Lecture 9 (Dental cements; Base materials)

A base is any substance placed under a restoration (1-2 mm in thickness) that blocks out undercuts in the preparation, acts as a thermal or chemical barrier to the pulp, and/or controls the thickness of the overlying restoration. Bases should have sufficient strength to withstand forces of mastication and condensation of permanent restorations (mechanical protection to the pulp). Zinc-phosphate, polycarboxylate, zinc oxide-eugenol (IRM), glass ionomer and resin cements have all been historically used as bases for direct and indirect restorations.........

Lecture 8 (Dental Cements; liner materials)

Dental cements have been widely used in various clinical applications since the early twentieth century. They are used as filling materials, protective cavity liners, luting materials for crowns, bridges, inlays and orthodontic appliances, root canal fillings, and pulp capping. Various types of cements are available for different purposes. Dental cements are mainly used to provide protection to the pulp against irritants as the following: 1. Thermal protection against temperature changes. 2. Electrical protection against galvanic currents. 3.

Theory of Structures - CH : Influence Line

Influence lines have important application for the design of structures
that resist large live loads. In this chapter we will discuss how to draw
the influence line for a statically determinate structure. The theory is
applied to structures subjected to a distributed load or a series of
concentrated forces, and specific applications to floor girders and
bridge trusses are given. The determination of the absolute maximum
live shear and moment in a member is discussed at the end of
the chapter.

 

The orbital region

The orbital region
The orbits are a pair of bony cavities that contain the eyeballs; their associated muscles,
nerves, vessels, and fat; and most of the lacrimal apparatus. The orbital opening is
guarded by two thin, movable folds, the eyelids.