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D2 - FALL - Par 2 > Fixed - L1 - Margin & Burs > Flashcards

Fixed - L1 - Margin & Burs Flashcards

1
Q

Conventional diamond burs are made by …?

A

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

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2
Q

What are limitations of diamond burs?

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

Why do diamond burs have short lifetimes?

A
  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
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4
Q

What are the types of bur designs?

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

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

A

widest part of the cutting surface

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6
Q

Objective of restorative therapy…?

A

to protect dentin, pulp, and other structures

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7
Q

Damages during tooth prep could occur to…?

A

adjacent teeth, soft tissues, and dental pulp

  • we are more concerned w/ mechanical dmg to pulp
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8
Q

Increase in frictionally generated heat is influenced by…?

A
  1. pressure
  2. duration of applied force (intermittence)
  3. condition of burs
  4. rotational speed
  5. use of coolant!
  6. remaining dentin thickness
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9
Q

what is the adequate force for the burs?

A

1-4oz of force

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10
Q

What condition should the burs be in?

A

use NEW burs consistently

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11
Q

What should the rotational speed of the HS handpiece be?

A

200,000rpm

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12
Q

What should the remaining dentin thickness be?

A

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

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13
Q

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

A

pulpal necrosis

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14
Q

Whenever possible, margin should always be placed _____.

A

supragingivally

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15
Q

Exceptions to placing margin supragingivally?

A
  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
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16
Q

What are the types of margin designs?

A

chamfer, shoulder, feather edge beveled shoulder

  • we only use the first 2
  • last one is most conservative
17
Q

What is CVD?

A

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
Q

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

A

bur will create more heat

19
Q

what are the 5 variables of bur design?

A
  1. TYPE (shape)
  2. LENGTH (total & cutting)
  3. SIZE (HEAD/(Ø)
  4. GRIT (texture)
  5. HANDPIECE
20
Q

which variable of bur design is most important?

21
Q

what are the most common types of burs for fixed?

A

parallel and tapered burs

22
Q

goal of using burs in fixed?

A

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

23
Q

what does grit depend on?

A

the size of the diamond particles

24
Q 
Color for the burs & Grit type:
gray - ?
white - ?
green - ?
red - ?
black - ?
yellow - ?
A 
white - ultra fine
yellow - super fine
red - fine
gray - medium
green - coarse
black - super coarse
25
Q

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

A

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

26
Q

range of size (head/(Ø)?

A

0.5 - 8.0mm

27
Q

range of grit for bur design?

A

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

28
Q

type of handpiece for fixed burs?

A

FG, Latch, Straight, Stryker

29
Q

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

A

modified round-end taper

30
Q

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

A

widest part of the cutting surface

31
Q

Tell me about the length, cutting length, head size, and grit of the modified round-end taper bur?ƒ

A 
TYPE: Modified Round End Taper 
LENGTH: 31 FG (19mm) 
CUTTING LENGTH: 8.0 mm 
HEAD SIZE Ø: 016 = 1.6mm 
GRIT: Coarse Medium Fine
32
Q

what do worn burs do?

A

have more touching area, so generate more friction, thus having more energy

33
Q

Depth of the prep affects what?

A

dentin permeability and odontoblast process amputation recovery

34
Q

incisal/occlusal remaining dentin thickness?

A

4mm combined enamel-dentin thickness in young teeth (5-7mm in older subjects)

35
Q

axial reduction of dentin?

A

0.3mm thickness remaining in young bicuspids when prep was 1.2 deep margin w/ TOC of 20 degrees

36
Q

Avoid full coverage on vital teeth before the age of…?

37
Q

Margin design is controlled by what?

A

your maneuvering of the bur shape

D2 - FALL - Par 2 (7 decks)

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