Week 1 Flashcards
1
Q
What are 2 types of hand pieces?
What’s the difference?
A
- Air driven:
- been around for many years - Electric:
- getting popular
- quieter
- cuts with higher torque
- higher power
- less stalling
- smoother cutting (more milling than chopping)
2
Q
RPM’s of slow, medium and high speed handpieces?
A
Slow: 200,000rpm
3
Q
which handpiece (low speed/high speed) will have less patient discomfort? why?
A
high speed bcz:
- it is more efficient
- less vibration
- less pressure
4
Q
what are the hole connectors in high speed?
A
drive air, exhaust, fiber opitc, water (coolant), air (coolant)
5
Q
what’s the function of coupler?
A
- attaches hand piece to the delivery unit
- supplies air and water to handpiece
6
Q
What are the uses of slow speed?
A
- finishing and polishing (whether it is restoration or a prep) (intra oral or extraoral)
- cleaning external surface of teeth (coronal polishing)
7
Q
what type of bur go into the straight handpiece?
what’s the straight handpiece used for?
A
long shank type bur / straight bur
use in extra oral procedures: finishing a crown
8
Q
what type of heads accept “latch type” burs?
A
low speed with either one of the following heads:
- swing latch
- push button latch
- spring latch
9
Q
what type of heads “friction grip” head? what’s the mechanism for each one?
A
low speed with either one of the following heads:
- push button type: friction generated from an internal spring assembly
- bur tool type: a special tool using force to overcome and generate friction
10
Q
what type of burs fit into the “latch type head”?
A
only latch end burs
11
Q
difference btwn friction grip type bur and latch type bur?
A
friction grip type bur are:
-smaller diameter and
-shorter shanks
than latch type
12
Q
components of rotary instruments
A
in order: head, neck, shank
13
Q
why is the neck of the rotary instrument small?
A
so it wouldn’t interfere with operator’s visibility
14
Q
classify bladed instruments based on the number of blades
A
- excavating / cutting burs (6 or 8 blades)
- finishing burs (10-20 blades)
2a. red: 10-12
2b. yellow: 16-20
2c. white: 30 blades
15
Q
what are the characteristics of the carbide burs?
A
stronger and harder than stainless steel
more brittle than steel
16
Q
composition of carbide burs?
A
tungsten carbide head is attached to the steel neck and shank by welding and brazing
17
Q
composition of the head of diamond burs?
A
METAL blank on which small DIAMOND particles are held together within a SOFTER MATRIX
18
Q
which type of bur is used for abrasive cutting?
A
diamond burs
19
Q
what are the colors of the shanks for the diamond instruments?
A
yellow: superfine
red: fine (60-74 micrometers)
blue: medium (88-125 micrometers)
green: coarse (125-150 micrometers)
black: supercoarse
20
Q
which way is ascending degree of grit? yellow to black? or black to yellow?
A
ascending degree of grit:
yellow to black
21
Q
what are the uses of carbide instrument? for diamond instrument?
A
uses of carbide instrument: intracoronal preparation
uses of diamond instrument: extracoronal preparation
22
Q
how are coated abrasives made?
A
abrasives (garnet, quartz, cuttlebone etc) placed on paper flexible backing to form discs or finishing strips
23
Q
what is used to attach abrasive discsto handpieces?
A
MANDRELS
24
Q
what are coated abrasives used for?
A
finishing restorations (not polishing)
25
what are the different abbrasives used in molding and coated abrasives?
coated abrasives: garnet, quartz, cuttlebone
| molding abrasives: SiC or Al2O3
26
what's the composition of molded abrasives?
molding abrasives (SiC or Al2O3) and matrix (rubber, resin) into certain shapes
27
how are molded abrasives catagorized? give examples
mounted: points and stones
unmounted: discs and stonewheels
or
rigid: griding and shaping
flexible: finishing and polishing
28
what are finishing strips? coated or molded
coated
29
shapes of burs? and numbers
```
round 1/4 - 11
inverted cone 331/2 or 40
pear shape 229 - 333
plain cylindrical fissure 55 to 59
plain tapered fissure 169 to 172
end cutting 900 series
cross cut 500 series also 700
```
30
state all the numbers that correspond to the mm for round burs
```
1/4 = 0.5 mm
1/2 = 0.6 mm
1 = 0.8 mm
2 = 1 mm
4 = 1.4 mm
6 = 1.8 mm
```
31
dimensions of 330?
length: 1.5 mm
taper: 8 degrees
diameter: 0.8 mm
32
dimensions of 245?
length: 3.0 mm
taper: 4 degrees
diameter: 0.8 mm
33
Mechanism of cutting? describe the mechanism of each
brittle fracture: brittle material fractures by crack formation upon tensile loading (like enamel)
ductile fracture: plastic deformation of the material by shearing.
teeth undergo both
34
which type of cutting is more efficient for brittle material? which one for ductile material?
brittle: abrasive cutting (microcracks)
ductile: bladed cutting (deform then shear)
35
what does the rake face and clearance face of blade do? which side is towards? which side is away from the direction of cutting?
