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Endodontics > Endodontic Materials > Flashcards

Endodontic Materials Flashcards

1
Q

What are the Endodontic Material Categories?

A
  • Instruments
  • Irrigants
  • Intra-canal medicaments
  • Obturation materials
  • Sealers
  • Pulp Capping materials
  • Root-end filling materials
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2
Q

What are the endodontic instruments used for?

A
  • For mechanical phase of chemo mechanical disinfection
  • Metal files used to remove soft and hard tissues
  • Removes micro-organisms
  • Creates spaces for disinfectants/ medicaments
  • Creates appropriate shape for obturation
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3
Q

What is Stress?

A
  • Deforming force measured across a given area
  • Tensile/compressive/shear/torsional

Stress = Force/ Area

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4
Q

What is the stress concentration point in regard to endodontic instrument?

A
  • Abrupt changes in the geometric shape of a file that leads to a higher stress at that point
  • Can be due to notch and change in file shape
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5
Q

What is Strain?

A
  • Response of a material to stress
  • Amount of deformation a file undergoes
    Strain = Delta L / L
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6
Q

What is Elastic Limit in regard to metal file?

A
  • A set value representing the maximal strain that when applied to a file, allows the file to return to original dimensions
  • File still has fracture point if stress vs strain too much
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7
Q

What is elastic deformation?

A
  • Reversible deformation that does not exceed elastic limit
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8
Q

What is plastic deformation?

A
  • Permanent bond displacement occurring when elastic limit exceeded
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9
Q

What is the Plastic Limit?

A
  • Point at which a plastic deformed file breaks
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10
Q

2 types of fatigue

A
  • cyclic
  • torsional
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11
Q

What is Cyclic Fatigue?

A
  • File is freely rotating in a curvature
  • Generation of tensions/ compression cycles
  • Leads to cyclic fatigue and eventually failure
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12
Q

What is Torsional fatigue?

A
  • file end is binded / locked
  • while the other end rotating
  • torsional/ twisting force
  • plastic deformation and failure
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13
Q

What is stainless steel for the Kfiles made of?

hand files

A
  • Alloy of iron, carbon and chromium
  • Nickel may also be present
  • Improved carbon steel – rusting
  • 13-26% chromium prevents rusting
  • Passivation layer of chromium oxide
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14
Q

How are kfiles manufactured?

A
  • Machined stainless steel wire
  • Square/ Triangular
  • Twisted
  • Work hardening occurs
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15
Q

What is the process of Work hardening?

A
  • Strengthening of a metal by plastic deformation
  • Crystal structure dislocation occurs
  • Dislocations interact and create obstructions in crystal lattice
  • Resistance to further dislocation formation develops
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16
Q

What is Nitinol?

A
  • Equiatomic alloy of nickel and titanium
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17
Q

What are the properties of Nitinol?

A

Exotic metal - Does not conform to typical rules of mettalurgy
Super-elasticity - Application of stress does not result in usual proportional strain

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18
Q

What is shape memory?

A
  • Alloys are materials that can be deformed at one temperature but when heated or cooled, return to their original shape.
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19
Q

What is the shape memory of KFile?

A
  • Martensitic Phase: At or below room temp the instrument is very malleable and has relaxed serpentine shape
  • Austenitic Phase: Warmer temp (>95degreesF), the instrument transitions to a more robust serpentine shape
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20
Q

What are the properties /use of Irrigant?

A

Plays central role for endo treatment

  • Facilitate removal of debris
  • Lubrication
  • Dissolve of organic and inorganic matter
  • Penetration to canal periphery
  • Kill bacteria/yeasts/viruses
  • Biofilm disruption
  • Biological compatibility
  • Does not weaken tooth structure
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21
Q

Sodium Hypochlorite
- conc
- main properties
- use
- amount per canal

A
  • 3%
  • dissolve organic material, bactericidal
  • disinfection
  • 30 ml for 10 min prior obturation
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22
Q

EDTA

  • conc
  • main properties
  • use
  • amount per canal
A
  • 17%
  • remove smear layer
  • penultimate rinse for 1 min
  • 3 ml
23
Q

Chlorhexidine digluconate

  • conc
  • main properties
  • use
  • amount per canal
A
  • 0.2%
  • check dam intgrity, disinfect tooth surface

or

  • 2%
  • antimicrobial
  • suspect iatrogenic damage
  • only when NaOCl is contraindicated
24
Q

Sterile saline

  • use
A
  • wash out canal hypochlorite accident suspected
25
Q

Why is Sodium Hypochlorite (NaOCl) used for Irrigant?

A
  • NaOCl ionises in water into NA+ and the hypochlorite ion, OCl-
  • Establishes equilibrium with hypochlorous acid (HOCl)
  • Acid/Neutral HOCl predominates
  • pH 9 and above OCl- predominates
  • HOCl is responsible for antibacterial activity
26
Q

Factors important for NaOCl function

A
  • volume
  • concentration
  • contact
  • mechanical agitation
  • exchange of ions
27
Q

Preparation of the canal can lead to

A
  • Smear layer formed during preparation
  • Organic pulpal material and inorganic dentinal debris
  • Superficial 1-5µm with packing into tubules
  • Bacterial contamination, substrate and interferes with disinfection
  • Prevents sealer penetration
28
Q

How do you remove Smear Layer?

