Monday morning, the doctor walks into the clinic relaxed

after the weekend and opens the appointment register.

Call on my first case he remarks, full of enthusiasm and

vigor and then what does he see-the first case is Oh no!

My God- BMP.

Good morning and welcome to today’s seminar on

Biomechanical preparation during endodontic therapy.

Let’s delve deeper under the following subheadings:

CONTENTS

Introduction

Definition and objectives

Basic terms and motions of instrumentation

General principles and Techniques of biomechanical preparation

a) Hand Apical coronal

Coronal apical

b) Automated

1

Curvatures and cleaning and shaping

Advances in automated instrumentation and adjuvant techniques

Conclusion and Bibliography

2

INTRODUCTION

Yes, the root canal system is complicatedly complex. Accessory and

lateral canals, isthmuses, calcifications, curvatures and what not combine

to form a daunting challenge to the astute clinician. Achieving not just

vertical access but true 3 dimensional preparation is an issue that has and

still vexes a majority of clinicians as evidenced by the myriad techniques

and instrumentation that have spawned in the quest for ideal cleaning and

shaping. Just as nothing is constant but change so too in the root canal

nothing is predictable except the unpredictable.

Along with diligent access preparation, canal location and working

length determination only through biomechanical preparation, will ensure

good obturation and healing. Understanding that a denture is as good as its

initial impression, an inlay as good as the tooth preparation and an

obturation as good as the biomechanical preparation, let us explore the

rationale and techniques to achieve that perfect canal preparation.

DEFINITION AND OBJECTIVES:

Schilder introduced the concept of “Cleaning and Shaping” almost 3-4

decades ago.

3

Biomechanical preparation refers to the controlled removal of dentin

and root canal contents by manipulation of root canal instruments and

materials. It consists of cleaning and shaping.

Cleaning:

Refers to the removal of all contents of the root canal system before

and during shaping including substrates, microflora, bacterial products,

foods, caries etc.

Shaping:

Refers to a specific root canal form with particular design

objectives. It involves the carving and predetermined removal of root canal

structure to achieve a uniform, tapering homogeneous design. The final

shape permits effective irrigation, obturating instrumentation and general

hydraulics required to transform and capture a maximum cushion of gutta-

percha and sealer into all foramina with three dimensionality and no

extrusion being achieved.

The purpose of this seminar is to provide the rationale and

techniques for proper cleaning and shaping of the root canal system, which

will enable the clinician to obturate the system.

4

As with many aspects of dental profession, such as a denture being

no better than the initial impression, or an inlay being no better than the

tooth preparation, it follows that canal obturation will be no better than the

cleaning and shaping of the entire system.

Generally speaking, the 2 main objectives in canal cleaning and

shaping are:

Biological: Biologically, the goal of intracanal procedures is to remove all

pulp tissue remnants and micro-organisms and their substrates along with

infected dentin.

Mechanical: Mechanically 3-D shaping of the canal is the objective which

must be accomplished to achieve biologic cleaning.

Biologic objectives include:

1. Confine all instrumentation within the root canal space (apical

constriction) to maintain its spatial integrity. Repeated

instrumentation extending beyond the constriction is unwarranted. It

causes peri-radicular inflammation and often destroys the normal

biologic constriction of the root apex.

2. Avoid pushing contaminated debris past the confines of the apical

constriction.

5

Many instances of post treatment pain and swelling can be

attributed to necrotic tissue and micro-organisms and their toxins

being inoculated into the peri-radicular tissues as a result of

indiscriminate cleaning procedures. This induces a rapid

immunologic response.

3. Remove all the potential irritants from the entire canal system. This

avoids recurrent peri-radicular inflammation and creates a condition

that permits prompt, uneventful healing.

4. Establish the exact W.L and completely clean and shape the canal

system.

5. Create sufficient width in the coronal half of the canal system to

allow for copious flushing and debridement.

