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1. Biomechanical preparation during endodontic therapy.
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
 Curvatures and cleaning and shaping
 Advances in automated instrumentation and adjuvant techniques
 Conclusion and Bibliography
1

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.
2

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.
3

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.
4

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.
5

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.
6

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.
7

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:
8

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.
A) 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.
B) 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.
C) 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.
9

10. D) 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.
E) 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.
10

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).
11

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
12

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.
13

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.
14

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
15

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
16

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
17

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
18

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.
19

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.
20

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).
21

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.
22

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.
23

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.
24

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.
25

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.
26

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.
27

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.
28

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.
29

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.
30

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:
31

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
32

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.
33

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
34

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
35

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.
36

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.
37

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.
38

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.
39

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.
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