Calcium Ion Electrode Research Articles

Comparative evaluation of diffused calcium and hydroxyl ion release from three different Indirect pulp capping agents in permanent teeth – An in vitro study

BackgroundIndirect pulp capping therapy has gained increased popularity in paediatric dentistry since it is less invasive, and is of low cost. The aim of the present study was to evaluate and to compare the diffusion of calcium (Ca2+) and hydroxyl (OH–) ions through coronal dentin into pulp after indirect pulp capping in vitro using TheraCal LC, ProRoot MTA and Calcimol LC. Materials and methodsTotal of 60 human caries-free maxillary first premolars were selected for the study. Samples were divided into 4 groups with 15 in each group: Group 1 TheraCal LC; Group 2 ProRoot MTA; Group 3 Calcimol LC; Group 4 Control Group. Indirect pulpcapping on the coronal RDT (remaining dentine thickness) system was performed using pulp-capping materials, such as TheraCal LC, ProRoot MTA and Calcimol LC, on the respective samples. The control group was completely filled with composite. Ca2+ ions (ppm) and OH– ions (pH) were analysed in deionized water using a multimeter connected to a calcium probe (calcium ion electrode) and pH metre connected to a temperature-compensated pH probe after 3 h, 24 h, 7 days, 14 days, 28 days and 60 days. ResultsCalcium release was significantly higher (P < 0.05) in the TheraCal LC group than in the other groups. Slightly alkaline pH values were observed in all the groups except for the control. ConclusionTheraCal is a new light-curable pulp capping material that initially releases high Ca2+ ions and creates an environmental pH close to physiological pH after 60 days.

Immobilized Ionophore Calcium Ion Sensor Modified by Montmorillonite

The effect of montmorillonite on the preparation of a calcium ion electrode was studied by combining and immobilization of ionophore and montmorillonite into a polymer membrane. Two types of electrodes to detect calcium ion concentrations were also compared. The results indicated that the montmorillonite-modified electrode exhibited higher performance than that without montmorillonite. The relationship between the potential and calcium ion concentration was obtained and the testing range of calcium ion concentration was from 4×10–6–10–1 M. The selectivity, reproducibility, and stability of modified electrodes with montmorillonite were better than electrode without montmorillonite. The optimal amount of the montmorillonite was 24.8 wt.%.

Immobilized Ionophore Calcium Ion Sensor Modified by Montmorillonite

The effect of montmorillonite on the preparation of a calcium ion electrode was studied by combining and immobilization of ionophore and montmorillonite into a polymer membrane. Two types of electrodes to detect calcium ion concentrations were also compared. The results indicated that the montmorillonite-modified electrode exhibited higher performance than that without montmorillonite. The relationship between the potential and calcium ion concentration was obtained and the testing range of calcium ion concentration was from 4×10–6–10–1 M. The selectivity, reproducibility, and stability of modified electrodes with montmorillonite were better than electrode without montmorillonite. The optimal amount of the montmorillonite was 24.8 wt.%.

A NEW APPROACH FOR DETERMINING THE REACTION RATIO BETWEEN CALCIUM AND SURFACTANT HAVING LOW CALCIUM TOLERANCE: APPLICATION TO BILE SALT

ABSTRACT Calcium-bile salt interaction plays an important role in gallstone formation and lipid solubilization in human digestive system. This paper presents a method of studying the calcium-bile salt interaction for several bile salts having low electrolyte tolerance. Sodium cholate, sodium glycodeoxycholate, sodium glyco-chenodeoxycholate and sodium deoxycholate were used in this study. Potentiometric titration was performed with calcium ion electrode to determine the calcium-bile salt reaction ratio and the equilibrium constant. Flocculation values by calcium or sodium ions were measured as a function of the bile salt concentration. The flocculation-concentration curves appear to be quite complicated. Precipitation of the bile salt was carefully avoided by adjusting the concentration of the reactants and taking the flocculation-concentration curve as a guidance. For sodium deoxycholate which has extremely low calcium tolerance, the precipitation was postponed by adding nonionic surfactant. Complete titration curves and stoichiometric reaction ratios between calcium and bile salts were obtained.

