Different types of natural substitutes for bone tissue are available on the market, generally of animal origin. These are subjected to physical, chemical or biochemical processes before utilization as biomaterials. Calcium carbonates, particularly those produced by marine organisms (coral, mother of pearl, etc.), have been used for
many years as substitutes for bone.
The idea that coral can replace defective parts of bone comes from the similarity in the structure of some coral skeletons with cancellous bone matter allowing colonization by cells and blood vessel penetration. The exoskeleton of coral polyps constitutes blocks of calcium carbonates with regular and interconnected porosity, according to a structure specific for each species. After selecting, cleaning and shaping, these materials can be implanted in bone locations, to serve as a framework for the new bone tissue. They are degraded due to a carbonic anhydrase, thus leaving
place for newly synthesized bone tissue [GUI 95]. These materials are biocompatible and their advantage essentially lies, on the one hand in their open porosity which facilitates bone colonization and on the other hand, on their rapid resorption due to the good solubility of calcium carbonates and their enzymatic degradation. Despite good mechanical strength, this is not sufficient to allow their use in bones subjected to high mechanical stresses (load bearing bones). Moreover, their structure is fixed with the considered species and their chemical composition is not well controlled, particularly with respect to trace elements.
Mother of pearl, also composed of calcium
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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