CONTENTS
Introduction
Definition and
objectives
Basic terms and
motions of instrumentation
General
principles and Techniques of biomechanical preparation
a) Hand: Apical
coronal And Coronal apical
b) Automated
Curvatures and
cleaning and shaping
Advances in
automated instrumentation and adjuvant techniques
Conclusion and
Bibliography
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.
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.
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.
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.
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.
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.
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:
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.
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
ž Is achieved with
files/ reamers.
ž 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.
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
ž 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)
ž 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).
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:
ž Hourglass canal
shapes were observed by Weine.
According to Schilder
ž 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
ž Is the
back-and-forth oscillation of a file (30-60°) right and left as the instrument
is pushed into the canal.
ž 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 and balancing tooth structure cutting
with instrument mechanics.
ž This
back-and-forth movement causes the files and reamers to plane the walls
efficiently.
ž 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
ž 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
ž This calls for
oscillation of the preparation instruments right and left with different arcs
in either direction.
ž 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.
ž Next, it is
rotated left (counterclockwise) at least 1/3rd of the revolution to
unthread the instrument and drive it from the canal.
Advantages:
ž 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.
ž 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.
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 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 prepared.
|
In which the coronal portion of the canal
is prepared before determining the WL
|
|
e.g.
-
Standardized.
-
Step-back.
-
Roane (balanced force)
|
Advantages:
ž Allows early
debridement of the coronal part of canal which may contain bulk of organic
debris.
ž Enables better
and deeper penetration of irrigant early in the preparation.
ž Tends to
shorten the effective WL and determining the WL after such enlargement will
reduce the problem of its alteration during preparation.
ž Allows better
control over apical instrumentation.
ž Reduces the
piston-in-a-cylinder effect responsible for debris extrusion
ž However, there
are risks of ledging, blockage and perforation.
e.g. :
-
Step-down.
-
Double-flare.
-
Crown-down pressureless.
-
Canal-master
|
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
-
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.
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.
-
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).
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.
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.
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.
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.
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.
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.
-
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 à enlargement of the coronal
part à apex is
completed à 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.
-
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
ž Available in 5
instruments – 25.0.25 at Do (0.03, 0.04, 0.045, 0.05, 0.055 /mm – tapers).
ž Used in gear
reduction handpieces at 340 rpm.
ž Made from Ni-Ti
in H-style.
ž Designed by
MacSpadden.
ž Ritano Files.
ž Hand instrument
with H-configuration with several tapers.
ž 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.
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.
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:
-
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
-
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.
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
-
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 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.
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.
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.
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.
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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