Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BDS3 DMS > Endodontic Materials > Flashcards

Endodontic Materials Flashcards

(66 cards)

Start Studying
1
Q

What are the different categories of endodontic materials?

A
  • instruments
  • irrigants
  • intra-canal medicaments
  • obturation materials
  • sealers
  • pulp capping materials
  • root-end filling materials
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the functions of endodontic instruments?

A

the mechanical phase of chemo-mechanical disinfection

  • removal of hard and soft tissues
  • removal of microorganisms
  • creation of space for disinfectants/medicaments
  • creation of appropriate space for obturation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What area of a stress-strain curve should endodontic files be kept in?

A

the elastic region
- does not exceed the elastic limit
- reduced the risk of fracture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What happens if an endodontic file passes the plastic limit?

A

instrument separation
- strain experienced by the instrument was too great
- fracture point of the instrument reached
- instrument failure
- challenging clinically

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the relevance of torsional fatigue in relation to endodontic files?

A
  • instrument binds to dentinal wall and is rotated
  • bound portion does not rotate like driven portion
  • increased rotation causes torque
  • elastic limit is reached
  • plastic deformation experienced resulting in failure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What practice must be used with NiTi files to prevent instrument fracture?

A
  • glide path must be created to reduce torsional fatigue
  • straight line access in crown-down instrumentation technique to prevent instruments from working in a high stress form
  • electric speed and torque controlled motors limit the torque applied to instruments
  • rotation can be reversed if inappropriate torque is sensed but this point should not be reached
  • rotary files in abruptly curved or dilacerated canals should be avoided.
  • instruments should not be overloaded, use gently.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What different classifications of endodontic instruments exist?

A
  • manually operated (ISO No.3630-1)
  • low speed instruments
  • engine-driven NiTi rotary instruments
  • engine driven instruments adapting to canal (XP shapers)
  • engine driven reciprocating instruments
  • ultrasonic instruments
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the components of stainless steel used for endodontic files

A
  • alloy of iron, carbon and chromium
  • some contain nickel
  • improved carbon steel to reduce rusting
  • chromium (13-26%) prevents rusting
  • passivation layer of chromium oxide prevents degradation
  • rust resistance is less important in single use files
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the 2 ways in which endodontic files can be manufactured

A
  1. Twisting
    • machined stainless steel wire
    • wire has square or triangular cross section
    • wire is twisted
    • work hardening occurs
  2. Cutting
    • machine stainless steel wire into desired shape
    • work hardening occurs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Is work hardening desirable in endodontic files?

A

Yes, it improves the physical properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe the process of work hardening

A

strengthening of a metal by plastic deformation

  • crystal lattice is regular in organisation
  • crystal structure is dislocated when strain is applied to the point of plastic deformation
  • dislocations create obstructions in the crystal lattice which create resistance to further dislocations
  • increased hardness of material
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is nitinol?

A

equiatomic alloy of nickel and titanium

  • exotic metal which does not conform to the typical rules of metallurgy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What property of nitinol is different to that of most metals?

A

Super-elasticity
- application of stress does not result in usual proportional strain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the crystal structure of NiTi

A
  • temperature dependent structures, altered crystal lattice
  • character and proportions determine the mechanical properties of the metal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the two crystal structures of NiTi

A

Martensite
- soft
- ductile
- easily deformed

Austenite
- strong
- hard

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What instrument uses the two crystal structures of NiTi?

A

XP shaper files
- malleable and relaxed shape in martensitic phase
- robust shape in austenitic phase (when heated)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the components of an endodontic rotary instrument?

A
  • taper
  • flute
  • leading/cutting edge
  • land
  • relief
  • helix angle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the taper of an endodontic file?

A

the diameter change along the working surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the flute of an endodontic file?

A

the groove to collect dentine and soft tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the leading/cutting edge of an endodontic file?

A

the edge which forms and deflects dentine chips

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the land of an endodontic file?

A

the surface extending between flutes
- touches the wall of the canal
- develops considerable friction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the relief of an endodontic file?

