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© 2006 J.Bringas, DMD, DDS, MS
Working Length Determination
Presented by:Josef Ma. Karlos S. Bringas, D.M.D., D.D.S., M.S.Department of Endodontics
© 2006 J.Bringas, DMD, DDS, MS
Radiographic Length
• The length of the tooth as it appears on the radiograph.
© 2006 J.Bringas, DMD, DDS, MS
Estimated Working Length
• Radiographic length minus 1mm.
© 2006 J.Bringas, DMD, DDS, MS
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.
© 2006 J.Bringas, DMD, DDS, MS
Select a Reference Point
© 2006 J.Bringas, DMD, DDS, MS
Take a Preoperative Radiograph
© 2006 J.Bringas, DMD, DDS, MS
Preoperative Radiograph
• Measure the radiographic length.
Reference pt.
Apex
© 2006 J.Bringas, DMD, DDS, MS
Measure the radiographic length
Ex. 22mm
© 2006 J.Bringas, DMD, DDS, MS
Compute for Estimated Length
• Estimated Length is radiographic length minus 1mm.
Ex. 22mm - 1mm = 21mm
© 2006 J.Bringas, DMD, DDS, MS
Treatment Record
© 2006 J.Bringas, DMD, DDS, MS
Treatment Record
Incisal edge
21 mm
© 2006 J.Bringas, DMD, DDS, MS
Set #15 file to Estimated Length
Insert the file into the canal to stopper length and take a radiograph at this time.
© 2006 J.Bringas, DMD, DDS, MS
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.
© 2006 J.Bringas, DMD, DDS, MS
Working Length Radiograph
• File appears to end 1mm short of the apex.
• No need to adjust the final working length.
© 2006 J.Bringas, DMD, DDS, MS
Working Length Radiograph
• In this case, estimated working length is equal to the final working length.
• EWL = FWL• Record FWL
© 2006 J.Bringas, DMD, DDS, MS
Treatment Record
Incisal edge
21 mm
21 mm
© 2006 J.Bringas, DMD, DDS, MS
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.
© 2006 J.Bringas, DMD, DDS, MS
Working Length Radiograph
© 2006 J.Bringas, DMD, DDS, MS
Working Length Radiograph
• Example: EWL=21mm
• Since radiograph shows that file is 1mm long then…
1mm
© 2006 J.Bringas, DMD, DDS, MS
Working Length Radiograph
• Example:• EWL – 1mm =
FWL
• 21mm – 1mm = 20mm
1mm
© 2006 J.Bringas, DMD, DDS, MS
Working Length Radiograph
• Example:• EWL – 1mm =
FWL
• 21mm – 1mm = 20mm
1mm
© 2006 J.Bringas, DMD, DDS, MS
Treatment Record
Incisal edge
21 mm
20 mm
© 2006 J.Bringas, DMD, DDS, MS
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.
© 2006 J.Bringas, DMD, DDS, MS
Working Length Radiograph
© 2006 J.Bringas, DMD, DDS, MS
Working Length Radiograph
• Example:• EWL=21mm
• Since radiograph shows that file is 0.5mm short then…
0.5mm
© 2006 J.Bringas, DMD, DDS, MS
Working Length Radiograph
• Example:• EWL+0.5
mm=FWL
• 21mm+0.5mm=21.5mm
0.5mm
© 2006 J.Bringas, DMD, DDS, MS
Treatment Record
Incisal edge
21 mm
21.5 mm
© 2006 J.Bringas, DMD, DDS, MS
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.
© 2006 J.Bringas, DMD, DDS, MS
Unacceptable discrepancy