silicon and calcium-phosphate--monobasic--anhydrous

The use of bone substitutes in the field of facial plastic and reconstructive surgery is well established. Because of the complexity of the anatomy in the head and neck region, reconstruction and augmentation of this area pose a challenge to the surgeon. In addition, the shortcomings of autogenous bone, such as resorption and donor site morbidity, have led to the need for alloplastic implants in the field of facial plastic surgery. Multiple alloplastic implants are currently in use today; however, those compounds that contain calcium, silicon, and carbon have been examined more closely in this article. This is because of their ability to osseointegrate and osseoconduct with surrounding fibro-osseous tissue, as well as demonstrate a higher immunogenic tolerance by the human body. The discussion of each compound includes a description of its composition and structure, the advantages and shortcomings of the material, and its current uses in the field of facial plastic and reconstructive surgery. With a better understanding of the available alloplastic implants, the surgeon can make a more informed decision as to which implant would be most suitable in a particular patient.

Topics: Bone Morphogenetic Protein 3; Bone Morphogenetic Proteins; Bone Regeneration; Bone Substitutes; Calcium Carbonate; Calcium Phosphates; Calcium Sulfate; Ceramics; Craniotomy; Glass Ionomer Cements; Humans; Plastic Surgery Procedures; Polyethylenes; Silicon; Skull

Zinc (Zn) enhances bone formation with mineralization and is an essential element of osteoblastic proliferation. Silicon (Si) is important in apatite formation coupled with the promotion of osteogenesis. The primary focus of this work was the assessment of the bone healing capacity of calcium phosphate cements (CPC) composed of Zn- and Si-incorporated β-tri calcium phosphate (TCP) and mono calcium phosphate mono hydrate (MCPM). Zn- and Si-incorporated β-TCP was synthesized through a sol gel process with varying amounts of Zn: (3, 6, or 9% w/w) and 15% w/w Si. Fabricated CPC samples were characterized by scanning electron microscopy, setting time, injectability, compressive strength and initial pH change with time. Compositional analysis and the effects of Zn and Si on cellular interaction were evaluated by energy dispersive X-ray spectroscopy mapping, viability determination and F-actin assay. The data were used to optimize the CPC formulation. The efficacy of bone healing was investigated via implantation into critical sized rabbit femoral condyle defects for 4 and 8 weeks. CPC cement with 6% (w/w) Zn content was the best candidate for faster bone healing (bone to tibial volume ratio in 8 weeks: 22.78% ± 0.02). Significantly faster degradation was also revealed. Bone healing was significantly delayed when CPC cement with 9% (w/w) Zn was used. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 260-271, 2017.

Topics: Animals; Bone Cements; Bone Regeneration; Calcium Phosphates; Cell Line; Femur; Mice; Rabbits; Silicon; Zinc

A dry-etch spark ablation method was used to produce calcium disilicide (CaSi2/Si) layers on silicon surfaces, and their biomineralization under zero bias was followed by means of scanning electron microscopy, X-ray energy dispersive analysis, and Raman spectroscopy. CaSi2/Si wafers are bioinert at 25 degrees C and bioactive at 37 degrees C. Mechanistic insights regarding biomineralization were derived from an analysis of film growth morphology and chemical composition after various soaking periods in standard simulated body fluid (SBF). Changes in CaSi2/Si calcification behavior as a function of reaction temperature and pH, SBF concentration, and various surface modification processes were also employed for this purpose. During CaSi2/Si calcification under zero bias, calcium phosphate (CaP) growth is strongly dependent on the structural degradation of CaSi2/Si grains. Surface silanol groups, initially present on the as-prepared material, cannot induce CaP nucleation, which begins only upon delamination of CaSi2/Si layers. The calcium phosphate phases, which are present during various growth stages, possibly include a combination of Mg-substituted whitlockite, monetite, and tricalcium phosphate.

