bio mechanical instrumentation

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Rotary CanalRotary CanalPreparationPreparationRotary CanalRotary CanalPreparationPreparation

Dr. Ebtissam Al-Madi, BDS, MSc, Cert Endo, Cert Med Informatics

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Outline Objectives of Cleaning & Shaping

Biological

Clinical

Mechanical

Instrumentation Techniques Stepback technique

Crowndown technique Rotary Instrumentation

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Biological Objectives Removal of all tissue, bacteria and bacterial

products and substrates from the rootcanal system

Mechanical Shaping of the root canal system to

facilitate placement of a root canal filling

Clinical Eliminate apical periodontitis and return

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Cleaning

Shaping Filling

Endodontic

Triad

Shaping to facilitate cleaning and Filling

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Access

Preparation

Cleaning & Shaping

of the canal

Obturation

Restoration

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Stepback

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Stepback Technique(1960s)

The most widely used preparationtechnique

Replaced Non-tapering Preparationtechnique

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Stepback Technique Apical Preparation:

1. Establish access (straightline)

2. Establish working length

3. File Instrument (watch-winding, file, ream, etc)

4. Place next larger file,instrument, and repeat till

you reach file 3-4 sizeslarger (MAF)

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Stepback Technique

Step back:1. Place next larger file to a

length 1 mm shorter ofworking length, file, irrigateand recapitulate

2. Repeat process withsuccessively larger files at 1mm increments shorter thanpreceding file.

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Stepback Technique Variations to the classic stepback

technique Initially enlarge coronal aspect with GG

burs

Complete coronal preparation with GGburs

Use of small GG burs in mid-root level

Use of Hedstrom files to flare thepreparation

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Stepback technique Advantages

Minimizeprocedural errors(transportation,ledging, apicalperforation)

Disadvantages Significant apical

extrusion of debris(post-operativepain)

Apical blockage

Canal deviation

Alteration of

working length

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Crown down

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Crowndown Technique

More recent technique Produce similar result to step-back

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Crowndown technique Development of straight-line access Eliminate pulp chamber obstructions

and check patency GG enlargement with size 4-3-2,

irrigate Coronal to mid root enlargement with

instruments from large to small,irrigate

Establish working length, irrigate Introduce progressively smaller files

deeper into the canal until resistanceis encountered Establish apical preparation size Complete preparation 14Al-Madi, 491 Den, 2008/904/Apr/09

Crowndown technique

Variations to the classic crowndowntechnique Crown-down pressure-less technique

Roane technique

Double flare technique

Modified double flare technique

Rotary Instrumentation

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Crowndown technique Advantages

Reduce apicalextrusion (reducepain)

Elimination coronalinterferences

Improved irrigation toapical part of canal

Facilitate workinglength determination

Disadvantages Early blockage of

canal

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Instruments

HandInstruments

RotaryInstruments

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Hand instruments

Been in use for over 100years

Still integral part ofcleaning & shaping

Better tactile sensation

ISO standardization

Broaches, k-files, Flex-R files, NiTi files, H-files

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Hand engine driven Properties of NiTi Alloy

Superelasticity High resistance to cyclic fatigue

Series 29

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Rotary Files Advantages

Less transportationand ledging

Shape canaluniformly

Reduced operatorfatigue

Improvedefficiency

Disadvantages Cannot be used in

some cases Buildup of debris Cannot use beyond

apical foramen Fracture can occur

suddenly Initial cost Loss of tactile

sensation

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Rotary Instruments

Lightspeed Profile

Hero

Quantec

K3

Flexmaster

GT

Protaper Sequence

RaCe

V-taper

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Design characteristics Non-cutting vs cutting

tip

Tip size

Taper

Cross section

Rake angle

Helix angle

Pitch

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Tip could be

non-cutting,

cutting

Tip shape

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Tip Size

Can be the same as ISO hand

tips sizes- color coded accordingly

Can be half sizes (12.5, 17.5,etc) as in Light Speed.

Can skip sizes ( only 20,30, 40)as in GT rotary

Can be nonspecific sizes(according to percentages ex.18.5, 20..) as in ProTaper.

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Increased radial landincreases peripheral

strength behind the

cutting blade

Smaller radial landequals decreased

strength for bladesupport

Cross section- Radial Lands

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Rake Angle

The rake angle is the angle formed by the cuttingedge and a cross section taken perpendicular to thelong axis of the instrument

Rake angles affect thecutting efficiency andthe aggressiveness ofthe file

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Overly Positive Rake Angle

Positive Rake Angle

Neutral Rake Angle

Negative Rake Angle

Rake Angle

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As the flute angle isincreased more debriscan be carried awayfrom canal.

