Cast Gold Restorations (Guest Lecture)

every dental material is the best material for certain indications, but?

no dental material is best for all indications

what are the advantages of gold restorations over amalgam?

1) no discoloration of tooth - as amalgam ages, it releases Ag ions into tooth, darkening it

2) longevity

3) no cracking of tooth - divergent prep, amalgam is convergent

4) support of marginal edges

why do you remove all of the old restorations, even if it looks okay?

there may be hidden decay, cracks (oblique cracks need to be chased and removed); you need to evaluate remaining tooth strength

when an instrument is dull, why do we see light reflecting off of it

it is no longer a thin sharp line, but a dull flat surface that is able to reflect light

what is the basic assumption in making a gold restoration by the indirect method

the die is the same size as the tooth! —> it is usually not as all gypsum materials tend to expand

what kind of stone should we use for casting if we are concerned w expansion

a low expansion stone wow

why do we not wash or soak the dies in water?

die stone is soluble in water!

what is the relationship between the units of measurements of mL, cc, and grams

1 mL = 1 g = 1 cc

primarock tends to have more expansion so we do not want to use it for inlays, but it is suitable for?

making cast posts

why else is primarock (Type IV die stone) suitable?

its yellow color allows it to photograph nicely

what are the advantages of direct gold restorations

1) no lab work

2) perfect fit (nothing between gold and tooth)

what is gold's wear compared to natural teeth

highly durable, long-lasting, and have a wear rate similar to natural enamel, meaning they won't excessively wear down opposing teeth

what are disadvantages of direct gold restorations

gold is softer; so you may get more pitting and anatomical occlusal changes, but the seal to the tooth is still preserved

what is the first step of cavity preparation

establishing outline form: depth, taper, and extension

what is the purpose of pins in restorations

to increase retention

what do we use for isolation (what is best)

rubber dam! has better vision and control; protects pt tissues

gold has cohesion, meaning?

it binds to itself!

when trying to visualize or get rid of cracks in a tooth, which burs are more suitable to do so

a straight bur will disguise the crack but a round bur will allow you to see the crack in the tooth

what kind of preparation do we want for a direct gold restorations

a divergent preparation! gold relies more on condensation and marginal adaptation, so it is okay to not have heavy undercuts in order to retain the restoration