Posterior restorative materials Flashcards
What is amalgam?
Metal alloy containing mercury, silver, tin, copper and other elements. Combination is necessary because no elements alone have suitable properties
What is the only piece of metal that is a liquid at room temperature?
Mercury
What are the noble metals?
Gold, platinum, Palladium, iridium, rhodium, osmium, ruthenium
What is amalgam used for?
Mainly used in class one and class to restorations as fillings for buccal pits and as build up material
What are the percentages of each metal found an amalgam?
Silver = 40 to 60% Tin= 27% Copper = 13 to 30% Zinc could be less than 1% Mercury based upon weight
How much mercury does the amalgam mixture usually contain my weight?
45 to 50%
Which metal has been found that when increased improves clinical performance and decreases the amount of mercury needed?
Copper
What form is amalgam supplied in?
Produced capsules which are most common and require less handling
Bulk in powder or tablet form
What is alloy?
Combined metals that are mutually soluble in a molten state
Which teeth Is amalgam usually limited to?
Posterior teeth
How are amalgams classified?
According to their shape:
- lathe cut- old type
-spherical type – also used years ago
-admixed Dash used presently and is a mixture of lathe cut and spherical
What is moldability?
When alloys are properly mixed. Will allow us to condense the material into the tooth preparation. Should be placed into the prep in small increments to avoid trapping voids in the bottom
What is used in now to mix amalgams?
A tritrator
What will happen from over trituration/longer trituration?
Slows sitting in the mix is shiny and sticky
What happens from under trituration/short?
Crumbly mixture and looks dull
What will mixed amalgam look like when triturated correctly?
Cohesive and shiny. Incorrectly mixed amalgam cannot be worked with
How long does it take for the amalgamation reaction to finish?
Reaction is continuous for several hours and not complete for a few days. Remind patient to avoid chewing in that area for several hours
How should amalgam capsules be disposed of? And why
Should be placed in an unbreakable tightly sealed container to reduce contamination of the operatory air
What happens when shrinkage occurs?
Causes a small space to occur around the restoration. In that space corrosion buildup but may not be a parent because toothbrushing removes it it
What is creep?
Dimensional change that could affect the margins. Slow progressing, permanent deformation that as a result of study force or stress acting on the material
What can moisture contamination do?
Because delayed expansion of the material, weaker restoration and other issues
What is corrosion?
When acids, salts etc. caused the material to have microscopic pores that fill with corrosive product which will weaken the material and cause it to look darker
What are the major causes for amalgam failure?
Secondary decay
Marginal breakdown
Fracture
Cusp fracture (weakened tooth wall)
What is the purpose of adhesives?
Help to seal Dentin tubules, helps tooth be more resistant fractures and less marginal break down
What are some types of adhesives?
Ketac-bond (ESPE)
OptiBOND Solo (KERR)
Prime and bond (caulk)
ProBOND
Uses for adhesives
Bass under composite or amalgam restorations, fissure sealing, blocking out undercuts of crown preparation‘s, core build ups, luting cement for endodontic posts and stainless steel crowns, shock absorber between restoration tooth structure, high bond strength with longevity, less shrinkage
What are composites?
Are and can be used for posterior restorations but do not perform as well as amalgams.
Suggested to be used in small to moderate class one or class to restorations. Not recommended for people who grind their teeth
More expensive than amalgam
What are some alternate names for composites?
Ceromer
Polyglass
Midfill
Minifill
Are composites light cured or self curing?
Most are light curing though there are a few that are self curing
What is the average lifetime of a composite restoration? What are the reasons for this?
Usually 3 to 5 years due to secondary decay, loss of form and/or marginal failure
Composites have higher irregular shapes to them so they can abrade opposing arches teeth or materials
What is direct filling gold also known as and what is it used for?
Also known as gold foil. Used for posterior and anterior restorations.
Not seen as much but it is soft and malleable with excellent resistance to tarnish and corrosion

What are the drawbacks to direct filling gold?
Lack of aesthetics, difficult to place, very high thermal conduct ability in danger to the pulp
Only minimal strength and resistance to abrasion
How is direct filling gold supplied?
Thin gold, matte gold, Matt foil and powdered gold. Often a combination of different types is used for one restoration
What is strain hardening?
When material is caused to sit in a harder state due to hammering
What are retention pins Used for?
Used to retain and support restorations in large decayed areas. One pin is used per missing cusp
What are temporary restorations?
IRM (intermediate restorative material)
Considered temporary in place while waiting for a permanent restoration, to check health of a tooth or for financial reasons
