Science Fair Project Encyclopedia
A veneer is a thin covering over something. It generally refers to a building construction method, such as brick veneer , where a thin layer of brick wall is used to cover the inner wall.
In architecture you often refer to veneer as wood veneer, obtained by slicing the trunk of the tree, which is the predominant area used for architectural veneers. The appearance of the grain, or "figure," in wood comes from slicing through the growth rings of a tree and depends upon the angle that the wood is sliced. There are three main types of veneer slicing equipment used commercially: A rotary lathe in which the wood is turned against a very sharp blade and peeled off in one continuous or semi-continuous roll; A slicing machine in which the flitch or piece of log is raised and lowered against the blade and slices of the log are made; A half round lathe in which the log or piece of log can be turned and moved in such a way to expose the most interesting parts of the grain. Each slicing processes gives a very distinctive type of grain, depending upon the species. In any of the veneer slicing methods, when the veneer is sliced, a distortion of the grain occurs. As it hits the wood, the knife blade creates a "loose" side where the cells have been opened up by the blade, and a "tight' side. Veneer layers are usually glued and pressed onto core panels of different materials to obtain doors, tops and side panels for cabinets and other pieces of furniture.
In the same vein, a veneer can also be used to describe someone displaying a false emotion on their face.
In dentistry a veneer is a thin layer of restorative material placed over a tooth surface, either to improve the aesthetics of a tooth, or to protect a damaged tooth surface. There are two types of material used in a veneer, composite and or porcelain. A composite veneer may be directly placed (built-up in the mouth), or indirectly fabricated by a dental technician in a dental laboratory , and later bonded to the tooth, typically using a resin cement such as Panavia. In contast a porcelain veneer may only be indirectly fabricated.
The advantages of using a veneer to restore a tooth are many. Very good aesthetics can be obtained, with minimal tooth preparation (ie drilling). Normally a reduction of around 0.5 mm is required for a porcelain veneer on a labial tooth surface. Composite veneers are becoming more popular as they are easy to repair, and porcelain veneers have a tendency to fracture. It can be very difficult to match the shade of an individual veneer to the remaining teeth, hence the tendency to place several veneers, giving a "hollywood" smile!
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