Calcium phosphate system in saliva-like media

Despite the well documented importance of carbon dioxide dissolved in physiological media, consideration of its effect on calcium phosphate solubilities has been neglected, an omission now shown to be serious. A solid titration technique has been developed to avoid a number of the difficulties inherent in solubility studies of calcium phosphates; this employed a graphical method based on pH and calcium-ion electrode potential to identify breakpoints. The solubility isotherm at 37.0 °C for hydroxyapatite has thus been determined for the chosen saliva-like medium. A numerical model of the system provided corroboration for the results obtained. An approximately 10-fold increase in the calcium-carrying capacity of that medium was then demonstrated with CO2 present at a fixed partial pressure of 0.035 bar, a result not explicable in terms of known equilibria. Two new complexes, CaH2PO4H2CO+3(β= 54) and CaH2PO4HCO3(β= 43), are postulated to account for the data.

Kinetic factors influencing the dissolution behavior of calcium oxalate renal stones: a constant composition study.

A constant composition method has been used to examine the dissolution kinetics of calcium oxalate renal stones over a wide range of undersaturation in vitro. Demineralization experiments have been carried out with the concentrations of calcium and oxalate ions and ionic strength (hence the solution undersaturation) held constant by the potentiometrically controlled addition of medium electrolyte solution as diluent, triggered by a calcium ion electrode. Kinetic data for renal stones have been compared with results obtained for synthetic calcium oxalate. In addition, constant composition results have been directly compared with results obtained using conventional dissolution methods for both calculi and synthetic calcium oxalate. Overall, calcium oxalate renal stones exhibited markedly different kinetic dissolution behavior as compared with synthetic controls. The renal stone samples dissolved more slowly at all undersaturations, exhibited increased kinetic orders of reaction, and showed reduced sensitivity to solution hydrodynamics. Stones composed of mixed hydrates of calcium oxalate (mono- and di-) came to dihydrate equilibrium in conventional experiments and underwent net dissolution in solutions supersaturated to monohydrate under constant composition conditions. No conversion of di- to monohydrate was observed under these experimental conditions. These results indicate that stone dissolution is strongly influenced by adsorbed inhibitors, presumably including matrix components, which may complicate efforts to develop systemic and/or irrigation measures effective for in situ solubilization.

Calcium Binding by Bile Acids in Vitro Studied Using A Calcium Ion Electrode

Calcium Binding by Bile Acids in Vitro Studied Using A Calcium Ion Electrode

The binding of free calcium ions in aqueous solution using chelating agents, phosphates and poly(acrylic acid)

AbstractOrganic chelating agents, phosphates, and polyelectrolytes were studied to determine their calcium ion binding power (CBP) and binding mechanism. A calcium ion electrode was used to measure the equilibrium calcium ion concentrations from which stability constants were calculated. Except for EDTA and NTA, the binding power did not correspond to the formation of complexes with a simple stoichiometry. In most cases, more than one equilibrium is involved. Increase in the level of binding agent decreased CBP, especially for those agents which formed complexes with low stability constants. CBP calculated on the basis of weight should be used to measure the relative cost effectiveness of commercial calcium binding agents. At an amount lower than required to form stable stoichiometric complexes, poly(acrylic acid) had a higher CBP than traditional organic chelating agents. The electrostatic effect accounts for the excellent CBP of poly(acrylic acid) at low concentrations. To get maximum efficiency in detergent and water treatment applications, use of low levels is recommended. aPresent address: The Clorox Co. Technical Center, Pleasanton, CA 94566.

