how to achieve the working length during root canal definition different techniques of taking working length slob rule apex locator radiographic technique of working length paper point general concept of working length histological understanding of working length significance pf working length problems with inaccurate working length how to check working length how to correct working length

1. LENGTH DETERMINATION

2. LENGTH DETERMINATION
 We are only concerned
with the pulpal space
 Respect the
periodontal space
 Different schools of
thoughts

4. LENGTH DETERMINATION
 The length between reference point and
apical constriction

5. LENGTH DETERMINATION
 Tactile senses ( HIGHLY UNRELIABLE)
 Radiographic technique
 Electronic method

6. RADIOGRAPHIC TECHNIQUE
 Tentative working length :
a) Preoperative radiograph can be used to
assess the working length of the tooth.
b) Knowledge of average length helps
 Exploring files are usually No 10 – 15
 Bigger files for young patient and larger
canals

8. RADIOGRAPHIC TECHNIQUE
 Exploring files are inserted until resistance is felt
and the stopper is adjusted to reference point
 Radiograph is taken at this stage
 Clinical working length: Measure the distance
from tip of file to stopper
 Measure the distance b/w the tip of file and the
radiographic apex
 Working length proper: Make any necessary
alteration after x ray

9. RADIOGRAPHIC TECHNIQUE
 Discrepancy more than 2mm, re do the
process
 A/B=A’/B’ formula can be used
 On removal also check and record any
curving of the files

10. PRE CURVING
 Exploring instruments should be pre curved
 Not with bare hands / sterile gauze
 Pre curved instruments are to follow the
visible and hidden curves
 Pre curving should always follow the curve
visible on the X ray

13. DO’S AND DON’T’S
 File should not be forced into canal but
gently pushed/wiggled to its length
 Radiograph would tell the reason for not
reaching the desired length
 Insertion should be done in wet canals( RC
prep, glyde)
 Glycerin be used in sclerosed canals

14. RADIOGRAPHIC TECHNIQUE
 Radiograph gives you a two dimensional
view
 Ideally two different radiographs should be
taken to see the hidden buccal or
palatal/lingual curves
 Two radiographs must for two canals – the
shift technique ( slob rule)

19. RADIOGRAPHIC TECHNIQUE
 Periapical resorption makes u change the
length( 1mm + 1mm)
 Xeroradiography makes edges enhanced

20. LENGTH CHANGES ACCORDING
TO DIFFERENT CONDITIONS

21. REFERENCE POINTS
 Reference point should be
stable during the entire
treatment.
 RP should be definite and
reliable
 Incisor edge and cusp tips are
usually selected
 Trim them for accurate
measurment

22. STOPPERS
 Stoppers can made from rubber dam sheet
or rubber band
 Metal, silicone and rubber stopper
 Tear drop stoppers
 Silicone stoppers can withstand the
sterilization temp up to 450 centigrade
 Stoppers should be positioned horizontally

24. ELECTRONIC METHOD
 This compares the electrical resistance of the PDL
and gingiva which are suppose to be the same.
 Probe or file attached to electronic instrument is
inserted into the canal
 False readings may occur if necrotic tissue,
foreign substance or pulp stone in canal.
 Reconfirm with radiographs
 Newer versions are very accurate

25. APEX LOCATOR

28. ACHIEVING AND
MAINTAINING THE
WORKING LENGTH IS THE
KEY TO SUCCESS

29. I THANK YOU ALL