Potential toxicity.
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Aluminum Compounds↗
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Results for “Calcium Compounds”
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Weakened anterior roots--intraradicular rehabilitation.
This paper highlights the fact that many anterior teeth requiring restoration are severely weakened having wide, flared canal spaces, and thin dentinal walls that are prone to fracture. Traditionally these teeth have been restored using metal posts and are often unsuccessful because of lack of retention or root fracture. This paper describes how mineral trioxide aggregate (MTA) can be used to form an immediate apical seal rather than waiting months for apexification. Weakened roots can be reinforced using dentine bonding agents and composite resin and if insufficient coronal tooth structure is present a quartz-fibre post can be placed to retain a composite core.
Aluminum Compounds↗
Calcium hydroxide lime--a new carbon dioxide absorbent: a rationale for judicious use of different absorbents.
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Absorption↗
A comparison of MTA, Super-EBA, composite and amalgam as root-end filling materials using a bacterial microleakage model.
AIM: The aim of this study was to compare traditional and newly developed root-end filling materials for resistance to bacterial microleakage. METHODOLOGY: Sixty extracted single-rooted teeth were randomly divided into five groups for root-end filling with mineral trioxide aggregate, Super-EBA, TPH composite resin with ProBond dentine bonding agent, Dispersalloy amalgam with and without ProBond, and positive and negative control groups. Root canals were instrumented using the step-back technique and simulated root-end resections performed. Root-end filling materials were placed in 3 mm ultrasonic retropreparations. Nail varnish was applied to all external root surfaces to the level of the resected root ends to prevent lateral microleakage. Samples were sterilized in an ethylene oxide sterilizer for 12 h. Using a newly designed model system, the apical 3-4 mm of the roots were immersed in BHI culture medium with phenol red indicator within culture chambers. The coronal access of each specimen was inoculated every 48 h with a suspension of Streptococcus salivarius. Culture media were observed every 24 h for colour change indicating bacterial contamination. Media demonstrating colour change were plated for S. salivarius. Samples were observed for 12 weeks. RESULTS: At 4 weeks 10% of specimens from each experimental group had evidence of leakage. At 8 weeks 20% of specimens filled with amalgam without dentine bonding agent, Super-EBA and MTA had evidence of leakage. At 12 weeks minor differences between materials were noted. CONCLUSIONS: Under the conditions of the study, despite some variations, there were no statistically significant differences in rate of microleakage among the five groups tested at either 4, 8 or 12 weeks.
Aluminum Compounds↗
The standardized-taper root canal preparation--Part 4. GT file technique in large root canals with large apical diameters.
AIM: To describe the GT file shaping steps required to create apical resistance in the presence of a wide root apex. SUMMARY: Canals are occasionally encountered with apices wider than 0.25 mm. These can be some of the most difficult to manage with conventional instruments, and overfills are common. Shaping such canals with GT files requires a paradigm shift of thinking, extending tapered files through the apex to create linear resistance in the apical few mm of the canal. GT standard and accessory files allow canals with apices up to around 0.7 mm to be prepared for tapered gutta percha cone-fit. Apices larger than this should be considered too large for further shaping, and repaired with MTA before filling. KEY LEARNING POINTS: Tapered apical preparations offer optimal resistance form for obturation. Tapered apical preparations can be prepared in most roots with wide apices by extending GT files and GT accessory files to or through the apex. Apices wider than 0.7 mm should be repaired with MTA prior to filling.
Aluminum Compounds↗
The effects of two different decalcification procedures on size and structure of embryonic epithelial tissue in objects prepared for light microscopy.
