WORKING LENGTH DETERMINATION in endodontics-2.pptx

Working length determination in endodontics

1. WORKING LENGTH DETERMINATION Dr.Genene Getachew (General dentist) @Jimma university 5/18/2024 1

2. Introduction Definition of terms and anatomical considerations Importance of Working Length Methods of Working Length Determination Radiographic methods Nonradiographic methods References 5/18/2024 2 Outline

3. Determination of accurate working length and its maintenance during cleaning and shaping procedures are key factors for successful endodontic treatment. The cleaning, shaping, and obturation cannot be accomplished accurately unless the working length is determined correctly. The procedure for establishment of working length should be performed with skill, using techniques which have shown to give valuable and accurate results and are practical and successful. 5/18/2024 3 Introduction

4. Working length : is defined as the distance from a coronal reference point to the point at which canal preparation and obturation should terminate. Reference point : is the site on occlusal or the incisal surface from which measurements are made. it should be stable and easily visualized during preparation 5/18/2024 4 Definition of terms and anatomical considerations

5. Usually , it is the highest point on the incisal edge of anterior teeth and buccal cusp of posterior teeth It should not change between the appointments To have stable reference point, undermined cusps and restorations should be reduced before access preparation 5/18/2024 5 Cont’d

6. Anatomic apex: is tip or end of root determined morphologically. Radiographic apex: is tip or end of root determined radiographically . Apical foramen: is the main apical opening of the root canal which may be located away from anatomic or radiographic apex. 5/18/2024 6 Cont’d

7. Cementodentinal junction (CDJ ): is the region where the cementum and dentin are united, the point at which cemental surface terminates at or near the apex of tooth. 5/18/2024 7 Cont’d Apical constriction (minor apical diameter): is the apical portion of root canal having narrowest diameter. It is usually 0.5–1 mm short of apical foramen.

8. 5/18/2024 8 Cont’d

9. determines how far into canal instruments can be placed and worked plays an important role in determining the success of the treatment It affects the degree of pain and discomfort the patient will experience during or after the treatment. If proper care is not taken, over or underinstrumentation can occur 5/18/2024 9 Importance of Working Length

10. means extension of instruments into periapical tissue Pain as a result of response from mechanical damage to the periapical tissue In infected teeth, extrusion of microbes and infected debris Overfilling, causes mechanical and chemical irritation of the periapical tissue Prolonged healing time and lower success rate due to incomplete regeneration of cementum , periodontal ligament, and alveolar bone 5/18/2024 10 Consequences of overinstrumentation

11. Incomplete cleaning and instrumentation of the canal Persistent discomfort due to presence of pulpal remnants Under filling of the root canal Incomplete apical seal Apical leakage which leads to poor healing and periradicular lesion. 5/18/2024 11 Consequences of under-instrumentation

12. Presence of debris in apical of canal Failure to maintain apical patency Skipping instrument sizes Ledge formation Inadequate irrigation Instrument separation Canal blockage 5/18/2024 12 Causes of loss of working length

13. 5/18/2024 13 METHODS OF DETERMINING WORKING LENGTH

14. When radiographs are used in determining working length, the quality of the image is important for accurate interpretations. Advantages Anatomy of the tooth and curvature of root canal can be seen on radiograph Radiograph helps in analyzing the relationship with adjacent teeth and anatomic structures. 5/18/2024 14 RADIOGRAPHIC TECHNIQUES FOR MEASURING WORKING LENGTH

15. Disadvantages Varies with different observers Superimposition of anatomical structures 2D view of 3D object Cannot interpret if apical foramen has buccal or lingual exit Risk of radiation exposure Time consuming Limited accuracy 5/18/2024 15 Cont …

16. Clinical Prerequisites Knowledge of average length of teeth. Instrument precurving Stable occlusal reference point 5/18/2024 16 Ingle’s radiographic technique of working length determination

17. 5/18/2024 17 Cont …

18. Take the preoperative radiograph Measure the estimated working length from preoperative radiograph The estimated working length is kept as 1 mm short of the length of the tooth measured on the radiograph. This is done to compensate for the radiographic image distortion and for the fact that the minor diameter is always present short of the anatomical apex. Adjust stopper of instrument to this estimated working length place it in the canal up to the adjusted stopper 5/18/2024 18 Clinical technique

19. Take the radiograph On the radiograph, measure the difference between the tip of the instrument and root apex. If the tip of the instrument ends 0.5 mm–1.0 mm from the radiographic root apex (working length established) If short of the radiographic apex by more than 1.0 mm add this value to the earlier estimated length and adjust stopper on the diagnostic instrument accordingly retake the working length radiograph If beyond the radiographic apex Reduce this value from the earlier estimated length and adjust stopper on the diagnostic instrument accordingly Retake the working length radiograph 5/18/2024 19 Cont …

20. 5/18/2024 20 Cont …

21. Weine modified calculation of working length according to presence or abscence of resorption No resorption - subtract 1 mm Periapical bone resorption - subtract 1.5 mm Periapical bone + root apex resorption - subtract 2 mm 5/18/2024 21 Weine’s Modification

