Functional role of inorganic trace elements in dentin apatite tissue-part III: Se, F, Ag, and B.

Dentin hydroxyapatite possesses a unique versatile structure which allows it to undergo ionic substitutions. Trace elements play pivotal roles within the oral cavity, especially in dentin apatite tissue. Therefore, it is critical to explore the role of these elements in dentin apatite structure. The roles of other inorganic elements in dentin apatite were discussed in part I (Mg, Sr, Zn, and Fe) and part II (Cu, Mn, Si, and Li) of these series. In the last part of the review series, the role of selenium, fluorine, silver, and boron in the regulation of dentin apatite structure and function was discussed. We evaluated how these elements affect the overall size, morphology, and crystallinity of dentin apatite crystals. Moreover, we investigated the importance of these elements in regulating the solubility of dentin apatite. An electronic search was performed on the role of these trace elements in dentin apatite from January 2010 to January 2022. The concentration of selenium in teeth has been explored only recently, particularly its incorporation into dentin apatite. Silver nanomaterials inhibit the growth of cariogenic microorganisms as well as arrest the degradation of collagen. Fluorine was found to have important roles in dentin remineralization and dentinal tubule occlusion, making it widely used for hydroxyapatite doping. Boron is critical for mineralized tissues like bone, dentin, and enamel, but its exact role in dentin apatite is unknown. Therefore, understanding the impact of these elements on dentin apatite is potentially transformative, as it may help to fill a significant knowledge gap in teeth mechanics.

The Effects of Calcium, Magnesium, Phosphorus, Fluoride, and Lead on Bone Tissue.

Bones are metabolically active organs. Their reconstruction is crucial for the proper functioning of the skeletal system during bone growth and remodeling, fracture healing, and maintaining calcium-phosphorus homeostasis. The bone metabolism and tissue properties are influenced by trace elements that may act either indirectly through the regulation of macromineral metabolism, or directly by affecting osteoblast and osteoclast proliferation or activity, or through becoming part of the bone mineral matrix. This study analyzes the skeletal impact of macroelements (calcium, magnesium, phosphorus), microelements (fluorine), and heavy metals (lead), and discusses the concentration of each of these elements in the various bone tissues.

Trace elements geochemistry in high-incidence areas of liver-related diseases, northwestern Ethiopia.

This paper reports the results of trace elements geochemistry from Tigray national state, northwestern Ethiopia. The area is part of the Arabian-Nubian Shield, where the dominant exposure is low-grade metamorphic rocks and has a long history of liver-related diseases. The increase in the number of liver-related disease patients of the area has been an environmental health issue of national concern. The aim of the study is to determine the level of trace element concentrations and distributions in water and stream sediments of the area and identify the possible sources in relation to human health. Water, stream sediment and rocks samples (20 water, 20 stream sediments, and 6 rock samples) were collected in March 2011 and analyzed for major and trace element contents using ICP-MS, ICP-OES, ion Chromatography, and XRF methods. Bromine, aluminum, fluorine, arsenic, and nitrate values exceed the WHO maximum acceptable concentration (MAC) for drinking purpose. Bromine ranges from 0.11 to 1.48 mg/l show higher values in all samples, and fluorine ranges from 0.21 to 16.49 mg/l show higher values in 20% of the samples. Other trace elements are aluminum-30%, arsenic-10%, and nitrate (NO3)-10%, and they are examples of elements which have above MAC for drinking water. Selenium deficiency may be the other problematic element in the area for which its deficiency is associated with liver damage and heart muscle disorder. The concentration of cobalt and chromium exceeded world geochemical background value in average shale at most sample stations indicated that these stations were in potential risk.

Condition of mineralized tooth tissue in a population of 15-year-old adolescents living in a region of Ukraine with slightly exceeded fluorine concentration in the water.

