Root Canal Instrumentation Dr. Soo, Eason DDS, MDS (Endo), AdvDipEndodont, M Endo RCSEd Assoc. Prof. Dr Dalia Abdullah BDS, MClinDent Endodontology, FDS RCSEd Unit of Endodontology & Endodontics Dept. of Operative Dentistry Faculty of Dentistry, UKM
Introduction Objectives of canal preparation History of endodontic files Design - Conventional file and greater taper files Techniques used: Based on Crown Down concept Modified Double Flare Technique (MDFT) Hand ProTaper Technique (PT) Modified ProTaper Technique (MPT)
Objectives of Canal Instrumentation : Aim : To clean and eliminate microorganisms (??), remove infected pulp tissue and debris.
To shape the pulp space so that it takes on a tapering form, being widest coronally and narrowest apically
How much can we clean the canal?
Problems in cleaning canal : Single rooted tooth
Problems in cleaning canal : Multi-rooted/complex root canal system
Chemomechanical Debridement
Chemical Irrigant Irrigant Antibacterial NaOCl (2.5 – 5 %) as main irrigant. Alternative? Chlorhexidine (0.12-2.0 %) Smear layer removal EDTA solution (17 %) MTAD
Lubricant - Glyde, File-Eze, RC Prep
Final irrigation protocol 2.5 % NaOCl, 17 % EDTA, saline/distilled water, 0.12-2.0 % Chlorhexidine solution Chlorhexidine – antibacterial, inhibit Matrix metalloproteinases (MMPs) ,hence preserve bond strength NaOCl if mixed with Chlorhexidine will form toxic precipitate i.e. para-chloroaniline Used prior to obturation and root canal post cementation
Effects of irrigations
Mechanical Shaping What are we trying to achieve ? A tapering conical shape from the canal orifice to the apex Original shape of the canal is preserved Original location and size of the apical foramen is preserved
Endodontic Files (Manual Instrumentation)
Types of Hand Files Conventional Files ISO sized files Made from stainless steel/NiTi Design K-File / NiTI Flex K-Flex K-Flexofile Flex-R file Hedstrom file Reamer
Greater Taper Files Non standardised files Made from NiTi Design GT, GTX Twisted Files (TF) RACE Protaper Universal Wave One
Conventional Files
Conventional Files Standard file - follow the ISO numbering Size of the file represents the diameter at the tip Constant taper : 0.02 mm per mm length Length of blade : 16 mm Length of file : comes in 21mm, 25mm, 31mm
Cross sectional configuration
File tip design
16 mm
Design: K-Files -
K file and K-reamer are the most common types of intracanal instrument used today
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First introduced at the beginning of the 20th century and received the name Ktype from the holder of the original patent, the Kerr Manufacturing Company (Romulus, Michigan, USA) (Heuer & Miserendino 1987).
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Made by twisting grounded wire.
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Can be square (K-File) or triangular (Kreamer) in cross section
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Sharp flutes, non-cutting tip.
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Reamers are flexible due to its cross section is triangular.
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Reamers are more effective in a reaming or rotary action whereas files are more suitable for use in a push-pull or rasping motion (without rotation).
Design: K-Flexofile A twisted instrument with a triangular as opposed to the traditional square crosssection Increased flexibility #6,8,10 are square shape (too flexible if triangular shape, cannot cut or get into canal) From #15 are triangular shape
Design: K-Flex File Diamond-shaped cross-section, brought about an improvement in flexibility due to a reduction in the cross-sectional area compared with a square one of the same maximum diameter. Greater cutting efficiency in laboratory testing than the standard K-files with a square cross-section (Sch채fer et al. 1995). The alternating low flutes were said to provide more area for enhanced debris removal compared with traditional K-files (Ingle & Bakland 1994).
Design : Flex-R File Roane et al. (1985) proposed a new technique for root canal instrumentation, the ‘balanced force technique’. The technique incorporated the use of a newly-designed, stainless steel instrument, which was later marketed as the Flex-R (Miltex, York, PA, USA – previously by Union Broach, Long Island, NY). Machined file, rather than twisted, from a piece of round wire and has a triangular crosssection over the spiraling portion. A rounded, non-cutting, pilot tip. Flex-R files have been found to be more flexible than K-files and reamers of the same size, possibly because of the triangular crosssection and of the lack of work hardening due to the absence of a twisting process (Heuer & Miserendino 1987).
Modified’ tip with rounded, non-cutting pilot tip, a lot of rotary instrument have such design
SEM of Flex-R File
Design: Hedstrรถm File Made by machining round stainless steel, thus producing the spiraling cutting edge and taper in a single process Sharp and aggressive Cut dentine by updown/filing motion in canal Ineffective in cutting when used in a reaming motion; they would engage and lock into the dentine much like a screw into a piece of wood. Smaller size - tend to break easily
How to use K-file/K-Flexofile ?
Technique of Canal Instrumentation Modified Double Flare Technique
Canal Preparation Traditional concept: Apical coronal preparation Canal preparation starts from the apex to the coronal part
Current concept: Coronal apical preparation Preparation of the coronal part first before preparation of the apical part
Crown-down Approach Using a combination of hand files and rotary (GG burs) Sequence :
– –
Access cavity - straight line access Coronal Flaring WL determination Apical Preparation
Canal Preparation
Crown-down Approach Advantages : • Removal of bulk microorganisms at the coronal
third to prevent accidental pushing the apical part
• Reduces the hydrostatic pressure that can occur in
the canal
• Give better access to the apical part of the root
canal
• Allows better penetration of the irrigant solution • Minimise loss of working length
Modified Double Flare: Stages: • Coronal Flare • Working length • Apical preparation (Step-back)
Access Cavity
Straight Line Access
Balance force technique
Coronal Flare
2/3 WL EWL
How big is your coronal flaring ? • Enough for irrigation needle to enter 2/3 into the
Coronal Flaring
Coronal Flaring • What if the coronal part is already big ?
• Which tooth ? – Anterior central incisors – Canines – Premolars (lower 1st and upper 2nd)
Working Length •
Estimation of working length –
•
Use electronic apex locator (EAL)
Confirm with radiograph
Apical Preparation •
Enlarge the diameter of the apical part
•
Aim : – – – –
To enlarge enough to allow penetration of needle and irrigant To remove infected tissues To allow good exchange of irrigant To determine the apical stop
Apical Preparation IAS
MAF
G a u g e 2/3 I A S
WL
Step Back
Apical Preparation • Step-back technique - to form apical taper
Technique - Step Back MAF
2/3 WL
WL
Shape of Final Preparation •
Continuous taper
•
Original curvature maintained
•
Original size and position of apical foramen maintained
•
Apex remained patent
Technique of Canal Instrumentation Hand ProTaper Technique
Greater Taper Files Designed based on crown-down concept
Nickel Titanium Advantages: • Flexibility • Strength • Shape memory • Anti-corrosive • Does not weaken following sterilization
SHAPERS SX, S1, S2
FINISHERS F1, F2, F3
PROTAPER Universal S1
S2
SHAPERS SX, S1, S2
F1
FOR HAND USE
F2
F3
FINISHERS F1, F2, F3
ProTaper Universal Files •
Initially introduced as rotary files only
•
Based on crown down concept
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Using a sequence of 6 files – –
S1, Sx and S2 --> coronal flare F1/F2/F3 --> apical preparation
Taper of file Multiple & Progressive Taper
Benefits of design: • Increased flexibility • Each instrument produces its own 'crown down effect'
as larger tapers make way for smaller tapers ･
• Protaper files engage a smaller area of dentine reducing
torsional loads and file fatigue
• The cross section reduces the contact area between file
and dentin
• Increased cutting efficiency without 'screwing' • Canal shapes which are uniformly tapered over length
Modification of Taper For S2 New ProTaper S2 Change : slight modification of tapers along the flute Result : work is better balanced between S1 – S2 and F1 Benefit : transition from S2 to F1 is smoother 0.80 0.70
New sequence
0.60 0.50 0.40 0.30
S2 outshape
0.20 0.10 0.00 -0.10
F1 out shape
0
1
2
3
4
5
6
7
8
9
-0.20 -0.30 -0.40 -0.50 -0.60 -0.70 -0.80
Current sequence sequence Root canal length [mm]
10
11
12
13
14
15
16
S1 out shape
Cross Section
Triangular Convex
Tip of Finishing Files Earlier - modified active tip
Removal of Transition Angle
ďƒ˜ Result : tip is now more rounded – Safer, less transportation
Blade Design
Variable Helical Flute Angle
