1
Q
What are the Endodontic Material Categories?
A
- Instruments
- Irrigants
- Intra-canal medicaments
- Obturation materials
- Sealers
- Pulp Capping materials
- Root-end filling materials
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
3
Q
What is Stress?
A
- Deforming force measured across a given area
- Tensile/compressive/shear/torsional
Stress = Force/ Area
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
5
Q
What is Strain?
A
- Response of a material to stress
- Amount of deformation a file undergoes
Strain = Delta L / L
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
7
Q
What is elastic deformation?
A
- Reversible deformation that does not exceed elastic limit
8
Q
What is plastic deformation?
A
- Permanent bond displacement occurring when elastic limit exceeded
9
Q
What is the Plastic Limit?
A
- Point at which a plastic deformed file breaks
10
Q
2 types of fatigue
A
- cyclic
- torsional
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
12
Q
What is Torsional fatigue?
A
- file end is binded / locked
- while the other end rotating
- torsional/ twisting force
- plastic deformation and failure
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
14
Q
How are kfiles manufactured?
A
- Machined stainless steel wire
- Square/ Triangular
- Twisted
- Work hardening occurs
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
16
Q
What is Nitinol?
A
- Equiatomic alloy of nickel and titanium
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
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
- 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
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
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
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
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**
26
Factors important for NaOCl function
- volume
- concentration
- contact
- mechanical agitation
- exchange of ions
27
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**
28
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!
29
what should you not mix in the canal
EDTA & NaOCl
NAOCl and CHX
30
what happen if you mix NaOCl and CHX
- forms para-chloroaniline
- cytotoxic and carcinogenic
31
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
32
What are Gutta-Percha cones made of?
- 20% **Gutta-percha**
- 65% **Zinc Oxide**
- 10% Radiopacifiers
- 5% Plasticizers
- Standardised, non-standardised and size-matched
33
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
34
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**
35
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**
36
disadvnatages of ZOE
- free eugenol remained can be **irritant**
- lose volume with time due to **dissolution**
37
Positive and negative of glass ionomer sealer?
- Advocated due to **dentine bonding properties**
- **Removal** upon retreatment is difficult
- **Minimal antimicrobial** activity
38
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
39
What is **EndoRez**? Give positives
- UDMA resin-based sealer
- **Hydrophilic**
- **Good penetration into tubules**
- **Biocompatible**
- Good **radio-opacity**
40
What is Epiphany?
- dual cure
- dental resin composite sealer
- requires self-etch primer
41
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**
42
What sealers are not acceptable?
- Sealers containing **Paraformaldehyde**
- Severe and permanent **toxic** effects on periradicular tissues
43
What are the two colours of mineral trioxide aggregate?
| MTA
- Grey
- White
44
What is an example of MTA?
Tricalcium silicate
Dicalcium silicate
45
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)
46
advantages of MTA
- Stimulate tissue **regeneration** of dentin and bone
- **Biocompatibility**
- Excellent **Sealing** Ability
47
components of MTA
* tricalcium silicate,
* dicalcium silicate,
* tricalcium aluminate,
* calcium sulfate,
* and a small amount of bismuth oxide
48
use of MTA
* Root Canal Repair:
* Pulp Capping:
* Apexification:
* Root End Filling:
*
49
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
50
Direct pulp capping material
- Dycal ( setting CaOH)
- Biodentine
51
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
52
disadvantages of Dycal as direct pulp cap material
- poor bonding to dentine
- mechanical instability
- continued resorption after placement (microleakage)
53
example of core build-up
- para core
- SDR (composite core)
Endodontics
flashcards
Decks in class (7)
# Cards
