Dental amalgams II Flashcards
problems with amalgam
not aesthetic lack of strength and toughness corrosion and creep non adhesive biocompatailty
lack of strength and toughness
due to the formation of gamma.2 i.e. tin silver phase
dispersed phase amalgam
silver copper used
gamma 2 reacts wth the silver copper
overall you have gamma gamma 1 and copper tin phase
- no gamma 2 in the structure
lathe cut particles
graded chipping
highly reactive without prior heating
spherical alloys
reach full strength quicker
easier to condence
easier to carve and pilish
lower merury content
admix
both spherical and lathe cut particles
corrosion in amalgam
due to the electrochemical difference in electrolytes
gamma 1 electroposituve
gamma 2 highly negative
electrochemical difference leads to corrosion
with no gamma 2 no electrochemical differnece
benefits of dispersed phase amalgam
easier to condense, carve and polish lower mercury content higher strength more resistant to corrosion reach full strength quicker
dental amalgam variations
conventional
high CU dispersed phase amalgams
high CU single phase amalgams
conventional amalgam variation
lathe cut
spherical cut
Ag3Sn
high CU dispersed phase amalgams varations
- lathe cut Ag3Sn and spherical AgCu
- lathe cut AgSnCu and spherical AgSnCu
3) High Cu single phase amalgams variations
- all spherical AgSnCu
- Lathe cut AgSnCu
risk of Hg exposure
respiratory failure kidney impairment cognitive disturbances reduced visuoperceptual and constructional skills memory loss hyper tension headaches
potential source of mercury contamination
spills
leaky dispensers or capsules
removing or polishing amlgam
sterilising Hg contamintaed instrumtns
storage and disposing
- store bulk mercury in unbreakable containers
- store amalgam scrap under radiographic fixer solution
- dispose contaminated items in sealed bags
- report and clean up spilled mercury when using a clean up kit
- wear professional clothing only in the surgery
