DM - CH16. Gypsum & Wax Products Question and answers verified to pass 2024/2025
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Course
DENTURES,DX AND TX PLANNING
Institution
DENTURES,DX AND TX PLANNING
DM - CH16. Gypsum & Wax Products Question and answers verified to pass 2024/2025 DM - CH16. Gypsum & Wax Products
Gypsum products
- dental impression vs gypsum?
- what is gypsum?
- gypsum powder products are produced by..
-> the byproduct of the chemical reaction is
-> when mixed with...
DM - CH16. Gypsum & Wax Products
Gypsum products
- dental impression vs gypsum?
- what is gypsum?
- gypsum powder products are produced by..
-> the byproduct of the chemical reaction is
-> when mixed with water again, it's converted back to.. - correct answer ✔-
A dental impression is a negative reproduction of the oral structure while
*gypsum* products are used mainly for making *positive reproductions or
replicas*, often referred to as casts, dies or models. = impressions are poured
into gypsum to form casts.
- a *mineral* found in nature in various parts around the world known *calcium
sulphate dihydrate* and has been used in dentistry since 1700 for making
casts and dies. Once the gypsum has reached its initial set, it'll loose its
glossy appearance.
- heating gypsum and driving off part of the water of crystallization by a
process called *calcination*, the resulting product is known as *calcium sulfate
hemihydrate*. ((calcination= Reduce, oxidize by strong heat. Determines the
type of gypsum product created.))
-> heat known as *exothermic reaction*.
-> a dihtdrate.
Casts
- definition
- diagnostic casts
- working casts
,- dies - correct answer ✔- Hard replicas of hard and soft tissue of the
patient's oral cavity made from gypsum products; *= models
- generally made from *dental plaster*(white) or stone, and used for patient
education, treatment planning, and tracking the progress of treatment, as with
*ortho models!!!*
-> poured in *plaster because of the low need to physical properties. AKA:
Model plaster, laboratory plaster, plaster of Paris.
((placed under very little stress and usually are produced from less expensive
materials such as plaster or stone that have lower properties of strength and
abrasion resistance.))
- casts generally made from one of *the dental stones*(white/yellow) that are
strong enough to resist the stresses of fabricating an indirect restoration or
prosthesis
-> poured in dental stone / required good strength and accuracy.
((resistant to greater stresses, thus requiring higher properties of strength and
abrasion resistance and precise accuracy.))
- replicas of prepared/individual teeth that are generally removable from the
working cast(used to fabricate crowns and bridges. white/yellow)
-> required dimensional accuracy and strength, and poured in high strength
stone. AKA: Improved Dental Stone.
- Plaster
vs
- Die stone
- *Calcination
- reverse reaction - correct answer ✔- contains the most excess water. (=
airboy). Produces bigger and more numerous air voids.
, - contains the least excess water. produces fewer, small air voids.
- Mineralsgypsum(dihydrate of calcium sulfate -> heat and pressure ->
Calcium sulfate hemihydratre + water
- Calcium sulfate hemihydrate _+ water = dihydrate of calcium
sulfate(=exothermic)
1. strength & hardness
- strength of gypsum is related to ..
-> 2 factors that contributing to the strength and abrasion resistance of the
final product
2. Dimensional Accuracy
- sth occurs with all gypsum products. What does expand the most and the
least?
-> Why is it important?
- *Setting expansion occurs when?
- what helps to minimize the amount of expansion?
- If gypsum needs to be soaked in water,,, - correct answer ✔1.
- the amount of water used in producing the "model". A product with *less
water has a higher density of crystals and is therefore a *denser and stronger
product*.
-> 1. shape of particles 2. porosity
2.
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