22. Technique Locate minor and major diameter on preoperative radiograph Estimate length of roots from preoperative radiograph Estimate canal width on radiograph . If the canal is narrow, use 10 or 15 size instrument. If it is of average width, use 20 or 25 size instruments. If the canal is wide, use 30 or 35 size instrument Insert the selected file in the canal up to the estimated canal length and take a radiograph If the file is too long or short by >1 mm from minor diameter, readjust the file and take second radiograph If the file reaches major diameter, subtract 0.5 mm from it for younger patients and 0.67 for older patients 5/18/2024 22 Kuttler’s Method

23. It is based on simple mathematical formulations to calculate the working length. In this, an instrument is inserted into the canal, stopper is fixed to the reference point and radiograph is taken. 5/18/2024 23 Grossman method of working length determination

24. It was designed by Everett and Fixott in 1963. It is a simple method in which a millimeter grid is superimposed on the radiograph This overcomes the need for calculation, But it is not a good method if the radiograph is bent during exposure 5/18/2024 24 Radiographic Grid

25. In this method, one uses the graduations on diagnostic file which are visible on radiograph But its main disadvantage is that the smallest file size to be used is number 25 5/18/2024 25 Endometric Probe

26. Electronic apex locators Currently, an electronic apex locator (EAL) is the most optimal and accurate method to establish the root canal working length. The working length is determined by comparing the electrical impedance of the periodontal membrane with that of the oral mucosa both of which should be similar at 6.5 kΩ. 5/18/2024 26 Non-radiographic Methods of Working Length Determination

27. 5/18/2024 27 Components of EALs

28. 5/18/2024 28 Cont’d

29. high degree of accuracy For patients with problem of gag reflex. Useful in pregnant patients Useful in children Valuable tool for detecting root perforations , external and internal resorption, horizontal and vertical root fracture Testing pulp vitality 5/18/2024 29 Advantages of apex locators

30. The accuracy of EAL may be altered in teeth with the following: Immature apices (open apex) Calcified or blocked canals Excessive hemorrhage/excessive inflammatory exudate in the canal Measurements get altered when the file contacts any metallic restoration T eeth with periapical radiolucencies necrotic pulp associated with root resorption, because of lack of viable periodontal ligament 5/18/2024 30 Limitations of apex locators

31. 5/18/2024 31 Classification of Electronic Apex Locators

32. 1. First-generation apex locator (resistance apex locator) known as resistance apex locator which measures opposition to flow of direct current, that is, resistance. It is based on the principle that resistance offered by periodontal ligament, and oral mucous membrane is the same, at 6.5 kΩ. Examples , root canal meter, endometric meter Dentometer , Endo Radar. 5/18/2024 32 Classification According to Generations of EALs

33. Inoue introduced the concept of impedance-based apex locator which measure opposition to flow of alternating current or impedance This apex locator indicates the apex when two impedance values approach each other. Sonoexplorer , Apex finder , Exact-A- Pex , 5/18/2024 33 2. Second-generation apex locator (impedance-based apex locator)/low-frequency apex locator

34. It is based on the fact that different sites in canal give difference in impedance between high (8 kHz) and low (400 Hz) frequencies Endex , Mark V plus, Root ZX , Root ZX II , Root ZX mini 4. Fourth-generation apex locator measures resistance and capacitance separately rather than the resultant impedance value AFA apex finder, i- Pex , Rayapex 4, Propex , 5/18/2024 34 3. Third-generation apex locator/high-frequency apex locator

35. based on comparison of data taken from the electrical characteristic of the canal and additional mathematical processing. These show accurate reading in presence of dry, wet, saline, EDTA, blood, or sodium hypochlorite. Examples: Rayapex , Propex  II, Propex Pixi , I -ROOT, Joypex  5 5/18/2024 35 5. Fifth-generation EALs (dual-frequency ratio type)

36. This apex locator is intended to overcome the disadvantages of fourth- and fifth-generation EALs. It eliminates the need of drying the canals. Examples: Adaptive apex locator, Raypex 6 5/18/2024 36 6. Sixth-generation EALs (adaptive apex locators)

37. In this, clinician may see an increase in resistance as file reaches the apical 2–3 mm. Advantages Time saving No radiation exposure Disadvantages Does not always provide the accurate readings increased resistance in narrow canals as file approaches apical 2–3 mm In immature apex, instrument can go periapically 5/18/2024 37 Digital tactile sense

38. based on patient’s response to pain But this method does not always provide the accurate readings in the case of narrow canals, canal with necrotic pulp and in the case of vital or inflamed pulp. 5/18/2024 38 Apical periodontal sensitivity test

39. In this method, paper point is gently passed in the root canal to estimate the working length‰ It is most reliable in cases of open apex where apical constriction is lost because of perforation or resorption Moisture of blood present on the apical part of paper point indicates that paper point has passed beyond estimated working length. 5/18/2024 39 Paper point measurement method

40. Garg , N., & Garg , A. (2019). Textbook of endodontics (4th ed.). Jaypee Brothers Medical Publishers.   Gopikrishna , V., & Grossman, L. I. (2020). Grossman’s endodontic practice (14th ed.). Wolters Kluwer Health (India). 5/18/2024 40 References

41. THANK YOU! 5/18/2024 41