INTRODUCTION: Fluorine is a common element in nature; however, the difference between a beneficial dose and a toxic dose for the organisms is small. The main source of fluoride for humans is water in addition to food. OBJECTIVE: The aim of this study was to estimate the degree of severity of pathological changes, namely, caries or fluorosis, in the mineralized tooth tissue of 15-year-old adolescents with respect to their hygienic and nutritional habits, and the content of fluorine in drinking water, soil and plant products. MATERIAL AND METHODS: 100 adolescents aged 15 from schools in Sosnilka, L'viv region, were examined. The condition of mineralized tooth tissue was evaluated by the caries severity, expressed by the mean number D3MFT, caries frequency and value of the SIC index. Fluorine in plant material and soil were determined according to the PN-G-04543:1982 standard, and water according to the PN-EN ISO 10304 - 1: 2009+ AC: 2012 standard. RESULTS: Severity of caries disease expressed by the D3MFT number in the examined group of 15-year-olds was 3.39; in the group of girls - 3.08, and in the group of boys - 3.76. In the examined group, the average number of teeth with fluorosis was 7.59. Value of the SIC index among the examined population of students (n-31) was 6.26: 5.89 (n-18) for girls and 7.31 (n-13) for boys. Fluorine concentration in the water was 0.78 - 1.25(mg·dm-3). In the soil, it also did not vary across the sampled areas and amounted, on average, to 176 mg·dm-3. The biggest fluorine content noted in the dry mass of beetroots was 3.50 (mg F· kg), and the lowest - 3.34 (mg F· kg). CONCLUSIONS: Close to optimal fluorine content lowers caries severity and frequency of fluorosis. Optimal fluorine content in drinking water and food does not require additional diet supplementation.

Vertical distribution of fluorine in farmland soil profiles around phosphorous chemical industry factories.

High concentration of fluorine (F) in agricultural soils has got significant attention considering its impacts on human health, but little information was available about F distribution in farmland soil profiles around phosphorous chemical industry factories. In present study, farmland soil profiles and relevant medium samples were collected from farmlands around a main phosphorous chemical base in southwest China. At 0-100-cm profiles, concentrations of soil total F (Ft, 400.9-1612.0 mg kg-1) and water soluble F (Fw, 3.4-26.0 mg kg-1) decreased with profile depth in industrial areas. Industrial activities enhanced F concentration in soil mainly at 0-40-cm profiles. No disparity for both Ft and Fw distributions in paddy-dry land rotation field and dry land indicates short-term land utilization could not affect the F distribution in soil profiles. Correlation analysis showed soil organic matter and wind direction were important factors influencing the distribution of F in soil profiles. The shutdown of factory and government control of industrial emissions effectively decreased the ambient air F (Fa) concentrations in industrial areas. In where Fa and dustfall F concentrations were high, high soil Ft, Fw, and crop edible part F concentrations were found.

Geochemical valuation and intake of F, As, and Se in coal wastes contaminated areas and their potential impacts on local inhabitants, Shaanxi China.

This study probe the human health risk of fluoride (F), arsenic (As), and selenium (Se) and their daily intake available quantity to human through different sources in different regions of Shaanxi, China. For this purpose, a number of samples, including coal and coal wastes, rocks, soil, and vegetables were collected from south Qinling Mountain stone-like coal (Geo type-I), Binxian-Jurassic (Geo type-II), Hancheng Permo-Carboniferous (Geo type-III), and countryside (Huanglong County) of Shaanxi province. All these samples were analyzed through atomic fluorescence spectroscopy and combustion hydrolysis methods. Results showed that Geo type-I was enriched with As, Se, and F, Geo type-II, III, and the countryside were slightly enriched with As and F and deficient in Se. The average daily intake (ADI) of Se in Geo type-I was 0.005-0.0045, Geo type-II 0.0005-0.0004, Geo type-III 0.0006-0.0005, and countryside 0.0002-0.001 in mg kg-1 day-1 adult-children, respectively, which was lower than the optimum level (0.06-0.075 mg kg-1day-1). ADI of As at Geo type-I was 0.0085-0.0075, Geo type-II 0.004-0.0037, Geo type-III 0.0008, and countryside 0.00022-0.00019 in mg kg-1 day-1 adult-children, respectively, which was above the acceptable range (10-6-10-4). ADI of F at Geo type-I was 0.0047-0.0041, Geo type-II 0.0098-0.0087, Geo type-III 0.002-0.0017 and countryside 0.0015-0.0013 in mg kg-1 day-1 adult-children, respectively. The toxicity level of Se and F at all the regions was lower than the NOAEL and LOAEL, while As was higher at Geo type-II and I. The extreme deficient of Se than the optimum range along with high F could deregulate the normal body growth especially causes bones and joint problems. However, the study found a rare patient with bone and joint disease (maybe Kashin-Beck disease) in the countryside. To find the exact cause of Kashin-Beck disease, the study needs further medical investigation in Se-deficient regions and their association with selenium deficiency and enriched fluoride.