Study on the Process of Precipitation of Calcium Sulfate Dihydrate from Aqueous Solution by Calcium Ion Electrode

Study on the Process of Precipitation of Calcium Sulfate Dihydrate from Aqueous Solution by Calcium Ion Electrode

Thrombin-platelet interactions investigated with the calcium electrode

The thrombin-induced release reaction of human platelets is studied using a calcium ion electrode to follow the release of calcium. A continuous tracing of the time course of calcium release shows three phases: 1) an initial lag phase of variable length, which is dependent on the thrombin concentration; 2) an exponential phase during which most of the calcium is released; 3) a final linear phase of slow calcium release which starts 90–120 sec after the addition of thrombin. The calcium yield (the amount of calcium released 90 sec after thrombin addition) is directly related to the thrombin concentration and platelet number. The release of calcium is inhibited by preincubation of the platelets with dibutyryl cyclic AMP, but this inhibition is overcome by additional thrombin. Results obtained with varying platelet number and thrombin concentration suggest that platelets stimulated by a low concentration of thrombin release only a portion of their releasable calcium. If thrombin is added in two increments rather than in a single increment, a second release of calcium is observed; the final calcium yield, however, decreases as the time interval between thrombin additions increases. The indication that platelets may undergo a partial release reaction without complete impairment of their hemostatic effectiveness suggests that platelets may be perceived as homeostatic as well as hemostatic cells, with implications for the maintenance of vascular integrity by circulating platelets.

Anomalous response of a calcium ion electrode in natural waters

Abstract Several chelating agents, both synthetic and natural, were selected for a study on their effects on the growth of hydrilla (Hydrilla verticillata Royle). These were disodium ethylenedinitrilotetraacetate dihydrate, Na2EDTA.2H2.O; ethyl‐enediamino‐N,N'‐diacetic acid, EDDA; disodium trans‐1,2‐diaminocyclohexanetetra‐acetic acid, Na2CDTA; ethyleneglycolbis(aminoethyl)tetraacetic acid, EGTA; and the natural chelators present in Lake Starvation (Hillsborough County, Florida) water. These chelating agents, in well‐water solutions, were incubated with hydrilla. Dissolved oxygen and dissolved carbon (inorganic and organic) were measured, and these values were related to hydrilla growth. In addition, values of calcium present were measured by atomic absorption spectrophotometry and by a calcium ion electrode. Only EGTA solutions exhibited anomalous behavior, and this is attributed to exceptional stability of Ca‐EGTA complexes and the effect on the response of the electrode. Results are compared with other...

Identification of Calcium Complexes in Solutions by Use of Calcium Ion Electrode

Identification of Calcium Complexes in Solutions by Use of Calcium Ion Electrode

A Study on the Determination of Ionized Calcium with an Ion-Selective Electrode

The properties of a calcium ion electrode (Orion Research Incorporated) were evaluated and the possibility of its application to medical and dental areas was studied. The electrode potential was affected by various factors; for example, the potential was increased by such monovalent cations as potassium or sodium, and by divalent cations such as magnesium. On the other hand, the potential was decreased by such anions as fluorine, phosphor and others. The decrease of the Nernst factor and the loss of linearity at a low concentration of calcium in the presense of those salts seems to be a characteristic trend of this electrode. Moreover, there were various other factors affecting the electrode potential: pH, ionic strengh, temperature of sample solution and others. In addition, variation from the normal potential is observed occasionally during repeated or continual use of the electrode.Therefore, in calcium determination of biological samples containing many various salts andions, the adjustment of pH and ionic strength is an essential procedure, and also the other affecting factors must be taken into consideration.It is possible to determine roughly the calcium content of the teeth if these affecting factors are taken into account. However, this electrode seems to be of limited usefulness because of the difficulty in adjusting these various factors.

Determination of exchangeable calcium and magnesium in soil by ion-selective electrode method

The potentiometric measurement of calcium ion activity with a calcium ion electrode and of magnesium ion activity with a divalent cation electrode in the presence of EGTA at pH 7 has been successfully applied to the determination of exchangeable calcium and magnesium in soil after the soil sample is extracted with ammonium acetate and the soil extract is evaporated to dryness and ignited. The results obtained by the ion-selective electrode methods are in good agreement with those obtained by the reference methods.

