Fixed - L1 - Margin & Burs Flashcards Preview

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Flashcards in Fixed - L1 - Margin & Burs Deck (37)
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1

Conventional diamond burs are made by ...?

...plating small industrial mineral diamond particles on stainless steel shanks by a galvanic process

2

What are limitations of diamond burs?

1. heterogeneity of grain shapes (irregular)
2. difficulty of automation
3. short lifetime

3

Why do diamond burs have short lifetimes?

1. repeated sterilization (loss of particles)
2. ultrasonic cleaning solns w/ pH greater than 11 corrodes the nickel matrix (loss of particles)
3. potential smearing of Nickel ions from metallic binder onto the dental substrate

4

What are the types of bur designs?

1. parallel
2. tapered
3. modified-(round, flat)-end)
4. end cutting
5. round
6. barrel
7. egg
8. flame
9. wheel

5

Per ISO standards, the diameter of a rotary instrument is defined as the...?

widest part of the cutting surface

6

Objective of restorative therapy...?

to protect dentin, pulp, and other structures

7

Damages during tooth prep could occur to...?

adjacent teeth, soft tissues, and dental pulp

- we are more concerned w/ mechanical dmg to pulp

8

Increase in frictionally generated heat is influenced by...?

1. pressure
2. duration of applied force (intermittence)
3. condition of burs
4. rotational speed
5. use of coolant!
6. remaining dentin thickness

9

what is the adequate force for the burs?

1-4oz of force

10

What condition should the burs be in?

use NEW burs consistently

11

What should the rotational speed of the HS handpiece be?

200,000rpm

12

What should the remaining dentin thickness be?

2mm ideal, 0.5mm increases risk of toxic injury by 25%

13

3 - 25% of teeth develop _____ as a result of tooth prep for CCC.

pulpal necrosis

14

Whenever possible, margin should always be placed _____.

supragingivally

15

Exceptions to placing margin supragingivally?

1. cervical erosion (sensitivity)
2. subgingival restorations
3. prox. contact extends to the gingiva
4. additional retention & resistance is needed
5. surveyed FDP where undercuts are planned for clasp retention

16

What are the types of margin designs?

chamfer, shoulder, feather edge beveled shoulder

*we only use the first 2
- last one is most conservative

17

What is CVD?

Chemical vapor deposition (CVD); technique most modern/urban companies are using to help form a more even and uniform grain shapes in diamond burs.

18

what happens when you lose the diamond particles on the tip of the bur?

bur will create more heat

19

what are the 5 variables of bur design?

1. TYPE (shape)
2. LENGTH (total & cutting)
3. SIZE (HEAD/(Ø)
4. GRIT (texture)
5. HANDPIECE

20

which variable of bur design is most important?

GRIT

21

what are the most common types of burs for fixed?

parallel and tapered burs

22

goal of using burs in fixed?

to generate the most type of cuts w/ the lease amt of burs

23

what does grit depend on?

the size of the diamond particles

24

Color for the burs & Grit type:
gray - ?
white - ?
green - ?
red - ?
black - ?
yellow - ?

white - ultra fine
yellow - super fine
red - fine
gray - medium
green - coarse
black - super coarse

25

range of length for bur design? (include total & cutting)

total: 14.5 - 25mm
cutting: 0.08 - 10mm

26

range of size (head/(Ø)?

0.5 - 8.0mm

27

range of grit for bur design?

Ultra fine (8μ) to Super Coarse (150μ)

28

type of handpiece for fixed burs?

FG, Latch, Straight, Stryker

29

what type of bur makes it easier to avoid J-margins?

modified round-end taper

30

Per ISO standards, the diameter of a rotary instrument is defined as the _____.

widest part of the cutting surface