Determination of fluorine in herbs and water samples by molecular absorption spectrometry after preconcentration on nano-TiO2 using ultrasound-assisted dispersive micro solid phase extraction.

This work presents ultrasound-assisted dispersive micro solid phase extraction (USA DMSPE) for preconcentration of fluorine (F) in water and herb samples. TiO2 nanoparticles (NPs) were used as an adsorbent. The determination with slurry sampling was performed via molecular absorption of calcium monofluoride (CaF) at 606.440 nm using a high-resolution continuum source electrothermal absorption spectrometry (HR-CS ET MAS). Several factors influencing the efficiency of the preconcentration technique, such as the amount of TiO2, pH of sample solution, ultrasonication and centrifugation time and TiO2 slurry solution preparation before injection to HR-CS ET MAS, were investigated in detail. The conditions of detection step (wavelength, calcium amount, pyrolysis and molecule-forming temperatures) were also studied. After extraction, adsorbent with the analyte was mixed with 200 µL of H2O to prepare a slurry solution. The concentration limit of detection was 0.13 ng mL-1. The achieved preconcentration factor was 7. The relative standard deviations (RSDs, %) for F in real samples were 3-15%. The accuracy of this method was evaluated by analyses of certified reference materials after spiking: INCT-MPH-2 (Mixed Polish Herbs), INCT-SBF-4 (Soya Bean Flour), ERM-CAO11b (Hard Drinking Water) and TMDA-54.5 (Lake Ontario Water). The measured F contents in reference materials were in satisfactory agreement with the added amounts, and the recoveries were found to be 97-109%. Under the developed extraction conditions, the proposed method has been successfully applied for the determination of F in real water samples (lake, sea, tap water) and herbs.

Hydrochemical characteristics of natural water and selenium-rich water resources in the Northern Daba Mountains, China.

The Northern Daba Mountains (NDM) of Shaanxi Province, China, are a well-known selenium (Se)-rich area, and the area is also known for endemic fluorine (F) and arsenic (As) poisoning. In order to study the hydrochemical characteristics and trace element contents of the natural waters of this region, 62 water samples were collected from Lan'gao area in the NDM. The hydrochemical composition was principally characterized by Ca·Mg-HCO3·SO4. F and As concentrations ranged from 0.01 to 0.67 mg/L and from 0.33 to 6.29 µg/L, respectively, lower than Chinese national standard and international guidelines for drinking water quality. One year of monitoring proved that F and As in natural water were not the sources of the local fluorosis and arseniasis in the NDM. The average Se concentration in fissure water was 5.20 µg/L. The average Se content of river water was 2.82 µg/L, 14 times that of the world's surface level (0.2 µg/L). The Se content in eight samples reached the Chinese national standards for mineral drinking water quality (>10 µg/L). Contrasting the water samples of May, July, and September in 2015 shows that the Se content is relatively stable and the increase of humidity might be beneficial to increase the content of selenium and strontium in water.

Method Development for the Determination of Total Fluorine in Foods by Tandem Inductively Coupled Plasma Mass Spectrometry with a Mass-Shift Strategy.

