4- estimation of working length

After making the opening…

What does the success of the root canal depend on?

Calmness, patience and concentration

What do we need to know about the root canal before the procedure?

Cbct shows anatomy, curvature, direction and calibre, existence of obstructions, possibility of apical access

In the exploration of a wide canal what file should be used?

15

In the exploration of a wide canal what file should be used?

8 or 10

What must be done to the files and why before the procedure?

Pre curve with fingers or special instrument, protect yourself with gauze to avoid punctures

What is odontometry?

Determining length of a tooth- distance between the occlusal edge and an apical reference point

so endodontic procedures are performed within root canal limits

Where is the apical reference point nearly always located?

At root apex, use x ray or electronic apexlocator

How is odotometry carried out by the radiographic/ingle method?

Take x ray with file in the canal to see relationship between its end and root vertex

What are the 3 possible situations you might see in odontometry by radiographic method?

End of file doesn’t reach root vertex- short

End of file at same level

End of file remains outside apical foramen- long

What precautions must be taken when using the radiographic method?

File doesn’t move when placing and holding the x ray plate

Observe contour of root apex- may need to take many x rays

What are the disadvantages of the radiographic method?

Need to do separately for each canal

Foramen doesn’t usually coincide with root apex,may not see lateral position or anatomical complexities

Not reliable in apical resorptions or superposition of diff structures

Subjective interpretation of x ray

What are the components of an electronic apex locator?

Line from 0-3, as file enters indicator bar shows position of tip of file

Handle connected to body, 2 cables- one places lip clip other holds file