CSA endo labs week 2 Flashcards
(36 cards)
What is working length ?
Length from apical limit of obturation (usually apical constriction) to a recordable reproducible reference point on the clinical crown
What is apical constriction ?
narrowest point of canal before reaching apex,
- 0.5-2mm away from apex
How to determine working length ?
after coronally flaring & removing interim dressing
- Insert a small file
- Feel for a stop near estimated working length (pre-op radiograph to determine)
- Slide rubber stopper to reference point
- Expose working length radiograph to x rays
- Leave file in place until radiograph checked
What file to use for working length determination ?
a. Size 15 shows up well on radiograph
b. In narrow canal may need to use size 8 & 10 first before 15
Where to slide rubber stopper to reference point ?
incisal edge for the incisor
What do electronic apex locators do ?
- save time & repeat radiographs
* be used routinely
Problems when determining working length
- Fractionally too short:
* Much too long/short
What happens when fractionally too short working length ?
o Check file length
o Add/Subtract accordingly
o Record working length
What happens when Much too long/short working length ?
o Check file length
o Reposition
o Take new radiograph
How do we create APICAL stop ?
• shape apical portion of the canal at working length
What do we do from apical stop ?
use step back technique to increase taper (2% to 5%) & make it flush with coronal portion
What are filing techniques ?
- Watch winding technique
- Twist & pull technique
- Circumferential
- Balance force technique
What is watch winding technique ?
• Repeated 60degrees to 120 anticlockwise rotations with light apical pressure
What is twist and pull technique ?
- Rotate 60Degrees clockwise turn
- Fell flutes engage & pull straight out again
- Lessen turning movement if resistance is too much
- useful to advance file if slight resistance
What is Circumferential filing?
- No rotation of file
- Move file with in & out motion – filing on outstroke only
- methodically around and against canal circumference
What is circumferential filing useful for ?
o Very wide canals
o Smooth junction between apical & coronal preparations
What is balanced force technique ?
for apical shaping
• file tip must remain same length throughout movement
• rotate clockwise 60Degr to engage flutes
• rotate 360O anticlockwise to cut
•only use K files
How to apical shape at working length with Balanced force technique ?
- Start at working length with file number 15
- balanced force technique to prepare apical area
- Increase file size until it is 2 sizes bigger than original file size
- This creates an apical stop >Stop gutta percha going through apex
What is Master apical file size ?
file size is 2 sizes bigger than original file size
- number 15 Now number 25
What does step back technique involve ?
using a larger file size every 1mm we move away from working length
What are steps of the step back technique ?
- Step back from the working length 1mm and increase file size by 5
- Irrigate after each file
- Before stepping up and moving back we must recapitulate:
- Check master apical file at working length – should fit
What technique used in step back ?
balanced force technique at each point – creates greater taper
What does recapitulate do ?
a. Insert small file 8/10 to full working length & irrigate
b. Frees up dentine debris at apical constriction/apex and ensure the MAF can still go way down
When does stepping back stop ?
when file no longer binds when you move 1mm back