A
  • 17% EDTA
  • 10% Citric Acid
  • MTAD (Mixture of a Tetracycline isomer, an Acid, and a Detergent
  • Sonic and Ultrasonic irrigation
  • Watch apical control!
29
Q

what should you not mix in the canal

A

EDTA & NaOCl

NAOCl and CHX

30
Q

what happen if you mix NaOCl and CHX

A
  • forms para-chloroaniline
  • cytotoxic and carcinogenic
31
Q

What are the properties of an Ideal Obturation material?

A
  • Easily manipulated with ample working time
  • Dimensionally by tissue fluids stable
  • Seals the canal laterally and apically
  • Non-irritatant
  • Impervious to moisture
  • Unaffected by tissue fluids
  • Inhibits bacterial growth
  • Radiopaque
  • Does not discolour tooth
  • Sterile
  • Easily removed if necessary
32
Q

What are Gutta-Percha cones made of?

A
  • 20% Gutta-percha
  • 65% Zinc Oxide
  • 10% Radiopacifiers
  • 5% Plasticizers
  • Standardised, non-standardised and size-matched
33
Q

What are the functions of Sealers?

A
  • Seals space between dentinal wall and core to create a homogenous seal
  • Fills voids and irregularities in canal, lateral canals and between gutta-percha points used in lateral condensation
  • Lubricates during obturation
  • antimicrobial - haematic seal
34
Q

What are the properties of an Ideal Sealer?

A
  • Exhibits tackiness to provide good adhesion
  • Establishes a hermetic seal
  • Radiopacity
  • Easily mixed
  • No shrinkage on setting
  • Non-staining
  • Bacteriostatic or does not encourage growth
  • Slow set
  • Insoluble in tissue fluids
  • Tissue tolerant
  • Soluble on retreatment
35
Q

What are the benefits of Zinc oxide and Eugenol as sealer?

A
  • Radio-opacity < GP
  • Rosin or Canada Balsam added to increase dentine adhesion
  • can be added with corticosteroid - anti-inflammatory
  • Zinc oxide effective antimicrobial and is cytoprotective
36
Q

disadvnatages of ZOE

A
  • free eugenol remained can be irritant
  • lose volume with time due to dissolution
37
Q

Positive and negative of glass ionomer sealer?

A
  • Advocated due to dentine bonding properties
  • Removal upon retreatment is difficult
  • Minimal antimicrobial activity
38
Q

Positive and negative of epoxy resin sealer?

AH plus

A
  • antimicrobial - haematic seal
  • Slow setting - 8 hours
  • Good sealing ability
  • Good flow
  • Initial toxiicity declining after 24 hours
39
Q

What is EndoRez? Give positives

A
  • UDMA resin-based sealer
  • Hydrophilic
  • Good penetration into tubules
  • Biocompatible
  • Good radio-opacity
40
Q

What is Epiphany?

A
  • dual cure
  • dental resin composite sealer
  • requires self-etch primer
41
Q

What are some properties of Calcium Silicate Sealers?

Bio Ceramic

A
  • High pH (12.8) during the initial 24 hours of the setting
  • Hydrophilic
  • Enhanced biocompatibility
  • Does not shrink on setting
  • Non-resorbable
  • Excellent sealing ability
  • Quick set - three to four hours – requires moisture
  • Easy to use
42
Q

What sealers are not acceptable?

A
  • Sealers containing Paraformaldehyde
  • Severe and permanent toxic effects on periradicular tissues
43
Q

What are the two colours of mineral trioxide aggregate?

MTA

A
  • Grey
  • White
44
Q

What is an example of MTA?

A

Tricalcium silicate
Dicalcium silicate

45
Q

setting rx of MTA

A
  • required water
  • extended setting times
  • for open apex, can draw moisture from apex
  • can’t be used in oral cavity (long setting time)
46
Q

advantages of MTA

A
  • Stimulate tissue regeneration of dentin and bone
  • Biocompatibility
  • Excellent Sealing Ability
47
Q

components of MTA

A
  • tricalcium silicate,
  • dicalcium silicate,
  • tricalcium aluminate,
  • calcium sulfate,
  • and a small amount of bismuth oxide
48
Q

use of MTA

A
  • Root Canal Repair:
  • Pulp Capping:
  • Apexification:
  • Root End Filling:
    *
49
Q

Biodentine use

calcium silicate cement

A
  • root perforation/ pulp floor
  • internal & external resorption
  • apexification
  • retrograde root canal obturation
  • direct/ indirect pulp capping
  • pulpotomy
  • temporary sealing of cavities
  • cervical filling
50
Q

Direct pulp capping material

A
  • Dycal ( setting CaOH)
  • Biodentine
51
Q

advantages of Dycal as direct pulp cap material

A
  • stimulate formation of reparative dentine (direct contact of pulp)
  • promote odontoblast differentiation
  • forming a dentine bridge
  • induce proliferation of pulp fibroblast
52
Q

disadvantages of Dycal as direct pulp cap material

A
  • poor bonding to dentine
  • mechanical instability
  • continued resorption after placement (microleakage)
53
Q

example of core build-up

A
  • para core
  • SDR (composite core)

Endodontics (7 decks)

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