Wet chemical methods are the most widely used routes for BIPHASIC CALCIUM PHOSPHATE bioceramics synthesis in which control of synthesis condition and reaction factors are very important. To predict and control the synthesis condition, mathematical models can be used. Artificial neural networks are computational tools inspired by the nervous systems of living organisms that help us to get better understanding about the complicated problems.Powders were synthesized using aqueous solution containing different CALCIUM/phosphorus ratio. HNO3 and NH4OH were used to adjust the pH of the solution mixture during the process. The precipitation was calcined at 1100oC for one hour. The chemical composition and Ca/P ratio were determined by inductively coupled plasma atomic emission spectroscopy. Phase identification of powders and evaluation of the functional groups of specimens were carried out by X-ray diffraction and Fourier transform infrared spectroscopy respectively.Four three-layered feed forward networks with ten neurons in the hidden layer, linear sigmoid stimulation and Levenberg-Marquardt learning algorithm were trained using data obtained from the experiments designed in four different patterns. The best result was obtained with the network consists of 80% training process, 15% validation process and 5% testing process samples by changing number of samples in each step. To ensure optimal performance of four networks, each network was studied using four new data. The predicted results show a good comparison with those obtained experimentally.

Background: The aim of this study was to make a bioactive bone cement based on poly (methyl methacrylate) (PMMA) with suitable mechanical properties. Methods: PMMA has been modified by fabricating a composite consisting of BIPHASIC CALCIUM PHOSPHATE (BCP) 68 wt%, PMMA 31 wt% and graphene (Gr) 1 wt% (PMMA/BCP/Gr), 32 wt% of PMMA, and 68 wt% of BCP (PMMA/BCP) and pure PMMA by milling, mixing with monomer liquid, and casting. The modified cements were evaluated regarding mechanical properties, bioactivity, degradation rate, and biocompatibility. Results: The scanning electron microscopy (SEM) images of hydroxyapatite (HA) formed on samples surface after 28 days of immersion in simulated body fluid (SBF) demonstrated that bioactivity was obtained due to the addition of BCP, and the degradation rate of the cement was enhanced as well. Investigations of mechanical properties revealed that BCP increased the elastic modulus of PMMA more than 1. 5 times, but predictably decreased elongation. The addition of 1 wt% Gr increased elongation and yield strength from 16. 39% ± 1. 02% and 61. 67 ± 1. 52 Mpa for PMMA/BCP to 35. 18% ± 2. 42% and 78. 40 ± 2. 06 Mpa for PMMA/BCP/Gr, respectively. MG63 cells survival and proliferation improved from 127. 55% ± 7. 03% for PMMA to 201. 41% ± 10. 7% for PMMA/BCP/Gr on Day 4 of culture. Conclusion: According to the obtained results of mechanical and biological tests, it seems that new PMMA/BCP/Gr bone cement has a potentiality for usage in orthopedic applications.

BIPHASIC CALCIUM PHOSPHATEs (BCPs) of hydroxyapatite/OctaCALCIUM PHOSPHATE (HA/OCP) with mixed morphology of whisker/spherulite were synthesized and characterized by the precipitationhydrolysis method in an acidic solution containing CALCIUM and PHOSPHATE ions and carbonyl diamide. The synthesized solutions were refluxed at 90 °C for 3 or 4 days. The crystalline structure of products was determined by X−ray diffraction (XRD). Fourier transformed infra-red spectroscopy (FTIR) was used to characterize the absorption spectrum. The morphology of products was evaluated by scanning electron microscopy (SEM). The results showed the presence of carbonyl diamide (CA) in synthesized solutions with a Ca/P molar ratio of 1.67 led spherulites to be formed and then whiskers such that an increase of CA concentration was associated with an increase in whisker length and a decrease in spherulite diameter. The concentration of CA was more effective than CALCIUM concentration and Ca/P molar ratio on the size of whiskers. The increase of reaction time may give rise to change the morphology of whiskers to lath-like one (increasing the whisker width) and spherulites from flowerlike forms to microspheres. The appropriate chitosan-based composite scaffolds containing various amounts of CALCIUM PHOSPHATE phase with a homogenous microstructure of 65−80 porosity are percent and pore size of 50-400 μm could be produced for hard tissue engineering applications. The porosity of scaffolds was decreased with increasing the CALCIUM PHOSPHATE phase.

