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
Apex
• Measure the
radiographic length.
Reference pt.
© 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
1mm
• Since radiograph
shows that file is 1mm
long then…
© 2006 J.Bringas, DMD, DDS, MS
Working Length Radiograph
• Example:
• EWL – 1mm = FWL
1mm
• 21mm – 1mm = 20mm
© 2006 J.Bringas, DMD, DDS, MS
Working Length Radiograph
• Example:
• EWL – 1mm = FWL
1mm
• 21mm – 1mm = 20mm
© 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
0.5mm
• Example:
• EWL=21mm
• Since radiograph
shows that file is
0.5mm short then…
© 2006 J.Bringas, DMD, DDS, MS
Working Length Radiograph
0.5mm
• Example:
• EWL+0.5 mm=FWL
• 21mm+0.5mm=21.5mm
© 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
© 2006 J.Bringas, DMD, DDS, MS