Working length determination is the measurement of the distance from a coronal reference point to the point where canal preparation and obturation should terminate. There are two main methods - radiographical and non-radiographical. Radiographical methods include Grossman's formula, Ingles method, Weine's method, and use of digital radiography or electronic apex locators. Non-radiographical methods include digital tactile sense, apical periodontal sensitivity testing, and use of paper points. The electronic apex locator is now considered the most accurate for determining working length as it detects the apical foramen directly. Maintaining apical patency and avoiding ledges or separated instruments is important to ensure an accurate working length determination.

1. WORKING LENGTH
DETERMINATION
Ahmed Hasan
Ug : 1330077
therapeutic Dentistry IV

2. WORKING LENGTH DETERMINATION
• The distance from a coronal reference point to the
point at which canal preparation and obturation
should terminate .

3. Anatomical considerations
• Anatomic apex: it is defined as the
tip or end of the root determined
(Radiographic apex)
• Apical foramen (physiological apex):
it is the main apical opening of the
root canal.when we make x-ray to
the end of canal
Distance between radograhic and physiological apex
in the past time 0.5 mm but in the moderan time 1
mm to 2 mm

4. METHODS OF WORKING LENGTH
DETERMINATION
RADIOGRAPHICAL
METHOD
1.Grossman’s formula
2. Ingles method
3.Weine’s method
4.Radiovisiography
5.Xeroradiography
NON RADIOGRAPHICAL
METHOD
1.Digital tactile sense
2.Apical periodontal
sensitivity
3.Paper point method
4.Electonic apex locator

5. How we measure this length
• First by x ray that taken while the file insert in canal
and this situation apical foramen is usually found
(0.5mm – 1mm ) from the radiographic apex so we
need to decrease the length ( radiographic method )

6. Or by non radiographic
Digital tactile sense
• In this clinician may see an increase in
resistance as file reaches the apical 2-3mm
• Time saving, no radiation exposure
• Do not provide accurate diagnosis always,
resistance felt earlier in narrow canals, in case
of teeth with immature apex instrument can
go periapically

7. Apical Periodontal sensitivity test
• Based on patient’s response to pain
• This method does not provide accurate readings,
for example in case of narrow canals, instrument
may feel increased response in apical 2-3mm,
immature apex, file goes beyond apex.
• In case of canals with necrotic pulp, instrument
can pass beyond apical constriction, and in case of
vital or inflamed pulp, pain may occur several mm
before periapex is crossed by instrument.

8. Paper point measurement method
• Most reliable in cases of open apex where
apical constriction is lost because of perforation
or resorption.
• Moisture or blood present on apical part of
paper point indicates paper point has passed
beyond estimated working length.
• Used as a supplementary method.

9. Electronic apex locator
• is an electronic device used in endodontics
determine the position of the apical
constriction and thus determine the length of
the root canal space
• It giving the reading when the
File tip at the apical foramen.

10. Causes of loss of working length
• Presence of debris in apical 2-3 of canal
• Failure to maintain apical patency
• Skipping instrument sizes
• Ledge formation
• Inadequate irrigation
• Instrument separation
• Canal blockage

11. Reference
• ENDODONTICS: PRINCIPLES AND PRACTICE,
4th Edition page ( 252 to 256)
• Textbook of Preclinical Conservative Dentistry
chapter 14 page ( 279- 281)

12. Thank you for your attention