The Metallography of dental amalgams
Date
1976
Authors
Abbott, John Russell
Editors
Advisors
Makinson, O. F.
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Thesis
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Abstract
Porosity in dental amalgam has been investigated by many workers
and several explanations of the probable cause of porosity have been
documented. Artefact development during preparation of amalgam
specimens for metallographic examination has had scant reference in
the dental literature, and therefore it is the primary concern of
this thesis to elucidate some of the factors which produce porosity
as an artefact on polished surfaces of amalgam specimens. The present
work has shown that porosity as an artefact can be produced by the
removal of phases during the polishing process and by ultrasonic
cleaning of specimens between polishing stages.
The ease of manipulation, adequate mechanical properties and low
cost has established amalgam as the primary choice material for dental
restorations. There have been many publications on amalgam failure
and it has been suggested that poor cavity design, faulty amalgam
manipulation, marginal failure, creep and corrosion are responsible
for defective amalgam restorations. The Y2 phase is the most reactive
phase of dental amalgam and the presence of this phase is believed by
some authors to predispose amalgam restorations to marginal breakdown.
The present work investigates the Y2 phase by describing a chemical
etch to define this phase, so allowing measurement of the volume
fraction of Y2 phase in a range of amalgam alloys. For in vitro
corrosion studies two chemical-methods for the dissolution of the Y2
phase are described. The thesis also describes an alternative polishing and etching
procedure and examines whether vibratory polishing is suitable for
final polishing of amalgam specimens.
School/Discipline
Department of Restorative Dentistry
Dissertation Note
Thesis (M.D.S.) -- University of Adelaide, Department of Restorative Dentistry, 1977.
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