Topics: Biocompatible Materials; Body Fluids; Calcification, Physiologic; Calcium Compounds; Calcium Phosphates; Crystallography, X-Ray; Electrochemistry; Hydrogen-Ion Concentration; Materials Testing; Microscopy, Electron, Scanning; Silicon; Silicon Compounds; Spectrum Analysis, Raman; Surface Properties; Temperature

The growth of known biologically-relevant mineral phases on semiconducting surfaces is one strategy to explicitly induce bioactivity in such materials, either for sensing or drug delivery applications. In this work, we describe the use of a spark ablation process to fabricate deliberate patterns of Ca(10)(PO4)6(OH)2 on crystalline Si (calcified nanoporous silicon). These patterns have been principally characterized by scanning electron microscopy in conjunction with elemental characterization by energy dispersive x-ray analysis. This is followed by a detailed comparison of the effects of fibroblast adhesion and proliferation onto calcified nanoporous Si, calcified nanoporous Si derivatized with alendronate, as well as control samples of an identical surface area containing porous SiO2. Fibroblast adhesion and proliferation assays demonstrate that a higher density of cells grow on the Ca3(PO4)2/porous Si/SiO2 structures relative to the alendronate-modified surfaces and porous Si/SiO2 samples.

Topics: Biosensing Techniques; Calcium Phosphates; Cell Division; Cell Survival; Electron Probe Microanalysis; Fibroblasts; Microscopy, Electron, Scanning; Nanotechnology; Silicon

Upon implantation, bioactive glass undergoes a series of reactions that leads to the formation of a calcium phosphate-rich layer. Most in vitro studies of the changes that occur on the surface of bioactive glass have employed the use of buffer solutions with compositions reflecting the ionic composition of interstitial fluid. Although these studies have documented the physical and chemical changes associated with bioactive glass immersed in aqueous media, they do not reveal the effect of serum proteins and cells that are present at the implantation site. In the present study, we document, using atomic force microscopy (AFM) and Rutherford backscattering spectrometry (RBS), significant differences in the reaction layer composition, thickness, morphology, and kinetics of formation arising from the presence of serum proteins. The data reveal that the uniform and rapid adsorption of serum proteins on the surface may serve to protect the surface from further direct interaction with the aqueous media, slowing down the transformation reactions. This finding is in agreement with previous studies that have shown that the presence of serum proteins significantly delays the formation of hydroxyapatite at the surface of bioactive glass. These data also support the hypothesis that initial reaction layers in vivo interact with cells in order to produce the tissue-bioactive glass interface typically observed on ex vivo specimens.

Topics: Alpha Particles; Biocompatible Materials; Blood Proteins; Calcium; Calcium Phosphates; Ceramics; Chemical Phenomena; Chemistry, Physical; Crystallization; Culture Media, Serum-Free; Durapatite; Glass; Immersion; Materials Testing; Microscopy, Atomic Force; Nephelometry and Turbidimetry; Phosphorus; Scattering, Radiation; Silicon; Solutions; Spectrum Analysis; Surface Properties

The kinetics of dissolution of pulsed laser deposited crystalline and amorphous thin films of hydroxyapatite on silicon substrates were measured at 37 degrees C and a pH value of 6.5 using the dual constant composition method. Solutions in which the pulsed laser deposited films were pre-conditioned (0.15 M NaCl) remained undersaturated or slightly supersaturated with respect to hydroxyapatite after equilibrium was reached, indicating only a very small coating release and the absence of re-precipitation on the surfaces. The amorphous films released more calcium and phosphate during pre-conditioning than the more crystalline films. Dual constant composition dissolution rates decreased as film crystallinity increased. The film with the lowest dissolution rate (approximately one sixth that of a crystalline film deposited using a hydroxyapatite powder target) was fabricated using a human tooth as the laser target. During pre-conditioning of plasma-sprayed coatings, more calcium and phosphate were released than for pulsed laser deposited films, and dual constant composition dissolution rates were much higher.

Topics: Calcium Phosphates; Hydrogen-Ion Concentration; Hydroxyapatites; Lasers; Silicon; Solubility; Temperature; X-Ray Diffraction