whitlockite and calcium-phosphate--dibasic--dihydrate

Topics: Apatites; Calcium Compounds; Calcium Oxalate; Calcium Phosphates; History, 18th Century; History, 19th Century; History, 20th Century; Humans; Magnesium Compounds; Minerals; Names; Phosphates; Struvite; Urinary Calculi

The purpose of this study was to evaluate the microtensile bond strength (microTBS) to human dentin of an experimental bonding agent containing calcium phosphates experimentally developed for direct pulp capping. Different concentrations of four types of calcium phosphates were added to an experimental bonding monomer, and six experimental bonding agents were thus prepared. Clearfil SE Bond/Bond was used as the control. Flat dentin surfaces of human molars were assigned to the experimental adhesive systems and the control. After Clearfil SE Bond/Primer was applied to the dentin surface, each experimental bonding agent was applied and photopolymerized, and then a resin composite paste was placed and photopolymerized. The specimens were subjected to microTBS testing. Results revealed that there were no significant differences among the microTBS values of the experimental bonding agents and the control. In other words, the calcium phosphate-containing experimental adhesives did not adversely affect the microTBS to dentin.

Topics: Adhesiveness; Calcium Phosphates; Composite Resins; Dental Bonding; Dental Pulp Capping; Dentin; Dentin-Bonding Agents; Durapatite; Humans; Materials Testing; Methacrylates; Microscopy, Electron, Scanning; Polymethacrylic Acids; Resin Cements; Stress, Mechanical; Surface Properties; Tensile Strength

To evaluate the compositions of the kidney stones obtained from different regions of Turkey and to present the gender and regional differences.. The study included 6453 kidney stones obtained from patients from different parts of Turkey. All of the stones were obtained using ureterorenoscopy, percutaneous stone surgery, laparoscopic or open stone surgery, or extracorporeal shock wave lithotripsy. X-ray diffraction crystallography method was used for analysis.. At the end of the analysis, 11 different stone types including calcium oxalate (Ca-ox) monohydrate (whewellite, COM), Ca-ox dihydrate (weddellite, COD), uric acid, cystine, struvite, biurea, xanthine brushite, quartz, whitlockite, and dahlite were determined either in pure or mixed conditions. Of the stones, 80.4% were Ca-ox (55.7% COM, 5.9% COD, 18.8% COM + COD), 4.8% uric acid, 3.1% cystine, and 3.3% were phosphate stones (dahlite, brushite, struvite, whitlockite). The remaining 8.4% of the stones were in mixed form with different combinations. Of the patients, 4411 were men (68.3%) and 2042 were women (31.7%).. Ca-ox was the most frequently encountered stone type in our country as it is worldwide. The distribution of the other stone types is different than the other countries. The information about the structure of the stone has significant contribution to the understanding of the stone formation etiology, programming of the treatment process, and prevention of the recurrences. The study is significant in presenting the stone profile of Turkey.

Topics: Apatites; Biureas; Calcium Oxalate; Calcium Phosphates; Crystallography, X-Ray; Cystine; Female; Humans; Kidney Calculi; Magnesium Compounds; Male; Phosphates; Quartz; Sex Factors; Struvite; Turkey; Uric Acid; Xanthine

In most industrialized countries, different epidemiologic studies show that chronic renal failure is dramatically increasing. Such major public health problem is a consequence of acquired systemic diseases such as type II diabetes, which is now the first cause for end stage renal failure. Furthermore, lithogenic diseases may also induce intratubular crystallization, which may finally result in end-stage renal failure (ESRF). Up to now, such rare diseases are often misdiagnosed. In this study, based on twenty four biopsies, we show that SR µFTIR (Synchrotron Radiation-µFourier transform infrared) spectroscopy constitutes a significant opportunity to characterize such pathological µcalcifications giving not only their chemical composition but also their spatial distribution in the tissues. This experimental approach offers new opportunities to the clinicians to describe at the cell level the physico-chemical processes leading to the formation of the pathological calcifications which lead to ESRF.

