Composition
As with other composite materials, a dental composite typically consists of a resin-based oligomer matrix, such as a bisphenol A-glycidyl methacrylate (BISGMA) or urethane dimethacrylate (UDMA), and an inorganic filler such as silicon dioxide (silica). Compositions vary widely, with proprietary mixes of resins forming the matrix, as well as engineered filler glasses and glass ceramics. The filler gives the composite wear resistance and translucency. A coupling agent such as silane is used to enhance the bond between these two components. An initiator package (such as: camphorquinone (CQ), phenylpropanedione (PPD) or lucirin (TPO)) begins the polymerization reaction of the resins when external energy (light/heat, etc.) is applied. A catalyst package can control its speed.
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Famous quotes containing the word composition:
“At painful times, when composition is impossible and reading is not enough, grammars and dictionaries are excellent for distraction.”
—Elizabeth Barrett Browning (1806–1861)
“Since body and soul are radically different from one another and belong to different worlds, the destruction of the body cannot mean the destruction of the soul, any more than a musical composition can be destroyed when the instrument is destroyed.”
—Oscar Cullman. Immortality of the Soul or Resurrection of the Dead? The Witness of the New Testament, ch. 1, Epworth Press (1958)
“If I don’t write to empty my mind, I go mad. As to that regular, uninterrupted love of writing ... I do not understand it. I feel it as a torture, which I must get rid of, but never as a pleasure. On the contrary, I think composition a great pain.”
—George Gordon Noel Byron (1788–1824)