Mechanical Objectives include:

1. Develop a continuously tapering form in the root canal preparation.

The final preparation of this system should be an exact replica of

the original canal configuration in shape, taper, and flow only larger.

Only too often, canals are simply “bored out” with the clinician failing

to consider the spatial relationship of the canal to the overall root

anatomy.

6

2. Prepare a sound apical dentin matrix at the DC junction.

This provides the resistance form to the intraradicular cavity

preparation. This also prevents the over-extension of instruments

and controls the apical movement of gutta-percha sealer during

obturation.

3. Prepare the canal to taper apically, with the narrowest cross-

sectional diameter at the apical termination (apical dentin matrix).

The apical third of the canal preparation must provide a

tapering / parallel, spatial configuration in order to ensure a firm

seating of the gutta-percha and sealer.

The three-dimensional shape of the preparation, especially of

the apical 1/3rd, must provide a retentive cavity to enhance

condensation procedures.

4. Confine cleaning and shaping procedures to the canal system,

thereby maintaining the spatial integrity of the apical foramen.

Adherence to this principle prevents violation of the peri-

radicular tissues. This principle is evident when foramina are

transported (moved) (zip and elbow)during excessive apical

instrumentation. This can be internal or external transportation.

7

5. Remove all residue of cleaning and shaping procedures that could

prevent patency of the apical foramen i.e. dentin shavings and tissue

debris. This will help prevent complications like ledges, loss of

canal length, development of false canals etc.

Recapitulation is essential to all cleaning procedures as ignoring

this important step will often lead to ledges, loss of canal length, dev of

false canals etc.

Procedural terms:

1) MAF-Master apical file: It is the largest file that binds slightly at

correct WL after straight line access. It is determined by passively

placing the successively larger files at the C.W.L. until correct size is

reached which binds at the tip. The file binding at first or smallest file

to bind is initial apical file.

2) Pre curving of instruments

Precurving of stainless steel instruments is mandatory while

negotiating curved canals. It is a valuable tool for feeling canal passages

and for moving around calcifications, ledges and around curved foramina.

It helps to prevent procedural problems and perform adequate shaping in

curvatures. Precurving can be done either with cotton or gauze or using

commercialy available devices utilizing the diagnostic x-ray.

8

3) Recapitulation : An essential step especially in apical coronal

techniques – it means the use of instruments in the correct size

sequence smaller to larger and returning to smaller instruments from

time to time before advancing to a larger size. E.g. after 15 no. 10mm

them proceed to 20, then use 10 and 15 and proceed to 25 and so on.

This helps prevent packing of dentinal filings and ensures patency of

root canal through to the apical foramen.

4) Anticurvature filing-Filing away from curvatures and danger areas

described in detail under curvatures.

Basic terms of Motions of instrumentation – BMP is a dynamically

delicate motion – flowing, rhythmic and energetic. Various motions

involved are:

Methods of Cleaning and Shaping

Cleaning and shaping are dynamically delicate motions,

flowing, rhythmic, and energetic. In order to use files and

reamers efficiently, the movements require distinction. There

are 6 distinctive motions of files and reamers.

A) Follow:

9

Usually performed with files. Are used initially during cleaning

and shaping or any time an obstruction blocks the foramen.

Irrigating, precurving different kinds of curves, curving all the

way to the tip of the instrument and multiple curves in multiple

directions of the instrument are all part of follow.

B) Follow-withdraw

Files are used. This motion is used once the foramen has been

reached and the next step is to create the path from access cavity to

foramen. The motion is follow, then withdraw or “follow and pull” or

“follow and remove”. It is simply an in – and – out passive motion that

makes no attempt to shape the canal.

C) Cart

Refers to the extension of a reamer to or near the radiographic

terminus. The reamer should gently and randomly touch the dentinal walls

and “cart” away debris.

D) Carve

Reamers are used for shaping. The key is not to press the

instrument apically but simply to touch the dentin with a

precurved reamer and shape on withdrawal randomly.