Electrolytic decalcification is a very fast and effective method for removing calcium compounds from bones with minimum damage to tissues. Changes of dimension of tissues in histological sections prepared from specimens decalcified by immersion in a formic acid solution and sections prepared from specimens treated in an electrolytic decalcifier were studied. Heads of mouse foetuses were cut in half, decalcified by one of the above-mentioned methods and embedded in histowax. Dimensional changes of skin, tongue and nasal epithelia in histological sections were evaluated by t-test. Significant shrinking and other unwanted effects of decalcification, such as acidophilia of nuclei, were found in objects decalcified by both methods. No significant differences in the effects of the two methods on tissue dimensions were demonstrated. It is concluded that both decalcification methods are equivalent from the qualitative point of view.
Animals↗
Calcium-enriched bread for treatment of uremic hyperphosphatemia.
OBJECTIVE: To assess phosphate-binding efficacy of a new food product, bread with unusually high calcium content (Ca-bread). DESIGN AND SETTING: A randomized parallel group trial in the university hospital outpatient dialysis unit. PATIENTS: Fifty-three randomly selected uremic patients who met the following inclusion criteria: (1) required maintenance hemodialysis treatment, (2) were not to receive vitamin D throughout the study, (3) were nondiabetic, and (4) were diagnosed with hyperphosphatemia. INTERVENTION: Fifty-three patients were randomized into 2 groups: control group (n = 26), which received calcium acetate as a phosphate binder throughout the study, and Ca-bread group (n = 27), which, after a 2-week washout period, received Ca-bread containing 2.5% of elemental calcium (by weight), which served as a phosphate binder. Bread was made using wheat flour, calcium carbonate, and fermented buttermilk. The amount of elemental calcium used as a phosphate binder was similar in both groups. Observation of both groups lasted 14 weeks. RESULTS: Mean serum phosphate concentration at randomization was 2.11 +/- 0.14 mmol/L in the control group and 2.20 +/- 0.13 mmol/L in the Ca-bread group. Mean serum calcium concentration at randomization was 2.12 +/- 0.21 mmol/L in the control group and 2.14 +/- 0.11 mmol/L in the Ca-bread group. The Ca-bread group patients' predialysis phosphate concentration decreased to a mean of 1.67 +/- 0.18 mmol/L (P <.05), and their mean calcium concentration increased to 2.27 +/- 0.11 mmol/L (P = NS). In the control group, neither value changed significantly from the original readings. After the hemodialysis session, the mean serum calcium concentration in the control group and the Ca-bread group increased by 7.5% and 7.9%, respectively (P = NS). Mean phosphate concentration simultaneously decreased to nearly 1/2 its original predialysis value in both groups. Ca-bread group patients saw a decrease in the mean phosphate concentration (from predialysis to postdialysis values) that was 13.8% greater than that of the control group (P = NS). CONCLUSION: A new form of calcium-containing phosphate binder was developed: Ca-bread with an elemental calcium content of 2.5%. Ca-bread allows for effective amelioration of hyperphosphatemia without inducing hypercalcemia. Furthermore, patient compliance may increase if hyperphosphatemia can be treated by consuming bread with an elevated calcium content.
Acetates↗
Nutritional Life History as Influenced by Dietary Enrichments: II. Body Weight and Body Calcium in Cases of Protein-Accelerated Growth.
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Body Weight↗
Occupational exposure to carbon/coke fibers in plants that produce green or calcined petroleum coke and potential health effects: 1. Fiber characteristics.
Carbon/coke fibers are found in bulk samples of calcined petroleum coke. Carbon/coke and other fibers, including calcium silicate, cellulose, gypsum, and iron silicate, have been found in exposure monitoring of workers who make or handle green or calcined petroleum coke. Carbon/coke fibers are not classified or regulated as carcinogens by any agency, and the available literature (summarized in this article) has not reported significant adverse health effects associated with exposure to these fibers or dusts containing these fibers. However, available epidemiological and toxicological studies have limitations that prevent a definitive assessment of carbon/coke fiber toxicity. Therefore, it is prudent to monitor and control workplace concentrations. Analyses by transmission electron microscopy (TEM) indicate that the carbon/coke fibers are amorphous, irregularly shaped, and generally rather short (94% less than 20 microm long). Nearly all carbon/ coke fibers satisfying NIOSH 7400 B counting criteria are detectable by phase-contrast optical microscopy (PCOM), which permits the use of a highly efficient sequential sampling strategy for analysis. Data are presented on the distribution of carbon/coke structure and fiber lengths and diameters. Bootstrap resampling results are presented to determine confidence intervals for structure/fiber length and diameter. Data on time-weighted average concentrations are given in a companion article, but nearly all time-weighted average carbon/coke fiber concentrations were beneath 0.1 fibers per milliliter.
