dr VLADIMIR IVANOVIC , DDS, MSc, PhD, SDS Professor in Restorative Odontology & Endodontics,

1. dr VLADIMIR IVANOVIC, DDS, MSc, PhD, SDS Professor in Restorative Odontology & Endodontics, University of Belgrade, Republic of Serbia

2. Mirjana Vujašković Katarina Beljić- Ivanović Jugoslav Ilić Ivana Bošnjak L E N G T H THE WORKING L E N G T H DETERMINING

3. SEEKING WHERE, WHEN, WHY AND HOW Joshua Moshonov TO LOCATE THE APICAL TERMINUS Julian Webber Paul Dummer OF THE ROOT CANAL PREPARATION William Saunders

4. Articles that have been “guiding light” in creating my own standpoints, and directing “pathways” of this lecture by their philosopohy and conception • Apical limit of root canal instrumentation and obturation (1 & 2) D Ricucci & K Langeland, 1998, IEJ • Apical terminus location of root canal treatment procedures. M-K Wu, P Wesselink & RE Walton, 2000, 4O’s & Endo • Considerations in working length determination. LRG Fava & JF Siqueira, 2000, Endodontic Practice • The fundamental operating priciples of ERCLMDs. MH Nekoofar, SJ Hayes & PMH Dummer, 2006, IEJ • Determination of true working length. R Mounce, 2007, EndoPractice

5. Predetermined “normal” tooth length Patient response to pain Tactile sensation of the therapist Paper point technique Radiographic method Electronic locators METHODS OF DETERMINING THE WORKING LENGTH

6. Patient response to pain - apical sensitivity Many false information, misleadings, & limitations; extremely subjective = => unreliable - remnants of vital pulp tissue - pressure of the instrument tip via debris - destruction of PA tissues – no sensation - individual sensitivity – pain threshold - local anaesthesia - poor / no evidence in literature Is it still in use, or gone to dental history ?

7. Tactile sensation of the operator Very subjective, with limitations, often misleading => unreliable -morphological irregularities: narrowing, calcification, multiple constrictions - tooth type & age - pathological resorption & wide AF - a few evidence in literature Still advocated as very useful in hands of an experienced practitioner to feel and identify AC !?

8. Tactile sensation “Belgrade clinical study” M.V. & M.P. : 1984 Literature data: to locate apical constriction accuracy varies: 30% - 44% - 60% with wide and random distribution of measured values Referent point from Rö apex : 0.5mm in <25 yrs; 1.0 mm in >25 yrs Preflaring enhances locating of the AC, and increases accuracy: 32% up to 75% Precise in only 19%; with +/- 0.5 mm tolerance accuracy in 42%. Significant under and overestimations up to 4.5 mm before and beyond RP !!!

9. Paper point technique Claimed as the most precise method to determine: i) working length to the end of the canal, and ii) min. apic. for.diam. (MAFD) in 3D Allows practitoner to “see” the cavosurface of the canal with the precison of 0.25 mm; - apical patency technique - Wet (blood) / dry interface coincides with the location of the CS Enables to customise gutta-percha master cone 3D upon the information from the PP

10. Paper point technique DB Rosenberg By courtesy of J. Webber

11. Paper point technique Even claimed as the most precise method in determining WL there is neither scientific nor clinical evidence in literature on its superiority In spite of being advocated by many endodontic experts, PP technique lacks in respect to morphological details and pathological state within the root canal and in periapical tissues “The use of PP as a simple device in sophisticated ways”- (Rosenberg) could be advised as an accessory / assisting mean to establish and confirm final WL, since it is non-aggressive, “soft” method, and therefore cannot injure tissues or disturb wound healing

12. Radiographic method REVEALS, ASSISTS, BUT OFTEN GIVES AN “ILLUSORY TRUTH” PREOPERATIVE – DIAGNOSTIC RADIOGRAPH IS MANDATORY !

13. Radiographic apex and anatomical apex do not (always) coincide ! . A Rö Apical foramen cannot be (always) visualised on a radiograph ! Important details are not always detectable on the clinical radiograph

14. Radiographic method “Belgrade clinical study” M.V. & M.P.:1988 Referent point from Rö apex : 0.5mm in <25 yrs; 1.0 mm in >25 yrs Literature data: Accuracy widely ranges from 50% - 77% - up to 97% Precise in 51%; tolerance +/- 0.5 mm -> accurate in 68%; tolerance extended +/-1 mm accurate in 88%; Under and overestimations not over 2 mm !

15. Measuring file is longer than it appears radiographically ! When instrument is short of the Rö apex surprisingly is beyond AF in 43% ! I.B. If AC is 0.5 mm before apex then 66% of all measurements are “beyond” !

16. NO DOUBT – BEYOND but could be solved successfully 22

17. When short of the Rö apex it is actually closer to the AF ! “... radiographic working length ending 0-2mm short of the radiographic apex provides,more often than expected, a basis for unintentional overinstrumentation”

18. NO DOUBT – SHORT But could be solved successfully 12 Radiographs are indispensable for calculating, but not for determining WL !

