PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Calcium Compounds”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40Linked to original sources
PubMed2006

Investigation into the stabilization/solidification performance of Portland cement through cement clinker phases.

This research studied the influence of individual heavy metal on the hydration reactions of major cement clinker phases in order to investigate the performance of cement based stabilization/solidification (S/S) system. Tricalcium silicate (C3S) and tricalcium aluminate (C3A) had been mixed with individual heavy metal hydroxide including Zn(OH)2, Pb(OH)2 and Cu(OH)2, respectively. The influences of these heavy metal hydroxides on the hydration of C3S and C3A have been characterized by X-ray diffraction (XRD) and differential scanning calorimetry-thermogravimetry (DSC-TG). A mixture of Zn(OH)2, Pb(OH)2 and Cu(OH)2 was blended with Portland cement (PC) and evaluated through compressive strength and dynamic leach test. XRD and DSC-TG data show that all the heavy metal hydroxides (Zn(OH)2, Pb(OH)2 and Cu(OH)2) have detrimental effects on the hydration of C3A, but only Zn(OH)2 does to the C3S at early curing ages which can completely inhibit the hydration of C3S due to the formation of CaO(Zn(OH)2).2H2O. Cu6Al2O8CO(3).12H2O, Pb2Al4O4(CO3)(4).7H2O and Zn6Al2O8CO(3).12H2O are formed in all the samples containing C3A in the presence of metal hydroxides. After adding CaSO4 into C3A, the detrimental effect of heavy metals increases due to the coating effect of both calcium aluminate sulphates and heavy metal aluminate carbonates. The influence of heavy metal hydroxide on the hydration of C3S and C3A can be used to predict the S/S performance of Portland cement.

Absorption↗
PubMed2003

Phosphate binder usage in kidney failure patients.

Phosphorus binders are used in patients with kidney failure because of the incomplete removal of phosphorus with dialysis and the inability to exclude phosphorus from the diet. Aluminium was the initial phosphorus binder used, but was replaced by calcium-containing binders because of the development of aluminium toxicity. Calcium-based binders have been the mainstay of therapy for many years, but recent investigations have pointed to increased rates of vascular calcification in patients taking calcium-containing binders. For this reason, alternative agents have been developed. Sevelamer (Renagel), GelTex Pharmaceuticals Inc.) is a polymer which has been found to effectively bind phosphorus. It has resulted in a decreased rate of vascular calcification compared to calcium-containing binders. Other agents under development include lanthanum carbonate and iron-complex preparations. Further research will likely concentrate on identifying binders that bind phosphate more efficiently, have minimal gastrointestinal side effects and provide other benefits to dialysis patients.

Acetates↗
PubMed2006

A qualitative X-ray analysis of white and grey mineral trioxide aggregate using compositional imaging.

Mineral trioxide aggregate (MTA) is used in endodontics as a filling and sealant material. An earlier commercial formulation Grey MTA (GMTA) was liable to became progressively discoloured, and a whiter version (WMTA) has been introduced for cosmetic reasons. This study compares the composition and particle size distribution of the two formulations using energy dispersive X-ray analysis in a scanning electron microscope. Particle size is smaller in WMTA. X-ray analysis reveals similar major peaks (calcium, silicon and bismuth) but those of the minor elements aluminium, magnesium and particularly iron are considerably less in WMTA, which may account for the colour difference. Neither contains phosphorus, a major constituent of the original formulation.

Aluminum↗
PubMed2003

Interfacial adaptation of a calcium aluminate cement used in class II cavities, in vivo.