```
rake face:
-forms the chip
-towards the direction of cutting
clearance face:
-clears the chips
-away from the direction of cutting
```
36
what's edge angle?
btwn rake and clearance surface
37
what's rake angle?
btwn radial line and the rake face
38
what's clearance angle?
btwn the cutting edge and the tooth structure
39
how is a positive rake angle defined?
| what are the Characteristics of positive rake angle
Positive rake angle: radius is ahead of the rake face (from cutting edge to axis of bur)
- higher cutting efficiency
- larger chips produced
- chip space smaller (clogging of chip space)
- always a chance to curve, fracture if material is not adequate
40
how is a negative rake angle defined?
| what are the Characteristics of negative rake angle
negative rake angle: when the rake face is ahead of the radius (from cutting edge to axis of bur)
- decreased cutting efficiency
- smaller chips are produced = no clogging of the chip space
- cutting edge is spared (less liable to fracture) since carbide burs are brittle
41
is negative rake angle used in dentistry or positive?
negative rake angle
42
characteristics of LARGE clearance angle?
- less friction
- dulling minimized
- bur life lengthened
43
what's the use of "hand cutting instrument"?
to refine and shape the cavity walls
44
what's the composition of hand cutting instruments?
blade: carbon steel (carbon is harder than stainless steel)
handle: stainless steel (Cr: corrosion resistant and retain the shine)
45
what's the component of each hand instrument?
handle, shank, blade
46
how many numbers are there in hand cutting instrument? what are they for?
2 numbers:
1. instrument formula (ID formula)
2. the manufacturer serial number
47
what groups are hand instruments divided into?
| what do each do?
examination (not cutting): examines the teeth, soft tissue and hard tissue
hand cutting instrument: refine the walls of the tooth preparation to receive the restoration
restorative instruments (non cutting): insert dental material in the cavity prep and carve back the tooth contour
accessory instrument: aid to complete the procedure (ex: bridge scissors)
48
what do the 3 numbers on the hand instrument represent?
1st number: width of the blade in mm X 10
2nd number: length of the blade in mm
3rd number: angulation of the blade to the long axis of the handle (expressed in 100th of circle) (always <50)
49
what do the 4 numbers on a hand instrument represent?
1st: width of the blade in mm X 10
2nd: primary cutting edge angle in centigrade (100th of circle) (always > 50)
3rd: length of blade in mm
4th: angulation of the blade to the long axis of the handle (expressed in 100th of circle)
- number angle number angle
50
1. definition of indirect cutting
2. motion
3. hand tool example
indirect cutting = scrapping = lateral cutting
1. force exerted is parallel to the cutting edge
2. from the bevel to the nonbevel side (away from bevel)
3. enamel hatchet and gingival margin trimmer
51
1. definition of direct cutting
2. motion
3. hand tool example
direct cutting = chiseling
1. force applied is perpendicular to cutting edge
2. the cutting edge in contact with the wall being planed. holding the instrument parallel to the wall being planed. the bevel side away from the wall
3. enamel hatchet
52
does gingival trimmer do direct cutting or lateral cutting?
Lateral cutting
| -the force applied is PARALLEL to the cutting edge
53
factors needed for dental caries to happen
1. time
2. carbohydrates
3. bacteria
4. tooth
54
what are stages of caries?
1. incipient (reversible): within enamel
2. small: just right at dentin
3. moderate: ONLY in dentin
4. extensive: in dentin, going towards pulp
55
what is it called when caries go under a preexisting faulty restoration?
recurrent or secondary caries
56
Classification of caries
class I:
- pits and fissures of occlusal surface of premolars and molars;
- buccal or lingual pits/fissure of molars
- lingual pit near the cingulum of the max incisors
```
class II:
-proximal of posterior tooth
```
```
class III:
-proximal of anterior tooth
```
```
class IV:
-proximal of anterior + incisal edge
```
```
class V:
-gingival 3rd of facial or lingual of any tooth
```
class VI:
- incisal edge of anterior teeth
- cusp tips of posterior teeth
- rare
57
fundaments concepts for all tooth preparation
1. remove caries
2. remove weak tooth structure
3. pulp protection
58
cavity walls
according to the proximity to the external surface
1. external wall: extends to the outer tooth surface
2. internal wall: doesn't extend to the outer tooth surface
according to the angulation from the long axis:
1. axial wall: parallel to the long axis
2. perpendicular wall
59
define isthmus in class I and II
```
isthmus in class I: narrowest portion of a cavity preparation
isthmus in class II: a portion of the cavity connecting an occlusal portion and a proximal portion together
```
60
what's the junction btwn the external walls of the cavity preparation and the uncut tooth surface?
cavosurface margin
61
What are the 2 outline form approaches in cavity preparation?
extension for prevention:
-extensive tooth preparation.