A method for total F determination in food and tea samples based on a mass-shift strategy using tandem inductively coupled plasma quadrupole mass spectrometry (ICP-MS-MS) was developed. This method consists of four steps: (1) conversion of the hardly ionized F atoms to BaF+ via ICP, (2) use of the first quadrupole (Q1, set at 157) to ensure only the m/z 157 ions (i.e., 138Ba19F+, 157Gd+, and 138Ba18OH+) enter the reaction cell (RC), (3) shifting 138Ba19F+ to a new mass 138Ba19F(14NH3)3+ by reacting with NH3 in RC to avoid the interfering ions (i.e., 157Gd+ and 138Ba18OH+), and (4) passing interference-free 138Ba19F(14NH3)3+ to the second quadrupole (Q2, set at 208) for detection by the MS detector. The mass-shift process of the target F (in ICP and RC) expected to follow the path: F + 138Ba+ → 157BaF+ + 3NH3 → 208BaF(NH3)3+, while the reaction pathway of dominant 157Gd+ in RC proposed to 157Gd+ + NH3 → 157Gd14N1H+ + nNH3 → 157Gd14N1H(14N1H3)n+ (n = 0-5). Under the optimized setting of tandem MS (Q1 → Q2 = 157 → 208) and RC reaction gas flow rate (NH3/He = 10:90, 8.0 mL min-1), the background equivalent concentrations (BECs) and limits of detection (LODs) were 0.021 and 0.022 µg mL-1, respectively. The calibration curve was linear in the range between 0.1 and 10 µg mL-1, with a correlation coefficient of R2 = 0.9999. The results obtained for 14 different food-related standard reference materials (SRMs) were in good agreement with the certified values on a 95% confidence level. The proposed method was then employed to evaluate the F contents of 13 branded tea samples. The total F concentrations ranged from 39.2 to 93.2 µg g-1. The tea infusions contained F between 23.5 and 85.4 µg g-1, with an extraction efficiency of 56.0-91.6%, and the water-soluble F contents of a Pu'er brick tea were 58.7, 21.4, 3.82, and 1.41 µg g-1 for filtrates 1, 2, 3, and 4, respectively.

Effects of Excess Dietary Fluoride on Serum Biochemical Indices, Egg Quality, and Concentrations of Fluoride in Soft Organs, Eggs, and Serum of Laying Hens.

This study was conducted to investigate the effects of excess dietary fluoride (F) on serum biochemical indices, egg quality, and concentrations of F in soft tissues, eggs, and serum of laying hens. Commercial laying hens (n = 576, 51 weeks of age) were randomly allotted to 6 treatments with 6 replicates of 16 birds. The basal diets contained fluorine inclusions at a level of 16 mg/kg, and graded sodium fluoride was added to the basal diet to achieve fluorine inclusions, respectively, at a level of 200, 400, 600, 800, and 1000 mg/kg in the experimental diets. Dietary F levels at 600, 800, and 1000 mg/kg decreased (P < 0.05) albumin height and yolk color, while eggshell strength and eggshell thickness significantly decreased at 800 and 1000 mg/kg, respectively, compared with the control group. Fluoride concentrations in eggshell, albumin, yolk, liver, kidney, ovary, and oviduct responded to dietary F levels positively, and F concentrations in eggshell were the highest. Fluorine concentrations in albumin and yolk increased with the feeding time at the same dietary F levels (P < 0.05). Dietary F level at 400 mg/kg increased serum calcium level and activity of glutamic oxalacetic transaminase (P < 0.05). In conclusion, dietary F levels at 600 mg/kg decreased albumin height and yolk color, while eggshell strength and eggshell thickness significantly decreased at 800 and 1000 mg/kg, respectively. F concentrations in soft tissues, albumin, yolk, and eggshell of layers had a positive correlation with dietary F levels. By disturbing Ca and phosphorus metabolism, dietary F levels affected the formation of eggshell, reducing eggshell strength and eggshell thickness.

Composition, distribution and risk of total fluorine, extractable organofluorine and perfluorinated compounds in Chinese teas.

To explore the residual characteristics of fluorine and perfluorinated compounds (PFCs) in tea, the total fluorine (TF), extractable organofluorine (EOF) and PFCs in 19 Chinese commercial teas of five categories were measured using cyclic neutron activation analysis combined with HPLC-MS/MS. The results showed that fluorine mainly existed as inorganic fluorine in teas, and identified fluorine (∑PFCs quantified as F) only accounted for 0.023-0.41% of EOF, indicating that most EOF in tea were still unknown. 50-99% of ∑PFCs in tea were short-chain (C⩽6), while perfluorooctanoic acid was the typical PFCs residual species. Less fermented teas contained significantly higher PFCs (mean, 20ng/g) than more fermented teas (3.0ng/g, p<0.01), suggesting that microbe may degrade PFCs during fermentation. The highest TF content was discovered in Hubei brick tea, which poses risk of fluorosis, whereas PFCs residues in teas caused no immediate harm.

Measurements of fluorine in contemporary urban Canadians: a comparison of the levels found in human bone using in vivo and ex vivo neutron activation analysis.

Non-invasive in vivo neutron activation analysis (NAA) was used to measure the fluorine concentration in 35 people in Hamilton, Ontario, Canada. Measurement and precision data of this second generation NAA system were determined in 2013, and the results were compared with the performance of a first generation system used in a pilot study of 33 participants from the Hamilton area in 2008. Improvements in precision in line with those predicted by phantom studies were observed, but the use of fewer technicians during measurement seemed adversely to affect performance. We compared the levels of fluorine observed in people between the two studies and found them to be comparable. The average fluorine concentration in bone was found to be 3 ± 0.3 mg and 3.5 ± 0.4 mg F/g Ca for 2013 and 2008 measurements respectively. Ten people were measured in both studies; the observed average change in bone fluorine in this subgroup was consistent with that predicted by the observation of the relationship between bone fluorine and age in the wider group. In addition, we observed differences in the relationship between bone fluorine level and age between men and women, which may be attributable either to sex or gender differences. The rate of increase in fluorine content for men was found to be 0.096 ± 0.022 mg F/g Ca per year while the rate of increase for women was found to be slightly less than half that of men, 0.041 ± 0.017 mg F/g Ca per year. A discontinuity in the rate of increase in fluorine content with age was observed in women at around age 50. Bone fluorine content was significantly lower ([Formula: see text]) in women age 50 to 59 than in women age 40 to 49, which we suggest may be attributable to bone metabolism changes associated with menopause. We also observed increased fluorine levels in tea drinkers as compared to non-tea drinkers, suggesting tea may be a significant source of exposure in Canada. The rate of increase in fluorine content of the tea drinkers and the non-tea drinkers were found to be 0.127 (± 0.029) and 0.050 (± 0.009) mg F/g Ca per year respectively. Finally, we also obtained twelve bone samples from cadavers' skulls. Neutron activation analysis was used to determine the fluorine levels in these ex vivo samples. The rate of increase of fluorine content versus age for in vivo and ex vivo measurements were found to be 0.078 ± 0.014 and 0.078 ± 0.050 mg F/g Ca per year respectively. Excellent agreement was found between the fluorine levels determined in vivo and ex vivo using the two separate systems, providing confidence in the fluorine concentration data being measured in vivo.

The role of glass ionomer cement on the remineralization of infected dentin: an in vivo study.

PURPOSE: This study's purpose was to investigate the effect of a glass ionomer cement as a liner over infected unexcavated dentin after 60 days and at 10 to 15 months. METHODS: Forty-five permanent molars with deep carious lesions were selected. Fragments of carious dentin were removed prior to lining the cavity (baseline sample) with glass ionomer cement (G1) or an inert wax material (G2). Cavities were restored with composite resin and reopened 60 days later, when other fragments were removed (60-day sample). The dentin morphology (scanning electron microscopy) and mineral content of calcium, phosphorus, and fluorine were assessed. During the follow-up periods (60 days and 10 to 15 months), restorations were evaluated and standardized radiographs were taken. A postprocessing routine was used to identify changes in the radiographic density between periods. RESULTS: After 60 days, the dentin exhibited a better organization, fewer bacteria, and signs of remineralization. The weight percents of calcium and phosphorus were higher 60 days after the cavity sealing, regardless of the group. Higher gray levels of carious and sound dentin were seen on the 10- to 15-month radiographs, irrespective of the group. The success rates of G1 and G2 were 89 percent and 88 percent, respectively. CONCLUSIONS: The lining material isn't fundamental for caries arrestment. Early (60-day) and late (10 to 15 months) dentin changes occurred, indicating the remineralization of dentin carious tissue.