Helical flute angles

The helical angle is the angle that the cutting edgemakes with the long axis of the file

Constant helical fluteangles allow debris toaccumulate and are moresusceptible to the effectof screwing in forces.

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Pitch

Pitch is the number of spirals or threads perunit length.

Constant pitch andconstant helical anglesproduce a pulling orsucking down into thecanal.

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Lightspeed(Senia & Wildey 1990s)

Long, thin non-cutting shaft

U shape design

Most flexible RI

Low incidence oftransportation,preparation errors,and loss of workinglength

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Profile(Ben Johnson 1994)

Increased taper

Began as series 29#0.02 taper, then#0.04 and 0.06 tapers

Profile (maillefer-Europe) manufacturedtips similar to ISO

Negative rake angle

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Coronally pre-enlarge

Use of Orifice shapers

Alternative use of #.04and #.06 tapers as wellas alternate tip sizes

Same basic techniquefor similarly designedfiles

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Profile41Al-Madi, 491 Den, 2008/904/Apr/09


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Profile

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K3(McSpadden)

Predecessors:

Quantec

Unique crosssectional designwith +ve rakeangle, 3 wide radiallands, peripheral

blade relief

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ProTaper(Cliff Ruddle, John West, Pierre Matchou)

Only 6 instruments Modified k file

with no radial lands

Varying taper thatincrease coronallyin shaping files andopposite infinishing files

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ProTaper52Al-Madi, 491 Den, 2008/904/Apr/09

Hybrid technique Instruments can be used in a manner that

promotes their individual strengths andavoids their weaknesses

Hand instruments secure a patent glidepath

Tapered rotary instruments efficientlyenlarge coronal canal areas

Less tapered instruments allow additionalapical enlargement

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Newer RotaryInstruments?

Light Speed Hero 642

GT files

Quantec

Flexmaster

RaCe V-Taper

Endo Sequence

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More information Pathways of the Pulp 9th e-edition

Endodontics- Ingle 5th

CD editon Advanced Endodontics- Rhodes Endodontics- Stock JOE IEJ Company brochures & Videos Internet

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ObturationObturationtechnologiestechnologiesObturationObturation

technologiestechnologies

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The ideal obturatingmaterial

Easily manipulated and provides ample working time Dimensionally stable with no shrinkage once inserted

into the canal Seals the canal laterally and apically, conforming toits complex internal anatomy

Nonirritating to the periapical tissues Impervious to moisture and nonporous Unaffected by tissue fluids-no corrosion or

oxidization Inhibits bacterial growth Radiopaque and easily discernible on radiographs Does not discolor tooth structure Sterile Easily removed from the canal if necessary 61Al-Madi, 491 Den, 2008/904/Apr/09

Obturating materials Core Materials

Silver cones

Gutta percha

Resilon

Sealers

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Resilon

Resin-basedobturation material Polyurethane Similar to GP:

Method of placement

Remove smear layer Use a self-etch primer Light cure coronal

surface

Advantages: Less coronal leakage Reduced PA

inflammation More resistant to

fracture

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Methods of obturation Lateral compaction Warm vertical Compaction

Continuous Wave compaction Warm Lateral Compaction Thermoplastic Injection Techniques Carrier based Gutta-Percha Thermo-mechanical Compaction Solvent Techniques Pastes

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Continuous WaveCompaction technique

Electric Heat Carrier (System B-Elements system)

Tapered Stainless steel pluggers(#.06, .08, .10, .12) with #50 tip(.5mm)

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System B

Fit master cone (Fine-medium-large) Prefit plugger to 5-7 mm of canallength

Set heat to 200c Sear off coronal GP Compact with heat to within 3 mm of

binding point Maintain non-heat position with firm

pressure for 5-10 sec Remove plugger with a 1 sec burst of

heat. Back fill with thermoplastic injection

technique or warm verticalcompaction 66Al-Madi, 491 Den, 2008/904/Apr/09


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Elements Obturation

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How & Where to learn? Read & understand the brochure-

Don't be fooled! Read the literature in textbooks andjournals- Be an informed consumer.

Try on extracted teeth till youmaster the technique- try before youbuy.

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