10

E) Smooth

Is accomplished with files. In the past, most endo procedures

were performed with a smoothing or circumferential filing

motion. If the previous four motions are followed smoothing is

rarely required.

F) Patency

Is achieved with files/ reamers.

It means that the portal of exit has been cleared of any debris

in the path.

Also included are 2 other terms given by Ruddle-Gauging and

Tuning.

Gauging refers to the knowing the cross sectional diameter of the

foramen that is confirmed by the size of the instrument that

“snugs in” at working length.

Tuning is ensuring that each sequentially larger instrument

uniformly backs out of the canal by 0.5 mm.

11

Also included is scouting that refers to using instruments to

gauge and estimate the root canal anatomy, form and variations

and is same as follow.

Motion of instrumentation / envelopes of motion:

A) Filing: Indicates a push-pull motion of the instrument. The

inward passage is powered by hand and file rigidity. Cutting is done

during withdrawal or pull stroke. Done using files and usually in

circumferential manner.

B) Reaming

Indicates clockwise / right-hand rotation of an instrument.

The instrument must be restrained from insertion to generate

a cutting effect. Instrument # is increased when this motion is

employed. It is a rotating-pushing motion limited to a quarter

to half turn.

C) Turn-and-pull(Combination)

Is a combination of reaming and filling, the file is inserted

with a ¼ turn clockwise and inwardly directed hand pressure

(i.e. reaming) positioned into the canal by this action, the file

is subsequently withdrawn (i.e. filling).

12

The rotation during placement sets the cutting edges of the file

into dentin and the non-rotating withdrawal breaks local the

dentin that has been engaged.

Disadvantages:

Hourglass canal shapes were observed by Weine.

According to Schilder

Clockwise rotation of a half-revolution followed by

withdrawal. The file is not inserted towards the apex, rather,

he gradually allows the preparation to progress out of the

canal.

¼ turn to right followed by straight pull out

D) Watch-winding

Is the back-and-forth oscillation of a file (30-60°) right and

left as the instrument is pushed into the canal.

It is an expanded use of the “Vaiven” technique described by

Ingle. This back and forth motion can be combined with a

pull stroke and effectively planes walls. It has various

advantages like canal centering, not necessitating precurving

13

and balancing tooth structure cutting with instrument

mechanics.

This back-and-forth movement causes the files and reamers

to plane the walls efficiently.

In a way, this is a predecessor to the balanced force

technique, as the 30-60° of clockwise rotation pushes the file

tip and working edges into the canal and the 30-60° of

counter clockwise motion partially cuts away the engaged

dentin.

E) Watch-winding and pull

When used with H-files, watch winding cannot cut dentin

with the backstroke. It can only wiggle and wedge the edges

tightly into the wall.

With each clockwise turn, the instrument moves apically

until it meets resistance and must be freed with a pull stroke.

F) Balanced force technique

This calls for oscillation of the preparation instruments right

and left with different arcs in either direction.

14

To insert an instrument, it is rotated to the right (clockwise) a

quarter turn. This pulls the instrument into the canal and

positions the cutting edges into the walls.

Next, it is rotated left (counterclockwise) at least 1/3rd of the

revolution to unthread the instrument and drive it from the

canal.

Advantages:

Simultaneous apical and counter-clockwise rotation of file

strikes a balance between the tooth structure and instrument

elastic memory. This balance locates the instrument very near

the canal axis, even in severely curved canals, so this

technique avoids transportation.

It works effectively without pre-curving.

General Guidelines for cleaning and shaping:

1. Direct straight line access should be obtained.

2. rubber dam is a prerequisite and microscopes are an

asset.

15

3. Accurate length determination is a prerequisite.

Remember canal length may shorten on

instrumentation of curved canals.

4. Instruments should be used sequentially with

recapitulation.

5. Instrument stops and reproducible reference points

should be used.