A

the reduction in surface of land
- reduces friction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the helix angle of an endodontic file?

A

the angle the cutting axis forms with the long axis of the file

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the function of shaped files?

A

the expanded form sweeps the wall of the root canal to more effectively debride the root surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What are the functions of irrigants?
- facilitates removal of debris - lubrication - dissolution of organic and inorganic matter in root canal space - penetration to canal periphery - antimicrobial activity - disruption of biofilm - biological compatibility - does not weaken tooth structure
26
What is the primary irritant used in endodontic treatment?
sodium hypochlorite (NaOCl)
27
Describe the structure and behaviour of sodium hypochlorite (NaOCl)
- NaOCl ionises in water into Na+ and OCl - - equilibrium established with hypochlorous acid (HOCl) - at pH 7 and below HOCl predominates - at pH 9 and above OCl- predominates
28
Describe the function of sodium hypochlorite (NaOCl)
- has effect on organic material - cannot remove the smear layer but can disrupt the organic component - may have an effect of dentine properties - HOCl is responsible for significant antimicrobial activity
29
What factors determine successful function of NaOCl?
- concentration - volume - contact with tissue - mechanical agitation - exchange
30
How is the smear layer formed and what challenges does it pose?
- formed during preparation - composed of organic plural material and inorganic dentinal debris - layer superficial at 1-5 micrometers depth with packing into tubules - results in bacterial contamination - interferes with disinfection - prevents sealer penetration
31
How is the smear layer removed
- 17% EDTA - 10% citric acid - MTAD (Mixture of Tetracycline isomer, Acid and Detergent) - sonic and ultrasonic irrigation (activates irritant, increases efficacy)
32
What must be considered careful when removing the smear layer?
- apical control
33
Why must irritants not be mixed?
precipitates can form - sodium hypochlorite must be withdrawn - EDTA can then be added - sterile water may be used in between parachloroaniline formed by NaOCl interactions - cytotoxic - carcinogenic - uncertain bioavailability
34
What is 0.2% chlorhexidine used for?
- checking dam integrity
35
Why would 2% chlorhexidine be used?
- check for iatrogenic damage - sodium hypochlorite contraindicated
36
What are the desired propertied of an obturation material?
- easily manipulated - ample working time - seals canal laterally and apically - non-irritant - impervious to moisture - unaffected by tissue fluids - inhibits bacterial growth - radiopaque - does not discolour tooth - sterile - easily removed if necessary
37
What is the most common obturation material?
gutta-percha
38
What is gutta-percha made from?
sap of trees from the sapodilla family
39
What is the structure of gutta-percha?
- trans isomer of polyisoprene
40
Describe the two forms of gutta-percha
Both are crystalline forms - alpha and beta Alpha - naturally occurring - melts into amorphous phase at 65 degrees - returns to alpha phase when cooled slowly - recrystallises to beta phase when cooled rapidly Beta - commercially prepared dental gutta-percha
41
What is the composition of gutta-percha cones?
- 20% gutta-percha - 65% zinc oxide - 10% radiopacifiers - 5% plasticisers
42
What are the different formats in which gutta-percha is available?
- standardised - non-standardised - size matched - thermal obturation (carrier-base system) - injectable pellets
43
In what ways can gutta-percha be modified to improve its characteristics?
- coatings can be added - material impregnated - improve antimicrobial activity - improve interactions with sealers - improved handling (bi-ceramic nanoparticles)
44
What are the functions of sealers?
- seal space between dentinal wall and core - fill voids and irregularities in canal, lateral canals and GP points used in lateral condensation - lubrication during obturation
45
What are the ideal properties of a sealer?
- tacky to provide good adhesion - establish hermetic seal - radiopaque - easily mixed - no shrinkage on setting - non-staining - bacteriostatic (ideally) or does not encourage growth - slow set - insoluble in tissue fluids - tissue tolerant - soluble on retreatment
46
What are the components of zinc oxide and eugenol?