Mineralization behavior of fluorine in perfluorooctanesulfonate (PFOS) during thermal treatment of lime-conditioned sludge.

The fate and transport of the fluorine in perfluorooctanesulfonate (PFOS) during the thermal treatment of lime-conditioned sludge were observed using both qualitative and quantitative X-ray diffraction techniques. Two main fluorine mineralization mechanisms leading to the substantial formation of CaF2 and Ca5(PO4)3F phases were observed. They had a close relationship with the thermal treatment condition and the PFOS content of the sludge. At low temperatures (300-600 °C), CaF2 dominated in the product and increases in treatment time and temperature generally enhanced the fluorine transformation. However, at higher temperatures (700-900 °C), increases in treatment time and temperature had a negative effect on the overall efficiency of the fluorine crystallization. The results suggest that in the high temperature environment there were greater losses of gaseous products such as HF and SiF4 in the transformation of CaF2 to Ca5(PO4)3F, the hydrolysis of CaF2, and the reaction with SiO2. The quantitative analysis also showed that when treating sludge with low PFOS content at high temperatures, the formation of Ca5(PO4)3F may be the primary mechanism for the mineralization of the fluorine in PFOS. The overall results clearly indicate the variations in the fate and transport of fluorine in PFOS when the sludge is subject to different PFOS contents and treatment types, such as heat drying or incineration.

Atmospheric emissions of F, As, Se, Hg, and Sb from coal-fired power and heat generation in China.

Coal is one of the major energy resources in China, with nearly half of produced Chinese coal used for power and heat generation. The large use of coal for power and heat generation in China may result in significant atmospheric emissions of toxic volatile trace elements (i.e. F, As, Se, Hg, and Sb). For the purpose of estimating the atmospheric emissions from coal-fired power and heat generation in China, a simple method based on coal consumption, concentration and emission factor of trace element was adopted to calculate the gaseous emissions of elements F, As, Se, Hg, and Sb. Results indicate that about 162161, 236, 637, 172, and 33 t F, As, Se, Hg, and Sb, respectively, were introduced into atmosphere from coal combustion by power and heat generation in China in 2009. The atmospheric emissions of F, As, Se, Hg, and Sb by power and heat generation increased from 2005 to 2009 with increasing coal consumptions.

Determination of fluorine in tea using high-resolution molecular absorption spectrometry with electrothermal vaporization of the calcium mono-fluoride CaF.

High-resolution continuum source molecular absorption of the calcium mono-fluoride molecule CaF in a graphite furnace has been used to determine fluorine in tea after acid digestion, alkaline solubilization and preparation of a conventional aqueous infusion. The strongest absorption 'line' of the CaF molecule is at 606.440 nm, which is part of the rotational fine structure of the X(2)Σ(+)-A(2)Π electronic transition; it has a bond dissociation energy of 529 kJ mol(-1), which is comparable with other molecules used for fluorine determination. One advantage of using Ca as the molecule-forming reagent is that spectral interferences are extremely unlikely in the spectral range of its strongest absorption. Another advantage is that Ca acts both as molecule forming reagent and chemical modifier, so that no other reagent has to be added, making the method very simple. The only disadvantage is that Ca has a somewhat negative influence on the graphite tube lifetime. The limit of detection was found to be 0.16 mg L(-1) F, corresponding to 1.6 ng F absolute, and the calibration curve was linear in the range between 0.5 and 25 mg L(-1) with a correlation coefficient of R=0.9994. The results obtained for a certified tea reference material were in agreement with the certified value on a 95% confidence level. There was also no difference between the results obtained after an acid digestion and an alkaline solubilization for 10 tea samples, based on a paired t-test. The values found in the 10 samples ranged between 42 µg g(-1) and 87 µg g(-1) F; the tea infusions contained between 21 µg g(-1) and 56 µg g(-1) F, with an extraction rate between 48% and 74%.