The aim of this in vivo study was to evaluate the interfacial marginal adaptation of a calcium aluminate cement, Doxadent (DD), and to compare it intra-individually with a resin composite, Tetric Ceram/Syntac Single-Component (TC/SS), in Class II cavities. Sixteen Class II box-shaped, enamel-bordered cavities were prepared in eight premolars scheduled to be extracted after 1 month's service for orthodontic reasons. The interfacial marginal adaptation (internal surfaces) of the restorations was evaluated by a quantitative scanning electron microscope analysis using a replica method. DD showed a statistically significant, lower degree of gap-free adaptation to enamel compared with TC/SS: 84% vs. 93%. To dentin, DD showed a significantly better adaptation than TC/SS: 72% vs. 49%. A high frequency of enamel fractures perpendicular to the margins was observed for the DD restorations, which may be explained by an expansion of the calcium-aluminate cement. It can be concluded that DD showed a better adaptation to dentin while TC/SS showed a better adaptation to enamel. The dimensional changes of DD have to be investigated before clinical use can be recommended.

Adolescent↗
PubMed2006

Treatment of lateral root perforation with mineral trioxide aggregate: a case report.

Root perforations are undesired complications of endodontic treatment which result in loss of integrity of the root and further destruction of the adjacent periodontal tissues. In recent literature mineral trioxide aggregate (MTA) has been regarded as an ideal material for perforation repair. In this case iatrogenic perforation was observed in a maxillary central incisor. It was not possible to reach the perforation from the access cavity due to the angulation and excessive bleeding even though the root canal was filled with calcium hydroxide paste between appointments. Therefore, surgical intervention was preferred. After the root canal was filled with gutta percha and AH plus, the perforation site was subsequently sealed with MTA. The restoration was made with strip crown and composite resin. The symptoms were ceased and the results were satisfactory after 15 months follow-up.

Adolescent↗
PubMed2003

Treatment of a non-vital immature incisor with mineral trioxide aggregate (MTA).

- A case of severe crown fracture and luxation in the upper permanent incisors of a 9-year-old boy is reported. The treatment of one of the injured teeth included apexification with calcium hydroxide and endodontic treatment with gutta-percha obturation. The other incisor was also treated with calcium hydroxide, but as there was no apical stop after 3 years of treatment, it was decided to use a new root-end filling material: mineral trioxide aggregate (MTA). At follow-up 12 months later, the tooth was asymptomatic and radiographically showed the initial repair of the radiolucent apical lesion.

Aluminum Compounds↗
PubMed2006

The use of a setting accelerator and its effect on pH and calcium ion release of mineral trioxide aggregate and white Portland cement.

The aim of this study was to evaluate the influence of adding 10% calcium chloride (CaCl2) indicated as setting accelerator on pH and release of calcium ions of commercially available materials: ProRoot MTA (tooth-colored formula), MTA Branco, and White Portland cement. The products were mixed for 30 seconds in previously established ratios. To estimate the values of pH and release of calcium ion, polyethylene tubes were filled with the materials and immersed in containers with 10 ml of deionized water. The analyses were performed baseline, 30 minutes, 60 minutes, and 24 hours after the mixing process. A pHmeter (MicroNal B 371, Sao Paulo, SP, Brazil) and an atomic absorption spectrophotometer (Model GBC 904; CG Corp, Melbourne, Australia) equipped with a hollow cathode lamp were used to determine the data. According to the Student's t-test, the comparison between the pure and the CaCl2-added products indicated that the presence of this substance increased immediately the pH, although the results were very similar when they were analyzed in the other intervals. In addition, products with CaCl2 released more calcium ions than pure materials in the 24-hour period (p<0.05). The results revealed that the addition of CaCl2 to MTA enhanced the physicochemical properties of this product. Thus, materials mixed with CaCl2 became easier to handle and needed lower amounts of water in the mixing process.

Aluminum Compounds↗
PubMed2005

Treatment of invasive cervical resorption with MTA: case report.

This paper presents a case report of a maxillary lateral incisor affected by invasive cervical resorption. The tooth was submitted to a 21-day treatment with calcium hydroxide followed by root canal filling. The area of resorption was sealed with MTA followed by glass ionomer cement and restored with composite resin. Two-year radiographic follow-up showed stability of the resorption site and normal coronal colour and depth of gingival sulcus.

Adult↗
PubMed2006

X-ray diffraction analysis of mineral trioxide aggregate and Portland cement.