6. Do not force instruments and regularly inspect and

debride instruments.

7. Use copious irrigation and instrument in wet canals.

Various chemical aids can be used to supplement

preparation like RC prep, EDTA, Glyde etc.

8. Confine instruments to root canal and do not force

debris apically.

9. How much to enlarge is a priceless question- How

large and how much to enlarge is dictated by the

anatomic structure, accessibility of the canal and

skill of the operator. Inadequate enlargement limits

cleaning, debridement, disinfection and obturation

16

while overzealous preparation leads to iatrogenic

problems, unnecessary weaking of tooth and

susceptibility to fracture, perforations, spatial

movement of apical foramen etc. Earlier 2 guidelines

were considered sacrosanct- enlarge a root canal at

least 3 sizes beyond the size of the first instrument

that binds and enlarge a canal until clean white

dentinal shavings appear in the flutes. However,

these are not considered valid criteria today by any

researcher or clinician. Studies have shown that only

enlargement upto 30 to 40 number permits effective

irrigation though this may not be always possible.

Thus enlarging the root canal should be done based

on myriad factors to achieve both biological and

mechanical objectives.

Techniques for preparing root canals:

Apical coronal technique Coronal-apical technique

In which the WL is established and the full length of the canal is then

In which the coronal portion of the canal is prepared before determining

17

prepared. the WL

e.g.

- Standardized.

- Step-back.

- Roane (balanced force)

Advantages:

Allows early debridement of the coronal part of canal which may contain bulk of organic debris.

Enables better and deeper penetration of irrigant early in the preparation.

Tends to shorten the effective WL and determining the WL after such enlargement will reduce the problem of its alteration during preparation.

Allows better control over apical instrumentation.

Reduces the piston-in-a-cylinder effect responsible for debris extrusion

However, there are risks of ledging, blockage and perforation.

e.g. :

- Step-down.

- Double-flare.

- Crown-down pressureless.

- Canal-master

18

Apical coronal

1) Standardized preparation:

- Done in narrow canals with circular cross-sections.

WL determined.

Smallest instrument adjusted to WL.

Sequentially enlarged entire canal.

Obturation with silver cone.

Disadvantages:

- Risk of extrusion of debris.

- Alteration of WL.

- Vertical root # is overinstrumentation is carried out.

- Unlikely to debride complex canals

19

- Possibility of canal deviation.

To overcome deficiencies a hybrid technique consisting of reaming the

apical third and filing the coronal twothird has been recommended with

coronal preparation obturated with gutta percha.

Step back preparation:

WL determined.

Instrument that fills to correct WL is chosen.

Enlarge 3 No’s larger at the apex.

Reduce the WL length by 1mm and continue to enlarge canal / flaring.

Recapitulate, irrigate for patency.

Coronal preparation done using GGD.

20

Disadvantages:

- Extrusion of debris.

- Apical blockage.

- Alteration of W.L.

- Tendency for canal deviations.

2) Roane Technique (Balanced Force)

Three of its main features are:

- Canals are prepared to predesigned dimensions of which 3 are

recognized and are 45, 60 and 80 according to the size of apical

preparation.

- These dimensions refer to the size of the file used at the third step

back.

- Each step-back from the master apical file at the PDL is 0.5mm

shorter than the previous one. This is termed as the “apical control

zone”.

- Flex R files are used.

21

- WL determined to the radiographic apex with the largest file placed

without force. This helps in determining the selection of

predesigned preparation (45, 60, 80).

22

Coronal apical technique

1) Step down technique:(Marshall and Papus)

- Is a modification of the step-back technique.

Prepare the coronal portion to 16-18 mm /beginning of the curve with

anti-curvature filling.

GGD’s are used to refine the coronal part.

Determine WL.

Using step-back, complete the apical preparation.

Disadvantages:

- Ledge formation.

- Apical blockage.

- Perforation.

23

Through this technique overcomes most of the disadvantages of the

step-back technique.