Topics: Adult; Aged; Apatites; Calcium Oxalate; Calcium Phosphates; Crystallization; Female; Humans; Kidney; Kidney Calculi; Male; Middle Aged; Nephrocalcinosis; Reproducibility of Results; Sensitivity and Specificity; Spectroscopy, Fourier Transform Infrared

Mechanical properties of renal calculi dictate how a stone interacts and disintegrates by shock wave or intracorporeal lithotripsy techniques. Renal stones of different compositions have large variation in their mechanical strength and susceptibilities to shock waves. Operated urinary stones and artificially developed stones using pharmaceutical methods, composed of phosphates were subjected to tensile, flexural and compressive strength studies using universal testing machine. The infrared spectra confirmed the presence of hydroxyapatite in both the natural stones and struvite with calcium oxalate trihydrate in one stone and struvite with uric acid in the other. The X-ray diffraction analyses confirmed their crystalline nature. It has been observed that the flexural properties depend on the size of the sample even for the samples cut from a single stone. The compressive strengths were almost 25 times larger than the tensile strengths of the respective natural stones as well as the artificial stones prepared.

Topics: Biomechanical Phenomena; Calcium Oxalate; Calcium Phosphates; Durapatite; Humans; Lithotripsy; Magnesium Compounds; Materials Testing; Phosphates; Spectrophotometry, Infrared; Struvite; Tensile Strength; Urinary Calculi; X-Ray Diffraction

The exact cause of the formation of sialoliths is unknown. Detailed knowledge of pathogenesis of sialolithiasis and composition of sialoliths is necessary to define new therapeutic procedures. The crystalline components of 23 sialoliths of human submandibular gland were investigated by X-ray powder diffraction analysis. All of the sialoliths localized in the ducts in the submandibular gland consisted of hydroxylapatite. However, in the sialoliths in the Wharton's duct, hydroxylapatite as well as whitlockite and brushite could be found in all except one case. Whitlockite was observed more often in the nucleus of the sialoliths and it was a common co-phase along with hydroxylapatite. The nucleus in one sialolith consisted of brushite and the cortex showed a co-phase of hydroxylapatite and brushite. The occurrence of whitlockite in the sialoliths in Wharton's duct may be due to a higher concentration of calcium and phosphate in saliva in this duct.

Topics: Adult; Aged; Calcium Phosphates; Crystallization; Durapatite; Female; Humans; Male; Middle Aged; Salivary Duct Calculi; Salivary Gland Calculi; Submandibular Gland Diseases; X-Ray Diffraction

The residues of 5 samples of powdered human enamel, each subjected to 5 sequential equilibrations at 37 degrees C with either 17 or 4 mmol/l phosphoric acid, were examined microscopically. With 17 mmol/l acid, both brushite and monetite were found after 1 equilibration but, after further equilibrations, brushite was no longer present and the abundance of monetite crystals increased. Formation of monetite probably contributed to the lower metastability of this system compared to similar low-pH systems at 25 degrees C, where monetite does not form. Neither brushite nor monetite were present after equilibration with 4 mmol/l acid. Whitlockite was identified by transmission electron microscopy and electron diffraction in all residues. In the 4 mmol/l systems, the ionic activity product (IMWH) for magnesium whitlockite, Ca9Mg(HPO4)(PO4)6, became constant after 1-3 equilibrations, at a mean value of 3.6 (+/-0.51 SE).10(-105), which may reflect saturation with respect to this solid. For the 17 mmol/l systems, higher values of IMWH, and supersaturation with respect to monetite, were interpreted as evidence for persistent metastability due to slow crystal growth of whitlockite and monetite. It is concluded that neither brushite nor monetite are likely to form within carious lesions, but the results are consistent with the known association of whitlockite with caries.

Topics: Calcium Phosphates; Crystallography, X-Ray; Dental Enamel; Dental Enamel Solubility; Electron Probe Microanalysis; Humans; Microscopy, Electron; Osmolar Concentration; Phosphoric Acids

Five samples of powered enamel were each sequentially equilibrated 5 times at 37 degrees C with either 4 or 17 mmol/l H3PO4, in contact with air, and the ionic activity product for hydroxyapatite (IHA) estimated. There was evidence for preferential release of Mg and Na, especially in the first equilibrations. In two experiments, raised values of IHA were observed in the first equilibration but otherwise IHA was reasonable constant within experimental error and was much closer to the solubility product of hydroxyapatite than many previous estimates, mainly at 25 degrees C, suggest. The mean value of IHA for the majority fraction, averaged over all samples, was 1.7 (+/- 0.7) x 10(-58). Non-apatitic solids formed in all systems but solubility appeared nevertheless to be controlled by an apatitic phase: either the enamel mineral itself or apatite reprecipitated during the course of equilibration. High values of IHA reported previously may be due to use of conditions favouring dissolution only of more soluble factions or to metastability artifacts associated with control of solubility by non-apatitic phases.

