1. Working Length Determination
Presented by:
Josef Ma. Karlos S. Bringas, D.M.D., D.D.S., M.S.
Department of Endodontics

2. Radiographic Length
The length of the tooth as it appears on the radiograph.

3. Estimated Working Length
Radiographic length minus 1mm.

4. 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.

5. Select a Reference Point

6. Take a Preoperative Radiograph

7. Preoperative Radiograph
Apex
Measure the radiographic length.
Reference pt.

8. Measure the radiographic length
Ex. 22mm

9. Compute for Estimated Length
Estimated Length is radiographic length minus 1mm.
Ex. 22mm - 1mm = 21mm

10. Treatment Record

11. Treatment Record
Incisal edge
21 mm

12. Set #15 file to Estimated Length
Insert the file into the canal to stopper length and take a radiograph at this time.

13. 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.

14. Working Length Radiograph
File appears to end 1mm short of the apex.
No need to adjust the final working length.

15. Working Length Radiograph
In this case, estimated working length is equal to the final working length.
EWL = FWL
Record FWL

16. Treatment Record
Incisal edge
21 mm
21 mm

17. 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.

18. Working Length Radiograph

19. Working Length Radiograph
Example:
EWL=21mm
Since radiograph shows that file is 1mm long then…
1mm

20. Working Length Radiograph
Example:
EWL – 1mm = FWL
21mm – 1mm = 20mm
1mm

21. Working Length Radiograph
Example:
EWL – 1mm = FWL
21mm – 1mm = 20mm
1mm

22. Treatment Record
Incisal edge
21 mm
20 mm

23. 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.

24. Working Length Radiograph

25. Working Length Radiograph
Example:
EWL=21mm
Since radiograph shows that file is 0.5mm short then…
0.5mm

26. Working Length Radiograph
Example:
EWL+0.5 mm=FWL
21mm+0.5mm=21.5mm
0.5mm

27. Treatment Record
Incisal edge
21 mm
21.5 mm

28. 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.

29. Unacceptable discrepancy