Patent GB-826738-A (GB)
Title: Improvements in or relating to processes for making dental impressions
IPC: A61K6/90
Filed: 1956-07-26
Abstract: A composition for use in making dental impressions consists essentially of (1) a diorganopolysiloxane capable of being hardened to the solid elastic state and, as hardening catalyst (2) a tetra-alkylsilicate or an alkylpolysilicate, and (3) a heavy metal alkyl carboxylic acid salt non-toxic under the conditions of use, the hardening catalyst (2) and (3) being used in amount of 9 to 70 parts (by weight) per 100 parts of siloxane (1).  The compositions may also contain fillers, e.g. kaolin, asbestos flour, burnt gypsum, chalk, siliceous chalk, kieselguhr, sulphur, quartz flour, shale flour, titania, zinc, oxide; precipitated chalk and calcium and magnesium silicates; carbon black, graphite, medicinal charcoal, aluminium and copper powders; dextrin, starch, cellulose, cellulose esters and glycollates, alginates, pectins and polyacrylates.  Liquid paraffin and polyvinylether resins, polyethylene and paraffin waxes dissolved in liquid paraffin, polyvinyl pyrrolidone dissolved in glycerol, hexanol or methylcyclohexanone, solvents and plasticizers, e.g. methyl, amyl and benzyl salicylates, benzylbenzoate, benzylphenylacetate, methylcyclohexanol, furfural and benzaldehyde, and wetting or emulsifying agents, e.g. fatty alcoholethylene oxide addition products, may also be added.  The compositions may be coloured with pigments or soluble organic dyes and may contain substances imparting a pleasant odour and taste, e.g. peppermint oil, coumarin and camomile extracts, and also disinfectants, e.g. parachlorometacresol.  In a typical example, a convertible liquid dimethylpolysiloxane, anhydrous burnt gypsum and liquid paraffin were made into a paste and mixed with a liquid mixture of ethylpolysilicate and dibutyltin dilaurate.  The only other catalyst disclosed is a mixture of dibutyltin dilaurate and tetramethylsilicate.ALSO:In making a dental impression, a diorgano-polysiloxane convertible to the solid elastic state is mixed with, as catalyst, a tetraalkyl-silicate or an alkylpolysilicate and a heavy metal carboxylate non-toxic under the conditions of use, the composition so obtained being applied to the patient's mouth and allowed to harden or solidify in the mouth within 10 minutes, the catalyst being used in amount of 9 to 70 parts (by weight) per 100 parts of siloxane.  Inorganic or organic fillers, pigments, dyes, solvents, plasticizers, wetting agents, substances imparting a pleasant odour and taste, and disinfectants, all of which are exemplified, may be added to the compositions.  The ingredients may be mixed in any order, a convenient method being the admixture of equal volumes or lengths of ribbons of different pastes as squeezed out of tubes having identical orifices, the siloxane comprising one paste and the catalyst the other.  In a typical example a convertible liquid dimethylpolysiloxane, anhydrous burnt gypsum and liquid paraffin were made into a paste and mixed with a liquid mixture of ethylpolysilicate and dibutyl tin dilaurate.  The resulting composition was then introduced into a rigid impression mould and an impression taken in the mouth.  Solidification in the mouth took about 3 minutes.