Operative Final Exam - Lectures: Basics, Instruments, and Class I Tooth Preps Flashcards
1
Q
What is the definition of caries?
A
the demineralization and subsequent cavitation of tooth structure
2
Q
What is the goal of restorative dentistry?
A
carefully remove the diseased tissue (cavity) in a precise manner and replace the missing part with restorative material
3
Q
What are the 3 most common areas in which cavities occur?
A
- occlusal pits and fissures of posterior teeth
- interproximal areas (between teeth below contact area)
- smooth surfaces of facial and lingual surfaces
4
Q
Where is a Class I prep located?
A
pit and fissure preps
- occlusal surfaces of premolars and molars
- occlusal 2/3 of facial and lingual surfaces of molars
- lingual surfaces of maxillary incisors
5
Q
Where is a Class II prep located?
A
proximal surfaces of posterior teeth
6
Q
Where is a Class III prep located?
A
proximal surfaces of anterior teeth that do not include the incisal angle
7
Q
Where is a Class IV prep located?
A
proximal surfaces of anterior teeth that include the incisal edge
8
Q
Where is a Class V prep located?
A
the gingival third of the facial or lingual surfaces of all teeth
9
Q
Where is a Class VI prep located?
A
on the incisal edges of anterior teeth or occlusal cusp tips of posterior teeth
10
Q
What are the 3 types of powered cutting equipment?
A
- rotary (routinely used since 1960s)
- laser (recent FDA approval for preparing teeth)
- air abrasion
11
Q
Which handpiece (high or slow speed) sprays water coolant to avoid tooth damage by heat?
A
high speed
12
Q
Is a high speed handpiece angled or straight? A low speed handpiece?
A
- high speed - angled
- low speed - angled or straight
13
Q
What metal makes up a bur?
A
carbide steel (stiff, strong, and brittle)
14
Q
What are the 3 anatomical parts of a bur?
A
- head - cutting portion of bur
- neck - connects head to shank
- shank - part of the bur that inserts into instrument
15
Q
What are the 5 shapes of a bur head?
A
- round
- inverted cone
- straight fissure
- tapered fissure
- pear
16
Q
How many flutes are found in a standard carbide bur? How many in a finishing carbide bur?
A
- 6 flutes in a standard
- 10, 12, 20, 30 in a finishing bur (more flutes = smoother finish)
17
Q
What is the purpose of the shank of the bur?
A
controls the alignment and concentricity
18
Q
What are the 3 types of shanks?
A
- friction-grip
- latch-type
- straight
19
Q
Of the 4 types of diamond grits for diamond burs (coarse, medium, fine, and very fine), which are the most efficient? Which are the least efficient?
A
- most efficient = coarse
- least efficient = very fine
20
Q
What are the 2 cutting mechanisms of diamonds and burs?
A
- ductile fracture
- brittle fracture
21
Q
Which type of fracture has deformation produced by shear forces?
A
ductile fracture
22
Q
Which type of fracture is associated with crack production from tensile loading?
A
brittle fracture
23
Q
Which type of cutting (bur or abrasive) is more efficient for cutting brittle materials like enamel?
A
abrasive cutting
24
Q
Which type of cutting (bur or abrasive) is more efficient for cutting ductile materials like dentin?
A
bladed or bur cutting
25
What speed (high or low speed) is used for abrasive cutting?
high speed
26
What speed (high or low speed) is used for bladed or bur cutting?
high and low speed
27
What is a round bur used for?
- initial enamel penetration
- caries removal
- retentive grooves and holes
28
What is an inverted cone bur used for?
providing an undercut in a preparation
29
What is a straight fissure bur used for?
- straight walls
| - flat floors
30
What is a tapered fissure bur used for?
straight but tapered walls
31
What is a pear bur used for?
similar to inverted cone undercuts but has rounded ends and a longer head
32
What are 5 precautions that need to be taken into consideration when using a high-speed handpiece?
