Cleaning and Shaping of the Root Canal System | PPT Download

December 17, 2012 | By | Reply More

Cleaning and Shaping of the Root Canal System | PPT Download

Powerpoint presentation | lecture slide | conservative dentistry

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Cleaning and Shaping of the Root Canal System

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Objectives of Canal Preparation

Start with the end in mind

 

Objectives of root canal preparation

The root canal system must be:

Cleaned of its organic remnants

Shaped to receive a three dimensional filling of the entire root canal space

 

Objectives of root canal preparation

The canal is

Cleansed primarily by irrigation

Shaped primarily by instrumentation

 

Cleansing of the root canal

Objectives

Removal of organic debris

Elimination of bacteria

 

Irrigation

An ideal irrigant:

Is nontoxic

Dissolves vital and necrotic tissue

Is bactericidal

Lubricates the canal

Removes the smear layer

 

Sodium hypochlorite

Dissolves vital and necrotic tissue

Is bactericidal

Lubricates the canal

 

Prolube

Facilitates placement of file

Entraps debris

Aids in removal of the smear layer

 

EDTA

Chelating agent

Effectively removes smear layer

 

Shaping of the root canal

Canal shape – produced by instrumentation

Objective is a smooth tapered preparation

Shaping of the root canal

 

Instruments

Instruments differ according to:

Metal

Taper

 

Tip design

 

Cross sectional geometry

 

Length of cutting blades

Sizing

 

Metals

Nickel titanium               Stainless steel

 

Excellen flexibility            Less flexible

 

Conforms to canal           Straightens and

curvature                       transports canal

 

Plastic deformation          Permanent                                                 deformation

Metals

Metals

Taper

Definition

 

Increase in diameter per unit length

What is Taper?

What is taper?

Taper

Taper of instruments in U of M file kit

Stainless steel files – 0.02 taper

OS – variable tapers ranging from 0.05 to 0.08

Series 29 rotary Profiles – 0.06 taper

NiTi hand files – 0.04 taper

Tip Design

Non-cutting tip

Bullet nose (60 degree) tip

Smooth transition angle where tip meets flat radial lands

 

Tip Design

Designed to follow a pilot hole

Guides instrument through canal during preparation

Tip Design

Cross-sectional geometry

Three radial lands

Each contains bidirectional cutting edges

Keep instrument centered in the canal

Cutting edges scrape dentin

Cross sectional geometry

Cross sectional geometry

Cross sectional geometry

Radial lands separated by three u-shaped flutes

Provide space for accumulation of debris

Moves debris out of canal

Length of cutting blade

Traditionally 16 mm

Orifice shapers – 10 mm

Sizing of instruments

ISO sizes

Number refers to tip diameter in tenths of mm

The tip diameter increases by 0.05 mm from sizes 10 to 60, then by 0.10 mm

Sizing of instruments

% increase in diameter from #10 to #15 file is 50%

Difference between #55 and #60 is only 9%

Sizing of instruments

Series 29

Progressive 29% increase in tip diameter

Instruments are better spaced

More instruments in smaller sizes and fewer large instruments

Crown Down Technique

The coronal portion is prepared before the apical portion

Follows medical principle of cleansing before probing a wound

Crown Down Technique

Crown Down Technique

Eliminates constrictions in the coronal region

Reduces effect of canal curvature

Improves tactile awareness during apical preparation

Crown Down Technique

Allows more effective irrigation

Removes majority of tissue and microbes before apical third is approached

Reduces change in working length during apical preparation

Crown Down Technique

Coronal third   Orifice shapers

Middle third    0.06 taper rotary Profiles

Apical third     0.04 taper hand Profiles

 

Clinical Procedure

Estimate working length

Parallel radiograph

Estimated working length is the distance from the reference point to the radiographic apex

Parallel Radiograph

Clinical Procedure

Establish straight line access to apical third

Clinical Procedure

Explore canal patency

Ensure that canal is negotiable to radiographic apex

Small file – #10 K-file

May need to precurve  these SS files

Clinical Procedure

Files used in a push/pull or quarter turn pull motion

Never rotate these files through 360 degrees

Clinical Procedure

Clinical Procedure

Clinical Procedure

Estimate canal size

Radiographic appearance

Crown/root morphology

Standardized tables

 

Estimation of canal size

Estimation of canal size

Clinical Procedure

Actual WL determination

Preparation should terminate at

Apical constriction

1 mm short of radiographic apex

 

Clinical Technique

Actual WL determination

Radiograph

Apex locator

Clinical Procedure

Clinical Procedure

Clinical Procedure

Apex Locator

Clinical Procedure

Crown down cleaning and shaping of canals

Clinical Procedure

This technique applies only to teeth ranging from 18 – 23 mm in length

Coronal third measurement is WL minus 8 mm

Middle third measurement is WL minus 4 mm

Apical third measurement is WL

Preparation of the coronal third

Coronal third measurement is working length minus 8 mm

Prepared using Profile orifice shapers

Preparation of the coronal third

Profile orifice shapers

In sequence larger to smaller

Preparation of coronal third

Measure WL minus 8 mm on largest OS

Lubricate the canal with Prolube

Preparation of coronal third

Rotate OS at 300 rpm

Note: Orifice shaper should be rotating at 300 rpm before it is placed in the canal

Advance the OS in 1 mm increments

When resistance is encountered retract OS while still rotating

Never force any instrument apically

 

Preparation of the coronal third

This OS will not extend to WL minus 8 mm

Irrigate copiously

 

Irrigation

Preparation of coronal third

Move to next smallest OS

This will extend further than previous instrument

Repeat the steps described for largest OS

Move to next smallest OS

Continue this sequence until working length minus 8 mm is reached

Preparation of coronal third

Return to largest OS

This will now extend further into the canal than it did previously

Repeat this  sequence until this (the largest) OS reaches WL minus 8 mm

Preparation of the coronal third

Never force any instrument apically

Irrigate after every instrument

Use copious amounts of Prolube

Preparation of coronal third

Preparation of middle third

Middle third measurement is WL minus 4 mm

Prepared using 0.06 taper Series 29 rotary Profiles in sequence larger to smaller

Preparation of middle third

Preparation of middle third

Measure working length minus 4 mm on the largest 0.06 taper series 29 rotary file

Set green rubber stop at that length

Lubricate the canal with Prolube

Preparation of middle third

Rotate at 300 rpm

File must be rotating at 300 rpm before it is placed in canal

Advance file in 1 mm increments

When resistance is encountered retract file while still rotating

Copious irrigation with NaOCl

Preparation of middle third

Preparation of the apical third

Prepare to actual working length

Use 0.04 taper NiTi hand files in sequence smaller to larger

 

Preparation of apical third

Preparation of apical third

Measure working length on #15 file

Set rubber stop at that length

Lubricate the canal with Prolube

Preparation of apical third

Advance size 15 file to working length

Rotate file through 360 degrees

Irrigate copiously with NaOCl after each file

Preparation of the apical third

Advance size 20 file to working length

Continue through sequence, seating each file to working length

 

Preparation of apical third

The largest file that extends to working length is the Master Apical file (MAF)

For large canals – minimum MAF #40 – 50

For small canals – minimum MAF #35 – 40

Master Apical File

Take a radiograph with MAF in place.  This confirms:

Length

Placement

Mission accomplished

Smooth tapered preparation

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