Endodontic Materials Flashcards
What are the Endodontic Material Categories?
- Instruments
- Irrigants
- Intra-canal medicaments
- Obturation materials
- Sealers
- Pulp Capping materials
- Root-end filling materials
What are the endodontic instruments used for?
- 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
What is Stress?
- Deforming force measured across a given area
- Tensile/compressive/shear/torsional
Stress = Force/ Area
What is the stress concentration point in regard to endodontic instrument?
- 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
What is Strain?
- Response of a material to stress
- Amount of deformation a file undergoes
Strain = Delta L / L
What is Elastic Limit in regard to metal file?
- 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
What is elastic deformation?
- Reversible deformation that does not exceed elastic limit
What is plastic deformation?
- Permanent bond displacement occurring when elastic limit exceeded
What is the Plastic Limit?
- Point at which a plastic deformed file breaks
2 types of fatigue
- cyclic
- torsional
What is Cyclic Fatigue?
- File is freely rotating in a curvature
- Generation of tensions/ compression cycles
- Leads to cyclic fatigue and eventually failure
What is Torsional fatigue?
- file end is binded / locked
- while the other end rotating
- torsional/ twisting force
- plastic deformation and failure
What is stainless steel for the Kfiles made of?
hand files
- 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
How are kfiles manufactured?
- Machined stainless steel wire
- Square/ Triangular
- Twisted
- Work hardening occurs
What is the process of Work hardening?
- 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
What is Nitinol?
- Equiatomic alloy of nickel and titanium
What are the properties of Nitinol?
Exotic metal - Does not conform to typical rules of mettalurgy
Super-elasticity - Application of stress does not result in usual proportional strain
What is shape memory?
- Alloys are materials that can be deformed at one temperature but when heated or cooled, return to their original shape.
What is the shape memory of KFile?
- 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
What are the properties /use of Irrigant?
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
Sodium Hypochlorite
- conc
- main properties
- use
- amount per canal
- 3%
- dissolve organic material, bactericidal
- disinfection
- 30 ml for 10 min prior obturation
EDTA
- conc
- main properties
- use
- amount per canal
- 17%
- remove smear layer
- penultimate rinse for 1 min
- 3 ml
Chlorhexidine digluconate
- conc
- main properties
- use
- amount per canal
- 0.2%
- check dam intgrity, disinfect tooth surface
or
- 2%
- antimicrobial
- suspect iatrogenic damage
- only when NaOCl is contraindicated
Sterile saline
- use
- wash out canal hypochlorite accident suspected
Why is Sodium Hypochlorite (NaOCl) used for Irrigant?
- 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
Factors important for NaOCl function
- volume
- concentration
- contact
- mechanical agitation
- exchange of ions
Preparation of the canal can lead to
- 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
How do you remove Smear Layer?
- 17% EDTA
- 10% Citric Acid
- MTAD (Mixture of a Tetracycline isomer, an Acid, and a Detergent
- Sonic and Ultrasonic irrigation
- Watch apical control!
what should you not mix in the canal
EDTA & NaOCl
NAOCl and CHX
what happen if you mix NaOCl and CHX
- forms para-chloroaniline
- cytotoxic and carcinogenic
What are the properties of an Ideal Obturation material?
- 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
What are Gutta-Percha cones made of?
- 20% Gutta-percha
- 65% Zinc Oxide
- 10% Radiopacifiers
- 5% Plasticizers
- Standardised, non-standardised and size-matched
What are the functions of Sealers?
- 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
What are the properties of an Ideal Sealer?
- 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
What are the benefits of Zinc oxide and Eugenol as sealer?
- 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
disadvnatages of ZOE
- free eugenol remained can be irritant
- lose volume with time due to dissolution
Positive and negative of glass ionomer sealer?
- Advocated due to dentine bonding properties
- Removal upon retreatment is difficult
- Minimal antimicrobial activity
Positive and negative of epoxy resin sealer?
AH plus
- antimicrobial - haematic seal
- Slow setting - 8 hours
- Good sealing ability
- Good flow
- Initial toxiicity declining after 24 hours
What is EndoRez? Give positives
- UDMA resin-based sealer
- Hydrophilic
- Good penetration into tubules
- Biocompatible
- Good radio-opacity
What is Epiphany?
- dual cure
- dental resin composite sealer
- requires self-etch primer
What are some properties of Calcium Silicate Sealers?
Bio Ceramic
- 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
What sealers are not acceptable?
- Sealers containing Paraformaldehyde
- Severe and permanent toxic effects on periradicular tissues
What are the two colours of mineral trioxide aggregate?
MTA
- Grey
- White
What is an example of MTA?
Tricalcium silicate
Dicalcium silicate
setting rx of MTA
- required water
- extended setting times
- for open apex, can draw moisture from apex
- can’t be used in oral cavity (long setting time)
advantages of MTA
- Stimulate tissue regeneration of dentin and bone
- Biocompatibility
- Excellent Sealing Ability
components of MTA
- tricalcium silicate,
- dicalcium silicate,
- tricalcium aluminate,
- calcium sulfate,
- and a small amount of bismuth oxide
use of MTA
- Root Canal Repair:
- Pulp Capping:
- Apexification:
- Root End Filling:
*
Biodentine use
calcium silicate cement
- root perforation/ pulp floor
- internal & external resorption
- apexification
- retrograde root canal obturation
- direct/ indirect pulp capping
- pulpotomy
- temporary sealing of cavities
- cervical filling
Direct pulp capping material
- Dycal ( setting CaOH)
- Biodentine
advantages of Dycal as direct pulp cap material
- stimulate formation of reparative dentine (direct contact of pulp)
- promote odontoblast differentiation
- forming a dentine bridge
- induce proliferation of pulp fibroblast
disadvantages of Dycal as direct pulp cap material
- poor bonding to dentine
- mechanical instability
- continued resorption after placement (microleakage)
example of core build-up
- para core
- SDR (composite core)
