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

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

Estimated Working Length Radiographic length minus 1mm.

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 Apex Measure the radiographic length. Reference pt.

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 Incisal edge 21 mm

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 Incisal edge 21 mm 21 mm

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… 1mm

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

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

Treatment Record Incisal edge 21 mm 20 mm

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… 0.5mm

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

Treatment Record Incisal edge 21 mm 21.5 mm

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