1. SESSION VIII - RADICULAR CAVITY PREPARATION dr B.Cerkaski
ENDODONTICS
preclinical course

2. Radicular cavity preparation
SESSION VIII - RADICULAR CAVITY PREPARATION dr B.Cerkaski
Radicular cavity preparation
‘step-back’ technique
PART I

3. Objectives of canal preparation
The root canal must be:
Cleaned of its organic remnants
by instrumentation and irrigation
Shaped to receive a smooth tapered preparation for three-dimensional filling of the entire root canal space
by instrumentation

4. Objectives of canal preparation
Cleaning assesment:
presence of clean dentinal shavings
canal enlargement three sizes larger than the first instrument that binds at the apical constriction (IAF)
canal walls should be smooth in all dimensions

5. Principles of canal preparation
Gradualy increasing taper
Preparation must flow and progressively narrow in an apical direction
Original anatomy maintained
Without ledging and transportation
Position of foramen maintained
Gently enlarged without relocating
Foramen as small as practical
Improves canal-shaping results and promotes confidence in canal obturation

6. Steps in root canal preparation
after the straight line access is done

7. Clinical steps after the access is done
Toilet of the cavity (NaOCl) + pulpotomy/pulpectomy
Root canal localization
Root canal preenlargement
Full pulp removal and root canal preparation

8. Toilet of the cavity
irrigation of pulp chamber with NaOCl (sodium hypochlorite)
removal of the coronal pulp (pulpotomy)
Bleaching effect of NaOCl makes easier to localize all root canals

9. Canal localization
+ patency control

10. Canal orifices localization
C-pilots (size 6, 8, 10)
Microopeners
Endodontic probe
NEVER SEARCH FOR A ROOT CANAL WITH A BUR!!!

11. canal orifice preparation
straight line access

12. objectives First step of canal preparation!
Orifice preparation and coronal part of canal preenlargement creates a straight-line access to apical portion of canal
It is a continuation of convenience form in the coronal part of the canal
Significantly improves cleaning and shaping procedures

13. orifice preenlargement → straight-line access to 1/3 apical

14. Armamentarium Gates-Glidden burs (work gently!!!)
Preenlargement can be accomplished with a variety of hand and rotary instruments
Gates-Glidden burs (work gently!!!)
Pesso reamers (work gently!!!)
Greater-taper rotary instruments
Ni-Ti files called „orifice openers”

15. Gates-Glidden bur Flame-shaped head Safe-ended – non-cutting pilot tip
6 sizes (#1 - #6)
Tend to „screw” themselves into the canal
Most effective cutting in back (withdrawing) motion

16. Preenlargement technique
Patency control – place initial file (#10 or less) and qualify the root canal as:
WIDE - purple file #10 gently inserted in about ½ of length without problems
NARROW – purple file #10 not possible to insert in the canal to about ½ of length
If 1. -> preenlargement with GG #4-3
If 2.-> do not preenlarge with GG!!! Open the canal with hand instruments up to size 20 and then preenlarge with GG
(sequence: 6->8->10->15->20->GG#3->GG#4)
PATENCY (of at least two coronal thirds) should always be checked BEFORE beginning of preenlargement procedure

17. Preenlargement technique
Observe initial file when introducing to obtain information about:
Diameter of canal
Initial angulations of centerline and curvatures
Obstructions
ALWAYS FOLLOW WITH GG bur THE ORIGINAL PATH OF ROOT CANAL

18. DANGER ZONE
Distal surface of mesial roots of lower molars

19. ORIFICE PREENLARGEMENT

20. Preenlargement technique

21. Benefits of preenlargement
Better tactile control with small files in the delicate apical third microanatomy
Reduces pressure from the more coronal cutting flutes of any file
Allows easier insertion of files (especially precurved)
Holds a greater volume of irrigants and lubricant
Promotes the removal of dentin mud
Removal of the bulk of the pulp and bacteria from passing through area

22. details of “step-back” shaping technique

23. Step-back technique objectives
Apical preparation first
From smaller to larger

24. STEP-BACK PROCEDURE step-by-step hand instrumentation
Phase I
Apical preparation with recapitulation
Phase II
Steping-back procedure
Refining Phase IIA
Coronal and midroot preparation
Refining Phase IIB
Apical finishing

25. Chemo-mechanical preparation!!!
Copious irrigation between each file!
(NaOCl)
Original anatomy
Mechanical
preparation

