Лако-красочные материалы — производство

The dentinal tooth substance exposed by the clinician in the process of cavity preparation has direct access to the sensitive pulp via the dentinal tubules and so is highly responsive to irritating effects and attacks originating from, or transferred through, the cavity-filling material. Although such effects are minimal and clinically acceptable with many of the […]

Although covered as a separate group (M2) in the FDI classification, the endodontic cements are to a large extent similar to the luting materials covered in Section II. B. One of the most frequently used cements is based on the ZOE system (see Section II. B.3) for reasons of simple and conventional application techniques and […]

Dental root treatment commonly comprises removal of the necrotic pulp or its remnants, cleaning, widening, and sterilization of the root canal, and filling of the prepared canal with core and sealing materials. Popular core materials are silver, gutta-percha, and silicon rubber points, and these are sealed in place by a cement sealer. A. Requirements The […]

The luting cements based on silicates, phosphates, ZOE, EBA, and simple methacrylate resins provide little, if any, chemical adhesion, and as pointed out before, the existing bonding forces, for the most part involving micromechanical retention, are weak. However, special biphasic resin compositions are available which, on account of the presence of both hydrophilic and hydrophobic […]

Basically composed of poly(methyl methacrylate) upon setting, the acrylic resin cements in the unfilled state are simpler, linear organic polymers. Although known in dentistry for several decades, they have not as such enjoyed much acceptance because of considerable volume shrinkage on polymerization (21 to 22%) [6] and consequent microleakage, a high coefficient of thermal expansion […]

For the development of cements of the glass ionomer (GI) type, features have been borrowed from both the polycarboxylates and the silicate cements. In the fundamental cementation process, polyacids, such as poly(acrylic acid) and acrylic-maleic or acrylic- itaconic acid copolymers, interact with inorganic cationic constituents of sodium aluminosilicate glass possessing a high Al content. The […]

Developed some 35 years ago, the polycarboxylate materials are based on polycarboxylic acids, such as poly(acrylic acid), poly(maleic acid) and various acrylic acid copolymers, and their principal setting reaction involves carboxylate salt and chelate formation with polyvalent cations, mainly Zn2+. Because of the polyvalent nature of the cations, the reaction leads to three-dimensional cross-linking. The […]

These two-part powder/liquid materials, close relatives of the ZOE cements, in the ulti­mate form are zinc chelates, resulting for the most part from reaction of ZnO with ortho — ethoxybenzoic acid: The zinc oxide-ethoxybenzoic acid (EBA) cements can thus be classified as zinc carbox — ylates in which the metal center is additionally bonded coordinatively […]

Closely related to the zinc phosphate luting cements, the silicophosphate materials are two-part bonding systems, which are mixed and applied essentially as described in the preceding section. Whereas the liquid component is a buffered aqueous phosphoric acid solution as before, the solid is a powdered mixture of a fluoride-containing, ion-leachable aluminosilicate glass and zinc oxide, […]

Luting cements based on zinc phosphate have been known for more than a century and are still in major use today. The fundamental process leading to cementation is the formation of hydrated zinc phosphate from zinc oxide and phosphoric acid: 3ZnO + 2H3PO4 + H2O! Zn3(PO4)2 • 4H2O Accordingly, the material is supplied as a […]