Journal of Dental Research, Vol 56, 40-45, Copyright © 1977 by International & American Associations for Dental Research Online Journals
Structure and effects of non-gamma-2 amalgam
T. Takatsu, M. Iwaku and T. Fusayama
The metallurgical structure of a non-gamma-2 amalgam was investigated by
using metallurgical microscopy, surface, point, and line analyses by an
electron probe microanalyzer, and a microhardness test. Referring to these
findings, their effects on clinical results were then discussed. Findings
were as follows: The residual dispersant particle was less hard than the
gamma 1 matrix, but the ring around it was much harder than the gamma 1
matrix or the residual gamma particle. The improved mechanical properties
seem to be the result of the presence of this ring. The gamma 2 phase was
absent in this amalgam. The absence of gamma 2 phase seems to improve
chemical resistance, to prevent the deformation by mercuroscopic expansion
of amalgam margins, and thus to decrease their fracture potential. The
minute gamma 1 crystals found adjacent to the ring around the residual
dispersant particle seem to indicate that they were late in
crystallization, resulting in low early strength.
