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Bone Health
Published in Carolyn Torkelson, Catherine Marienau, Beyond Menopause, 2023
Carolyn Torkelson, Catherine Marienau
Calcium can also be taken as hydroxyapatite, or microcrystalline hydroxyapatite concentrate, which is a bioavailable source of calcium derived from whole bone. Hydroxyapatite also contains other minerals that are naturally found in healthy bone along with the other active and supportive constituents of bone.
Surgery of the Hand
Published in Timothy W R Briggs, Jonathan Miles, William Aston, Heledd Havard, Daud TS Chou, Operative Orthopaedics, 2020
Norbert Kang, Ben Miranda, Dariush Nikkhah
The extensor tendons are retracted from over the CMC joints and soft tissue excised to expose the specific joint. Use of an image intensifier confirms that the correct joint has been identified. The joint surfaces are excised, and bone graft is inserted. The graft is harvested from the distal radius. Bone substitute (e.g. hydroxyapatite) can also be used. The joint is secured with an oblique K-wire passed through the base of the respective metacarpal and the corresponding trapezoid, capitates or hamate. The wire is buried and removed after 8 weeks.
Nanotechnological Strategies for Engineering Complex Tissues
Published in Lajos P. Balogh, Nano-Enabled Medical Applications, 2020
Tal Dvir, Brian P. Timko, Daniel S. Kohane, Robert Langer
Among the most investigated tissues in the field of tissue engineering is bone. It contains a unique nanocomposite material mainly made of inorganic hydroxyapatite nanocrystallites and a collagen-rich organic matrix [60]. Hydroxyapatite serves as a chelating agent for mineralization of osteoblasts in bone regeneration while the collagen provides mechanical support, promoting adhesion and proliferation. The crystals, 50 nm long, 25 nm wide and 2–5 nm thick, reside in the grooved regions formed by the 3D organization of the fibrils (Fig. 12.2d) [61]. In attempts to orchestrate a microenvironment that will promote the assembly of bone tissue, several groups have investigated the effect of scaffolds based on a combination of natural bone ECM and hydroxyapatite, reporting superior osteoblast adhesion, growth and stimulation for mineralization, compared with matrices without hydroxyapatite [62–64]. In the past year, scaffolds containing various shapes and sizes of hydroxyapatite particles have been fabricated and their bioactivity investigated. The researchers found that nanocomposite coated scaffold of needle-shaped hydroxyapatite particles showed the strongest osteoblast differentiation profile compared with rod and spherical shaped particles [65]. Such observations emphasize that in addition to the dimension scale of the particles, their specific topography is of great importance for the interaction with cells.
Nano-hydroxyapatite use in dentistry: a systematic review
Published in Drug Metabolism Reviews, 2020
Ioana Roxana Bordea, Sebastian Candrea, Gabriela Teodora Alexescu, Simion Bran, Mihaela Băciuț, Grigore Băciuț, Ondine Lucaciu, Cristian Mihail Dinu, Doina Adina Todea
Hydroxyapatite is a calcium phosphate compound with the molecular formula Ca10 (PO4) OH2 and a calcium-to-phosphorus ratio of 1:67. There are other forms of calcium phosphate in nature but hydroxyapatite is the most stable and the least soluble of them. Hydroxyapatite is a material with good biocompatibility and bioactivity. Biocompatibility is given by appropriate response from the host during the performance of a material, whereas bioactivity refers to the material’s ability to adhere to a living tissue. However, the disadvantages of this material come from its porous structure and poor mechanical properties (Crisan et al. 2015). The nanoscale ranges from 1 to 100 nm. From these dimensions derives a distinct activity of the particles. Their large reaction surface and small size enhance the hydration of the material, thus gaining better physical and chemical characteristics (Ramesh 2018).
Ultrastructural analysis of the submandibular sialoliths: Raman spectroscopy and electron back-scatter studies
Published in Ultrastructural Pathology, 2020
Dmitry Tretiakow, Andrzej Skorek, Jacek Ryl, Joanna Wysocka, Kazimierz Darowicki
Similar results are also described by other authors. The powder and single-crystal electron diffraction patterns demonstrated that Ca- and P-based electrolytes tended to crystallize in a hexagonal crystal structure close to that of hydroxyapatite. The presence of Mg in the mineralized regions suggests the formation of whitlockite, although the phase has a minor presence and could not be detected by the powder and single-crystal electron diffraction experiments.29,31 The study demonstrates that hydroxyapatite is not at all the main constituent, the majority of them are constructed with other apatites, among them are amorphous carbonated calcium phosphate and carbonated apatite and whitlockite. The inner part of sialoliths is thinly stratified by apatites and/or proteins according to their history of creation and their growth.32
Intraoral appliances for in situ oral biofilm growth: a systematic review
Published in Journal of Oral Microbiology, 2019
Nizam Abdullah, Farah Al-Marzooq, Suharni Mohamad, Normastura Abd Rahman, Hien Chi Ngo, Lakshman Perera Samaranayake
Enamel, when used as a substrate, could be either of human or bovine origin, and is preferably employed for evaluating cariogenic biofilm development [57]. However, in research related to endodontic therapy, both human [58] and xenogenic [59] dentine were popular substrates. Nevertheless, many workers have used synthetic substrates such as polymethyl methacrylate, glass and hydroxyapatite as substrates as these provide standardized and uniform surface features compared with enamel and dentine. Also, it is well known that oral bacteria adhere well to glass surfaces and develop profuse biofilms [60]. Many workers have also used hydroxyapatite in the form of either beads [61,62] or discs [63,64] for AGOB development. Hydroxyapatite represents the chemical and structural architecture mimicking dental tissues, thereby avoiding the need to use human enamel/dentine. Yet, other workers have used polystyrene as their substrate surface for studying biofilm formation. Loo et al. used polystyrene substrate to study Streptococcus gordonii biofilm and particularly to identify the genes that code for biofilm phenotypes [65]. Others applied 96-well polystyrene plates to investigate the effects of antibiotics on biofilm formation [66].