2) Double Flared Technique:

Determine W.L.

Prepare till 14 mm / coronal to the curve.

Irrigate and clean.

Go 1mm deeper, maintaining instrumentation coronal to the curve and file.

Again 1mm deeper.

Continue till WL is achieved.

Prepare using step-back

Indications:

- For straight canals or

- For straight portions of curved canals.

24

Contra indications:

- In calcified canals.

- In young permanent teeth with open apices.

3) Crown-down pressureless technique:

- For curved canals without causing deviations. Rotary action is used

to cut dentine with the apical part of files.

Determine WL and prepare till # 35 till 16mm (widen the canal with

smaller files first)

Reduce size + go down and enlarge till apex.

Change to #40 + repeat.

4) Canal master technique:

- Its aim is to aid the maintenance of curves using a rotary instrument

designed so that only the apical 1-2mm is engaged in dentine

removal.

25

Advantages:

- Avoids the need for recapitulation.

- The apical 0.75mm of the hand instrument is safe-ended to facilitate

maintenance of canal curvature.

Determine WL

Prepare to the beginning of the curve

Use canal master in step-back fashion.

Hybrid-technique

- An amalgamation of various techniques can be used combing

different desirable aspects and convenience to achieve thorough

biomechanical preparation.

26

SPECIAL CONSIDERATIONS IN CURVATURES-CONVENTIONS

AND COMPLICATIONS

CURVATURE-THE ENGINE OF COMPLICATIONS

- As an instrument is curved, elastic forces develop internally. These

forces attempt to return the instrument to its original shape and are

responsible for straightening of the final canal shape and location.

- These internal elastic forces (i.e. restoring forces) act on the canal

wall during preparation and influence the amount of dentin

removed. They are particularly influential at the junction of the

instrument tip and its cutting edges. This region is the most efficient

cutting surface along an instrument, and when activated by the

restoring forces, it removes more tissue. This phenomenon is

responsible for apical transportation and its consequences.

1) Pre-curving of instruments.

2) Anti-curvature filing

- Is the controlled and directed preparation into the bulky/safety zones

and away from the thinner portions or danger zones of the root

structure, where perforation or stripping of the canal walls can

occur.

27

Need:

- It is a method of applying instrument pressure so that shaping will

occur away from the inside of the root curvature in the coronal and

middle 1/3rd of a canal.

- Was described by Abou-Rose, Frank and Glick. They emphasized

that during shaping procedures, files should be pulled from canals as

pressure is applied to the outside canal wall. This dimensionally

applied pressure, prevents dangerous midcurvature straightening in

curved canals.

Advantages:

- It maintains the integrity of canal walls at their thin portion and

reduces the possibility of root perforation / stripping.

- Maintains digital control over the instrument and the preparation of

the curved canal is used.

3 Radicular access

- Was first promoted by Schilder.

28

- This creates space in the more coronal regions of the canal which

enhances placing and manipulating subsequent files as it increases

the depth and effectiveness of irrigation.

- May be accompanied by rotary instrument / circumferential filing.

4 Reverse Flaring / Pre-flaring

- Is the presently preferred development of flaring whereby the

coronal portion of the preparation is flared before the completion of

the apical portion.

- In the standard flaring technique, the apical portion of the tooth is

completed before any filling is performed.

- In the reverse flaring and aspects of preparations are carried out.

- Minimal filling at the tip enlargement of the coronal part apex

is completed apical flaring.

Advantages:

- Irrigants are allowed to get down the canal earlier and farther to

produce cleaning.

- In curved canals, more effective preparation of the apical area is

provided when the file has fewer obstructions in the coronal part.

29

- Files, pluggers, filling material can penetrate to the apex more easily

three a larger orifice.

Instruments used for Reverse Flaring

- 0.4 taper instruments (Ni-Ti).

- MeXIM

Available in 5 instruments – 25.0.25 at Do (0.03, 0.04, 0.045,

0.05, 0.055 /mm – tapers).

