Dental Materials Midterm Review Flashcards

1
Q

What is the anatomical portion of a dental model?

A

structural portion of a dental model created from alginate impressions

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2
Q

What is an articulator?

A

dental lab device that stimulates the movement of the mandible and temporomandibular joint when the dental cast is attached to it

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3
Q

What is a die?

A

accurate replica of the prepared portion of tooth used in lab for fabrication of a cast restoration

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4
Q

what is a dihydrate?

A

related to gypsum products indicating 2 parts water to 1 part calcium sulfate

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5
Q

What is dimensionally (material characteristic)?

A

dental material that retains its original dimension when exposed to change in temp and humidity

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6
Q

what is a face bow?

A

portion of articulator used to transfer the relationship of the maxillary arch and temporomandibular joint to dental cast

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7
Q

What is gypsum chemically known as? what is it used in

A

chemically known as calcium sulfate dihydrate used in formation of plater of paris and dental stone

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8
Q

What is a hemihydrate?

A

when gypsum is heated, it loses water and converts to calcium sulfate, forming powder product of gypsum

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9
Q

what is homogenous?

A

having a uniform quality and consistency throughout

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10
Q

What is a monomer?

A

molecule that when combined with other molecules forms a polymer

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11
Q

what is nuclei crystallization?

A

chemical process in the setting of dental stone and plater in which a cluster of crystals interlink giving strength and ridgity

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12
Q

what is a polymer?

A

chemical compound consisting of like units bonded together

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13
Q

what is a slurry?

A

mixture of gypsum and water used in finishing of models

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14
Q

what is volatile?

A

substance that can evaporate easily and is very explosive

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15
Q

What is a model trimmer and what is its function?

A

machine used to trim stone or plaster using abrasive grinding wheels
used to grind away excess plaster and stone
- stream of water to control dust

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16
Q

What is a vacuum former and what is its function?

A

used to construct custom trays (bleaching trays) the upper part of the unit is the heating element that softens the plastic and the bottom has holes that act as the vacuum

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17
Q

what is the vibrator?

A

used to remove air from the mix of plaster or stone

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18
Q

what is the laboratory hand piece used for ?

A

used to trim custom impression, adjusting dentures and polishing provisional restorations

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19
Q

what is the sandblaster used for?

A

sprays sand at high speeds to to create an etching or pitting on surfaces this adds added retention for repairs

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20
Q

What is the dental lathe?

A

used to trim and polish custom trays

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21
Q

What are wax spatulas?

A

double ended instrument used in waxing a pattering or when working with wax on a partial or full denture

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22
Q

what is the most common wax spatuala

A

number 7

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23
Q

what is a mixing spatula?

A

used to mix, many kinds depending on the strength of material

24
Q

what is a rubber bowl

A

used to mix alginate and stone or plasterr

25
Q

what is a dental model?

A

3d reproduction of the teeth and surrounding soft tissue

26
Q

why are dental models so useful?

A

allows the dentist to analyze the patients mouth from viewpoints that are not seen by a clinical exam

27
Q

what is gypsum in its unrefined state

A

a dihydrate form of calcium sulfate

28
Q

when gypsum is heated is the water removed or added? what does gypsum now converted into?

A

removed leaving it a hemi hydrate ( 0.5 parts water to 1 part calcium sulfate)

29
Q

When mixing gypsum with water the hemihydrate crystals dissolve in the water to form clusters known ____ ___ ________

A

nuclei of crystallization

30
Q

Type I Gypsum: what is it called?

A

Impression Plaster

31
Q

Type II Gypsum: What is it called and what are some characteristics

A

plaster of paris
- white and used for pouring premilimary impressions for study models

32
Q

what type of gypsum requires the most about of water for mixing?

A

Type II

33
Q

Type III Gypsum: what is it called? what are some characteristics

A

Dental Stone
- yellow
used for more durable diagnostic cast
stronger and denser than plater

34
Q

Type IV Gypsum: What is it called? what are some characteristics?

A

Die stone (densite)
- strength hardness and dimensional accuracy
- ideal for creating a die for use in fabrication of a wax pattern (crown, bridges, inlays)

35
Q

Type V Gypsum: What is it called? What are some characteristics?

A

Hight Strength Stone
- green
strongest and least amount of expansion
require least amount of water

36
Q

What type of gypsum is NOT recommended for the use in fabrication of inlays and onlays

A

Type V: creates too tight of a casting fit

37
Q

Model plaster (Type II) has a powder to water ratio of 100g powder to _______ mL of H2O
a. 28-30 mL
b. 45-50 mL
c. 19-24 mL

A

B

38
Q

Dental Stone (Type III) has a powder to water ratio of 100g powder to _______ mL of H2O
a. 28-30 mL
b. 45-50 mL
c. 19-24 mL

A

A

39
Q

Die Stone (Type IV) has a powder to water ratio of 100g powder to _______ mL of H2O
a. 28-30 mL
b. 45-50 mL
c. 19-24 mL

A

C

40
Q

What happens if too little water is used in gypsum mixing?

A

it will be dry which = a shorter mixing time

41
Q

what happens if too much water is used in gypsum mixing?

A

the crystallization setting process will be disturbed and the model wont have strength

42
Q

what occurs if you add water after the stirring process has begun?

A

it will break up the crystals resulting in a weak and brittle cast

43
Q

What is a double-pour?

A

anatomic portion of model is poured first then a second mix of plaster or stone is used to prepare the art portion

44
Q

What is a box-and-pour?

A

impression is surrounded with a box made of wax and is poured as one unit

45
Q

what is the inverted pour method?

A

one large batch of plaster or stone is mixed and both portions of models are poured in a single step

46
Q

What does the anatomic portion of a dental model include?

A

teeth, oral mucosa and muscle attachment

47
Q

what is the art portion of a dental model?

A

forms the base

48
Q

What is the process of polishing a plaster model? (SSD)

A

Slurry- Mix a slurry of gypsum and fill any void
Soak- the model in a soapy mix for 24 hours
Dry- dry the model and then polish it with a soft cloth

49
Q

Custom Tray Impression: What should be done with Undercuts? What causes them?

A

Filled with wax or other molding material. Air bubbles, carious lesions and fractured teeth may cause it

50
Q

Custom Tray Impression: What is outlining the tray?

A

designates the area to be covered by the tray

51
Q

Custom Tray Impression: What is a spacer?

A

Creates froom for impression material

52
Q

Custom Tray Impression: Spacer Stops

A

Allow for adequate impression material

53
Q

Custom Tray Impression: Separating Medium

A

so the completed tray can be removed from the cast

54
Q

Custom Tray Impression: Handle

A

Easier placement and removal

55
Q

Custom Tray Impression: Spacer Removal

A

So adhesive will sick properly

56
Q

Custom Tray Impression: Finishing

A

So rough edges do not injure the patient

57
Q

What is an advantage of self-curing resin?

A

The resin provides a strong and easily adaptable material to create a custom tray