Calcium Compounds↗
Occupational exposure to carbon/coke fibers in plants that produce green or calcined petroleum coke and potential health effects: 2. Fiber concentrations.
We monitored exposure to various fibers among workers in eight plants operated by ConocoPhillips that produce green or calcined petroleum coke. Carbon/coke and other fibers, including calcium silicate, cellulose, gypsum, and iron silicate, were found in occupational samples. Carbon/coke fibers were found in bulk samples of calcined petroleum coke, the probable source of these fibers in occupational samples. Time-weighted average (TWA) total fiber concentrations were approximately lognormally distributed; 90% were < or = 0.1 f/ml. Although consistently low, TWA total fiber concentrations varied with plant, job (tasks), and type of coke. This was expected given the substantial differences in plant configuration, technology, and workplace practices among refineries and carbon plants. Carbon/coke fibers (identified and measured using transmission electron microscopy [TEM]) were found at all plants producing all types of calcined coke and not detected at any plant producing only green coke. Approximately 98% of all carbon/coke TWAs were < or = 0.1 f/ml. Analysis of task length average (TLA) data by various statistical techniques indicates that the average carbon/coke TLA is certainly < or = 0.05 f/ml and probably < 0.03 f/ml.
Calcium Compounds↗
The use of waterworks sludge for the treatment of vegetable oil refinery industry wastewater.
Water treatment works using coagulation/flocculation in the process stream will generate a waste sludge. This sludge is termed as ferric, alum, or lime sludge based on which coagulant was primarily used. The works in Adana, Turkey uses ferric chloride. The potential for using this sludge for the treatment of vegetable oil refinery industry wastewater by coagulation has been investigated. The sludge acted as a coagulant and excellent oil and grease, COD and TSS removal efficiencies were obtained. The optimum conditions were a pH of 6 and a sludge dose of 1100 mg SS l(-1). The efficiency of sludge was also compared with alum and ferric chloride for the vegetable oil refinery wastewater. At doses of 1300-1900 mg SS l(-1), the sludge was as effective as ferric chloride and alum at removing oil and grease, COD, and TSS. In addition, various combinations of ferric chloride and waterworks sludge were also examined. Under the condition of 12.5 mg l(-1) fresh ferric chloride and 1000 mg SS l(-1) sludge dose, 99% oil and grease 99% TSS and 83% COD removal efficiencies were obtained.
Alum Compounds↗
Simulation of pulp mill wastewater recycling after tertiary treatment.
The aim of this work is to study the possibilities of effluent recycling in a bleached Kraft pulp mill, for a better water management. To avoid problems associated with effluent recycling (corrosion, odors, loss in pulp and paper quality), wastewaters have to be treated before recycling. This study is particularly focused on organic matter removal. Several treatments are applied on a biological secondary effluent: adsorption on activated carbon, coagulation with ferric chloride or alum sulfate, precipitation with lime, ozonation and catalytic ozonation. These techniques are compared in terms of COD (Chemical Oxygen Demand) removal. Catalytic ozonation is finally chosen as the most effective solution to achieve 50% of COD removal in the effluent. The characteristics of the effluent treated according to this technique are then used to simulate the impact of its reuse in the process for pulp production. The study is focused on the changes in these parameters in the various stages of bleaching and final washing when water is replaced by the wastewater treated or directly issued from the wastewater treatment plant. The simulation demonstrates the need of a tertiary treatment to eliminate COD in order to avoid possible reactant overconsumption and decrease in pulp brightness. Chloride and sulfate ions which could cause corrosion should also be removed.
