Working Length Determination for 5TH stage students

Working Length Determination for 5TH stage students
Presented by:
Ameer H, AL-Ameedee
Ph.D in Operative and Esthatic Dentistry
Radiographic Length
The length of the tooth as it appears on the radiograph.
Electronic apex locators

Final Working Length
is determined to be -1 mm from the anatomical apex as measured from the working length (WL) radiograph.

THIS IS THE LENGTH TO WHICH THE CANAL WILL BE CLEANED & SHAPED AND OBTURATED.
Select a Reference Point
Take a Preoperative Radiograph
Preoperative Radiograph
Measure the radiographic length.
Measure the radiographic length
Ex. 22mm
Compute for Estimated Length
Estimated Length is radiographic length minus 1mm.
Ex. 22mm - 1mm = 21mm
Treatment Record
Treatment Record
Set #15 file to Estimated Length
Insert the file into the canal to stopper length and take a radiograph at this time.
Working Length Radiograph
The best case scenario is that there is no radiographic distortion with the preoperative radiograph.
The working length radiograph should show that the file ends 1mm short of the apex.
Working Length Radiograph
File appears to end 1mm short of the apex.
No need to adjust the final working length.
Working Length Radiograph
In this case, estimated working length is equal to the final working length.
EWL = FWL
Record FWL
Treatment Record
Working Length Radiograph
Sometimes, the radiograph shows that the file extends more apical than the ideal.
This means that the EWL is long.
Deduct this discrepancy from your EWL to arrive at the Final Working Length.

Working Length Radiograph
Working Length Radiograph
Example:
EWL=21mm

Since radiograph shows that file is 1mm long then…

Working Length Radiograph
Example:
EWL – 1mm = FWL

21mm – 1mm = 20mm


Working Length Radiograph
Example:
EWL – 1mm = FWL

21mm – 1mm = 20mm


Treatment Record
Working Length Radiograph
Sometimes, the radiograph shows that the file does not reach the ideal length.
This means that the EWL is short.
Add this discrepancy to your EWL to arrive at the Final Working Length.
Working Length Radiograph
Working Length Radiograph
Example:
EWL=21mm

Since radiograph shows that file is 0.5mm short then…
Working Length Radiograph
Example:
EWL+0.5 mm=FWL

21mm+0.5mm=21.5mm
Treatment Record
Working Length Radiograph
If the radiograph shows that the discrepancy is more than 2mm, then a new radiograph should be taken after computing for the working length.
Unacceptable discrepancy