19. Digital radiography 37 K..B-I. Assisted by RVG, only ! S. Andjelkovic Radiovisiography - RVG

20. Digital radiography - RVG Quantifies distances Image could be varied by software programme Fine file tip – low contrast structures – affect visualisation and measuring precision Better results with #15 or #20 files Image quality bellow conventional Rö Inferior to ELs – longer measurements S. Andjelkovic

21. Radiographic method relies still on many assumptions, arbitrary calculations, averages, speculations and “illusory images”, that add to the confusion rather than giving solution ! “GIVE LOCATORS A CHANCE” Adequate radiographs, knowledge of anatomy, and tactile sense, and not “apex locators” - - will help to determine apical constriction !

22. Resistance-based devices I Low frequency oscillation devices II High frequency (capacitance-based) devices II Capacitance & reistance device (access. look-up table) IV Voltage gradient-based devices ?? Two frequences (impedance diference)-based devices III Two frequences (impedance ratio-quotient) devices III Multi frequency-based devices III ELECTRONIC APEX LOCATORS ELECTRONIC FORAMEN LOCATORS ERCLMD, . . . - ”lot of words descriptive” – no length CLASSIFICATION of EFLs “The use of “generation X” to describe and clasify these devices is unhelpful, unscientific and perhaps best suited to marketing issues” These are the very same devices, but just under different brand-name, showing how market functions and manufacturers „cooperate“

23. In vitro (ex vivo) measuring the accuracy of EFLs - variables influencing and affecting results - • Embedding media - simulate clinical conditions (peridontal ligament) • Electrical properties of intracanal solution: extreme conductivity and ion concentration (type of EFL) • File size in respect to the diameter of the AC and AF: wise to use smooth canal instruments - less damage to fine structures • Type of EFL:the newer model the better and more consistent results

24. Variables influencing and affecting results of ex vivomeasuring the accuracy of EFLs: • Preflaring:improves determination of apical diameter and first file that binds, stabilises readings, increases precision • Range of tolerance:from +/- 0.1 mm, mostly +/- 0.5 mm, up to 2 mm; the wider the range the higher the percent of EFL accuracy ! - Apical land mark chosen to determine “real/actual length” (RA / AL) Most are valuable / useful for practice; majority was conducted in single rooted / canal teeth and suffer of too many variables !

25. Are differences between real values and on EFL’s significant ? Figures/marks on a display of EFL’s scales do not representvalues in mm ! 303 300 Differences bellow 0.5 mm are clinically not significant due to our manual abilities !

26. What about occasionally unstable readings - bouncing indicating marks ? In clinical use to wait for 3-5 seconds to achieve stable reading !

27. Tolerate small differences which are not noticeable clinically ? 202m 300m Bellow 0.5 mm ! Differences clinically acceptable !!

28. How strong readings on a display correspond to the real values on a high-tech measuring instrument ? 0.012– 0.038mm 0.022– 0.065 mm Far away of any concern! Precision and high resolution ! Extremely small distorsions from the real measures!

29. How exact readings on a display correspond to the real values on the high-tech measuring instrument ? What do they indicate ? What is the clinical relevance ? 1.45 -1.25=0.20mm 0.35-0.19=0.16mm <0.06 mm 0.001 mm Indicate high level of resolution ! Differences far bellow clinically tolerable +/- 0.5 mm !! The closer to the apex, the more precise the readings are & higher is the resolution!!

30. Can we follow with confidence what display indicates upon manufacturer’s instructions ? EFLs scales do not represent values in mm ! Four yellow segments indicate region between AF and AC(0.5 – 1.0 mm)!

31. Follow what display indicates and manufacturers instructions, but ”filtrate” and reconsider unusual and “strange” readings !! Three green segments indicate region of the apical constricion (~1.0 mm)

32. Do different foramen locators display the same values for the same distance in the same root canal ? Until spreader reached plastic barrier Tip of the finger spreader to the flat plastic surface placed firmly at the plane of the anatomical foramen !

34. Do different foramen locators display the same values for the same distance in the same root canal ? No, they do not !

35. Distance between warning “beyond foramen” => reading foramen => ”switch” to one mark/segment “short of foramen” (m) 0 - 508 - 701 193 (300) 0 - 354 - 705 351(340) 0.0 0.1 0 - 305 – 380 75 (48) - 0.0 Apex0.25 0 - 367 - 674 307 (350) Apex 169 (202) 0 - 143 - 312 AP EX 0.0 0.1

36. Different foramen locators show different values with different level of resolution for the same distance in the same root canal ! All deviations are far bellow range of clinically acceptable tolerance of +/- 0.5 mm, therefore they do not significantly influence the accuracy of EFLs in locating apical foramen !!

