The Effect of Liquid Phase Concentration on the Setting Time and Compressive Strength of Hydroxyapatite/Bioglass Composite Cement

Composite scaffolds of hydroxyapatite (HAp) nanoparticles and bioactive glass (BG) have been applied as appropriate materials for bone tissue engineering. In this study, hydroxyapatite/bioglass cement in different ratios was successfully fabricated. To prepare HAp and HAp/BG cement, synthesized HAp and HAp/BG powder were mixed in several ratios, using different concentrations of sodium hydrogen phosphate (SP) and water as the liquid phase. The liquid to powder ratio used was 0.4 mL/g. The results showed that setting time increased with BG content in the composite. The results also showed that with the addition of bioglass to the HAp structure, the density decreased and the porosity increased. It was also found that after immersion in simulated body fluid (SBF) solution, the compressive strength of the HAp and HAp/BG cements increased with BG concentration up to 30 wt.%. SEM results showed the formation of an apatite layer in all selected samples after immersion in SBF solution. At 30 wt.% BG, greater nucleation and growth of the apatite layer were observed, resulting in higher bioactivity than pure HAp and HAp/BG in other ratios.

Characterization, Thermal and Biological Properties of PCL/PLA/PEG/N-HA Composites

Initially, the use of Additive Manufacturing (AM) technology is mainly for the production of prototypes of a new invention and design. However, the AM technology had extended to the tooling industry, medical scaffolding, and direct part production. This is due to the extensive research and development carried out around the globe regardless of the material, equipment, and technology of AM. In this study, characterization and properties of PCL/PLA/PEG/Nano-HA polymer composites were investigated. Polycaprolactone (PCL), polylactic acid (PLA), polyethylene glycol (PEG), and nano-hydroxyapatite (n-HA) composites were prepared by melting and compounding the mixture using a Brabender machine. The composition of the materials was determined by previous research that it is the optimum recipe, with the ratio of PCL:PLA is 7:3 while the composition of PEG and nano-HA is 5% per hundred resin each. The temperature of the Brabender machine was set at 160°C, and the speed of the mixer was set at 30 rpm. After the mixing, the composites were characterized by using Fourier Transform Infrared Spectroscopy (FTIR) to determine the spectrum and quality of the composite mixed. Based on the spectrum, it can be verified that the characteristic of n-HA powder had been incorporated well into the PCL/PLA/PEG polymer blend. The thermal properties of the composites were investigated by using Thermogravimetry Analyzer (TGA). The results showed that the addition of n-HA lowered the initial degradation temperature and peak degradation temperature. Apparently, the addition of n- HA did not increase the degradation temperature of the composites. Furthermore, Simulated Body Fluid (SBF) test was carried out to access the bioactivity properties of the composites after the addition of n-HA. The results had proved that the addition of n-HA had triggered the growth of apatite layer on the surface of the samples treated with SBF. The growth of the apatite layer was verified by the X-ray Diffraction pattern, and the results proved the initial assumptions.

Morphological and Spectroscopic Study of an Apatite Layer Induced by Fast-Set Versus Regular-Set EndoSequence Root Repair Materials

This study aimed to evaluate the morphology and chemistry of an apatite layer induced by fast-set versus regular-set EndoSequence root repair materials using spectroscopic analysis. Holes of a 4 mm diameter were created in the root canal dentin, which were filled with the test material. Fetal calf serum was used as the incubation medium, and the samples incubated in deionized water were used as controls. The material-surface and material-dentin interfaces were analyzed after 28 days using Raman and infrared spectroscopy, scanning electron microscopy/energy dispersive X-ray, and X-ray diffraction. After incubation in fetal calf serum, both materials formed a uniform layer of calcium phosphate precipitate on their surfaces, with the dentinal interface. This precipitated layer was a combination of hydroxyapatite and calcite or aragonite, and had a high mineral maturity with the regular-set paste. However, its crystallinity index was high with the fast-set putty. Typically, both consistencies (putty and paste) of root repair material have an apatite formation ability when they are incubated in fetal calf serum. This property could be beneficial in improving their sealing ability for root canal dentin.

Synthesis of ternary bioactive glass derived aerogel and xerogel: study of their structure and bioactivity

In this work ternary bioactive glasses with the molar composition 63 % SiO2, 28 % CaO, and 9 % P2O5 have been prepared via sol-gel processing route leading to xerogel or aerogel glasses, depending on the drying conditions. Two types of drying methods were used: atmospheric pressure drying (evaporative), to produce xerogels, and supercritical fluids drying, to obtain aerogels. Both dried gels were subjected to heat-treatment at three different temperatures: 400, 600 and 800 ºC in order to the removal of synthesis byproducts and structural modifications. The resulting materials were characterized by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and differential thermal analysis (DTA), and by in vitro bioactivity tests in simulated body fluid. The influence of the drying and the sintering temperature of their structure, morphology, and bioactivity of the final products were evaluated. The results show a good bioactivity of xerogel and aerogel bioactive glass powders with the formation of an apatite layer after one day of immersion in SBF solution for aerogel bioactive glass powders and a particle size less than 10 nm. An apatite layer formed after 3 days in the case of xerogel bioactive glass powders and a particle size around 100 nm.