AIM: To compare the major constituents present in ProRoot mineral trioxide aggregate (MTA), ProRoot MTA (tooth coloured formula), ordinary Portland cement and white Portland cement using powder X-ray diffractometery. METHODOLOGY: X-ray diffractometery of the four materials was carried out with the divergence and scatter slits set at 1 degree and the receiving slit at 0.10 mm. The scan range was set at 5-70 degrees and continuous scans for the theta-2theta range were run with a scan speed of 2 degrees min(-1). The patterns obtained were then compared with the Powder Diffraction Files (PDF) found in the International Centre for Diffraction Data database. The three strongest peaks were used for the identification of the constituents. The relative intensities were plotted against the angle 2theta and compared with the plots in the PDF. RESULTS: The main constituents were found to be tricalcium silicate, tricalcium aluminate, calcium silicate, and tetracalcium aluminoferrite in all the four cements with the additional presence of Bi2O3 in ProRoot MTA and ProRoot MTA (tooth coloured formula). CONCLUSIONS: The four cements had similar major constituents. Data on Portland cement may be used for the further development or modification of ProRoot MTA in order to improve its physical characteristics and expand its scope of clinical applications.

Aluminum Compounds↗
PubMedDate not supplied

The complete endodontic obturation of an avulsed immature permanent incisor with mineral trioxide aggregate: a case report.

The use of mineral trioxide aggregate (MTA) for complete endodontic obturation of an immature maxillary central incisor is reported. The injured tooth of a 9-year-old male was avulsed secondary to a sports-related traumatic event. Early attempts at pulpal revascularization of the replanted tooth proved unsuccessful, as evidenced by radiographic signs of external inflammatory root resorption in the middle to cervical thirds of the root. Calcium hydroxide apexification over a 1-year period promoted cessation of the resorptive process, but was unable to adequately form an apical root canal barrier. Due to the extent of external resorption and the lack of an apical stop, a novel endodontic treatment using mineral trioxide aggregate was utilized. At 865 days post-injury, the tooth remained asymptomatic with clinical and radiographic evidence of periodontal health.

Aluminum Compounds↗
PubMedDate not supplied

Coating analysis of implant materials used in orthopaedic surgery.

Biocompatibility of orthopaedic surgical implants with bone tissue allows adequate osseointegration between the bone and implant. To achieve this, implants are coated with biocompatible materials. The costly plasma spray procedure is routinely used to coat implants but uses high temperatures (over 16,000 degrees C), which affect the surface quality and microstructure of the implant. We analysed the effect of sintering temperature, time and rate on coated and uncoated implants using a dipping method. The effectiveness of synthetic hydrated calcium silicate compound as an interlayer was also investigated, using the dipping method and electrophoretic deposition. Sintering temperature, time and rate all affected the quality of the bond with the coating, but the interlayer bonded effectively with both implant and biocompatible coating. Electrophoretic deposition resulted in imperfect bonding and some irregularity on the substrate surface was seen. This technique may be improved by using coating particles of a smaller size.

Biocompatible Materials↗
PubMed1997

T-jump study of calcium binding kinetics of calcium chelators.

Recent experimental studies have investigated the kinetic competition between calcium chelators and the secretion apparatus at a fast central synapse. Simultaneously, mathematical modelling studies indicate the importance of a quantitative knowledge of the binding kinetics of the chelators in studying fast physiological processes operating on a millisecond time scale. Using the temperature-jump relaxation method, I have studied the in vitro kinetics of Bis-Fura-2, Furaptra, Fluo-3, Calcium-Green-1, Calcium-Green-5N, Calcium-Orange-5N as well as EGTA, BAPTA and H-EDTA in conditions which are identical to those implemented in our patch clamp recordings, i.e. 100-140 mM CsCl, 20-40 mM Cs-HEPES, 8 mM NaCl, pH = 7.2 at 22 degrees C. The results can be summarized as follows: all fluorescent indicators have on rates in the range of 10(8)-10(9) M-1s-1. They differ significantly with respect to their off-rates from each other according to their affinities, ranging from 100 s-1 up to 26,000 s-1. BAPTA is kinetically almost indistinguishable from Fura-2. EGTA and H-EDTA have small binding rate constants for calcium in the range of 3 x 10(6) M-1s-1 since, at pH 7.20, protons need to be dissociated from the chelators before they can bind calcium ions.

