, M, Sánchez Retana, IM, Gonsebatt, ME, Del Razo, LM
Annals of global health. 2018;(2):257-273
Abstract
BACKGROUND Mexico is included in the list of countries with concurrent arsenic and fluoride contamination in drinking water. Most of the studies have been carried out in the adult population and very few in the child population. Urinary arsenic and urinary fluoride levels have been accepted as good biomarkers of exposure dose. The Biomonitoring Equivalents (BE) values are useful tools for health assessment using human biomonitoring data in relation to the exposure guidance values, but BE information for children is limited. METHODS We conducted a systematic review of the reported levels of arsenic and fluoride in drinking water, urinary quantification of speciated arsenic (inorganic arsenic and its methylated metabolites), and urinary fluoride levels in child populations. For BE values, urinary arsenic and fluoride concentrations reported in Mexican child populations were revised discussing the influence of factors such as diet, use of dental products, sex, and metabolism. RESULTS Approximately 0.5 and 6 million Mexican children up to 14 years of age drink water with arsenic levels over 10 μg/L and fluoride over 1.5 mg/L, respectively. Moreover, 40% of localities with arsenic levels higher than 10 μg/L also present concurrent fluoride exposure higher than 1.5 mgF/L. BE values based in urinary arsenic of 15 μg/L and urinary fluoride of 1.2 mg/L for the environmentally exposed child population are suggested. CONCLUSIONS An actual risk map of Mexican children exposed to high levels of arsenic, fluoride, and both arsenic and fluoride in drinking water was generated. Mexican normativity for maximum contaminant level for arsenic and fluoride in drinking water should be adjusted and enforced to preserve health. BE should be used in child populations to investigate exposure.
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Ossification of posterior longitudinal ligament and fluorosis.
Reddy, KVS, Mudumba, VS, Tokala, IM, Reddy, DR
Neurology India. 2018;(5):1394-1399
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Abstract
OBJECTIVE Ossification of posterior longitudinal ligament (OPLL) is a progressive disease that causes spinal canal compromise and serious neurological sequelae in advanced cases. The incidence of OPLL in the Asiatic population is 2%-3%, but the incidence is more in the background of fluorosis. Our aim was to study the association of OPLL with fluorosis by comparing urine fluoride levels and to study the types of OPLL. MATERIALS AND METHODS Thirty consecutive patients with OPLL, observed on cervical skiagram, and confirmed by the computed tomography (CT) of the cervical spine, underwent a 24-h urine fluoride level assessment by the ion-selective electrode method. Due consent of all the patients was obtained and the data was collected. Thirty patients with a normal cervical radiograph were taken as a control group and their 24-h urine fluoride levels were compared with the test group. The 24-h urine fluoride level above 1.6 mg/L was taken as the diagnostic parameter of fluorosis. Imaging analysis of the study group focused on the subtype of OPLL, the mass occupying ratio, the sagittal cervical angle, the signs of dural penetration, and the spinal levels involved. Urinary fluoride levels were correlated with the presence of OPLL and different types of OPLL. RESULTS Of the 30 patients with OPLL, 25 were males and 5 were females. The most common presentation was myelopathy. Continuous type of OPLL was seen in 11 (36.6%), segmental in 8 (26.6%), focal in 5 (16.6%), and mixed variant in 6 (20%) patients. 24-h urinary fluoride levels ranged from 0.26 mg/L to 12.2 mg/L. 18 (60%) of the patients in the study group were found to have urinary fluoride levels above 1.6 mg/L and only 1 patient (4%) of the control group had the urine fluoride level >1.6 mg/L. This difference was statistically significant. Patients with continuous and mixed types of OPLL had a higher mean urine fluoride level than those with a segmental and focal type of OPLL. The continuous variant of OPLL had a statistically significant occupancy ratio when compared to the other three variants, and the high mass occupancy ratio of the OPLL was directly associated with the presence of dural penetration. CONCLUSION Fluorosis is associated with a higher incidence of OPLL. Higher urinary fluoride levels correlate with the severe forms of OPLL.
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The In Situ Effect of Titanium Tetrafluoride Gel on Erosion/Abrasion Progression in Human Dentin.
