Endo - Instrumentation

Question 1

What are the aims of instrumentation?

Answer 1

To remove all infected soft and hard tissue
Give disinfecting irrigant access to the apex
Create space for medicaments and subsequent obturation.
Keep as the same shape as before

Question 2

What should be the shape of the canal after instrumentation?

Answer 2

Continuously tapering funnel shape

Most maintain the apical seal

Question 3

What is the minimum size of file that must be taken down to the apex of the tooth in order for irrigants to get to the area?

Answer 3

25 K file

Question 4

Define estimated working length?

Answer 4

This is the estimated length of the canal using peri-operative radiographs (-1mm)
The distance from the coronal reference point to the apex of the tooth

Question 5

Define correct WL?

Answer 5

This is the length at which instrumentation and subsequent obturation are limited too.
Can be done using an apex locator or WL radiograph.

Question 6

How would you find out the correct working length?

Answer 6

An apex locator

WL radiograph

Question 7

Define master apical file?

Answer 7

This is the largest file size that has been taken to the apical region of the tooth.
Therefore represents the size of prep at working length

Question 8

What is the main technique used when using hand files? and the method.

Answer 8

Balanced force technique
1/4 turn CC
1/2 turn AC 
Maintaining apical pressure 
3x then clear debris and irrigate

Question 9

What do the components of a NiTi K file mean?
Taper 
Flute 
Cutting edge 
Land 
relief 
Helix angle

Answer 9

Taper - this is the diameter change along the working surface.
Flute - Groove to collect dentine and soft tissues
Cutting edge - forms and deflects dentine chips.
Land - surface extending between flutes
Relief - reduction in the surface of land
Helix angle - angle cutting axis forms with long axis of the file

Question 10

What are the advantages of NiTi files of SS?

Answer 10

More flexible can bend in canals.
better cutting efficiency
Good safety use
User friendly

Question 11

Disadvantages of NiTi

Answer 11

Expensive

Not good at navigating complex canals

Question 12

What is instrument fracture a result of?

Answer 12

Torsional stress
Flexural stress
N.B don’t jump the size of files early and be gentle

Question 13

Two aseptic techniques?

Answer 13

Dental dam

NaOCl irrigation