Instrumentation + Irrigation Flashcards
What is the purpose of instrumentation?
- Removal of vital and necrotic tissue from root canal system
- Remove as much bacteria as possible from system
- Creation of sufficient space for irrigation and medication and obturation
- Preserve integrity and location of apical root canal anatomy
What should be done to preserve optimal condition of the tooth and periodontium?
- Avoid iatrogenic damage to canal systems
- Avoid further irritation or infection of periodontium
- Preservation of sound root dentine to allow long term function
- Maintain shape, location and length of canal as much as possible
What does the letter and number refer to in the terms, D1, D2, D3, etc.
The number refers to the distance in mm from the tip of the file
D refers to the diameter at said distance
What does D0 mean and how is it calculated?
Diameter of the file at the tip. It is calculated by dividing the file size by 100 (e.g. size 10 file will be 0.10mm wide at the tip)
What does the taper on a file mean? e.g. 2% taper.
Taper is the amount of increase in the diameter of the file per mm away from the tip.
The amount of increase is the file’s taper divided by 100 (i.e. 2% taper will increase in diameter by 0.02mm per mm from the tip)
What is the standard length of a file? What other lengths are they available in?
Standard: 25mm
Also available: 21, 28, 31mm
What types of files are there? Which is predominantly used? What is the difference?
K-file (predominantly used): stainless steel blanks, ground into square/triangle cross sections and twisted: use watch winding technique
H-file: Steel blanks have round cross sections, more flexible and efficient cutting but also increased risk of fracture
Barb broach: used to remove pulp tissue
What materials are used to make the files? What are the positives and negatives of each?
Stainless steel (more common): cheap to manufacture but less flexible Nickel-Titanium: More flexible, less likely to transport canals
What are the steps for instrumentation?
-Determine CWL
Crown down
- Gates gidden in brushing motion to remove dentine in coronal half of root–> better access and decreased chance of blockage than if try to prepare apical first
- Also increased tactile awareness in apical region
- Irrigate copiously
Apical preparation
- Determine first file to bind
- Use watch winding technique to get file to full length
- Take file out, check colour of debris and irrigate again
- Recapitulate
- Go one file size up and repeat
- Do this until 2-3 file sizes up from first file to bind (final file is MAF and should be min. size 25)
Step back:
- Create 5% taper for irrigation and obturation
- Go one file size up from MAF and work to 1mm short of CWL
- Go another size up and work to 2mm short of CWL
- Finish by going one more file size up and working 3mm short of CWL
- Use paper points to dry canals or aspirate using needle to dry
- If using aspiration technique and two canals dry at same time, indicates canals merge apically
What is the purpose of Irrigation?
- Remove microbes
- Dissolve organic and flush inorganic debris + remove smear layer
- Improve filling efficiency
- Lubricate canal
What are the ideal properties of irrigants?
- Fulfills all functions listed
- Non toxic + no adverse effects on remaining tissue
- Low surface tension/good wetting
- Economical
What is the relationship between bacterial killing properties and biocompatability of irrigants?
Inversely related
What are the gold standard irrigants, their properties and how should they be used?
Sodium hypochlorite (0.5-6.0%)
(+)Potent antimicrobial (Potent antimicrobial: irreversibly inactives bacterial enzymes and oxidises, hydrolyses and draws fluid out of tissues→ kills most bacteria on contact)
(+)Dissolves vital and necrotic pulp (few other irrigants do this)
(+)Dissolves organic part of smear layers (subsequent removal possible with chelating agent)
(-)Bad taste
(-) Toxic past apex
(-)Only dissovles organic component of smear layer
(-) Poorer results in vivo vs in vitro
(-)Possibly reduces flexural strength, elastic modulus, microhardness of dentine
EDTA (+) Chelates inorganic dentine (+) Widens tubules (+) Softens dentine to help with prep (+) Increases dentine permeability (more penetration of irrigants and medicaments and enhances cement adhesion) (+) Improves antimicrobial ability of disinfecting agents (-) Ineffective on its own (-) Little to no antimicrobial activity (-) Leaves superficial debris
*Use NaOCl throughout procedure followed by a 5 minute rinse with EDTA at the end and finish off with a final rinse of NaOCl to remove film leftover from EDTA
What are some consequences to inadequate irrigation?
- Smear layer remains
- Debris remains in canal: apical blockage, ledging, loss of working length
- Insufficient lubrication: filling less efficient, file binding increase risk of brekage
- More microorganisms remain
What can be done to increase irrigation effectiveness?
- Heat solution/increase concentration
- Ultrasonic/sonic activation (put tip in canal to force solution into other areas)
- Vacuum unit/endo vac: uses vacuum system to draw fluid to apical third + along walls, however very fiddly and can lock up frequently
