SuccessfulSuccessful endodonticsendodontics

Biomechanical Preparation

cleaning & shaping microbial control.

Root canal obturation

DIAGNOSIS

CleaningCleaning

Is the removal of all potential irritants from

the root canal. This includes:

•Infected material•Organic Remnant•Microbes

This goal is achieved through: 1) proper instrumentation

2) Use of irrigants

Role of irrigant in cleaning &

shaping.

• Flushing out gross debris.• Prevent dentin mud formation.• Remove smear layer.• Antimicrobial effect.• Lubrication→↑ cutting efficiency.• Bleaching.

Saline.

Sodium hypochlorite.

Hydrogen peroxide.

Organic acid irrigants.

Calcium hydroxide.

Chlorohexedin gluconate.

Types of irrigant:

Refers to the specific shape ,(which is a

continuously tapering, and funnel shaped

preparation from the canal orifice to the

apical constriction), given to the canal to be

compatible with the filling material.

Shaping:

Biological objectives for cleaning & shaping:Biological objectives for cleaning & shaping:

Totally clean root canal system.

Avoid pushing debris beyond the apex.

Confine all your instrument within the root

canal.

Do no harm.

Mechanical objective for cleaning & Mechanical objective for cleaning &

shaping:shaping:

Mechanical objective for cleaning & Mechanical objective for cleaning &

shaping:shaping:1. Develop a continuous tapering conical form,

from the canal orifice to the apical foramen.

2. Make the canal narrower apically with the

narrowest cross section diameter at its

terminus.

3. Make preparation in multiple planes.

4. Never transport foramen.

5. Keep the apical foramen as small as practical.

Principles of root canal cleaning and

shaping.

1- Totally clean the root canal system.

2-Assume curvature in all canals.

3- pre-curving of files.

4- Avoid aggressive4- Avoid aggressive apical Instrumentationapical Instrumentation

Forcing debris byond the apex

Root apexfracture

Alter Canal path

5- Avoid overzealous canal shaping

6 -avoid apical blockage.

Etiology.

Effect.

Depends

On.

Canaldiameter

File motionProximity of

file tip

How to avoid

Convenience form. Resistance form. Retention form. Extension. Toilet of the cavity.

1

2

3

4

5

ReamingFiling

Quarter Turn Pull

Watch-Wind

Balanced-Force

H- File

30-60° B-F

Techniques of RC Preparation

Techniques of RC Preparation

1-Never files a dry canal. Copious Irrigation before during and after each file.2-The exact working length must be established at first.3- regular checking of stopper position at the established WL4-Use clean instruments to re-enter the canal. 5- Never forces an instrument if it binds.

Basic Consideration duringCleaning and Shaping

6- Use instrument in sequence without skipping sizes.7-Duplicate a curve in each instrument before entering the curved canal.8 -Maintain a patent apical constriction following each file size.9- After the access opening preparation, the air- water syringe must never be used till the end of treatment forcing drug, air…etc., through the apical foramen10-When an interacanal instrument has been severely bent or weakened it should be discarded.

Basic Consideration duringCleaning and Shaping

1.Apical-coronal Standardized Step-back Balanced force (Roane)

2 - Coronal-Apical• Crown- down pressureless .• Step – down• Double- flared.• Canal master

3 – Combination (Hybrid tech).4 – Automated

Engine driven e.g. Profile & Lightspeed Sonic Ultrasonic

5 – laser aided.

♦♦Instrumentation starts at the apex and go back

to coronal portion .

1) Standarized technique.1) Standarized technique.

2) Step-back technique.2) Step-back technique.

Complete apical preparation with master apical file # 25

Stepping-Back 3-4 sizes larger than MAF Each file is 1mm shorter than the previous one

Is the procedure of returning to the original working length of the tooth with the master apical file after each step-back file

Coronal Flaring with GG drills# 1,2,3

or H-file

Pre-Curving the K- Reamer K-File instrument #15 #15

Typical sizes for instrumentation:

• Maxillary anterior teeth #60-80

• Mandibular anterior teeth #35-50

• Single canal bicuspids #35-40

Buccal canals of maxillary molars • and mesial canals of mandibular molars #25-35 with moderate curves. • Maxillary molar (palatal canal) #50-60

• Severely curved fine canals #20-25

• Severely curved large canals #35-45

3 (Balanced Force Tech. (Roane Tech.)

-Modified tip- Triangular cross-sec.

- Anti-clockwise effic.

Flex-R file in clockwise/anticlockwise

rotational motion

Apical preparation is termed “Apical control Zone”

By carrying the preparation to the radiographic apex.

25

45

30

60

40

80

Modified Balanced Force

Advantages of Balanced force prep. 1- little or no measurable apical transportation.

2- less deviation from the original canal curvature.

3- Modified preparation allow easier preparation with less extruded debris and less apical transportation.

Disadvantages

1- excessive clockwise rotation than 90° →

↑ working load, instrument tip locked into canal wall → instrument separation.

2- large radicular shaping with GG may cause strip perforation

♦♦ Instrumentation starts at the coronal portion and

go on to the apex.

Advantages of early radicular access in coronal apical preparation techniques:

Elimination of microbes and infected dentin. Better and deeper penetration of irrigant. Instrument approach apical 1/3 with less

strain and better tactile sense. Provides more tactile sense in the apical 1/3. Less extruded debris. Less time for preparation. Less chances of apical blockage.

1)1)Crown-down pressurelessCrown-down pressureless

technique.technique.

Crown Down

Pressure-less Tech.

Radicular Coronal Flaring Crown-Down Preparation

Access Length

2 (Step – down Tech.

2 (Step – down Tech.