- damage to tooth from heat (need to use a coolant with vital teeth)
- damage to soft tissue from lack of control
- eye protection (safety glasses)
- inhalation precautions (mask)
- ear protection (plugs)
33
What is the difference between the primary and secondary cutting edge of a hand cutting instrument?
- primary cutting edge - edge that performs the most cutting (the edge of a hatchet that would scrape the pulpal floor)
- secondary cutting edge - edge that also performs some cutting (the edges of the hatchet that would scrape the vertical walls of the prep)
34
In an instrument formula with 3 numbers, what does each of the numbers represent?
- 1st number - width of the blade in 10ths of a mm
- 2nd number - blade length in mm
- 3rd number - blade angle relative to long axis in centigrade
35
In an instrument formula with 4 numbers, what does each of the numbers represent?
- 1st number - width of the blade in 10ths of a mm
- 2nd number - primary cutting edge angle in centigrade (*different than with 3 numbers)
- 3rd number - blade length in mm
- 4th number - blade angle relative to long axis in centigrade
36
What is the difference between a chisel and a hoe?
- chisel - used to push; less than 12.5 degrees
| - hoe - used to pull; greater than 12.5 degrees
37
What are the 3 characteristics that are used to categorize caries? What are the two subtypes of each characteristic?
- location - primary or secondary (recurrent) caries
- extent - incipient (reversible) caries or cavitated (irreversible) caries
- rate - acute (rampant) caries or chronic (slow or arrested) caries
38
What are the 3 morphologic types of caries observed clinically?
- lesions originating in enamel pits and fissures
- lesions originating on enamel smooth surfaces
- lesions originating on root surfaces
39
What is the definition of tooth preparation?
mechanical alteration of a defective, injured, or diseased tooth such that placement of a restorative material re-establishes normal form and function
40
What is the difference between an internal and external wall?
- internal wall - a prepared surface that does not extend to the external tooth structure
- external wall - prepared surface that extends to the external tooth surface and takes the name of the surface it is adjacent to
41
Is a facial wall an internal or external wall?
external
42
Is the axial wall an internal or external wall?
internal
43
Is the mesial wall an internal or external wall?
external
44
Is the pulpal floor an internal or external wall?
internal
45
What is the definition of the cavosurface margin?
junction of a prepared wall with the uncut tooth surface
46
What is the difference between conventional preparations and modified preparations?
- conventional preparations - precise preparations resulting in uniform depths and particular wall and marginal forms
- modified preparation - without specific depths, particular wall designs or retentive features
47
What type of restoration uses conventional preparations? What type uses modified preparations?
- amalgam uses conventional
| - composite uses modified
48
What are the 4 forms that make up the principles of cavity preparation?
- outline form
- retention form
- resistance form
- convenience form
49
What is outline form?
- conservative preparation
- margins on sound enamel
- include defective enamel (pits and fissures)
- depends on carious lesion or previous restoration
50
What is retention form?
features that lock or retain the amalgam in the tooth
51
What is resistance form for the tooth prep?
features that prevent the enamel from fracturing as a result of occlusal forces
52
How is retention form seen in Class I preps?
slight occlusal convergence of prepared facial and lingual walls
53
How is resistance from seen in Class I preps?
- preservation of cusps and marginal ridges
- pulpal floor flat and perpendicular to occlusal forces
- rounded internal preparation angles
- removing unsupported tooth structure
- divergence of mesial and distal prepared walls
54
What is resistance form in the amalgam?
features that help the amalgam resist fracture and wear under function
55
How thick should amalgam be in a restoration? How far into the dentin?
1.5-2 mm (adequate depth of pulpal floor) which should be 0.5 mm in dentin
56
Between what angles should the tooth prep be on the buccal and lingual walls for the resistance form of the amalgam?