- eugenol (mixing vehicle) - finely sifted zinc oxide (enhances flow) - may be modified with germicides - rosin or canada balsam - corticosteroids
47
What are the properties of zinc oxide and eugenol?
- less radiopaque than gutta-percha - effective antimicrobial - may provide cytoprotection - dentine adhesion (rosin/canada balsam) - resin acids in rosin affect lipids in the cell membrane so are antimicrobial/cytotoxic - toxic in the early stages of setting
48
Describe the setting process of zinc oxide and eugenol
- chemical process combined with physical embedding of zinc oxide in matrix of zinc eugenolate - eugenolate formation constitutes hardening (accelerated by CaOH so must be removed from canals)
49
What are the disadvantages of zinc oxide and eugenol as a sealer?
- free, unreacted eugenol can act as an irritant - volume lost over time due to dissolution (apical seal especially diminished) - dissolution evident on extrusion of previous treatments - unstable long term
50
What are the advantages and disadvantages of glass ionomer sealers?
Advantages - good dentine bonding properties Disadvantages - removal on pretreatment is difficult - minimal antimicrobial activity - little clinical data to support use Not widely adopted in practice
51
Give examples of resin sealers
- AH Plus - Epiphany + Resilon - EndoRez
52
Describe AH Plus
- endodontic sealer - contains epoxy resin - paste-paste mixing - slow setting (8 hours) - good sealing ability - good flow - rapid decline in toxicity (24 hours)
53
Describe Epiphany + Resilon
dual cure resin composite endodontic sealer Contains - BisGMA - Ethoxylated BisGMA - Urethane-dimethacrylate (UDMA) - Hydrophilic difunctional methacrylate - fillers (CaOh, BaSO4, Ba glass, silica) - required self etch primer which is challenging to used in canals
54
Describe EndoRez
- resin endodontic sealer - hydrophilic - good penetration into dentine tubules - biocompatible - good radiopacity
55
Describe Calcium Silicate Sealers
- high pH - pH 12.8 - initial 24 hours - antimicrobial - osteoinductive - hydrophilic - react well with moisture in dentinal tubules - enhanced biocompatibility - apical tissues found to react well adjacent - no setting shrinkage - non-resorbable - excellent sealing ability - quick setting - 3-4 hours - requires moisture - easy to use - increasingly used in practice - expensive - potentially challenging to retreat
56
Describe medicated sealers
NOT USED NOW - sealers containing paraformaldehyde - lead and mercury components have been removed - severe, permanent toxic effects on periradicular tissue - highly antimicrobial - Sargenti paste, endomethasone, SPAD
57
What is mineral trioxide aggregate?
- pulp capping/root end filling material
58
What is the difference between grey and white mineral trioxide aggregate?
Grey - earliest formulations - results in tooth discolouration - contains - tricalcium silicate - dicalcium silicate - tricalcium aluminate - tertracalcium aluminoferrite - bismuth oxide White - smaller particle size - reduced discolouration - contains - tricalcium silicate - dicalcium silicate - calcium aluminate - dehydrated calcium sulphate - bismuth oxide
59
What is the mineral trioxide aggregate setting reaction?
- several phases of hydraulic cement setting - water is required for setting - delayed setting reaction with a dormancy period in which the material remains unset - delayed hardening until final set (many hours)
60
What can mineral trioxide aggregate be used for?
- apical areas - perforation good where moisture can be drawn upon by surrounding tissues
61
What can mineral trioxide aggregate not be used for?
restorations in the oral cavity - material will be washed away before it sets
62
What is biodentine?
- bioceramic cement (modified MTA)
63
How is biodentine used?
- direct pulp capping - building up restorations (cut back and restored with composite)
64
What are the advantageous properties of biodentine?
- sets rapidly (within minutes) - can be used in anterior teeth (reduced staining)
65
What is the tissue response to MTA?
- where MTA is placed osteogenesis is induced - osteogenesis related to pH change - hydroxyapatite formed on surface - cementum forms directly on MTA plug
66
Who can use orthograde MTA?
only hight specialised practitioners should use this - used instead of GP - very difficult to manipulate and remove

BDS3 DMS (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions