title: Apparent viscosity of materials used for making edentulous impressions.
abstract: The viscosity of commercially available impression materials used for making edentulous impressions was determined as a function of time and rotational speed. The impression materials studied showed large differences in viscosity and could be ranked into three groups. The values for one group--Plastogum, Ackerman cement (1:1 powder-to-liquid ratio), and light-bodied Permlastic--ranged from 23,800 cp to 57,200 cp. The viscosity values for a second group--Unilastic, syringe Elasticon, Luralite, and Coe-Flo--ranged from 92,200 cp to 107,000 cp. For a third group--Omniflex, Jeltrate, and Ackerman cement (2:1 powder-to-liquid ratio)--the viscosity values ranged from 239,000 cp to 257,000 cp. Light-bodied Permlastic, Ackerman cement (1:1 powder-to-liquid ratio), Jeltrate, and syringe Elasticon functioned as Newtonian liquids immediately after mixing. All other materials were non-Newtonian in behavior. The viscosity of most impression materials increased dramatically with time; the only exceptions were the zinc oxide-eugenol impression materials.
mesh_terms: D000464:Alginates; D002133:Calcium Sulfate; D003760:Dental Impression Materials; D006801:Humans; D009066:Mouth, Edentulous; D012212:Rheology; D012826:Silicone Elastomers; D013696:Temperature; D014783:Viscosity; D015035:Zinc Oxide-Eugenol Cement
chemical_list: D000464:Alginates; D003760:Dental Impression Materials; D012826:Silicone Elastomers; D015035:Zinc Oxide-Eugenol Cement; D002133:Calcium Sulfate