Introduction: This study aimed to investigate the effects of photobiomodulation (PBM) therapy associated with BIPHASIC CALCIUM PHOSPHATE on calvaria critical defects in rats. Methods: Forty-eight (90 days old) adult male rats (Rattus norvegicus, Albinus variation, Wistar) received critical defects of 5 mm in diameter, which were made on their skull, and they were randomly assigned into the following groups: C-blood clot, B-BIPHASIC CALCIUM PHOSPHATE, L-photobiomodulation therapy, and B + L-BIPHASIC CALCIUM PHOSPHATE + photobiomodulation therapy. A low-level a gallium aluminum arsenide (GaAlAs) laser was applied in a single dose during surgery, in a wavelength of 660 nm and total energy density of 45 J/cm2. On 30th and 60th days, the animals from each group were euthanized. Histological and histomorphometric analyses were performed. Results: In 30 days, almost all specimens (C, L, B and B + L) showed bone neoformation areas in regions near the borders of the surgical defect. In 60 days, in many specimens (C, L, B, B + L), it was possible to see a narrow neoformed bone structure along almost the whole extension of the surgical defect, though it was thinner than the original calvary bone. Data were recorded as mean ±,standard deviation, and after normality was tested, a suitable statistical test was applied (α,= 5%). On day 60, there was a statistically significant difference when comparing the proportion of neoformation area between group L (0. 52% ±,0. 13) and group B + L (0. 20% ±,0. 08). Group L showed a difference compared with all the groups when we compared the remaining distance between the edges of neoformed bone (C × L, P = 0. 0431,B × L, P = 0. 0386,L × B + L, P = 0. 0352), demonstrating a great defect closure. Conclusion: Our findings suggest that although BIPHASIC CALCIUM PHOSPHATE exerts some osteogenic activity during bone repair, PBM therapy is not able to modulate this process.

CALCIUM PHOSPHATE cements (CPCs), using B-triCALCIUM PHOSPHATE (ß-TCP, Ca3 (P04)2), diCALCIUM PHOSPHATE (DCP, CaHP04), CALCIUM carbonate (Ca CO3), and hydroxylapatite (HAp, Ca10(P04)6(OH)2) as powder cement and disodium hydrogen PHOSPHATE (Na2HP04) solution as liquid component were prepared. After mixing the powder and liquid constituents, injectable and self-setting CALCIUM PHOSPHATE cements (CPCs) were prepared with different liquid to powder ratios (UP) that formed hydroxylapatite and ß-triCALCIUM PHOSPHATE as the only end products, which were characterized by FTIR, XRD and SEM techniques. The results showed that, at certain concentration of Na2HP04 (6 wt%), the initial and final setting times decreased by decreasing the UP ratio.

In order to prepare spherical CALCIUM PHOSPHATE granules for biomedical applications, several methods have been investigated by the researchers. In this study, the spherical granules with a potential for tissue growth and drug carrying were prepared by a process, known as the rotary oil method, which was based on the hydrophilic and olephobic features of CALCIUM PHOSPHATE slurry. This process is a simple and fast method to produce the granules with a controllable size and porosity suitable for different applications in the biomedical field. The process was optimized by Taguchi method using a L9 orthogonal array. Four parameters including stirring rate of oil, oil temperature, needle diameter, and weight ratio of gelatin to water, each of them in three levels, were used. The starting CALCIUM PHOSPHATE powder was a CALCIUM-deficient hydroxyapatite which was synthesiezed by an alkaline hydrolysis method. The sintered granules and starting podwer were characterized by XRD and SEM. The rotary oil method produced granules with a size in the range of 120-1580 μ m and porosity 35-45% suitable for a range of biomedical applications.