Ceramics used for the repair and reconstruction of diseased or damaged parts of the musculo-skeletal system, termed bioceramics, may be bioinert (alumina, zirconia), resorbable (tricalcium phosphate), bioactive (hydroxyapatite, bioactive glasses, and glass-ceramics), or porous for tissue ingrowth (hydroxyapatite-coated metals, alumina). Applications include replacements for hips, knees, teeth, tendons, and ligaments and repair for periodontal disease, maxillofacial reconstruction, augmentation and stabilization of the jaw bone, spinal fusion, and bone fillers after tumor surgery. Carbon coatings are thromboresistant and are used for prosthetic heart valves. The mechanisms of tissue bonding to bioactive ceramics are beginning to be understood, which can result in the molecular design of bioceramics for interfacial bonding with hard and soft tissues. Composites are being developed with high toughness and elastic modulus match with bone. Therapeutic treatment of cancer has been achieved by localized delivery of radioactive isotopes via glass beads. Development of standard test methods for prediction of long-term (20-year) mechanical reliability under load is still needed.

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Bioceramics: From Concept to Clinic

Apatites in biological systems

Nanocrystalline calcium phosphate ceramics in biomedical engineering

http://ntur.lib.ntu.edu.tw/bitstream/246246/127988/1/18.pdf

Thermal decomposition and reconstitution of hydroxyapatite in air atmosphere.

When soluble salts are used in the sol-gel processing of bioactive glasses, the resulting materials are not homogeneous. To produce homogeneous gel-glasses, a sol-gel method using all alkoxide precursors was developed. In this work the in vitro bioactivity of the new all-alkoxide gel-glasses is investigated. Three compositions in the system, CaO-P2O5-SiO2, were studied. Solid samples were soaked in Tris buffer and simulated body fluid (SBF), and the rate of formation of hydroxy carbonate apatite (HCA) on the surface of the glasses was measured by Fourier transform infrared spectroscopy. The solutions were analyzed before and after reaction by inductively coupled plasma. All compositions studied formed a hydroxy carbonate apatite (HCA) layer within 8 h in both test solutions. The HCA layer grew rapidly when SBF was used.

Calcium phosphate formation on sol‐gel‐derived bioactive glasses in vitro

Types of “H2O” in human enamel and in precipitated apatites are characterized using X-ray diffraction, infrared (IR) absorption spectroscopic and thermogravimetric analyses. Changes in lattice parameters (principally in the α-axis dimensions) and in the character of the IR absorption bands are correlated with weight losses at pyrolysis temperatures of 100° to 400°C and with effect of rehydration and reignition of previously ignited samples.

Racquel Z. LeGeros

Papers

Types of "H2O" in human enamel and in precipitated apatites.