26. STEP-BACK PROCEDURE Phase I
To start Phase I instrumentation, it must be assumed that the canal has been explored, preenlargement was done
Flood the cavity with irrigant
WL measurement with AL (using file nr 10) confirmed with x-ray according to Ingle’s method (on x-ray file 15 or larger!)
Identification of IAF
Initial Apical File – the first file that binds (fits smugly, tight) at the working length
Most fequently it is No. 10 SS K-file or c-pilot
- IAF gives us information about original size of the canal and apical constriction!
- Only one IAF size for each canal

27. IAF

28. STEP-BACK PROCEDURE Phase I
Using IAF with WL established (stopper) with „watch-winding” and rasping motion, work against the canal walls until it fits loosely to the working length
Irrigate NaOCl
Place the next larger file (if IAF=10→15) to the working length, with „watch-winding” and rasping motion, work against the canal walls until it fits loosely to the working length
IMPORTANT:
The instrument must be to full depth when the cutting action is made

29. STEP-BACK PROCEDURE Phase I
Recapitulation
If it is not possible to skip to another file size (file doesn’t go to the full WL insert a prior size file to the working length, for debris removal and maintaining patency)
Hedstroem file is usually most effective in debris removal
Irrigation NaOCl
Repeat steps 6-10 until widest provided file reaches the WL
= Master Apical File (MAF)
IAF: 8,10,15
MAF 35

30. Master Apical File (MAF)
the widest file fitting the WL
MAF size is recommended to be usually three sizes wider than IAF, minimum ISO 35 in infected cases (in smaller preparation than MAF 35 irrigant doesn’t penetrate properly the apical part). In not infected cases the rule is: 3x larger than IAF not less than ISO 25
More infected root canal is  more root dentine should be eliminated  larger MAF should be selected

31. I phase of step back technique
WL set precisely at each file
Start with nr 10 – if not possible to insert to the full WL(root canal
to narrow) try nr 8 or nr 6!
MAF established as 35 in infected cases (in not infected 3x larger than IAF
not less than 25)
copious irrigation between each file size!!!

32. STEP-BACK PROCEDURE Phase II
SESSION VIII - RADICULAR CAVITY PREPARATION dr B.Cerkaski
STEP-BACK PROCEDURE Phase II
Place a file one size larger than MAF into the canal 1mm short of the working length
Work the instrument against the walls until it is loose within the canal
Recapitulation to full length with MAF file to maintain patency and removal of dentin chips.
Copious irrigation before introducing next size instrument
50 WL-3mm 45 WL-2mm
40 WL-1mm 35 WL
50 WL-3mm
45 WL-2mm
40 WL-1mm
MAF 35 WL

33. STEP-BACK PROCEDURE Phase II
Repeat steps using next larger file until midroot of the canal – usually three sizes more than MAF
RECAPITULATION and irrigation after every next file with MAF file to full WL
50 WL-3mm
45 WL-2mm 40 WL-1mm
35 WL

35. STEP-BACK PROCEDURE Refining phase IIA
Reshaping of midcanal
Lubricate canal and the #1 or #2 GG drill
Run engine
Place drill into the canal
Let the drill find its way without forcing
Put a gentle pressure while removing the drill from the canal
RECAPITULATION
Irrigation
Use larger size of GG drill and repeat sequence reaching 1-2mm shallower
Phase IIA can be performed also using large SS Hedstroem or K-files

36. STEP-BACK PROCEDURE Refining phase IIB
return to a MAF
Smoothing all around the walls with vertical push-pull strokes
Placing the file into the canal and pressing it laterally while withdrawing it along the path of insertion to scrape (plane) the wall
Hedstroem file is the most efficient

37. STEP-BACK PROCEDURE COMPLETED PREPARATION
Ready to fill continuously tapered canal
At this point NaOCl can be left in place to the apex for 2-5min for possible debris and auxiliary ramifications cleaning
Diameter MAF 35

38. II phase of step back (+IIA and IIB refinishing phases)
SESSION VIII - RADICULAR CAVITY PREPARATION dr B.Cerkaski
II phase of step back (+IIA and IIB refinishing phases)
MAF
at WL
1 size
larger
at WL-1 I R G A T O N
MAF
at WL
(reca
pitu
lation)
2 sizes
larger
at WL-2 I R G A T O N
MAF
at WL
(reca
pitu
lation)
3 sizes
larger
at WL-3 I R G A T O N
IIA) I R G A T O N
IIB

39. step-back vs crown-down
Step-Back Technique: Beginning with the smallest files and aiming just shy of the apex and moving back from that point while increasing the file size.
The Crown Down Technique: Beginning with a larger file to remove coronal debris first and moving to smaller files as the files move closer to the apex.

40. Hybrid approach
crown-down
step-back

41. … so, let’s have small break …