Mantilla, TF, Turssi, CP, Ramos-Oliveira, TM, Silva, CVD, Suzuki, LC, Freitas, PM
Brazilian dental journal. 2017;(3):337-345
Abstract
Erosion incidence is increasing and its control is still a challenge in clinical practice. This study evaluated 4% TiF4-gel effects on eroded human dentin subjected to in situ erosive/abrasive episodes. Seventy-two previously eroded dentin slabs (0.05 M citric acid, pH 2.3, 20 min) were allocated to 6 groups (n=12) according to the treatment to be performed during the in situ phase and number of erosive/abrasive cycles, as follows: 4% TiF4-gel applied once (TiF41), twice (TiF42) or three times (TiF43) followed by 1, 2 and 3 erosive/abrasive cycles, respectively. Gel was applied before the beginning of the next cycle. Control groups were subjected to 1 (C1), 2 (C2) and 3 (C3) erosive/abrasive cycles only. A seventh group (n=12) comprised in vitro uneroded samples (UN) subjected to 3 erosive/abrasive cycles. Each cycle corresponded to 2 days of erosive (citric acid 0.5%, pH 2.6, 6x/day) and abrasive (electric toothbrush, 10 s/sample, 1 x/day) challenges. Samples were evaluated under profilometry and environmental scanning electron microscopy (ESEM). Atomic force microscopy images (AFM) were also made (n=3). Repeated measures 2-way ANOVA and Tukey test (p<0.001) showed that TiF42, which did not differ from TiF41 and TiF43, revealed a significant reduction in surface loss compared to all control groups. TiF41 and TiF43 showed no significant difference from C1, but both groups demonstrated significantly smaller surface loss than C2 and C3. ESEM and AFM micrographs suggested alterations on treated surfaces compared to samples from control groups, showing reduced diameters of dentinal tubules lumens. Therefore, TiF4 was able to reduce the progression of erosive/abrasive lesions.
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Anticaries Potential of a Sodium Monofluorophosphate Dentifrice Containing Calcium Sodium Phosphosilicate: Exploratory in situ Randomized Trial.
Parkinson, CR, Siddiqi, M, Mason, S, Lippert, F, Hara, AT, Zero, DT
Caries research. 2017;(2):170-178
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Abstract
Calcium sodium phosphosilicate (CSPS) is a bioactive glass material that alleviates dentin hypersensitivity and is postulated to confer remineralization of caries lesions. This single-centre, randomized, single (investigator)-blind, placebo-controlled, crossover, in situ study explored whether the addition of 5% CSPS to a nonaqueous fluoride (F) such as sodium monofluorophosphate (SMFP)-containing dentifrice affects its cariostatic ability. Seventy-seven subjects wore 4 gauze-covered enamel specimens with preformed lesions (2 surface-softened and 2 subsurface) placed buccally on their mandibular bilateral dentures for up to 4 weeks. Subjects brushed twice daily with 1 of the 5 study dentifrices: 927 ppm F/5% CSPS, 927 ppm F/0% CSPS, 250 ppm F/0% CSPS, 0 ppm F/5% CSPS, or 0 ppm F/0% CSPS. Specimens were retrieved after either 21 (surface-softened lesions; analyzed by Knoop surface microhardness [SMH]) or 28 days (subsurface lesions; analyzed by transverse microradiography). The enamel fluoride uptake was determined for all specimens using a microbiopsy technique. The concentrations of fluoride and calcium in gauze-retrieved plaque were also evaluated. Higher dentifrice fluoride concentrations led to greater remineralization and fluoridation of both lesion types and increased plaque fluoride concentrations. CSPS did not improve the cariostatic properties of SMFP; there were no statistically significant differences between 927 ppm F/5% CSPS and 927 ppm F/0% CSPS in percent SMH recovery (p = 0.6788), change in integrated mineral loss (p = 0.5908), or lesion depth (p = 0.6622). Likewise, 0 ppm F/5% CSPS did not provide any benefits in comparison to 0 ppm F/0% CSPS. In conclusion, CSPS does not negatively impact nor does it improve the ability of an SMFP dentifrice to affect remineralization of caries lesions.
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Impact of biannual treatment with fluoride varnish on tooth-surface-level caries progression in children aged 1-3 years.
Anderson, M, Dahllöf, G, Soares, FC, Grindefjord, M
Journal of dentistry. 2017;:83-88
Abstract
OBJECTIVE This study describes caries progression at tooth-surface level in children from 1 to 3 years of age and the impact of biannual treatment with fluoride varnish. METHODS Children who participated in a cluster-randomized controlled trial and had shown signs of dental caries were included in this study (n=801). International Caries Detection and Assessment System (ICDAS) was used to classify dental caries. The present study compared children receiving a standard yearly intervention to children receiving the same standard preventive intervention supplemented with an application of fluoride varnish every half year. RESULTS The maxillary incisors were the first teeth to develop cavitation (ICDAS 3-6) and also mostly affected. Further analyses focusing on maxillary incisors buccal surfaces showed that sound surfaces had least progression and that progression to extensive decay was more common in teeth that had exhibited moderate decay. A summarizing progression index (PI) was calculated for the buccal surfaces of the maxillary incisors. Between 1 and 2 years of age PI was 26% and between 2 and 3 years of age PI was 21%. The progression on buccal incisors and on occlusal first primary molars did not differ between intervention groups (p≤0,05). CONCLUSION No impact on caries progression for biannual treatment with fluoride varnish was found. CLINICAL SIGNIFICANCE Using fluoride varnish as a complement to standard intervention in toddlers did not add in the prevention of dental caries or its progression. The education of parents in the use fluoride toothpaste as they start brushing the teeth of their children is essential.