80-100 degrees with an ideal angle of 90 degrees
57
What is convenience form? What are some examples?
preparation features that make the area more accessible or the procedure easier
- extension of walls to provide greater access for caries removal
- extension of walls to ensure the preparation is wide enough to fit the smallest condenser to ensure adequate condensation of amalgam
58
What makes up the armamentarium of tooth preparation?
- mouth mirror
- pig-tail and sickle explorer
- periodontal probe
- small and large spoon excavator
- 8-9 hatchet
- cotton pliers
- marginal trimmers #28 and #29
- miller forceps
- articulating paper
- high/low-speed handpieces
- burs #330, 245, 169, and 256
59
What is the appearance of a #330 bur?
pear-shaped, normal length
60
What is the appearance of a #245 bur?
pear-shaped, elongated
61
What is the appearance of a #169 bur?
tapered fissure
62
What is the appearance of a #256 bur?
straight fissure
63
What is a #245 bur generally used for?
proximal box formation in a Class II cavity preparation
64
Which bur is recommended for most conservative amalgam preparations?
#330 bur
65
What is the length and diameter of a #330 bur?
1.5 mm in length of cutting edge and 0.80 diameter at the tip
66
True or false: During a preparation of a tooth, the angle of the bur should be parallel to the long axis of the tooth.
true (mandibular teeth are lingually tilted so the bur must also be angled)
67
Should light, short strokes or long, heavy strokes be used while preping a tooth?
light, short strokes
68
When prepping a tooth, should you move mesial to distal or distal to mesial?
distal to mesial
69
In comparison to the length of a #330 bur, how deep should the pulp floor depth be? A #245 bur?
- full length of a #330 bur (1.5 mm)
| - half of the length of a #245 bur
70
Why should the mesial and distal walls diverge?
to maintain resistance form by conserving the ridge supporting dentin
71
True or false: The shape of a Class I prep is butterfly or dog-bone shaped.
true
72
How deep should the axial wall depth be in a buccal or lingual extension?
1.5-2.0 mm (0.2-0.5 mm into dentin)
73
How fast does a high speed handpiece rotate (in rotations per minute)?
200,000 rpm and above
74
How fast does a low speed handpiece rotate (in rotations per minute)?
12,000 rpm and below
75
Other than high, medium, and low speed handpieces, what are two alternative pieces of power equipment that can be used for removal of tooth tissue?
laser equipment and air-abrasion unit
76
How does laser equipment work? What are some of the drawbacks?
produce beams of coherent and very high intensity light
- currently expensive
- high amount of heat generated
- inefficient at removing large amounts of tooth structure
- special safety precautions required
77
How does air-abrasion work?
transfer of kinetic energy from a stream of powder particles onto tooth surface or a restoration, producing a fractured surface layer which results in roughness for bonding or disruption for cutting
78
On a bur, what is the name of the side of the blade towards which the bur is cutting?
rake face
79
On a bur, what is the name of the side of the blade away from which the bur is cutting?
clearance face
80
On a bur, what is the name of the angle between the rake face and the radius of the head diameter?
rake angle
81
What does a negative rake angle do?
minimizes fractures of the cutting edge, increasing tool life
82
What is the most important design characteristic of a bur blade?
rake angle
83
On a bur, what is the name of the angle between the rake face and the clearance face?
edge angle
84
What does increasing the edge angle do?
reinforces the cutting edge and reduces likelihood for fracture of the blade's edge
85
On a bur, what is the name of the angle between the clearance face and the tooth surface?
clearance angle
86
What type of rake angles, edge angles, and clearance angles does a carbide bur normally have?
- slightly negative rake angles
- edge angles of approximately 90 degrees
- low clearance angles
87
What are the 3 components of diamond burs?
- metal blank - resembles a bur without blades (head, neck, and shank)
- powdered diamond abrasive
- metallic bonding material
88
What are the two universal types of grasps used when holding hand instruments?
- modified pen grasp
| - inverted pen grasp
