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Instruments For Canal Preparation
Endodontic Week For 5th Year StudentsUniversiti Sains Malaysia
10-14 September, 2007
Dr. Sam’an Masudi
Introduction
Success and failures of RCTObjectives of canal preparationHistory of endodontic filesDesign - Conventional file and greater taper filesTechniques used:
Crown Down concept 2 Techniques - Modified Double Flare & Hand Protaper Preparation
Success and Failure
Depends on thorough cleaning of the canalHow?
IsolationChemomechanical debridement -cleaning and shapingGood obturationCoronal seal
Success Case
46
Pre - operative
46
2 years review
Failure
Pre - operative
36
1 year review
36
Objective of Root Canal Preparation1. Eliminate microorganisms.2. Remove remaining pulp tissues.3. Remove debris.4. Shape the root canal system so that it may
be obturated. [1,2,3 are Cleaning process][4 is Shaping process]
Debridement of the root canal created during cleaning and shaping process.Irrigation and disinfection are integral parts of debridement
The principle of shaping
Develop a continuously tapering funnel from the apex to coronal orifice.Maintain the original shape of the canalMaintain the apical foramen in its original positionKeep the apical opening as small as possible.
Root Canal Preparation
2 approaches1) prepare the coronal section of the canal
system 1st with large instruments and progress towards the apex [Crown Down]
2) start at the apex with fine instruments and progress back towards the cervical orifice with large instruments [Step Back preparation]
RC Preparation (Cont’d)
Advantages of (1) method:1. Reduce the possibility of microbial
inoculation into the apical portion of the canal and then into the periapicaltissues
2. Early coronal flaring allows better penetration of irrigation solution
3. Early coronal flaring gives better access to the apical part of root canal
`
Techniques
1. Step-back2. Step-down3. Double-flare4. Crown down pressure-less5. Mechanized techniques of root canal
preparation(e.g. rotary technique)
Objectives of Canal Prep :
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
Access cavityThe most important phase of the technical aspect of root canal treatmentWithout adequate access preparation instrument preparation and material placement would be very tedious and often result in despair and frustration.
Most indefinitely will affect the outcome and success rate of the treatment
Lets look at some of these access cavities
Why access so crucialAccess
Most important especially when using rotary instrument*Curved canal can be
Naturally occurringArtificially created via poor access
When an instrument bends in the canal the metal experiences compressing forces on the inner curvature and stretching forces on the outer curvature
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 ProtocolIrrigant
AntibacterialNaOCl (2.5 - 5%) as main irrigant. Alternative?
Smear layer removalEDTA solution (17%) as final rinseMTAD
Lubricant - Glyde, RC Prep
Effects of irrigations
Mechanical ShapingWhat are we trying to achieve ?
A tapering conical shape from the canal orifice to the apexOriginal shape of the canal is preservedOriginal location and size of the apical foramen is preserved
Endodontic Files(Manual Instrumentation)
Types of Hand Files
Conventional Files Greater Taper FilesISO sized filesMade from stainless steel/NitiDesign
K-FileFlexofileHeadstrom fileReamer
Non standardisedfilesMade from NiTi
DesignGT filesProtaper files
Conventional Files
Conventional Files
Standard file - follow the ISO numberingSize of the file represents the diameter at the tipConstant taper : 0.02 mm per mm lengthLength of blade : 16 mmLength of file : comes in 21mm, 25mm, 31mm
16 mm
Design:K-Files/Flexofiles
- Made by twisting grounded wire
- Can be square or triangular in cross section
- Sharp flutes
- Non-cutting tip
- Flexible esp if the cross section is triangular. Therefore it will follow the canal curvature
Design: Headstrom File
Made by machining rod wire to make the flutesSharp and aggressiveCut dentine by up-down movement in canalSmaller size - tend to break easily
How to use K-file ?
Technique of Canal Preparation
Modified Double Flare Technique
Canal Preparation
Traditional concept:Apical coronal preparationCanal preparation starts from the apex to the coronal part
Current concept:Coronal apical preparationPreparation 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 accessCoronal Flaring WL determinationApical Preparation
Canal Preparation
Crown-down ApproachAdvantages :
Removal of bulk microorganisms at the coronal third to prevent accidental pushing the apical partReduces the hydrostatic pressure that can occur in the canal Give better access to the apical part of the root canalAllows better penetration of the irrigantsolutionMinimise loss of working length
Modified Double Flare:
Stages:
• Coronal Flare
• Working length
• Apical preparation (Step- back)
Access Cavity
Straight Line Access
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 incisorsCaninesPremolars (lower 1st and upper 2nd)
Working Length
Estimation of working lengthUse apex locator
Confirm with radiograph
Apical Preparation
Enlarge the diameter of the apical partAim :
To enlarge enough to allow penetration of needle and irrigantTo remove infected tissuesTo allow good exchange of irrigantTo determine the apical stop
Apical Preparation
2/3
WL
Gauge
IAS
IAS MAF
Step Back
Apical Preparation
Step-back technique - to form apical taper
Technique - Step Back
2/3 WL
WL
MAF
Shape of Final Preparation
Continuous taperOriginal curvature maintainedOriginal size and position of apical foramen maintainedApex remained patent
Common Error
Greater Taper Files
Designed based on crown-down concept
Nickel Titanium
Advantages:
Flexibility
Strength
Shape memory
Anti-corrosive
Does not weaken following sterilization
Earlier File
GT files
SX
S1S2 F1
F2F3
FINISHERS F1, F2, F3SHAPERS SX, S1, S2
PROTAPER FOR HAND USE
Protaper Files
Initially introduced as rotary files onlyBased on crown down conceptUsing a sequence of 6 files
S1, Sx and S2 --> coronal flareF1/F2/F3 --> apical preparation
Taper of file
-0.80
-0.70
-0.60
-0.50
-0.40
-0.30
-0.20
-0.100.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Root canal length [mm]
S 1
S 2F 1F 3 F 2
SX
Multiple & Progressive Taper
Benefits of design:Increased flexibilityEach 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 fatigueThe cross section reduces the contact area between file and dentinIncreased cutting efficiency without 'screwing' Canal shapes which are uniformly tapered over length
ProTaper New Shaping File S2
-0.80
-0.70
-0.60
-0.50
-0.40
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Root canal length [mm]
New sequence
Current sequence
New ProTaper S2Change : slight modification of tapers along the fluteResult : work is better balanced between S1 – S2 and F1Benefit : transition from S2 to F1 is smoother
S1 out shape
S2 outshape
F1 out shape
Modification of Taper For S2
Cross Section
Triangular Convex
Tip of Finishing Files
Earlier - modified active tip
Removal of Transition Angle Result : tip is now more
rounded – Safer, less transportation
Blade Design
Variable Helical Flute Angle
Overall Design of Protaper
Nickel-TitaniumMultiple & Progressive TaperTriangular Convex X- SectionModified Rounded TipVariable Helical Flute Angle
Improvements of Design
X-section of F3Introduction of F4 & F5
ProTaper New Finishing File F3
New Cross Section
New ProTaper F3Changes : cross section has been reduced by
making grooves along the flute Result : improved flexibility – reduced stiffnessBenefit : better respect the canal path
ProTaper F4
ProTaper New Finishing File 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
ProTaper New Finishing File F5
Tip Size : 050
Taper (first mm) : 5%
Easy to recognize :
Yellow handle + marking F5 on the top for the manual version, double yellow rings for the rotary version
Feature
Lightened Cross Section
Large Tip Size