Alum Compounds↗
Physical properties and composition of femurs of rat fed with diets based on corn tortillas made from different processes.
In this study the effect of calcium absorption on some physical properties and composition of rat femurs was evaluated, comparing rats fed with raw whole corn (RC), tortillas made from extruded masa with 0.25% lime content (TEWL) and without lime (TE), and nixtamal tortillas (NT). The diets were formulated to contain the same amount of protein, oil, fiber, vitamins and minerals other than calcium. In all diets 0.20% calcium was added. At the end of the trials, the femurs were extracted, weighed and measured for ash, calcium and phosphorus content, some physical dimensions, and the crystallinity percentage. The femurs of rats fed with TEWL and NT were heavier, thicker, longer and had higher calcium content. On the other hand, the force required to break the femur of rats fed on ETWL and NT was 1.25 kg greater than that required to break the femurs of rats fed with RC. Higher crystallinity percentage values were observed in the femurs of the rats fed with NT (37.66%) and TEWL (36.98%) as compared to a 30.31% value obtained with the RC.
Animals↗
Preparation of calcium silicate absorbent from iron blast furnace slag.
Calcium silicate hydrate (CSH) solids were prepared from hydrated lime and iron blast furnace slag in an aqueous agitated slurry at 92 degrees C. While it was hoped a minimal lime/slag ratio could be used to create near-amorphous CSH, the surface area of the product improved by increasing the lime/slag weight ratio to 2. The addition of gypsum to the lime/slag system dramatically improved the formation of surface area, creating solids with 139 m2/g after 30 hr of reaction when only a minimal amount of lime was present. The SO2 reactivity of solids prepared with gypsum greatly exceeded that of hydrated lime, achieving greater than 70-80% conversion of the alkalinity after 1 hr of reaction with SO2. The use of CaCl2 as an additive to the lime/slag system, in lieu of gypsum, also produced high-surface-area solids, 115 m2/g after 21 hr of reaction. However, the SO2 reactivity of these sorbents was relatively low given the high surface area. This emphasized that the correlation between surface area and SO2 reactivity was highly dependent on the solid phase, which was subsequently dependent on slurry composition.
Absorption↗
Sensory and associated reactions to mineral dusts: sodium borate, calcium oxide, and calcium sulfate.
Occupational exposure limits (OELs) for irritant dusts have had no quantifiable bases. This study (1) charted chemosensory feel, denoted chemesthesis here, to dusts of calcium oxide (1 to 5 mg/m(3)), sodium tetraborate pentahydrate [sodium borate] (5 to 40 mg/m(3)), and calcium sulfate (10 to 40 mg/m(3)); (2) examined correlates of the chemesthetic sensations; and (3) sought to illuminate the basis for potency. Twelve screened men exercised against a light load while they breathed air in a dome fed with controlled levels of dust for 20 min. Measured parameters included nasal resistance, nasal secretion, minute ventilation, heart rate, blood oxygenation, mucociliary transport time, and chemesthetic magnitude, calibrated to pungency of carbon dioxide. Subjects registered time-dependent feel from exposures principally in the nose, secondarily in the throat, and hardly in the eyes. Calcium oxide had the greatest potency, followed by sodium borate, with calcium sulfate a distant third. Of the physiological parameters, amount of secretion showed the best association with chemesthetic potency. That measure, as well as mucociliary transport time and minute ventilation, went into calculation of mass of dust dissolved into mucus. The calculations indicated that the two alkaline dusts increased in equal molar amounts with time. At equal molar concentrations, they had, to a first approximation, equal chemesthetic magnitude. On the basis of mass concentration in air or dissolved into mucus, calcium oxide and sodium borate differed in potency by a factor just above five, equal to the difference in their molecular weights. This relationship could inform the setting of OELs for a critical effect of irritation.
