Advanced Materials Based on Nanosized Hydroxyapatite

The development of new materials based on hydroxyapatite has undergone a great evolution in recent decades due to technological advances and development of computational techniques. The focus of this review is the various attempts to improve new hydroxyapatite-based materials. First, we comment on the most used processing routes, highlighting their advantages and disadvantages. We will now focus on other routes, less common due to their specificity and/or recent development. We also include a block dedicated to the impact of computational techniques in the development of these new systems, including: QSAR, DFT, Finite Elements of Machine Learning. In the following part we focus on the most innovative applications of these materials, ranging from medicine to new disciplines such as catalysis, environment, filtration, or energy. The review concludes with an outlook for possible new research directions.

Study of nanosized hydroxyapatite material annealing at different retention times

The aim of the study was to investigate the influence of low heating temperatures with two different retention times to optimize the process for obtaining nanosized hydroxyapatite material that can possibly be used in the fields of biology and pharmacy. Nanosized hydroxyapatite was successfully obtained by wet chemical precipitation. The annealing of the material performed at 300 oC with two different retention times i.e. 3 and 6 hours in air atmosphere. Low annealing temperature with extended retention time was selected in terms to reduce energy consumption. FTIR spectroscopy was used to confirm characteristic vibrational bands of hydroxyapatite samples, and presence of carbonate bands of hydroxyapatite annealed for 3h and 6h. X-Ray powder diffraction analysis were used to examine phase composition, determine the size of unit cells and crystallite sizes, and SEM-EDS methods were used to obtain particle size and arrangement also grain growth morphology and confirmed the presence of calcium, phosphorous oxygen and carbonate peaks. The results show that different retention time has influence on particle growth as well as unit cell parameters and crystallite sizes changes of hydroxyapatite material

The effect of calcinated hydroxyapatite and magnesium doped hydroxyapatite as fillers on the mechanical properties of a model BisGMA/TEGDMA dental composite initially and after aging

The aim of this study was to investigate the possibility of modifying model BisGMA/TEGDMA dental composite by substituting 10 wt. % of conventional glass fillers with bioactive fillers based on calcinated nanosized hydroxyapatite (HAp) and Mg doped hydroxyapatite (Mg-HAp). HAp and Mg-HAp powders were synthesized hydrothermally. Mechanical properties: hardness by Vickers (HV) and flexural strength (Fs) were tested initially and after being stored for 28 days in simulated body fluid (SBF). The experimental composites with HAp and Mg-HAp particles showed no statistically significant difference in HV compared to the control (p>0.05) either initially or after storage. Although mean Fs values of modified composites tested initially were lower (62 MPa) than those of the control (72 MPa), after 28 days of storage in SBF Fs values were greater for modified composites (42 MPa control sample, 48 MPa HAp and Mg-HAp samples). In vitro bioactivity of BisGMA/TEGDMA composites with HAp and Mg-HAp particles after 28 days in SBF was not detected. Keywords: hydroxyapatite; magnesium; dental composite; mechanical properties;