2- Poly(methyl methacrylate):
In 1943, a protocol for the chemical production of bone cement was established in the companies of Degussa and Kulzer. A lot of research and development work has been done since then. In 1958, Sir John Charnley first succeeded in femoral prosthesis in the femur with self-polymerizing PMMA. Since then, the PMMA bone cement (now known simply as bone cement) emerged as one of the premier synthetic biomaterials in contemporary orthopedics. It is currently the only material used for cemented arthroplasties to the contiguous bones.
A typical PMMA bone cement consists of two parts, a solid part in a packet and a liquid part in a vial (See Table 11. 2 ) . When the two parts are mixed before use, the viscosity of mixture will gradually increase and become the dough in a few minutes. The dough will harden in another few minutes. This process actually involves a MMA polymerization process. Polymer PMMA is used to minimize the shrinkage and the heat release caused by the polymerization of monomer MMA, because the pure MMA will exhibit a shrinkage of about 21% due to the change of density and the heat release which can cause the temperature to increase to over 100°C .
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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