Flaring of coronal 2/3

Apical preparation

Stepping back

Step-Down

Advantage Disadvantage

Double – Flared Tech.

Double – flared tech.Double – Flared Tech.

File gently

Crown Down prep. till WL without rotary GG

Crown Down prep. till WL

without Rotary GG.

Apical Preparation

Stepping-Back

Crown Down

Pressure-less Tech.

2 (Step – down Tech.

Double – Flared Tech.

Canal Master Tech.

Canal MasterInstrument

*Smooth flexible non-tapered shaft .

*Short cutting head .

* Non-cutting pilot tip.

* Intermediate sizes

Middle and cervical thirds of the root canals are instrumented with Canal Master rotary

instruments to a point of curvature .

#50 #80

Canal Master hand instruments are used for apical preparation

with #20 - #40 or #50

#20

#50

Canal Master hand instruments are used for 0.5 mm step-back technique

Canal Master Tech. Advantages

1- Ledges, perforation, Zipping.

2- Maintain original canal curve.

3- round cross-section.

Disadvantage

*Instrument separation

Advantage of mechanical

instrumentation:

Less Effort.

Canals are enlarged quickly.

Debris is removed easily.

Canals are more uniform and smoother.

Disadvantage of mechanical

instrumentation:

Greater chance for canal ledging.

Greater chance for canal perforation.

Greater chance for instrument breakage.

Loss of tactile sensation.

Rotary NiTi instruments:Rotary NiTi instruments:

The unique properties of NiTi alloy have allowed

instruments to be manufactured for use in a

rotary handpiece and these have been shown to

be effective in canal preparation.

flexibility Dec. ledges &

perforations

Dec. inst .separation

Rotary Instrumentation using

Ni-Ti instrument

SS

Step-backHand Instrument

• Profile.

•Protaper.

•Light speed.

•Great taper.

•Quantec.

•K3 Rotary

Rotary NiTi instruments:

Variable Tapers

PROFILE 0.4 : Angle Taper 4%

PROFILE 0.6 : Angle Taper 6%

ISO Standard : Angle Taper 2%

PROFILE O.S. : Angle Taper from 5 to 8%

PROFILE PROFILE

PPROROFFILEILE Motor and Speeds

Stable speed : 150

– 350 r.p.m.

PROFILE PROFILE

LightSpeed

LightSpeed

LASER-ASSISTED CANAL PREPARATION

The 308-nm excimer laser was used successively for preparation of root canals as it has a good transmission through water.

Advantages.Disadvantages.

Excimer Laser

Erbium :YAG

Nd:YAG

Intracanal dentin surfaces (apical third)under SEM–1500X- laser parameters:

Dentin surface lased e Erbium :YAG 100 mJ and 15 Hz. Effective debris removal.

Control; unlased dentin surface.

Nd:YAG reduced to 80 mJ and 10 Hz.

Note melted and recrystalized dentin surface .

ND:YAG

Control

Erbium:YAG

A

B

C

Problems encountered in R.C. Cleaning and Shaping

(Instrumentation Errors)

• Underinstrumentation.• Overinstrumentation.• Apical foramen perforation.• Ledge formation. • Change in canal curvature.• Apical transportation ‘Zipping’.• Root Perforation.• Loss of WL• Instrument separation ‘breakage’.• Canal can not be negotiated.

1-Underinstrumentation

Inadequate filing in coronal 2/3Insufficient enlargement

of apical 1/3

Failure

Root Fracture

2 -Overinstrumentation

3 -Apical foramen perforation

“Is an artificially created irregularity in root canal wall that prevents the placement of

instrument to WL.”

4 -Ledge Formation

Etiology

1- straight instrument 2- large # inst. In curved canal3- forcing inst. e apical pressure4- Skipping

Management

- Bypassing it. if can not - instrument to ledge level

5 -change in original canal curvature6 -Apical foramen transportation “zipping’’

• Outside wall of the curve. • Inner side wall of the curve

7 -Root Perforation

Perforation In apical

1/3

- Etiology- Diagnosis- Management

Root perforation

These problems may be overcome by:1. Reducing the area of instrument actively engaged in cutting.

2 .Reducing uncontrolled forces on canal wall: Precurving the file. Use of smaller files. Use of intermediate files (golden sizes). Use of flexible files ( flex file , NITI files ). Use of preflaring techniques. Anticurvature filing

Anticurvature Filing“Filing preferentially away

from the inner curve or furcal aspect (site of potential perforation)”

Filing safety zones with more strokes than furcal wall 3:1

8 -File short of determined WL

Etiology: Prevention 1- apical blockage

2- lack of recapitulation

3- canal ledge

4- fractured instrument

5- change stopper position

6- skipping instrument sizes

9- Instrument breakage

“Separation”

Old files

Dry canals

Large # in fine canal

H-file in reaming

Skipping sizes

Etiology

Management of Fractured instruments

may be removed with special extractor mechanically.

It may be bypassed if it is not too far inside the canal.

Management of Fractured instruments

If it can not be bypassed (more apically located), the canal is prepared to the point of breakage and filled to this point.

Management of Fractured instruments

10- Canal can not be10- Canal can not be negotiated to WL.negotiated to WL.

due to

Sharp curvatureor

Calcified canal

Plus EDTA EDTA

Root canals prepared with laser irradiation were cleaner than that prepared with hand instruments

and the smear layer was removed.

The main limitation of the laser is the fiber which carried the laser beam in one parallel direction so,

The main effect of the laser is kept concentrated at the

apical foramen resulting in damaging effect on the

periapical tissues.

While the lateral walls of the canal are affected only by reflected and scattered part of irradiation with minimal

indirect effect.

Laser canal prep.

Adv.

Dis