Used in gear reduction handpieces at 340 rpm.

Made from Ni-Ti in H-style.

Designed by MacSpadden.

Ritano Files.

Hand instrument with H-configuration with several tapers.

Made in lengths shorter than 21mm.

5 Also for curved canals copious irrigation is

mandatory.

6 Safe sided instruments and files dulled on one side

can be employed or NiTi instruments can be used.

30

7 Extremely narrow canals require the use of smaller

instruments and mid size Golden Medium files along

with chemical chelators etc.

8 Double curved or bayonet shaped canals-Here after

the apical foramen has been cleaned and shaped the

middle third curve is eliminated with H-files taking

care not to strip and perforate and then regular

instrumentation carried out. This is done by

introducing a small H-file at the junction of middle

an apical third and filing away inner portion of the

curve.

9 Dilacerated roots require coronal flaring and then

using flexible and safe sided instruments.

Preparation using Automated Devices or Mechanical Instrumentation

The lure of faster, easier and more efficient cleaning and shaping has

spawned various types of automated devices. There is literally a revolution

going on in automated devices with new brands and techniques introduced

everyday.

31

Disadvantages:

- Loss of tactile sense and lack of control of where and how much

dentine is removed from the root canal wall.

Classification:

I Rotary

- Used in slow running standard handpiece e.g., GGD, Peeso, Canal

master – used only in the structure part.

- Latest addition is the new 16:1 gear reduction handpiece NiTi matic

at 300rpm.

- Ni-Ti files are used.

- Used for preparation of severely curved canals.

- Files are manufactured with an off-centre tip that facilitates

negotiating around curvatures and ledges.

- Myriad nickel titanium generation of instruments and devices like

ProFile, ProTaper, Quantec, Light Speed, OS etc have been

introduced.

II) Reciprocal quarter turn:

32

- This uses a special handpiece that contrarotates the instrument three

90°.

- E.g. Giromatic (1964).

- Endocursor.

- Endolift – has a vertical component in addition to the rotation.

Disadvantages of Automated

- Hand instrument requires the same amount of time as automated.

- Flare preparation with hand instrument tends to remove debris from

within the canal system than automated.

- Automated is difficult to use in the most post regions of the oral

cavity.

- There is greater propensity for the automated system to produce

zipped canals, ledges etc.

- A controlled power-assisted system designed to eliminate the

original problems encountered by Giromatic appeared in 1981.

- Dynatrak

33

- Uses stainless steel instruments with increased flexibility consist

flute depth and curved canals and rounded tip to minimize and

control ledges, zips, etc.

III) Vertical

- Canal finder.

- Has a vertical movement of 3-1 mm and free rotational movement.

- Instrument used is canal master (H-file with a safe ended tip).

- Canal Lender.

- Vertical movement of 0.4-0.8 mm

3 instrument K-file with a safe ended tip.

H-file.

Universal file (flexible H-file with a safe-ended tip).

There are few basic guidelines for rotary shaping:

2) Straight line access.

3) Estimating the cross-sectional diameter.

4) Familarizing with specific root canal anatomy and seating.

34

5) Speed and sequencing with gear reduction and electric motor

and using large to small files.

6) Lubrication and a light or feather touch equivalent to using

sharp lead pencil.

IV) Random

- E.g. Excalibur.

- K-files.

- 20,000-25,000rpm.

V) Sonics

- Endostar 5

- Endosonic Air 3000

Advantages:

- Reduces fatigue and stress during preparation.

VI) Ultrasonics

Magnetostrictive Piezoelectric

- Requires H2O cooling - Most common

- No H2O cooling

35

- May produce apical widening

and ledges in curved canals.

Advantages:

- Cleaning effect is by acoustic streaming.

