Лако-красочные материалы — производство

In addition to certain biological requirements, such as cariostatic properties and lack of pulp irritability or systemic toxicity, a filling material should possess low water absorption and should not dissolve in the oral fluids. The dimensional changes (generally involving contraction) on hardening of the material should be minimal so as to preclude tensile and/or shear stress concentrations at the interface with tooth structure with resultant development of microleakage, and the thermal properties (e. g., coefficient of thermal expansion and thermal diffusivity) should resemble as far as possible those of the tooth substance so as to minimize the development of interfacial shear and tensile stresses. Ideally, the mechanical properties, notably strength and stiffness, should match those of enamel and dentin, and some bonding mechanisms, micromechanical and/or chemical, should be operative between cement and cavosurface. Additional requirements, of no major interest in the present context, are concerned with cosmetic considerations, radio — pacity, and rheological behavior, the last-named two features being of importance in the clinical application.