Spherical vs. admixed Dental Amalgam- clinical trials

By Dr.Swathi Pai on Thursday 1 May 2008 with 0 comments



Spherical

-contains spheres of various sizes, each of which contains silver, tin and copper.

-need 10% less Hg to amalgamate due to less surface area.

-higher strength 15 min after condensation than admixed.

-less condensation force but voids easier to occur

-greater capsule-capsule consistency

-smaller particles-smoother surface

-excellent corrosion resistance

Spherical alloys amalgamate very readily (due to increased surface area). Therefore, amalgamation can be accomplished with smaller amounts of mercury than is generally required for many lathe-cut alloys. . . The condensation pressures are less. . . Forcing the band against the opposing tooth to develop a positive contact becomes more of a problem with spherical alloys. . . Spherical alloys have greater compressive strength at 15 minutes and 1 hour. Ref.: Baum L, Textbook of Operative Dentistry. W.B. Saunders, 1995.



Admixed

-more resistance to condensation

-contain both spherical and irregularly shaped particles

-easier adaptation to cavity walls and better contacts

-medium to high strength

-very good corrosion resistance

-handling characteristics

-setting time: personal choice, range 3-20 mins.

-condensability: spherical easier than lathe-cut or admixed, however, contacts harder to achieve with spherical

-carvability

-tensile strength of spherical improved over pure lathe cut

-early compressive strengths (15min.-1hr.) are higher for spherical than those for lathe-cut alloys

- good for cores or large buildups

Category: Conservative and Endodontics Notes

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