Hyperparathyroidism due to clear cell hyperplasia: Serial determinations of serum ionized calcium, parathyroid hormone and calcitonin

Serial determinations of serum ionized calcium (Ca ++), serum total calcium (Ca), parathyroid hormone (PTH) and calcitonin levels were made in a patient with hyperparathyroidism due to clear cell hyperplasia. Although serum Ca declined to normal levels prior to parathyroidectomy, serum Ca ++ and PTH levels remained elevated until after operation. This suggests that the calcium ion electrode may prove valuable in the diagnosis and management of patients with hyperparathyroidism, especially when they are normocalcemic. The excised parathyroid glands yielded very low PTH concentrations upon extraction, implying that in this form of hyperparathyroidism PTH secretion is excessive whereas storage is markedly reduced. CT levels were normal in both serum and excised glands. This finding is of interest in relation to the patient's associated generalized neurofibromatosis and serves further to distinguish the present syndrome from that characterized by mucosal neuromas, hyperparathyroidism and medullary carcinoma of the thyroid.

Effect of ACD Blood Prime on Plasma Calcium and Magnesium

The changes in the total plasma calcium, ionized calcium, total magnesium, and ionized magnesium during cardiopulmonary bypass were measured in 38 patients in whom acid citrate dextrose (ACD) preserved blood was used in the pump-oxygenator prime. The ionized calcium was measured directly using a calcium ion electrode. It was found that reconstitution of ACD blood with 10% calcium chloride in an amount equivalent to 8 ml. per unit of ACD blood resulted in a normal ionized calcium level in the plasma. There was severe depression of the ionized magnesium when ACD blood was used in the pump-oxygenator prime; however, addition of 10% magnesium sulfate in an amount of 3 ml. per unit of ACD blood returned the ionized magnesium to the normal range.

The kinetics of dissolution of calcium sulfate dihydrate

The dissolution of calcium sulfate dihydrate crystals into subsaturated solutions of the salt has been studied at various temperatures between 10° and 30°C using a calcium ion electrode. The process follows an equation first order in relative subsaturation and is sensitive to changes in the rate of stirring indicating film diffusion control. The rate of dissolution is considerably faster than that for barium, strontium and lead sulfates for which a surface controlled reaction has been suggested. The activation energy for dissolution of CaSO 4·2H 2O is 10 ± 1·5 kcal/mole.

Cation Replacement Studies on Heteroionic Bentonitic Clay Fractions Using Specific Ion Glass Electrodes

AbstractCentrifuged fractions, ranging in size from 2·0 to 0·05 μ of a Wyoming bentonite, Bentonita de Durango from Mexico, and Helms clay from Texas were studied. The variation in replacement of Na+, Ca2+, Mg2+, K+, and H+ from these heteroionic clay systems under specific equilibrium conditions of salt concentrations was measured.The displacement cation distribution was monitored by using specific ion glass electrodes, such as a sodium ion electrode, a cationic glass electrode, a calcium ion electrode and a Tektite electrode. Some factors affecting the exchange reactions are discussed and application of findings to drilling and production techniques is indicated.

Study on the Change of Solubility of CaSO4&middot;1/2H2O in water by Measuring Ionic Concentration Using Calcium Ion Electrode

Study on the Change of Solubility of CaSO<SUB>4</SUB>&middot;<SUP>1</SUP>/<SUB>2</SUB>H<SUB>2</SUB>O in water by Measuring Ionic Concentration Using Calcium Ion Electrode

Measurement of serum ionic calcium using a specific ion electrode.

Abstract : A recently developed calcium ion electrode was evaluated for use in the routine measurement of serum ionic calcium. The electrode, used in conjunction with an expanded scale pH meter, permits the direct and accurate assay of ionic calcium in fresh serum samples with a minimal expenditure of time and materials. Factors found to be critical to reliable operation include electrode mounting configuration, diluent for the calibration standards, sample preparation, control of pH, uniformity of sample volume and thermostasis. Analytic precision--a function of electrode placement, instrumental stability and readout parallax--is routinely excellent. Discrimination and recovery studies indicate the minimal assayable concentration differences to be between 0.2 and 0.3 mg.%. The electrode appears to be applicable to a wide variety of clinical and nonclinical investigations. (Author)