Overall Design of ProTaper • Nickel-Titanium • Multiple & Progressive Taper • Triangular Convex X- Section • Modified Rounded Tip • Variable Helical Flute Angle
Improvements of Design X-section of F3 Introduction of F4 & F5
New ProTaper F3 Changes : cross section has been reduced by making grooves along the flute Result : improved flexibility – reduced stiffness Benefit : better respect the canal path
New Cross Section
ProTaper F4
Tip Size : 040 Taper (first mm) : 6%
Easy to recognize : Black handle + marking F4 on the top for the manual version, double black rings for the rotary version Feature Lightened Cross Section Large Tip Size Benefits Improved flexibility Respect the root canal path
ProTaper F5 Easy to recognize : Yellow handle + marking F5 on the top for the manual version, double yellow rings for the rotary version
Tip Size : 050 Taper (first mm) : 5%
Feature Lightened Cross Section Large Tip Size Benefits Improved flexibility Respect the root canal path
Hand ProTaper Universal: Clinical Procedures
Files Sequence:
ProTaper for Hand Use Clinical Procedures • Explore canal w/ #10
hand file
ProTaper for Hand Use Clinical Procedures •
Explore Canal w/ #10 hand file
• Negotiate to #15 w/ hand
file
ProTaper for Hand Use Clinical Procedures
•
Explore Canal w/ #10 hand file
•
Negotiate to #15 w/ hand file
• Coronal Flaring w/ S1 (2/3 of
EWL)
Insert file with slight apical pressure until resistance
½ turn clockwise
½ turn anticlockwise
Withdraw (also can use Balance force technique)
Clean
ProTaper for Hand Use Clinical Procedures
• Explore Canal w/ #10 hand file • Negotiate to #15 w/ hand file • Coronal Flaring w/ S1
• Coronal Flaring w/ SX
(optional) using same motion – May replace w/ GG Drill
ProTaper for Hand Use Clinical Procedures • Explore Canal w/ #10 hand file • Negotiate to #15 w/ hand file • Coronal Flaring (S1, SX)
• Working length determination • Coronal & middle 1/3 Preparation
w/ S1 & S2 (up to full WL) using same motion
•
ProTaper for Hand Use Clinical Procedures Explore Canal w/ #10 hand file
•
Negotiate to #15 w/ hand file
•
Coronal Flaring (S1, SX)
•
Working Length Determination
•
Coronal 1/3 Preparation w/ S1
•
Middle 1/3 Preparation w/ S2
•
Apical 1/3 preparation w/ F1 & F2
•
Gauge w/ #25 hand file
ProTaper for Hand Use Clinical Procedures
•
Explore Canal w/ #10 hand file
•
Negotiate to #15 w/ hand file
•
Coronal Flaring (S1, SX)
•
Working Length Determination
•
Coronal 1/3 Preparation w/ S1
•
Middle 1/3 Preparation w/ S2
•
Apical 1/3 Preparation (F1F2 F3)
• Gauge w/ #30 hand file
ProTaper for Hand Use Clinical Sequence
Note: Balance force technique can be applied for file motion.
Technique of Canal Instrumentation Modified ProTaper Technique
Knowledge check •
ProTaper Universal sequence
•
Coronal flaring files (S1, S2, Sx)
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Apical finishing files (F1, F2, F3, F4, F5)
•
For MAF >♯30, what should you do? – – –
•
F4, F5 Conventional SS files preparation with “modified double flare technique” Modified ProTaper technique : prepare canal up to F3, then step back technique
How about MAF >♯50? –
Conventional SS files preparation with “modified double flare technique”?
•
Questions ?
Comparison ProTaper Hand Files
SS Files
Fewer instruments needed for preparation The canal can be prepared with moderate speed ProTaper design increases cutting efficiency Canal curvature is well maintained
Many instruments are needed for preparation Preparation is slow
Consistent tapered preparation coronal to apical with minimal foramen enlargement
Cutting efficiency poor due to poor design Transportation is very common Tapered preparation always inconsistent with over enlargement apically highly probable
Comparison Protaper Hand Files
SS Files
Less debris is extruded apically
Debris extrusion apically is high
Can be used in abrupt curvature WHEN pathway established by hand SS files (pre-curved)
Can be used in abrupt curvature but final preparation never smooth
Instrument separation is low due to good tactile feedback
Instrument separation has not been a historic problem
Temporization with “Double seal” IRM IRM Cavit Cavit Cotton Cottonpellets pellets
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Questions ?
Thank you ..