Aniline Compounds↗
PubMed1976

Long-term study of pulp capping in monkeys with three agents.

The pulps of 40 permanent teeth of two monkeys were mechanically exposed and contaminated with adjacent saliva or plaque for 3 to 5 1/2 hours. The pulps were then capped with either Keflin (an antibiotic), Durelon (a polycarboxylate cement), or Dycal (a calcium hydroxide compound). Varnish and then amalgam were inserted. Each monkey received at least one dose of Procion red H-8BS vital dye. The teeth were extracted from one monkey 23 months after capping and from the other monkey 29 months after capping. Serial, decalcified, 7 mum-thick paraffin sections were prepared. Alternate slides were stained with hematoxylin ane eosin. Unstained sections were examined for Procion labeling, and selected slides were stained by the Brown-Brenn method for bacteria. Of 13 teeth capped with Keflin, only 4 responded satisfactorily. All of the Dycal and Durelon-capped pulps were successful at both time intervals. All of the Dycal-capped pulps showed complete bridging and no inflammation or pulp obliteration. Bridging was complete in only three of the Durelon-capped pulps. The findings of this study support the findings in our previous study3 and further substantiate the effectiveness of Dycal as a pulp-capping agent. The often-repeated claim that calcium hydroxide compounds exert a persistent stimulating effect on the pulp resulting in its eventual obliteration was not supported. Durelon is not recommended for pulp capping since the material apparently lacks an antibacterial effect and does not stimulate reparative dentinogenesis at the exposure site. The low rate of satisfactory responses of pulps capped with Keflin, as used, precludes its use of pulp capping.

Acrylates↗
PubMed1979

The role of cell-fixed calcium in histamine release by compound 48/80.

1. Histamine release by compound 48/80 was substantially reduced in a time-dependent manner (maximum at 30 min) by pre-incubating mast cells in calcium-free medium at 37 degrees C but not at 2 degrees C. This effect was optimal at pH 7.0 to 7.5. 2. The re-introduction of calcium (0.1 to 3 mmol/l) restored histamine release to the control value; this effect was independent of temperature. 3. Strontium (1 to 30 mmol/l) partially reversed the effect of calcium deprivation but the same concentrations of barium and magnesium depressed histamine release even further. Magnesium (3 to 15 mmol/l) antagonized the effect of calcium replacement. 4. Results suggest that the level of cell-fixed calcium involved in compound 48/80-induced histamine release may be controlled by the combination of rapid passive influx and slow active efflux.

Animals↗
PubMed1997

Compositional dependence of bioactivity of glasses in the system Na2O-K2O-MgO-CaO-B2O3-P2O5-SiO2.

The bioactivity, i.e., bone-bonding ability, of 26 glasses in the system Na2O-K2O-MgO-CaO-B2O3-P2O5-SiO2 was studied in vivo. This investigation of bioactivity was performed to establish the compositional dependence of bioactivity, and enabled a model to be developed that describes the relation between reactions in vivo and glass composition. Reactions in vivo were investigated by inserting glass implants into rabbit tibia for 8 weeks. The glasses and the surrounding tissue were examined using scanning electron microscopy (SEM), light microscopy, and energy-dispersive X-ray analysis (EDXA). For most of the glasses containing < 59 mol % SiO2, SEM and EDXA showed two distinct layers at the glass surface after implantation, one silica-rich and another containing calcium phosphate. The build-up of these layers in vivo was taken as a sign of bioactivity. The in vivo experiments showed that glasses in the investigated system are bioactive when they contain 14-30 mol % alkali oxides, 14-30 mol % alkaline earth oxides, and < 59 mol % SiO2. Glasses containing potassium and magnesium bonded to bone in a similar way as bioactive glasses developed so far.

Animals↗