Adolescent↗
Treatment of phosphoric acid plant wastewater using Fenton's reagent and coagulants.
The results of treatability studies viz., Fenton reaction and physico-chemical (coagulation) treatment using lime, alum, Fe salts and polyaluminium chloride (PAC) performed on wastewater generated from a unit manufacturing technical grade phosphoric acid are reported. Due to low biochemical oxygen demand (BOD) chemical oxygen demand (COD) ratio and very low pH, this wastewater is not amenable for biological treatment. The treatability studies indicated that it is possible to remove 75-80% COD using Fenton's reagent at optimum doses of 1.0 g/L FeSO4 and 2 ml of 30% H2O2. Simultaneously, significant quantities of suspended solids, phosphate and fluoride are also removed. Polyaluminium chloride is found to be more effective towards suspended solids (SS), COD, phosphate and fluoride removal, when compared to other coagulants used in the present study. Addition of an anionic polyelectrolyte (Magnafloc 156) to PAC improved the performance further. A treatment scheme that consists of neutralization (pH 4) + Fenton's reagent + neutralization (pH 7.5) + PAC/Magnafloc 156 is found to be effective in treating phosphoric acid plant wastewater to meet marine discharge standards.
Alum Compounds↗
An effective and better strategy for reducing body burden of radiostrontium.
In this study we have examined the effect of different calcium salts, Ca gluconate (CaG), Ca lactate (CaL), Ca carbonate (CaC) and Ca phosphate (CaP), on the clearance of radiostrontium (*Sr) administered either intraperitoneally (ip) (*Sr-ip group) or orally (*Sr-oral group) in rats. The influence of these Ca salts was examined in a group of animals administered *Sr ip, while the effect of three Ca salts (CaG, CaL and CaP) was studied in another group of rats given *Sr orally and compared with that of Ca alginate (CaA), normally advised for *Sr decorporation. Rats from both groups were subdivided into control and four experimental subgroups and were housed individually. The experimental subgroups were given the respective Ca salts (elemental Ca = 9 mg/rat/day) 2 h post 85Sr, and thereafter once daily. In the *Sr-ip group, CaG was administered ip while the other Ca salts were given orally. In the *Sr-oral group all Ca salts were administered orally. In addition, the diet of all the experimental subgroups was supplemented with the respective Ca salts to 2% elemental Ca. The whole-body retention (WBR) of *Sr in animals treated with Ca salts was found to be significantly reduced from 50-60% at 24 h to 20-30% at the end of 15 days compared with 70-80% at 24 h to 50-60% at the end of 15 days in the untreated control animals. The results strongly suggest that CaA could be replaced by any of the commonly used Ca salts for curtailing the WBR of *Sr. CaG which was administered ip, in the *Sr-ip group, was found to be more effective in reducing the WBR of *Sr.
Administration, Oral↗
Effect of lime composition on the formation of reactive oxygen species from areca nut extract in vitro.
Lime, representative of that used by betel quid chewers, was collected in a region of Papua New Guinea where the incidence of oral cancer is high. The free calcium hydroxide content and pH of 25 lime samples were highly correlated with the generation of reactive oxygen species from areca nut extract in vitro, and DNA damage in vitro, measured as 8-hydroxy-2'-deoxyguanosine. Fe2+ and Mg2+ levels in the lime samples were too low to modify formation of reactive oxygen species, but hydrogen peroxide formation was almost entirely inhibited by addition of Mg2+ to the reaction mixture. These results suggest that the calcium hydroxide content of lime in the presence of areca nut is primarily responsible for the formation of reactive oxygen species which might cause oxidative damage in the DNA of buccal mucosa cells of betel quid chewers.
8-Hydroxy-2'-Deoxyguanosine↗