Assessment of the Effects of Si Addition to a New TiMoZrTa System

Ti-based alloys are widely used in medical applications. When implant devices are used to reconstruct disordered bone, prevent bone resorption and enhance good bone remodeling, the Young’s modulus of implants should be close to that of the bone. To satisfy this requirement, many titanium alloys with different biocompatible elements (Zr, Ta, Mo, Si etc.) interact well with adjacent bone tissues, promoting an adequate osseointegration. Four new different alloys were obtained and investigated regarding their microstructure, mechanical, chemical and biological behavior (in vitro and in vivo evaluation), as follows: Ti20Mo7Zr15Ta, Ti20Mo7Zr15Ta0.5Si, Ti20Mo7Zr15Ta0.75Si and Ti20Mo7Zr15TaSi. 60 days after implantation, both in control and experimental rabbits, at the level of implantation gap and into the periimplant area were found the mesenchymal stem cells which differentiate into osteoblasts, then osteocytes and osteoclasts which are involved in the new bone synthesis and remodeling, the periimplant fibrous capsule being continued by newly spongy bone tissue, showing a good osseointegration of alloys. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay confirmed the in vitro cytocompatibility of the prepared alloys.

Effect of implants of hydroxyapatite with tricalcium phosphates alloyed with Si on histomorphological and biochemical parameters in cases of bone defects of rabbits

Complex comminuted fractures are accompanied by development of bone defects and loss of reparative potential of the bone tissue in the region of the trauma. This brings the necessity of using implants with optimum osteoconductive and osteointegration properties. The objective of the study was determining the condition of biochemical bone markers and peculiarities of histomorphological changes under the influence of ceramic hydroxyapatite (HA) implants with various physical-chemical properties in the conditions of diaphyseal bone defects in rabbits. We composed control and experimental groups of rabbits with 10 individuals in each with diaphyseal bone defects (3 mm) of the radial bones formed under general anesthesia. In one experimental group, they were filled with granules of hydroxyapatite with α-tricalcium phosphate, and in the second group – with β-tricalcium phosphate, alloyed with Si. In the control rabbits, the defects healed under a blood clot. Blood was analyzed on the 3rd, 7th, 14th, 21st and 42nd days, and as reference we used biochemical parameters of blood of clinically healthy rabbits (n = 10). Bone biopsied materials were taken on days 21–42 under general anesthesia. When using hydroxyapatite with β-tricalcium phosphate, alloyed with Si, we determined early intensification of the levels of nitrogen oxide, angiogenesis and development of bone regenerate in conditions of shortening of inflammatory resorption phase, which was verified according to the level of tartrate-resistant acid phosphatase. According to the level of bone isoenzyme of alkaline phosphatase in the blood serum of animals of the control group, the reparative osteogenesis developed slowly and peaked on day 42, whereas in animals implanted with α-tricalcium phosphate, its development peaked peaked on days 14–42, and when using Si-alloy – on days 7–14. Histomorphologically, on the 21st day, in the case of replacement of bone defect with hydroxyapatite with α-tricalcium phosphate, coarse-fibered type of bone regenerate developed with no dense contact with the elements of the regenerate, while spongy bone trabeculae occurred when hydroxyapatite was applied with β-tricalcium phosphate alloyed with Si, and the control rabbits were observed to be in the stage of cartilaginous callus. On the 42nd day, under the influence of implants of hydroxyapatite with α-tricalcium phosphate, the spongy bone tissue transformed into compact tissue with further mineralization. With implants alloyed with Si, there occurred compact bone tissue, and bone regenerates of the control animals were regions of coarse-fibered and spongy bone tissue without dense contact with the parent bone. This study revealed that hydroxyapatite with β-tricalcium phosphate alloyed with Si had notable osteoinductive and osteointegrating properties, as indicated by early angiogenesis and osteoblast reaction, positive dynamics of the marker biochemical parameters with faster and better development of bone regenerate as spongy bone trabeculae.

In Vitro Evaluation of the Allogeneic Bone Matrix Effect on the Adipose Mesenchymal Stromal Cells Characteristics in Combined Tissue Engineering

The aim of the study was to evaluate in vitro the effect of native and deproteinized compact and spongy allogenic bone matrices on the characteristics of adipose mesenchymal stromal cells (ASC) in combined tissue engineering.Material and Methods. 24 samples of native and deproteinized compact and spongy bone were examined, which were exposed to mechanical treatment, modeling, followed by sterilization of the samples by ionizing radiation and bacteriological control of sterilization. Some of the samples underwent deproteinization. The characterized cultures of human ASC were used as test cultures to assess the interaction with the bone samples. The Cytation-5 fluorescent imager and Hoechst 3334 fluorochromes (BD Pharmingen™) and calcein (Calcein AM, BD Pharmingen™) were used to characterize the degree of adhesion, migration, and viability of ASC on bone matrix samples. Matrix cytotoxicity was evaluated by MTT assay on days 1 and 7 of extraction.Results. The bone matrix samples are characterized by the absence of cytotoxicity (rank 1). ASC demonstrated good adhesion and migration on any surface of the bone matrix and preservation of cell viability during 7 days of observation. Nuclei sizes of the cells adhered to the deproteinized bone matrix of the spongy structure increased by 25–30% compared to other samples. The cells on deproteinized bone matrix had greater size (the size of the cells from nuclei 8.8 to 11.5 μm, the average size of cells nuclei from an 86.3 μm to 129,0 μm, the average perimeter of the cells nuclei from 30.7 μm to 40.7 μm) than in the native bone matrix samples.Conclusion. The results of the study of various allogeneic bone matrices demonstrate that deep purification of the bone matrix determines the absence of cytotoxicity and the most favorable conditions for the adhesion, migration, proliferation and viability of ASC. Also makes it possible to use tissue engineering based on bone matrices of different structures. Deproteinized spongy bone matrices are best suited for this purpose.

