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Operative Dentistry > bds2 intro to dental materials > Flashcards

bds2 intro to dental materials Flashcards

1
Q

questions to ask regarding treatment plan for removal of caries and restoration

A

which material is suitable
how to use material
explain the options to the patient
select the material

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2
Q

the behaviour of dental materials affects which stages of the clinical episode, explain why

A

selection - best type
preparation - cavity design and tooth surface
placement - technique
performance - quality of fit and longevity
patient expectations - aesthetics and durability

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3
Q

what does the CE mark indicate

A

that a material is safe provided you use it for the designated purpose

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4
Q

list some common restorative materials

A

amalgam
composites
glass ionomer cements
composers
porcelain

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5
Q

which impression material is a hydrocolloid

A

alginate

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6
Q

which impression material is an elastomer

A

polysulphides
polyethers
silicones

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7
Q

features of composite resin in restorations

A

initially will flow out of the cartridge (low and high viscosities exist)
sets within margins and hardens

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8
Q

what is the negative replica of impressions materials

A

the recorded dentition - ie initial impression

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9
Q

describe the features of impression materials

A

flows into tray with low viscosity and undergoes a setting reaction to become firm and stable

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10
Q

what is the positive replica of an impression

A

gypsum - the “fake” teeth

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11
Q

what can happen to a material when forces are applied

A

stretch or compression depending on the force
deformation either temporary or permanent
fracture

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12
Q

calculation for stress

A

force / unit area

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13
Q

what are the units for stress

A

pascals

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14
Q

what is strain

A

change in length / original length

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15
Q

what is Youngs modules discussing

A

elasticity

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16
Q

what is the definition of Youngs modulus

A

elastic (Youngs) modulus is equal to stress over strain

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17
Q

FS

A

fracture stress

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18
Q

PL

A

proportional limit

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19
Q

mechanical property terms

A

hard vs soft
strong vs weak
rigid vs flexible
brittle vs ductile

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20
Q

what is the typical biting force

A

500 to 700N

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21
Q

biting force in kg

A

50-70kg

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22
Q

what kind of force is biting

A

compressive

23
Q

force directions for compression

A

force going up and force going down

24
Q

force directions for tensile

A

stretching to create fracture - pulling in opposite directions

25
Q

force directions for sheer

A

one force acting sideways

26
Q

what does tensile force do to dimension

A

change

27
Q

what is stress measured in

A

mega pascals

28
Q

describe what happens with forces to the tooth during grinding and chewing

A

tooth slides along the surface of the other, frictional forces are experienced

the tooth surface may be abraded, loss of layers of enamel

29
Q

why is it important that materials adhere to enamel

A

otherwise the enamel would be removed by masticatory forces

30
Q

what to consider when choosing restorative materials

A

what treatment options are there
what material suits each procedure
will that material suit the patients needs and requirements

31
Q

what’s the design of amalgam

A

undercut

32
Q

what is the design of composite resin

A

minimal

33
Q

what is the retention type of amalgam

A

mechanical

34
Q

what is the retention type of composite resin

A

adhesive

35
Q

what are the benefits of an undercut design

A

keeps the material in place

36
Q

what are the key features required for materials when filling the cavity

A

the material must be pliable, fit the shape of interest, and set to form hard, strong material

37
Q

what is the failure mechanism of a fracture

A

large force causes catastrophic destruction of materials structure

38
Q

what is the failure mechanism of hardness

A

ability of surface to resist indentation

39
Q

what is the failure mechanism of abrasion

A

material surface removal due to grinding

40
Q

what is the failure mechanism of abrasion resistance

A

ability to withstand surface layers being removed, so compromising surface integrity

41
Q

what is the failure mechanism of fatigue

A

repetitive small stresses cause material fracture

42
Q

what is the failure mechanism of creep

A

gradual dimensional change due to repetitive small forces

43
Q

what is the failure mechanism of deformation

A

applied stress causes permanent changes in materials dimensions but does not fracture it

44
Q

what is the failure mechanism of debonding

A

applied forces sufficient to break the material to tooth bond

45
Q

what is the failure mechanism of impact

A

large, sudden force causes fracture

46
Q

what is abrasion

A

when the tooth grinds along the opposing tooth surface or restorative material at its surface. the surface is abraded and there is loss of material surface layers, causing a roughened surface

47
Q

how are most failures brought about

A

when repeated loads are applied, small flaws in a material grow and this allows the fracture when only a relatively small force is applied

48
Q

what is creep

A

repetitive forces causing dimensional change

49
Q

what results in permanent deformation

A

releasing stress that is greater than the elastic limit

50
Q

how is debonding used in orthodontics

A

to remove the appliance, shear force is applied to separate the bracket/bonding material from the tooth surface

51
Q

main chemical properties for dental materials

A

setting mechanism
setting time
corrosive potential

52
Q

main physical properties for dental materials

A

viscosity
thermal conductivity
thermal expansion
density
radiodensity

53
Q

elements of the oral environment that can impact dental material behaviours

A

saliva
temperature variations
pH variations
oral bacteria

Operative Dentistry (22 decks)

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