1. An amorphous brittle substance consisting of the hardened secretion of a number of plants, probably derived from a volatile oil and similar to a stearoptene. 2. rosin 3. A precipitate formed by the addition of water to certain tinctures. 4. A broad term used to indicate organic substances insoluble in water; these monomers are named according to their chemical composition, physical structure, and means for activation or curing, e.g., acrylic r., autopolymer r. [L. resina]
acrylic r. a general term applied to a resinous material of the various esters of acrylic acid; used as a denture base material, for other dental restorations, and for trays.
activated r. autopolymer r
anion-exchange r. See anion exchange, anion exchanger.
autopolymer r. , autopolymerizing r. any r. that can be polymerized by chemical catalysis rather than by the application of heat; used in dentistry for dental restoration, denture repair, and impression trays.activated r., cold cure r., cold-curing r., quick cure r., self-curing r;
carbacrylamine r.'s a mixture of the cation-exchange r.'s, carbacrylic r. and potassium carbacrylic r. (87.5%) and of the anion-exchange r., polyamine-methylene r. (12.5%), used to increase the fecal excretion of sodium in edema associated with excessive sodium retention by the kidneys, e.g., in congestive heart failure, cirrhosis of the liver, and nephrosis.
cation-exchange r. See cation exchange, cation exchanger.
chemically cured r. a r. which contains an initiator, usually benzoyl peroxide, and an activator, usually a tertiary amine, in separate pastes. When mixed, the amine reacts with the benzoyl peroxide to form free radicals and polymerization occurs.
cholestyramine r. a strongly basic anion-exchange r. in the chloride form, consisting of a copolymer of styrene and divinylbenzene with quaternary ammonium functional groups; it lowers the blood cholesterol by binding the bile acids in the intestine, thus promoting their excretion in the feces instead of reabsorption from the bowel; used in the treatment of hypercholesterolemia, xanthomatous biliary cirrhosis, and other forms of xanthomatosis.
cold cure r. , cold-curing r. autopolymer r
composite r. a synthetic r. usually acrylic based, to which a glass or natural silica filter has been added. Used mainly in dental restorative procedures. [L. compositus, put together, fr. compono, to put together]
copolymer r. synthetic r. produced by joint polymerization of two or more different monomers or polymers.
cross-linked r. cross-linked polymer
direct filling r. an autopolymerizing r. especially designed as a dental restorative material.
dual-cure r. a r. which utilizes both light and chemical initiation to activate polymerization.
epoxy r. any thermosetting r. based on the reactivity of epoxy; used as adhesives, protective coatings, and embedding media for electron microscopy.
gum r. the dry exudate from a number of plants, consisting of a mixture of a gum and a r., the former soluble in water but not alcohol, the latter soluble in alcohol but not water.
heat-curing r. r. that requires heat to initiate polymerization.
Indian podophyllum r. r. obtained from Podophyllum emodi; a cathartic and cholagogue.
ion-exchange r. See ion exchange, ion exchanger.
ipomea r. r. obtained from the dried root of Ipomoea orizabensis; a cathartic. See also scammony.
jalap r. r. extracted from the dried tuberous root of Exogonium purga; a purgative.
light-activated r. light-cured r
light-cured r. a r. which uses visible or ultraviolet light to excite a photoinitiator which interacts with an amine to form free radicals and initiate polymerization. Used mainly in restorative dentistry.light-activated r;
melamine r. a plastic material mixed with plaster of Paris for casts. Such a cast is lighter and stronger than one made with plaster of Paris alone.melamine formaldehyde;
methacrylate r. polymerized methacrylic acid;a translucent plastic material, used for the manufacture of various medical appliances, surgical instruments, and seating components used in total joint replacement; it possesses the optical properties of fused quartz, and is readily molded when heated; formerly used in electron microscopy for embedding tissues, now superseded by epoxy r.'s.
Podophyllum r. a r. extracted from the dried roots and rhizomes of Podophyllum peltatum, a perennial herb common in moist, shady situations in the eastern parts of Canada and the United States. The drug has been used by American Indians as a vermifuge and emetic. The chief constituents of the r. belong to the group of lignins, which are Cl18 compounds related biosynthetically to the flavonoids and derived by dimerization of two C6-C3 units. The most important ones present in podophyllum r. are podophyllotoxin (about 20%), beta-peltatin (about 10%) and a-peltatin (about 5%). All three occur both free and as glucosides. The r. has been used as a purgative but has been replaced by milder agents. It is cytotoxic and used as a paint in the treatment of soft venereal and other warts.
podophyllum r. a mixture of r.'s obtained from the dried rhizomes and roots of Podophyllum peltatum or P. hexandrum; used as a laxative.May apple root, podophyllin, wild mandrake;
polyamine-methylene r. a synthetic acid-binding r. used as a gastric antacid.
polyester r. r. in which the polymers are insoluble in most organic solvents and are polymerized by light, heat, or oxygen; used in electron microscopy as a tissue embedding medium.
quick cure r. autopolymer r
quinine carbacrylic r. azuresin
self-curing r. autopolymer r
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