37. In vivo studies - on teeeth to be extracted: more realistic / relevant / reliable information useful for practitioners Factors that affect readings and/or accuracy of EFLs: - Vital – necrotic cases - Preflaring - Diameter of the minor and major foramen (pathol. – instrum.) - Size of the measuring file - Type of material the measuring file is made of - Canal content: infl. pulp tissue, puss, detritus; empty/dry - Conductive properties and ions concentration of irrigating solution - Tooth type: front - posterior / single – multi canal

38. More consistent, straight forward, faster and precise readings when: - coronal /middle/ portion preflared - pulp tissue extirpated – debris removed - foramen is not enlarged by periapical pathosis / instrumentation - size of the file coincides with lumen of the apical portion - moderately conductive irrigating solution: 2% NaOCl, CHX, EDTA No affect on readings and accuracy: - Tooth type: front - posterior / single – multi rooted (canal) - Type of material the measuring file is made of

39. Contradictory & controversial results / statements on: - vital vs. necrotic - moist vs. dry:type of EFL - high conductive vs. low conductive irrigant:type of EFL Adverse effect on readings: - PA lesions associated with destruction of PL, AF, AC and bone - wide open AFin immature teeth - extremes in conductive properties of a solution in the canal: saline vs. destilled water

40. Variables influencing clinical results of EFLs accuracy : (varies from 15% up to 100%) - method to establish precision of the locator: micrsocsopy measurement - software programmes for extracted teeth samples vs. comparison with clinical radiograph - range of tolerance/targeted interval: +/- 0.5; +/- 1.0; +/- 1.5 mm; higher tolerance -> higher % of accuracy • mark on a display chosen to be “apical terminus” for EWL: “00” / “Apex” vs. “-0.5”/”AC; -1.0; yellow or green segment – or each operator will chose the mark that he wants to call his OWN APICAL TERMINUS - anatomical land mark chosen to measure distance from the file tip: AC & CDJ vs. AF & AnAp Manufacturers should define clearly which lendmark their product locates !

41. “Belgrade clinical studies on EFLs” M P, M V & V I : in early 80’s of the last century “Odontometer” – Goof, DK Domestic hand-made device “Diapex”

42. “Belgrade clinical studies on EFLs” M.V. & D. I.: 1996 M.P & M.V. : 1988 - 1990 Referent point from Rö apex : 0.5mm in <25 yrs; 1.0 mm in >25 yrs “Odontometer” Alternating current impedance measuring device- in dry canal Precise in 67% of vital teeth, and in 76% of teeth with necrotic pulp, with +/- 0.5 mm range of tolerance. Mostly underestimations of -1.0 mm ! Precise in 77% with +/- 0.5 mm tolerance. Overestimations of + 0.5 mm in only 4% !

43. Accuracy of EFLs checked in clinical situation by Rö? Traditionally EFLs accuracy has been corroborated by Rö, but any correction of the file position according to Rö projections would invariably lead to overextension ! Comparison of precision of EFLs with Rö is not accurate because Rö is unreliable method in determining AC & AF !

44. “Propex I”:Dentsply/MAILLEFER(D. Nobs & S. Fultinavicius) “Raypex 5”:VDW(L. Satanovskij) “Apex NRG XFR”:Medic NRG(M. Zach, A. Beker, E. Friedman) “ApexPointer+”:MicroMega(C. Dort & A. Stephany) “Dentaport ZX”:J. Morita(J. Bohnes) “Belgrade in vivo studies” In vivo - in molars and multirooted premolars to be extracted: 30 canals per locator !

45. Referent point was tangential line to the AF Mark on a display indicated AF: “0.0”, “Apex”, “red segment”

46. Mean distance from the file tip to the AF - in vivo determined Ø 0.148 (0.079) + 0.076 + 0.131 0.165 (0.222) 2; 0.169 (0.149) 9;+ 0.226(0.102) + 0.119 + 0.208 + 0.075 0.187 (0.142) 3; 1;+ 0.129 0.189 (0.168) Majority showed high SD – dispersion of values All EFLs 100% precise within 0.2 mm range of tolerance; Seldom overestimations with small values - clinically acceptable NRG XFR small SD - consistent measuring; no beyond AF

47. “When apical foramen is located the position of the apical constriction (if exists) can be estimated”

48. Always have preoperative radiograph and stay within confines of the root canal ! K..B-I. Determining WL upon preop Rö and EFL, only !

49. Extreme narrow canals: Rö and EFL WL upon preop RVG, and EFL, only !! K..B-I. TRUST in EFLs , BUT NOT BLINDLY !!

50. Crown-down tapered preparation; WL - 0.25 mm before AF: tactile sensation, EFL, Rö and PP; rotary NiTi instrumentation & cold lateral COMBINING AND COMPARING SEVERAL METHODS GIVE MORE CONFIDENCE, ACCURACY AND SUCCESS THAN USING ONLY ONE OR EVEN NONE !