Oral environment Flashcards
(52 cards)
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
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
3
Q
three limitations of the oral environment
A
- what can and cannot used safely
- type of tx, long-term clinical needs of the tx
- condition of the oral cavity (oral hygiene and health; loss of teeth; broken down teeth)
4
Q
restorative
A
- to reconstruct tooth structure
5
Q
therapeutic
A
- the ability to treat disease
6
Q
aesthetic
A
- aestetically pleasing appearance
7
Q
therapeutic agents
A
- generally used for short periods of time
8
Q
restorative agents
A
- expected to remain in contact with tissues for indefinite periods of time
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
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)
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
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
13
Q
what is a biting force
A
- a measure of the strength of the muscles of mastication during normal chewing
14
Q
what is stress
A
- the internal force, which resists the applied force
15
Q
what is strain
A
- distortion or deformation occurring when an object cannot resist a stress
16
Q
what is a force
A
- any push or pull on matter
17
Q
what are the 3 types of forces
A
- compressive: pushes the material together
- tensile: pulls and stretches the material (applied in opposite directions)
- shearing: breakdown of material as a result of something sliding over the 2 areas (in a twisting or rotating motion)
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
19
Q
forces enamel can handle (in lbs/in2)
A
- compressive: 56,000 lbs/in2
- tensile: 1500 lbs/in2
20
Q
forces dentin can handle (in lbs/in2)
A
- compressive: 43,000 lbs/in2
- tensile: 4500 lbs/in2
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
what is fatigue failure
- repeated stresses, produce microscopic flaws that grow and over time result in fractures
26
what is flexural stress
- bending stress, a combination of tension (tensile) and compression
27
pH of oral cavity depends on:
- foods
- beverages
- medications
- the amount of biofilm (acid-producing bacteria) present
28
the breakdown of most restorative materials is directly related to:
- acid
- moisture
- stress
29
what is solubility
- susceptibility to being dissolved
30
what is water sorption
- the ability to absorb moisture
31
what is corrosion
- breakdown of metal from chemicals or an electrochemical reaction between metals due to moisture and acid in the oral cavity
32
what is tarnish
- discolouration caused by oxidation on the surface of a metal
33
what is galvanism
- an electric current transmitted between to dissimilar metals
34
what is galvanic shock
- when the electric current caused by galvanism results in stimulation to the pulp
35
what is dimensional change
- all forms of matter will expand when heated and contract when cooled
36
what happens when there is excessive expansion (heat)
- leads to fracture of cusps
37
what happens when there is excessive contraction (cold)
- leads to microleakage
38
what is percolation
- 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
what happens when there is percolation
- allows bacteria and oral fluids to accumulate at the margin of a restoration which can lead to
- recurrent caries
- staining
- pulpal irritation
40
what is thermal conductivity
- the rate at which heat flows through a material
41
what are insulators
- matter that prevents the passage of electricity, heat, or sound through an object
42
what is retention
- the ability of a material to maintain its position without displacement under stress
43
what is mechanical retention
- when material is locked into place through the use of undercuts or other projections
44
what is chemical retention
- when a reaction takes place between two materials to form a bond
45
what is bonding
- the ability to hold two components together
46
what is the acid etch technique
- 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
what is microleakage
- the seepage of harmful materials
- responsible for:
- recurrent caries
- marginal staining
- postoperative sensitivity
48
aesthetics-wise, there are 3 components of colour in dentistry:
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
light considerations (4):
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
how can we identify restorative materials
- appearance
- location of margins
- tactile sensitivity
- radiographs
51
what tools can we use to identify restorative materials
- adequate illumination
- air
- sharp explorer
- magnification
52
materials must be:
- biocompatible
- exhibit long-term clinical durability
- be aesthetically acceptable
