Burs - Background Info

Question 1

rotary cutting instruments consist of a ____ and the _____/_____

Answer 1

handpiece

Bur/abrasive

Question 2

The handpiece provides the ___

Answer 2

rotational energy

Question 3

The bur/abrasive makes contact with and____ or ____ the tooth

Answer 3

Cuts

Abrades

Question 4

Straight handpiece

Answer 4

Long axis of bur = long axis of handpiece
Always low speed
Long burs - HP
Friction grip chuck
Rarely used intraorally

Question 5

HA burs

Answer 5

Long friction grip burs for use in the straight handpiece

Question 6

Contra-angle handpiece

Answer 6

Long axis of bur about 115 degrees from long axis of handpiece by two bends in the rotational shaft

Question 7

Low speed handpieces operate up to _____ rpm

Answer 7

8k-35k rpm

Question 8

High speed handpieces operate up to ____ rpm

Answer 8

160k - 500k rpm

Question 9

Why do high speed handpieces require water coolant spray?

Answer 9

Produces a lot of heat that can damage tooth tissue and pulp

Question 10

High speed handpieces are used for…

Answer 10

gross reduction

Question 11

High speed handpieces are involved in ___% of the cavity prep

Answer 11

90%

Question 12

Low speed handpieces are used for…

Answer 12

Cavity refinement and restoration finishing and polishing

Bc they provide greater tactile feedback to DDS

Question 13

Slow speed contra-angle handpiece

Answer 13

friction grip or latch head
LA/RA - latch burs - wider shank
FG - friction grip burs

Question 14

LA/RA burs

Answer 14

latch burs to be used in the slow speed contra-angle handpiece
wider shank diameter than friction grip burs

Question 15

FG burs

Answer 15

friction grip burs to be used in the slow speed contra-angle handpiece

Question 16

High speed handpieces are always ______ and have _______ chucks

Answer 16

contra-angled

friction grip

Question 17

Carbide burs

Answer 17

Head made of tungsten carbide - very hard, still sharp at high temps
Neck/shank - nickel plated steel

Question 18

Round burs

Answer 18

We have 4 carbide FG round burs
Used for various aspects of cavity prep
Low or high speed

Question 19

“Caries removal burs”

Answer 19

WE DON’T HAVE THESE
LA round burs
Used for removing soft, leathery dentin in caries lesion

Question 20

Fissure burs

Answer 20

6 bladed carbide FG burs
Long, slender profile
Used for extending prep into occlusal pits and fissures
Straight or Tapered

Question 21

Plain straight fissure bur

Answer 21

creates sharp internal line angles

Question 22

Plain rounded fissure burs

Answer 22

Creates internal anatomy with rounded line angles

Question 23

Crosscut burs

Answer 23

Additional set of cuts across each blade
Increase cutting efficiency
Comb-like appearance
More agressive
Less chatter

Question 24

At high speeds there is _____ difference between burs with and without crosscuts

Answer 24

little

Question 25

Tapered fissure burs

Answer 25

Sides are convergent Sides tapered 2-4 degrees off vertical axis Used for cast gold preps where cavity wall taper is desireable

Question 26

Finishing burs

Answer 26

12 bladed FB burs Less aggressive at cutting than the 6 bladed carbides but have smoother finish Low speed - finishing restorations

Question 27

Abrasives designed for use with rotary instrumentation are generally designed for use with the ______ handpiece

Answer 27

Low speed

Question 28

Mounted stones

Answer 28

WE HAVE 3 Green carrot stone - coarse Green sphere stone - coarse White carrot stone (Arkansas stone) - medium Used for early stages of finishing metallic restorations FG or LA

Question 29

Mounted stones should NEVER be used on...

Answer 29

composite resin restorations

Question 30

Impregnated rubber points

Answer 30

``` Carrot shaped FG shanks Brownie - coarser Greenie - less abrasive Used for fine finishing and polishing of metallic restorations ```

Question 31

Impregnated rubber points shoud NEVER be used on _____

Answer 31

composite resin restorations

Question 32

Light colored LA rubber abrasives

Answer 32

Enhance - fine PoGo - superfine Used for composite resin finishing and polishing Various shapes

Question 33

What are the 2 styles of mandrel

Answer 33

1. Moore's - snap - square hole | 2. Soflex/pop-on - round hole

Question 34

a dull bur results in a ______ prep

Answer 34

oversized This is due to the DDS needing to use extra force to get bur to cut Control and tactile feedback greatly diminished

Question 35

A dull bur can damage the underlying pulp through ____

Answer 35

generation of excessive heat

Question 36

How can you identify a dull bur?

Answer 36

Visual inspection doesn't work | Behavior under function

Question 37

Signs that a bur might be dull:

Answer 37

- Burns, chars, darkens tooth - Chatters/vibrates rapidly - Requires pushing to get it to 'bite' into tooth - Anytime bur seems sluggish/reluctant to cut, it may be dull

Question 38

When evaluating if a bur is dull, is it critical that the handpiece is functioning at _____ and _______

Answer 38

optimum speed | in the forward direction of rotation