Ceramics:
5.2.1 Inorganic Salts (Dental Cements)
Dental cements are typically formulated as powders and liquids. The powders are basic (proton acceptors) in nature while the liquids are acidic (proton donors). A viscous paste is formed when the powder and liquid are mixed. This subsequently hardens to a solid mass. The equation for the cement forming reaction can be simplified as:
XO + H2A XA + H2O
Proton acceptor Proton donor Gel-salt
Clinical usage of these cements includes temporary and permanent restoration of teeth:
• Cementing of inlays, crowns, bridges, and orthodontic brackets;
• Lining of cavities; and
• Filling of root canals.
Amongst the various inorganic salts, the glass ionomer cements are worthy to be highlighted. They are derived from aqueous polymeric acid and a glass component, which is usually a fluoroalumino silicate. The glass is obtained by fusing silica, alumina, and calcium fluoride at high temperature, followed by fine grinding the shocked-cooled molten mass. They have the dual advantages of chemical adhesion to teeth and sustained fluoride release. The lack of exotherm during setting, the absence of monomer as well as the improved release of incorporated therapeutic agents have led to the development of glass ionomer cements for biomedical applications. They have been successfully used to stabilize implanted devices and bony fragments, and likewise in the reconstruction/obliteration of bony defects in osteological and reconstructive surgery. In order to improve biocompatibility and biomechanically match glass ionomers to bone, HAIonomer (Hydroxyapatite¬Ionomer) cements are currently being developed.
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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