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BDS3 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 = F/A

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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 root 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

What is Cyclic Fatigue?

A
  • Stress and strain, and deformation induced in a material by cyclic loading
  • File is freely rotating in a curvature
  • Generation of tensions/ compression cycles
  • Leads to cyclic fatigue and eventually failure
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11
Q

What is Torsional fatigue?

A
  • The damage to the torque shafts caused by torsional loading which leads to a different form of throwing stress
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12
Q

What is stainless steel for the Kfiles made of?

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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13
Q

How are kfiles manufactured?

A
  • Machined stainless steel wire
  • Square/ Triangular
  • Twisted
  • Work hardening occurs
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14
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 dislocation formation develops
  • Observed work hardening
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15
Q

What is Nitinol?

A
  • Equiatomic alloy of nickel and titanium
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16
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

17
Q

What is mettalurgy?

A
  • Branch of science and technology concerned with properties of metals and their production and purification
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.
19
Q

What is the shape memory of KFile?

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

What are the properties of Irrigant?

A

Plays central role for endo treatment
- Facilitate removal of debris
- Lubrication
- Dissolution of organic and inorganic matter
- Penetration to canal periphery
- Kill bacteria/yeasts/viruses
- Biofilm disruption
- Biological compatibility
- Does not weaken tooth structure

21
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
22
Q

Why do we need to prepare the canal for obturation?

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
23
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!
24
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
25
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
26
Q

What are the functions of Sealers?

A
  • Seals space between dentinal wall and core
  • Fills voids and irregularities in canal, lateral canals and between gutta-percha points used in lateral condensation
  • Lubricates during obturation
27
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
28
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
  • Is a corticosteroid
  • Zinc oxide effective antimicrobial and is cytoprotectant
29
Q

Positive and negative of glass ionomer sealer?

A
  • Advocated due to dentine bonding properties
  • Removal upon retreatment is difficult
  • Minimal antimicrobial activity
30
Q

Positive and negative of epoxy resin sealer?

A
  • Long history of use
  • Slow setting - 8 hours
  • Good sealing ability
  • Good flow
31
Q

What is EndoRez? Give positive and negative

A
  • UDMA resin-based sealer
  • Hydrophilic
  • Good penetration into tubules
  • Biocompatible
  • Good radio-opacity
32
Q

What are some Resin Sealers?

A
  • BisGMA
  • Ethoxylated BisGMA
  • Urethane-dimethacrylate UDMA
  • Hydrophilic difunctional methacrylates
  • Fillers of calcium hydroxide, barium sulphate, barium glass and silica
33
Q

What are some properties of Calcium Silicate Sealers?

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
34
Q

What sealers are not acceptable?

A
  • Sealers containing Paraformaldehyde
  • Severe and permanent toxic effects on periradicular tissues
35
Q

What are the two colours of mineral trioxide aggregate?

A
  • Grey
  • White
36
Q

What is an example of MTA?

A

Tricalcium silicate
Dicalcium silicate

BDS3 Endodontics (5 decks)

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