-unnecessary loss of healthy tooth structure
conservative approach:
-preservation of the remaining tooth structure.
-minimal extension of the outline form
62
what are the 6 basic principle of cavity preparation?
1. outline form
2. resistance form
3. retention form
4. convenience form
5. finishing
6. debridement (cleaning) (toileting)
63
how far apart should 2 cavities be before we connect them together?
<0.5mm
64
what main factor dictate the prep outline?
position of pit and fissure
65
how deep should a class I cavity prep be?
- 1.5 mm
| - 0.2 to 0.5 mm into dentin
66
Cavosurface margin has to establish a _____ degrees amalgam margin
90 degrees
| -bcz both amalgam and enamel have low edge strength
67
what's the diameter of the small end of the small condensor?
1 mm
68
what are the 2 special cases when preping? and what do we have to do for each case?
Max molars: DO NOT extend into the oblique ridge of max molars unless it has caries
Mand 1st premolar: DO NOT extend into transverse ridge of mand 1st premolar unless it has caries
69
what's the relationship btwn isthmus and intercuspal distance?
isthmus width shouldnt exceed 1/3 of intercuspal distance
- preferably 1/4 of intercuspal distance
- in general, isthmus width should be 1-1.2 mm
70
when preping, what should the distance be btwn cavosurface margin and he proximal contact area?
1.6 mm
| twice the width of the point of 330 or 245
71
what are the markings on a preio prob?
1, 2, 3, 5, 7, 8, 9, 10 mm
| -missing 4 and 6
72
what tooth has to have a sloped pulpal floor?
mand 1st pm
73
what's a class I with extension refered to as?
compound class I
74
which teeth and which surfaces are prone to compound class I caries?
Max molar: lingual fissure
| mand molar: buccal fissure
75
occlusal portion of a class I w/ extension is the same as class I prep, except...
the pulpal floor assumes an occlusal elevation as following the contour of the occlusal surface and the DEJ, which rises occlusally
76
class I with extension:
- mesial and distal wall (converge/diverge)
- axial wall (curves/doesn't curve)
- axial depth should be ... mm
- mesial and distal wall CONVERGE
- axial wall CURVES
- axial depth should be 1-1.2mm
77
advantages and disadvantages of rubber dam
advantages:
-dry, clean operating field
-improved access and visibility
-patient protection
-increased operating efficiency
-improved properties of dental material
disadvantages:
-time consuming
-patient objection
-interferes with access
78
advantages of using a napkin under the rubber dam?
improves patient comfort
absorbs excess saliva
acts as a cushion
79
2 types of clamps are...
1. winged retainer
| 2. anterior retainer
80
what tool is used to place the clamp on tooth?
rubber dam forceps
81
steps of removing the rubber dam frame?
1. cut the septa
2. remove the retainer/clamp
3. remove the rubber dam/frame
4. examine the rubber dam
82
What's the purpose of isthmus?
to preserve triangular ridge
83
what should be the depth in relation to central fissure? in relation to cavosurface margin?
central fissure: 1.5 mm
cavosurface margin: 2 mm
(week 5, page 1, slide 6)
84
what's the height of the axial wall in class II prep?
1.0 mm
85
T/F
| The enamel portion of the gingival wall should be parallel to the dentin part
False
the enamel portion of the gingival wall should be beveled TWENTY DEGREES
(week 5, page 5, slide 5)
86
In class 2, what's the buccal and lingual clearance to the adjacent tooth?
0.2 to 0.3 mm
87
In class 2, what's gingival clearance to the adjacent tooth?
0.5 mm
| pg 741, figure F
88
class 2, what's the characteristic of the walls of the box
convergent
89
what's the purpose of retention grooves in class II prep?
retention
| resistance
90
what bur is used for class II retention
169
91
how deep should we go into the dentin for the class II retention
0.2 mm into dentin
92
```
class II
location of the proximal lesion to the proximal contact area
```
lesion is gingival to proximal contact area
93
compound class II vs simple class II
```
simple class II: accessing ONLY the proximal surface (not occlusal)
compound class II: 2 surface (occlusal and proximal) preparation (compound class II = conventional)
```
94
in a direct cutting, what's the relationship btwn the force, cutting edge, and blade?
force is parallel to blade
| force is perpendicular to cutting edge
