The Rheological Properties of Endodontic Sealers,

摘要

The rheological properties of seven endodontic sealers were assessed by rotational viscometry as a function of time and rotational speed at a constant temperature. Data were recorded initially at two minutes after the start of mixing and continued for a maximum period of 15 minutes. Initial viscosities at 1 rpm were: (a) 7,000 cp; (b) 9,000 cp; (c) 20,000 cp; (d) 59,000 cp; (e) 123,000 cp; (f) 240,000 cp, and (g) 678,000 cp. The viscosity-time behavior of the test materials exhibited one of four discrete patterns: (1) low initial viscosity with a gradual change in viscosity over a 15-minute period (materials A and B); (2) moderately low initial viscosity with a rapid increase in viscosity at 7 to 10 minutes after mixing (materials C, D, and E); (3) high initial viscosity with a gradual increase in viscosity over a 15-minute period (material F); and (4) high initial viscosity with an abrupt increase in viscosity over a 1-minute period (material G). Thixotropy appeared to be an additional feature of the viscosity-time behavior of material E. The data make possible the selection of specific materials to meet the clinical needs of both the experienced and inexperienced operator.