Topics: Calcium; Calcium Phosphates; Carbonates; Dental Enamel; Dental Enamel Solubility; Durapatite; Fluorides; Humans; Magnesium; Particle Size; Phosphoric Acids; Phosphorus; Sodium; Temperature

By calculation, apatite is more soluble than brushite at low pH and less soluble at high pH. Apatite, therefore should be able to transform spontaneously to brushite at low pH and brushite to apatite at high pH. The aim was to describe this mutual conversion as related to the aqueous phase composition. Powdered enamel, brushite or 1:1 mixtures of the two salts were suspended in distilled water for up to 12 weeks at 20 degrees C, pH was adjusted to 4, 5, 6, 7, 8, 9 or 10 by drops of perchloric acid or potassium hydroxide. The calcium and the phosphate concentrations and pH were determined, and the nature of the calcium phosphate powder was examined by X-ray diffraction. At pH 8 and above, brushite was invariably converted to apatite, whilst it was transformed to octacalcium phosphate at pH 7. In the pH range 6-4 brushite was not converted to apatite and enamel apatite was not transformed to brushite spontaneously within 2 months. In the enamel apatite suspensions, the apatite ion product altered with pH, which explained why apatite did not transform to brushite at pH 5-4. At pH 3.7, however, the enamel apatite was converted to brushite. No transformation of apatite to brushite was identified in apatite-brushite mixtures at pH 6-4. Supplementary experiments showed that ethanol, used as an agent for removal of water, salted out the water-free dicalcium phosphate, monetite.

Topics: Apatites; Calcium Phosphates; Chemical Phenomena; Chemistry, Physical; Dental Enamel; Dental Enamel Solubility; Humans; Hydrogen-Ion Concentration; Solubility; Temperature; X-Ray Diffraction

All biological calcium phosphates form in various neutral aqueous solutions containing [CaCl2] = 1 or 3 mM, [MgCl2] = 0-9 mM, [Na2HPO4] = 0.1-90 mM and NaCl (total 300 mosM) kept quiescently at 37 degrees C for 21 days. In all solutions containing 1 mM Ca and in solutions with [Ca] = 3 mM and [PO4] less than 10 mM, heterogeneous nucleation of octa-calcium phosphate (for Mg/Ca less than or equal to 1) or brushite (for Mg/Ca greater than 1) was observed; the former transforming to apatite with time. In contrast, homogeneous nucleation of an unstable amorphous calcium magnesium phosphate occurred in solutions with [Ca] = 3 mM and [PO4] greater than or equal to 10 mM, transforming to apatite, to brushite, and to whitlockite (and newberyite) depending on Mg/Ca and [PO4] values.

Topics: Apatites; Calcium Phosphates; Chemical Precipitation; Crystallization; Durapatite; Hydrogen-Ion Concentration; Hydroxyapatites; Magnesium; Magnesium Compounds; Phosphates; Solutions; X-Ray Diffraction

Selected area electron diffraction of sections and individual crystal fragments of human dental calculus has demonstrated that octacalcium phosphate, hydroxyapatite and whitlockite form the inorganic part of both supragingival and subgingival dental calculus. However, the major constituents in supragingival calculus are platelet-shaped crystals of octacalcium phosphate and needle-shaped crystals of hydroxyapatite, while bulk crystals of whitlockite is the predominant component in subgingival calculus. The subgingival samples seemed to be better crystallized than the supragingival ones. The results obtained by the electron optical and X-ray powder investigations are in good agreement.

Topics: Calcium Phosphates; Crystallization; Crystallography; Dental Calculus; Durapatite; Gingiva; Humans; Hydroxyapatites; Microscopy, Electron; X-Ray Diffraction

Topics: Calcium; Calcium Phosphates; Chemical Phenomena; Chemical Precipitation; Chemistry, Physical; Crystallization; Durapatite; Hydrogen-Ion Concentration; Hydroxyapatites; Magnesium; Microscopy, Electron, Scanning; Phosphates; Solubility

A micro-focus X-ray diffractometer was applied to a ground section of sialolith, and localization of brushite and whitlockite was found. The sialolith was composed of a central core of organic material and a layered cortex of mineral components. The major component of the mineral cortex is apatite. Brushite and whitlockite locate independently at the surface layer of the cortex.

Topics: Apatites; Calcium Phosphates; Humans; Hydroxyapatites; Male; Middle Aged; Salivary Duct Calculi; X-Ray Diffraction