Apex Locators Flashcards
In terms of WL what increase chance failure?
More 2mm short
Extend beyond apex
Anatomical apex?
End of root from macro-perspective
What is radiographic apex?
Similar anatomical
Dertmined by radiograph
Why is radiographic apex inaccurate?
Foramen often at ride of apex - varies usually 0.3-0.6mm
What is major apical constriction?
Widest point foramen
Issue with WL being major apical constriction?
No natural stop for filling materia
What is minor apical constriction?
Narrowest point of foramen - usually 0.5-1mm short radiographic apex
Ideal limit of root filling?
At CDJ - considered point canal system finish and periodontium begins
Why CDJ not practical to use?
Only detected on histology
Method determine WL?
Tactile feel
Paper point
Radiographic determination
Electronic apex locator
Issue w/ tactile feel?
Not reducible / tricky
What is paper point technique?
Based on premise root canal system of uninfected tooth is dry while periodontium is wet - use wet/dry interface
How use radiographic determination?
Must use parallelling technique
Premise apical constriction 0.5-1mm short radiographic apex
Disadv radiographic determination?
Diff to determine if superimposition of canals
Expose pt ionising radiation
Most commonly used method of WL?
Reliable - uses resistance/ impedance of root canal/PDL
How use electronic apex locator?
Electrical circuit formed Light green at nears apex Red line = into PDL Aim for green Measure file with stopped and deduct 0.5mm so otherside apical constriction
Why take 0.5mm away apex locator reading?
Don’t want filling in contact w/ PDL
What would cause problem when using apex locator?
Amalgam
Perforations
Lateral canals
Why are amalgam issue w/ apex lcoator?
Metallic short cut locator = mis-reading
Why perforation issue w/ apex lcoator?
Trigger apex response as contact PDL
How can using apex locator on perforation be advantageous?
If unsure if have perforation
If using apex locator can skip pre-op radiograph?
No always need pre-op radiograph
When accept apex reading?
Bar is stable and moves with movement of file