Finite Element Analysis on All on Four Implant Screw Retained Mandibular Fixed Prosthesis. (Material Selection Role)

Aim: to indicate the importance of adequate selection of all on four-fixed implant supported hybrid mandibular prosthesis material to reduce bone stresses. Materials and methods: one three-dimensional simplified geometric model, for bone and fixed prosthesis, was created by using engineering CAD/CAM software. On the other hand, implant system manufacturer data gave sufficient geometrical data to model it exactly. The modelled part was transferred to ANSYS for assembly, meshing, and analysis. Three overlying materials were tested; Acrylic, Polycarbonate, and Zirconia above the cobalt chromium bar. The lowest area of the cortical bone was set to be fixed in place as boundary condition. While unilaterally load of 250N was applied vertically on central fossa of first and second molars as two loading cases. Results: changing overlying material resulted in, cortical bone and implant complex receiving Von Mises stress in sequence with material rigidity. The more rigid the overlying material the less bone stresses with first molar loading, while, opposite trend (sequence) appeared with second molar loading. On the other hand, bar, coping, screws, mucosa, and spongy bone deformations and stresses decreased with increasing overlying material rigidity. Where, all the model components showed stresses and deformations within the physiological limits. Conclusions: More rigid overlying material is recommended to reduce stresses on bar, coping, screws, mucosa, and spongy bone. Overlying material selection for cortical bone and implant complex is extremely tricky. That it showed same behaviour as other soft tissues with applying load close to the bar (short cantilever arm), then inverted behaviour with shifting the applied load away from first to second molar (increasing cantilever arm).

Anatomy of Trabeculae Lumbar Vertebrae On a Bats (Megachiroptera)

Bats are the only mammals that can fly. Because of their ability to fly, making the tension received by the bat's spine comes from the front and back.Spongy bone, also known as cancellous bone or trabecular bone, is a very porous type of bone found in animals. It is highly vascularized and contains red bone marrow. Spongy bone is usually located at the ends of the long bones (the epiphyses), with the harder compact bone surrounding it. It is also found inside the vertebrae, in the ribs, in the skull and in the bones of the joints. Spongy bone is softer and weaker than compact bone, but is also more flexible. It is characterized by a lattice-like matrix network called trabeculae (Latin for little beam) that gives it its spongy appearance. Observation of trabeculae can be done by removing the flesh, muscles, and all the tissues attached to the lumbar vertebrae bone. Then the lumbar vertebrae was sanded and to know the anatomy of the trabeculae, it was done by observing the lumbraris vertebrae using a binocular microscope and taking pictures using a camera. Then the structure is analyzed. The observations showed that the anatomical structure of the lumbar vertebrae trabeculae in bats are stressed by tension must be withstood, a ligament being as strong for its weight.

BIOMECHANICAL MODELING OF ELASTIC PROPERTIES OF BONE TISSUE

An original method for studying the morphometric characteristics of spongy bone tissue was proposed. Using this method the distribution of the density of the spongy bone tissue of the distal metaepiphysis of the radius was studied. A decrease in the content of spongy bone tissue along the longitudinal axis of the bone has been experimentally proved. Modeling the mechanical properties of spongy bone tissue, according to the known versions of models for the elastic modulus of discontinuous media, makes it possible to calculate the behavior of bone tissue in conditions of various types of interaction. The comparison of the elastic moduli obtained according to our data with the results of other researchers has shown their comparability.

Seat of vata as majja and majja as brain

In Ayurveda ,vata is one among the three basic humors that plays a major role in balancing the health. Most of the vata disorders discussed in Ayurveda are being diagnosed under neurological disorders in modern medicine . It is a known fact that vata has predominance of vayu and akasha mahabhuta having dual properties of sound (shabda) and touch (sparsh), which is one of the characteristic function of the brain. Majja, one of the sapta dhatus is located inside the bones. The femoral bone has the largest quantity of majja as compared to other bones, hence we can say that porosity of femur or femoral bone , is nothing but seat of vata and there is a good porosity within cranial cavity (spongy bone) where the majja (brain) is located, proving that there is a vatasthana . Hence an attempt has been made to understand the seat of vata as majja and majja as brain.