Dimensional stability of alginate impression materials measured by a non-pressure direct method.

概要

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It is well known that the dimensional change occurring in an impression material is an important factor affecting the fitting accuracy of the final restoration. However, no method of directly measuring the dimensional changes in impression materials, from immediately after initial setting, with accuracy and ease has yet been firmly established. In the direct method which necessitates measurement pressure, force may be applied to impression materials which have great plasticity immediately after initial setting, and a flow may thus be created producing dimensional changes. The indirect method is more advantageous in this respect, but its measurement with the passage of time is complicated, and it is difficult to apply under clinical conditions.<BR>In the present report, a method divised by the authors for measuring changes in dimension directly, without the application of pressure, is described, and will hereinafter be referred to as the "non-pressure direct method." The method was used to measure dimensional changes in powdered alginate impression materials available on the market at 100% relative humidity and in water.
日本大学歯学部の論文