Benefits
Improved flexibility
Respect the root canal path
Hand Protaper- Clinical Procedures
Files Sequence:
ProTaper for Hand UseClinical Procedures
Explore canal w/ #10 hand file
Explore Canal w/ #10 hand file
Negotiate to #15 w/ hand file
ProTaper for Hand UseClinical Procedures
Explore Canal w/ #10 hand fileNegotiate to #15 w/ hand file
Coronal Flaring w/ S1Insert file with slight apical pressure until resistance
½ turn clockwise
½ turn anticlockwise
Withdraw
Clean
ProTaper for Hand UseClinical Procedures
S1
Insert w/ slight apical pressure until resistance
S1
¼ to ½ turn clockwise
S1
¼ to ½ turn anticlockwise
=S1
Withdraw & clean file
Explore Canal w/ #10 hand fileNegotiate to #15 w/ hand fileCoronal Flaring w/ S1Coronal Flaring w/ SX (optional) using same motion
May replace w/ GG Drill
ProTaper for Hand UseClinical Procedures
SX
2
3
4
1
SX
Explore Canal w/ #10 hand fileNegotiate to #15 w/ hand file
Coronal Flaring (S1, SX)
Working Length Determination
ProTaper for Hand UseClinical Procedures
Explore Canal w/ #10 hand fileNegotiate to #15 w/ hand file
Coronal Flaring (S1, SX)
Working Length Determination
Coronal 1/3 Preparation w/ S1 again (up to full working length) using same motion
ProTaper for Hand UseClinical Procedures
Explore Canal w/ #10 hand fileNegotiate to #15 w/ hand file
Coronal Flaring (S1, SX)
Working Length Determination
Coronal 1/3 Preparation w/ S1
Middle 1/3 Preparation w/ S2 (up to full working length) using same motion
ProTaper for Hand UseClinical Procedures
S1,S2 TO WORKING LENGTH
Explore Canal w/ #10 hand fileNegotiate 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, using the same motion
ProTaper for Hand UseClinical Procedures
F1, F2 TO WORKING LENGTH
ProTaper for Hand UseClinical Procedures
Explore Canal w/ #10 hand fileNegotiate 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
Explore Canal w/ #10 hand fileNegotiate 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 (F1 F2)
For larger canals, continue apical prep w/ F3, using also the same motion
ProTaper for Hand UseClinical Procedures
F3 TO WORKING LENGTH
ProTaper for Hand UseClinical Procedures
Explore Canal w/ #10 hand fileNegotiate 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 (F1 F2 F3)
Gauge w/ #30 hand file
ProTaper for Hand Use Clinical Sequence
a. Establish straight line accessb. Explore canal w/ #10, then #15c. Flare coronal w/ S1, followed
by SX if necessary (penetration ≤ #15)
d. Measure/confirm working length w/ #15
e. Use S1 to lengthf. Use S2 to lengthg. Use F1 to lengthh. Use F2 to length
(recommended min.), followed by apical gauging
i. Use F3 to length (optional for larger canals)
Cut by rotating clockwise with sufficient apical pressure until engages the dentin. Rotate counter-clockwise to disengage, remove and wipe the file clean. Repeat rotating motions until desired length is achieved
ProTaper for Hand Use User Guidelines
a. Prepare straight line accessb. Use patency filesc. Check instruments before used. Use files in correct motione. Clean flutes and irrigate regularlyf. Use lubricants, e.g. Glyde
ComparisonProtaper 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
Consistent tapered preparation coronal to apical with minimal foramen enlargement
Many instruments are needed for preparation Preparation is slow
Cutting efficiency poor due to poor designTransportation is very common
Tapered preparation always inconsistent with over enlargement apically highly probable
ComparisonProtaper Hand Files SS Files
Less debris is extruded apically
Can be used in abrupt curvature with prebentinstrument WHEN pathway established by hand SS files
Instrument separation is low due to good tactile feedback
Debris extrusion apically is high
Can be used in abrupt curvature but final preparation never smooth
Instrument separation has not been a historic problem
Questions ?