Oral environment Flashcards

1
Q

what causes the oral environment’s complexity

A
  • amount of saliva and pH of saliva
  • oral hygiene
  • forces upon the area to be restored
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2
Q

selection of the most appropriate dental material depends upon

A
  • extent of decay
  • type of defect
  • condition of oral cavity
  • visibility of restoration
  • cost
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3
Q

three limitations of the oral environment

A
  1. what can and cannot used safely
  2. type of tx, long-term clinical needs of the tx
  3. condition of the oral cavity (oral hygiene and health; loss of teeth; broken down teeth)
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4
Q

restorative

A
  • to reconstruct tooth structure
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5
Q

therapeutic

A
  • the ability to treat disease
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6
Q

aesthetic

A
  • aestetically pleasing appearance
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7
Q

therapeutic agents

A
  • generally used for short periods of time
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8
Q

restorative agents

A
  • expected to remain in contact with tissues for indefinite periods of time
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9
Q

common dental restorative materials

A
  • composite resins
  • amalgam
  • sealants and preventive resins and restorations
  • glass ionomers
  • temporary materials
  • tooth whitening products
  • gold alloys
  • veneers
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10
Q

who makes sure standards are being followed for dental materials by manufacturing companies

A
  • the committee on clinical and scientific affairs (a subcommittee of the canadian dental association)
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11
Q

criteria for all dental material

A

must not be:
- poisonous or harmful to the body
- harmful or irritating to the tissues of oral cavity (o.c)
must be:
- help protect the tooth and tissues
- resemble the natural dentition acap for aesthetics and function
- be easily formed and placed to restore natural contour
- conform and function despite limited access, wet conditions and poor visibility
- biocompatible
- durable
- non-reactive in acidic and alkaline conditions
- compatible with other materials
- aesthetically acceptable

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12
Q

biomechanics

A
  • functions of material dependent on properties, and on what the material is expected to do
  • withstand varying degrees of force or load caused by muscular actions of pushing and pulling during mastication and bruxism
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13
Q

what is a biting force

A
  • a measure of the strength of the muscles of mastication during normal chewing
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14
Q

what is stress

A
  • the internal force, which resists the applied force
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15
Q

what is strain

A
  • distortion or deformation occurring when an object cannot resist a stress
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16
Q

what is a force

A
  • any push or pull on matter
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17
Q

what are the 3 types of forces

A
  1. compressive: pushes the material together
  2. tensile: pulls and stretches the material (applied in opposite directions)
  3. shearing: breakdown of material as a result of something sliding over the 2 areas (in a twisting or rotating motion)
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18
Q

normal masticatory forces

A
  • on occlusal surfaces: 90-200 lbs
  • on a cusp tip can = 28,000 lbs/square inch
  • decreased in incisor areas
  • increased during bruxism
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19
Q

forces enamel can handle (in lbs/in2)

A
  • compressive: 56,000 lbs/in2

- tensile: 1500 lbs/in2

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20
Q

forces dentin can handle (in lbs/in2)

A
  • compressive: 43,000 lbs/in2

- tensile: 4500 lbs/in2

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21
Q

forces amalgam can handle (in lbs/in2)

A
  • compressive: 45,000 - 64,000 lbs/in2

- tensile: 7000 - 9000 lbs/in2

22
Q

forces porcelain can handle (in lbs/in2)

A
  • compressive: 21,000 lbs/in2

- tensile: 5400 lbs/in2

23
Q

forces composite resins can handle (in lbs/in2)

A
  • compressive: 30,000 - 60,000 lbs/in2

- tensile: 6000 - 9000 lbs/in2

24
Q

forces acrylic can handle (in lbs/in2)

A
  • compressive: 11,000 lbs/in2

- tensile: 8000 lbs/in2

25
Q

what is fatigue failure

A
  • repeated stresses, produce microscopic flaws that grow and over time result in fractures
26
Q

what is flexural stress

A
  • bending stress, a combination of tension (tensile) and compression
27
Q

pH of oral cavity depends on:

A
  • foods
  • beverages
  • medications
  • the amount of biofilm (acid-producing bacteria) present
28
Q

the breakdown of most restorative materials is directly related to:

A
  • acid
  • moisture
  • stress
29
Q

what is solubility

A
  • susceptibility to being dissolved
30
Q

what is water sorption

A
  • the ability to absorb moisture
31
Q

what is corrosion

A
  • breakdown of metal from chemicals or an electrochemical reaction between metals due to moisture and acid in the oral cavity
32
Q

what is tarnish

A
  • discolouration caused by oxidation on the surface of a metal
33
Q

what is galvanism

A
  • an electric current transmitted between to dissimilar metals
34
Q

what is galvanic shock

A
  • when the electric current caused by galvanism results in stimulation to the pulp
35
Q

what is dimensional change

A
  • all forms of matter will expand when heated and contract when cooled
36
Q

what happens when there is excessive expansion (heat)

A
  • leads to fracture of cusps
37
Q

what happens when there is excessive contraction (cold)

A
  • leads to microleakage
38
Q

what is percolation

A
  • movement of fluid between the restoration and the tooth
  • as a result of different expansion and contraction rates of tooth and restoration with temperature changes from the ingestion of hot and cold fluids and foods
39
Q

what happens when there is percolation

A
  • allows bacteria and oral fluids to accumulate at the margin of a restoration which can lead to
  • recurrent caries
  • staining
  • pulpal irritation
40
Q

what is thermal conductivity

A
  • the rate at which heat flows through a material
41
Q

what are insulators

A
  • matter that prevents the passage of electricity, heat, or sound through an object
42
Q

what is retention

A
  • the ability of a material to maintain its position without displacement under stress
43
Q

what is mechanical retention

A
  • when material is locked into place through the use of undercuts or other projections
44
Q

what is chemical retention

A
  • when a reaction takes place between two materials to form a bond
45
Q

what is bonding

A
  • the ability to hold two components together
46
Q

what is the acid etch technique

A
  • creates microscopic pores in enamel and dentin
  • a fluid bonding material then flows into these pores to form a mechanical lock into the tooth structure
  • restorative materials are then placed that adhere chemically to the bonding material
47
Q

what is microleakage

A
  • the seepage of harmful materials
  • responsible for:
  • recurrent caries
  • marginal staining
  • postoperative sensitivity
48
Q

aesthetics-wise, there are 3 components of colour in dentistry:

A
  1. hue: the dominant colour of the wavelength
  2. chroma: the intensity or strength of the colour
  3. value: describes how light or dark the colour
49
Q

light considerations (4):

A
  1. transparent: is when light passes directly through an object
  2. opaque: when light is completely absorbed by the object
  3. reflect: when light is thrown back off the object
  4. translucent: when diffuse light is let through an object
50
Q

how can we identify restorative materials

A
  • appearance
  • location of margins
  • tactile sensitivity
  • radiographs
51
Q

what tools can we use to identify restorative materials

A
  • adequate illumination
  • air
  • sharp explorer
  • magnification
52
Q

materials must be:

A
  • biocompatible
  • exhibit long-term clinical durability
  • be aesthetically acceptable