Properties of calcium silicate-monobasic calcium phosphate materials for endodontics containing tantalum pentoxide and zirconium oxide

Novel root-end filling materials are composed of tricalcium silicate (TCS) and radiopacifier as opposed to the traditional mineral trioxide aggregate (MTA) which is made up of clinker derived from Portland cement and bismuth oxide. The aim of this research was to characterize and investigate the hydration of a tricalcium silicate-based proprietary brand cement (Biodentine™) and a laboratory manufactured cement made with a mixture of tricalcium silicate and zirconium oxide (TCS-20-Z) and compare their properties to MTA Angelus™. The materials investigated included a cement containing 80% of TCS and 20% zirconium oxide (TCS-20-Z), Biodentine™ and MTA Angelus™. The specific surface area and the particle size distribution of the un-hydrated cements and zirconium oxide were investigated using a gas adsorption method and scanning electron microscopy. Un-hydrated cements and set materials were tested for mineralogy and microstructure, assessment of bioactivity and hydration. Scanning electron microscopy, X-ray energy dispersive analysis, X-ray fluorescence spectroscopy, X-ray diffraction, Rietveld refined X-ray diffraction and calorimetry were employed. The radiopacity of the materials was investigated using ISO 6876 methods. The un-hydrated cements were composed of tricalcium silicate and a radiopacifier phase; zirconium oxide for both Biodentine™ and TCS-20-Z whereas bismuth oxide for MTA Angelus™. In addition Biodentine™ contained calcium carbonate particles and MTA Angelus™ exhibited the presence of dicalcium silicate, tricalcium aluminate, calcium, aluminum and silicon oxides. TCS and MTA Angelus™ exhibited similar specific surface area while Biodentine™ had a greater specific surface area. The cements hydrated and produced some hydrates located either as reaction rim around the tricalcium silicate grain or in between the grains at the expense of volume containing the water initially present in the mixture. The rate of reaction of tricalcium calcium silicate was higher for Biodentine™ than for TCS-20-Z owing to its optimized particle size distribution, the presence of CaCO₃ and the use of CaCl₂. Tricalcium calcium silicate in MTA hydrated even more slowly than TCS-20-Z as evident from the size of reaction rim representative of calcium silicate hydrate (C-S-H) around tricalcium silicate grains and the calorimetry measurements. On the other hand, calcium oxide contained in MTA Angelus™ hydrated very fast inducing an intense exothermic reaction. Calcium hydroxide was produced as a by-product of reaction in all hydrated cements but in greater quantities in MTA due to the hydration of calcium oxide. This lead to less dense microstructure than the one observed for both Biodentine™ and TCS-20-Z. All the materials were bioactive and allowed the deposition of hydroxyapatite on the cement surface in the presence of simulated body fluid and the radiopacity was greater than 3mm aluminum thickness. All the cement pastes tested were composed mainly of tricalcium silicate and a radiopacifier. The laboratory manufactured cement contained no other additives. Biodentine™ included calcium carbonate which together with the additives in the mixing liquid resulted in a material with enhanced chemical properties relative to TCS-20-Z prototype cement. On the other hand MTA Angelus™ displayed the presence of calcium, aluminum and silicon oxides in the un-hydrated powder. These phases are normally associated with the raw materials indicating that the clinker of MTA Angelus™ is incompletely sintered leading to a potential important variability in its mineralogy depending on the sintering conditions. As a consequence, the amount of tricalcium silicate is less than in the two other cements leading to a slower reaction rate and more porous microstructure. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The aim of the present study was to evaluate the physicochemical properties of a bioceramic root canal sealer, Endosequence BC Sealer. Radiopacity, pH, release of calcium ions (Ca(2+)), and flow were analyzed, and the results were compared with AH Plus cement.

The carbonate and phosphate vibrational modes of different synthetic and biological carbonated apatites were investigated by Raman microspectroscopy, and compared with those of hydroxyapatite. The nu1 phosphate band at 960 cm-1 shifts slightly due to carbonate substitution in both A and B sites. The spectrum of type A carbonated apatite exhibits two nu1 PO43- bands at 947 and 957 cm-1. No significant change was observed in the nu2 and nu4 phosphate mode regions in any carbonated samples. The nu3 PO43- region seems to be more affected by carbonation: two main bands were observed, as in the hydroxyapatite spectrum, but at lower wave numbers. The phosphate spectra of all biominerals apatite were consistent with type AB carbonated apatite. In the enamel spectrum, bands were observed at 3513 and at 3573 cm-1 presumably due to two different hydroxyl environments. Two different bands due to the carbonate nu1 mode were identified depending on the carbonate substitution site A or B, at 1107 and 1070 cm-1, respectively. Our results, compared with the infrared data already reported, suggest that even low levels of carbonate substitution induce modifications of the hydroxyapatite spectrum. Increasing substitution ratios, however, do not bring about any further alteration. The spectra of dentine and bone showed a strong similarity at a micrometric level. This study demonstrates the existence of acidic phosphate, observable by Raman microspectrometry, in mature biominerals. The HPO42- and CO32- contents increase from enamel to dentine and bone, however, these two phenomena do not seem to be correlated.