Abstract
Pressures produced during compression of impression materials between parallel disks were measured with diaphragm pressure transducers and analyzed hydrodynamically to clarify the relationships between the impression pressures exerted on tissues and factors affecting them in impression procedures.
The amount of pressures ranged according to the viscosity of materials, tray seating speed, and the thickness of materials, which was the most effective when the tray seating speed was constant. The force applied to the tray seems to be important in regulating the impression pressures because it is the integrated value of the pressure distribution.
On the other hand, the form of pressure distribution depended on the tray designs. It was flat in a relieved area but the effect to reduce pressures was limited by the depth that the tray was relieved, while pressures beneath an escape hole were extremely reduced when the diameter of the hole was more than about 2 mm.
The pressure distributions obtained from theoretical analyses were larger than those of the experiments in absolute values but well reflected their tendencies. Thus, this method of analyses and the basic theories are thought to be useful guides when the impression pressures are controlled clinically.