I) Microbrushes:

Advancement in small wire technology, injection molding, bristle materials

and bristle attachment have enabled the creation of endodontic

microbrushes. These can be activated by rotary or ultrasonics and are

primarily intended for finishing root canals. They contain 16mm bristle

with D0 diameter of 0.4, 0.5, 0.6 and 0.8. Rotary brushes are run at about

300 rpm while ultrasonic ones are run with NaOCl and 17% EDTA.

II) Lasers:

In 1971, Weichman and Johnson were probably the first to suggest the use

of laser in endodontics.

Initially Nd:YAG and CO2 lasers were used. They are mainly advocated as

a coadjunct for microbial reduction and to readily root surface.

Recently, argon lasers, excimer laser, holmium:YAG laser, diode laser and

erbium : YAG laser with various wavelength have been investigated. These

36

can be delivered using a optical fibre 200-400µm diameter equivalent to #

20-40 file cooling systems with air water sprays may accessory this.

Levy compared the laser technique with a step back procedure finding the

form better. The technique was:

1. Enlarge apical region with # 15 file + copious

irrigation.

2. Preparation begins with the laser energy level set at

150milli joules.

3. Fibre optic is inserted to W:L and enlargement done

circumferentially first apically tehn moving

coronally to enlarges upto #60 instrument.

The avg. time to complete the preparation was 1 minute.

Although hand instruments left some walls untouched and smear layer was

found covering walls, laser preparation showed remarkable cleanliness.

However Levy also found melting of dentin and closing off of tubules and

melting of silicon fiber optic.

Similarly various other lasers have been experimented with.

37

Currently wavelength at UV plaster appears promising. The ArF excimer

laser at 193nm and XeCl (308nm) laser appear well suited. Second

harmonic alexandrite laser (377nm) also shows promise.

Mainly today lasers are advocated for cleaning or sterilizing the root canal

and shaping is a modality under investigation. The laser is excellent at

satisfying the root canal. Future promises of efficient preparation, sterile

canals, shorter treatment time and minimum effort with maximum result

are fuelling laser research at break neck speed. Potential disadvantages of

cost, safety, coolants, effective control etc have to be overcome. Lasers

have a definitive future in endodontics only the direction has to be

delineated.

Non instrumented root canal cleansing:

Lussi et al introduced devices to cleanse the root canal without

instrumentation. The 1st device reported in 1993 consisted of a ‘pump’ that

inserted an irrigant (like NaOCl) creating bubbles and cavitation that

loosened debris. This process was followed by negative pressure (suction)

that removed debris.

More recently a smaller new improved machine was introduced. Also

ozone pumps like healizae have been veritified in cleansing root canal

systems.

38

Finalizing the preparation:

After cleaning and shaping by any of the mind baggling variety of

techniques it is necessary to finagling the preparation and manage the

smear layer. Through a controversial topic, if divided to be removed, smear

layer removal and final finishing is accomplished cutter with EDTA and

ultrasonics, EDTA and microbrushes with NaOCl or other newly available

chemicals for its management to provide a root canal now ready for

obstruction.

39

CONCLUSION:

“Try cleaning a house after a wild party.” Cleaning and shaping root

canals is just more difficult. The complex anatomy, convoluted curvatures,

non-negotiable interconnections and hard to reach nooks and crevices make

for a challenging and daunting task. “Purity is considered the hallmark of

sanctity”. Obtaining clean and sterile root canals is the secret of good

healing.

Also the revolution of automated endodontic combined with advances in

hand instrumentation have changed the long we shape and clean canals.

Thus combining the art of proper shaping and the science of immaculate

cleaning will culminate in ideal biomechanical preparation that will lay the

foundation for ideal obturation and healing and ultimately successful

therapy.

40

Bibliography:

1. Endodontics – Stock, Gulabivala, Walker, Goodman.

2. Endodontics – Ingle and Bakeland.

3. Endodontic practice – Grossman, Oliet, Rio.

4. Endodontics – Cohen and Burn.

5. DCNA.

41