Universidad Autónoma de Ciudad Juárez. ICBSilicone by addition.Dra. Dianely Contreras Escobar.Dr. Alfredo Nevárez Rascón.
*History of the materials of impression:• 1856 beeswax.• 1864 Gutta hanger.• 1900 Gypsum of impression.• 1925 Hidrocoloides reversible.• 1940 Alginatos.• 1954 Mercaptanos (silicone by addition)/polysulfuros. • 1955 Silicone by condensation.• 1964 Polyteros.• 1975 Silicone by addition.• 1985 Silicone by addition "hidrofílicas".
Receive this name an elastic impression materials group, of similar nature to the rubber. they are of hydrophobic character that is to say that they reject the water, from there the term of not watery. The process by means of which they harden is called: POLYMERIZATION, that form of macromolecules from small molecules, simple calls as monómeros , exist hree different classes. picture 2 picture 3picture 1 Oilcloths of polisulfuro silicone polieteres http://dentizta.ccadet.unam.mx/
siliconeThe silicone are the result of the investigators in dental materials to create a product withthe positive characteristics of the oilcloths of polisulfure; but without their disadvantages.They are presented in diverse tenants, depending on the commercial mark and of theirconsistency, they can be in flasks of wide mouth for those of consistency heavy and veryheavy, in pipes collapses for those of consistency medium and light. The catalyzer ispresented also in the shape of liquid in glass dropper flask. The most recent presentationis in gun of self cueing with cartridge and case.CONSISTENCIES: Very heavy or Heavy Regular Light or light putty. picture 4 http://dentizta.ccadet.unam.mx
COMPOSITIONExist two varieties or types of silicone relating to theircomposition and their form of polymerization.A) POLYMERIZATION BY CONDENSATIONB) POLYMERIZATION BY ADDITION.
picture 5 They are of addition because they do not free a byproduct as such, only there is liberation of H2, that doesMateriales dentales, Barceló not affect thesantana y palma calero. contraction, only the emptied.
Silicone of addition.The silicone of addition are materials ofnot stiff impression, irreversible (reactionof chemical polymerization by addition), it proceeds to it takes of final impressionsthat belong to the group of the by means of silicone of additionelastómeros. They present biological,physical, chemical properties andadequate viewpoints that permit them tobe one of the dental materials for moreused final impressions currently. Thesilicone of addition is manufactured withhigh, average, low consistency and a http://www.oclusion.es/2007/02/26/pro picture 6 tocolo-en-rehabilitacion-oral-integral/putty, and is a polisiloxano.
Use:This material of impression is the materialof election in fixed prosthesis Picture 7 bustamantelab.blogspot.com
impression obtained (savings of material,picture 8 absence of pores and draggings) http://www.dentsply.es
*- rowboat= base. and proportion : Presentations-Pipe =catalyser.-Pipe =silicone flowed.-It can be presented in a deviceof auto mixes.-To mix in equal quantities thebase and the catalyser.
Characteristics :oResultant byproduct of the reaction by condensation of H2O and I oxidize ofPH.oSuffers during the polimerizado a reaction exotérmica of approximately 3ºC.oOf scarce use on the part of the dental surgeon. ConsistencyoDeformation permanentoFlexibility (the tension before compressionalloads)oHardnessoResistance to the traction picture 10 http://www.medilegis.com/Banc oConocimiento/O/Odontologica -v1n3- materiales/materiales.htm
Handling : 1. For the medium and light consistencies, besides the techniques already indicated, this material can be manipulated with accessories, such as two united cartridges in whose exit a spiral mixer of plastic is inserted, that permits, through a special gun, to expel the pastes in the proportions required, to homogenize the mescla and to inject it directly in the zone that goes to impress or to fill the small spoons without need of syringe.
picture 11 Materiales dentales, Barceló santana y palma calero.
Handling2. The mixture of the very heavy consistencyis facilitated for being done in equalproportions base and catalyser.3. It is not recommendable the mixture of thevery heavy consistency with the hands andwith gloves of latex, since the sulfur of itsformulation impedes that polimerice theproduct.4. The sulfurs that are removed of somethreads used to shrink the gum they can inhibitthe polymerization upon entering contact withthe product.
Handling 5. The time of work is but short that with the sulfur cop oilcloths. But the technique of mesclado described permits us to include a little but of time of work. 6. It is the material but exact and with greater stability you measure of all the elastómeros. 7. Can be electroposives with silver and copper. 8. Is a hydrophobic material, for which one must be careful upon devising the model of gypsum. 9. The control of septic infections without there can be carried out be changes in the dimensions of the impression. 10. They are the most expensive of all the elastómeros not watery, by the product in if and by the accessories required for their handling.
• Are the most exact available. • Smell • Expensive.and pleasant flavor. • Sensitive to contaminant.• Excellent stability dimensional. • Liberation of hydrogen (volatile) during the• High recovery to the deformation. polymerization as this produces deformation in the emptied, the emptied should not• Stable to the disinfection. be done immediately (1 –24 hrs).• Available in devices of automezclawhen we utilize devices of automezclawe avoid the formation of bubbles,since the proportions are exact.• Hidrofílicos.• It Emptied after 1 hour, as aminimum thingthat the H2 is found freed and alter notthe emptied in the gypsum.