Potable water recovery from As, U, and F contaminated ground waters by direct contact membrane distillation process.

In this study, the feasibility of the direct contact membrane distillation (DCMD) process to recover arsenic, uranium and fluoride contaminated saline ground waters was investigated. Two types of membranes (polypropylene, PP; and polytetrafluoroethylene, PTFE) were tested to compare the permeate production rates and contaminant removal efficiencies. Several experiments were conducted to study the effect of salts, arsenic, fluoride and uranium concentrations (synthetic brackish water with salts: 1000-10,000 ppm; arsenic and uranium: 10-400 ppb; fluoride: 1-30 ppm) on the desalination efficiency. The effect of process variables such as feed flow rate, feed temperature and pore size was studied. The experimental results proved that the DCMD process is able to achieve over 99% rejection of the salts, arsenic, fluoride and uranium contaminants and produced a high quality permeate suitable for many beneficial uses. The ability to utilize the low grade heat sources makes the DCMD process a viable option to recover potable water from a variety of impaired ground waters.

Fluoride in chilies from southwestern china.

The purpose of this research is to investigate the fluoride contents in the chilies from southwest China and other countries in order to calculate the difference in fluoride levels in the fresh chilies. The standard method in China for analysis of fluoride in food (GB/T 5009.18-2003) was applied to determinate the fluoride content in chilies. By determining the fluoride content in 176 fresh chili samples from 77 counties in southwest China and 31 chili samples from other countries, the research not only aims to find the regularity of fluoride distribution in fresh chili, but also to determine the origin of fluoride in fresh chili in China compared with the foreign samples. The geometric mean of fluoride content in the fresh chili was 8.9 mg kg(-1) (dry weight, 176 samples, confidence level: 95%). According to the study on the contents of fluoride in fresh chili, it seems that the fluoride content standard for vegetables in GB2762-2005 in China is inappropriate for chili, and 24.7 mg kg(-1)(dry weight) and 5.2 mg kg(-1) (fresh weight) in recommend as the fluoride contaminated discrimination values for fresh chili.

[Mineral elements content in smoked fish]. / Zawartosc skladników mineralnych w rybach wedzonych.

The content of macroelements (phosphorus, calcium, magnesium potassium and sodium) and microelements (copper, zinc, iron, manganese, chromium, selenium, fluorine and iodine) in the following smoked fish: sprat, mackerel, salmon, smoked herring and trout were determined. The most of calcium, phosphorus, iron, zinc, copper and manganese contain smoked sprat. The amount of calcium in fish's remaining species is considerably lower, and phosphorus approximated to his content in sprat. The selenium and the fluorine occur on approximate level in all examined fish, however the amount of iodine was diverse but high. Smoked salmon and trout contain the most iodine, and the least smoked herring, sprat and mackerel. Contribution of fish in the recommended daily intake for mineral elements was estimated.

Rebonding of orthodontic brackets. Part II, an XPS and SEM study.

OBJECTIVE: The hypothesis of this two-part study is that adhesive systems for bonding orthodontic brackets (ie, two self-etch primers [Transbond and M-Bond] and a conventional phosphoric acid etch [Rely-a-Bond]) would show a difference with respect to rebonded enamel surface morphology and chemical composition. MATERIALS AND METHODS: This study examined the enamel surface before and after debonding with scanning electron microscopy and the enamel surface chemical composition for the elements Ca, P, O, F, Si, and C using x-ray photoelectron spectroscopy. RESULTS: The etching of the two self-etch groups is less aggressive and less uniform than that of phosphoric acid. The change in the concentration of C indicated that the separation of the bracket from the enamel surface is at the resin-enamel interface for the phosphoric acid-etched adhesive and a mixed mode involving the enamel-resin-bracket interfaces for the self-etching systems. F release appears to occur for Transbond but not for M-Bond. CONCLUSIONS: The results confirm the original hypothesis that differences in adhesive systems are manifested in less aggressive etches and less adhesive left on the enamel surface for the self-etching adhesive systems.