CLEANING AND SHAPING USING ROTARY ENDODONTIC INSTRUMENTS /certified fixed orthodontic courses by Indian dental academy

CLEANING AND SHAPING
USING ROTARY
INSTRUSMENTS

INDIAN DENTAL ACADEMY
Leader in Continuing Dental Education
www.indiandentalacademy.com


CONTENTS
• INTRODUCTION
• ROTARY SHAPING GUIDELINES
• CROWN DOWN TECHNIQUE
• CORONAL 2/3 ROTARY SHAPING TECHNIQUE
• APICAL 1/3 ROTARY SHAPING TECHNIQUE
• ROTARY SHAPING INSTRUMENTS
• CLEANING AND SHAPING WITH DIFFERENT
ROTARY INSTRUMENTS
• CONCLUSION

INTRODUCTION
Rotary Shaping instruments are replacing the
conventional hand file systems to enhance shaping
ability of the canal , reduce clinical mishaps like
blocks, ledges, transportations and perforations.
When the clinician masters the “method-of-use”
protocols of rotary shaping instruments
unpredictable file breakage, metal fatigue, loss of
cutting efficiency, variation in length, diameter and
curvature of the canal can be avoided and better
shaping of the canals with desired taper will be
achieved.


Directions for use of NITI


Rotary Niti shaping instruments
There are various Rotary shaping instruments that are
available in the markets. The concepts, strategies
and techniques for successful use are not unique to
any one system; they generally apply to all niti rotary
systems regardless of their brand names or
geometries.

Most widely used Rotary Niti instruments are : Profile
system GT, Profile .04 .06 taper, Protaper, Quantec
series, Light speed, Hero 645, k3 file series and
many more..


Common features of nickel tittanum files.

instrument year Cross taper Rake angle tip
section

Light Speed 1992 U file 00 -ve Non cutting

Profile 1993 U file 02-06 -ve Non cutting

Orifice 1993 U file 05-08 -ve Non Cutting
Shaper

Quantec 1996 Modifiled k 02-12 +ve Cutting
file

Hero 642 1999 Modified H 02-10 -ve Cutting
file

RaCE 1999 Modified K 02-10 -ve Non Cutting
file

Flex master 2000 Modified K 02-06 -ve
file
Cutting

ProTaper 2001 Modified K Multiple -ve Non Cutting
file reverse

K3 2001 Modifies k 02-10 +ve Non Cuttingt
file

RADIAL LANDS

A Radial land is a surface that projects
axially from the central axis, between flutes
as far as the cutting edge.
Another way of evaluating radial land is blade
support.
Rotary files has full radial lands. Ex: Profile,
GT.
Or their lands were recessed Ex: Quantec


 RAKE ANGLE
the rake angle is the angle formed by the
cutting edge and a cross section taken
perpendicular to the long axis of the
instrument
 The cutting angle on the other hand is the
angle formed by the cutting edge and a
radius when the file is sectioned
perpendicular to the cutting edge.

 HELICAL ANGLE: is the angle that the cutting
edge makes with the long axis of the file
Variable helical angle debris will be removed in a
more efficient manner and the file will be less
likely to screw into the canal.

 PITCH : is the number of spirals or threads per
unit length. The result of a constant pitch and
constant helical angles is a “pulling down” or
“sucking down into the canal”.
This is particularly significant in rotary files with a
constant taper.
K3 is the only file that addressed this issue. This
file has purposely been designed with constant
tapers but with variable pitch and helical angles.


Active and passive
Instruments
The Nickel titanium rotary instrument systems
2 main categories: active and passive instruments.
Active instruments: Have active cutting blades
similar to K flexo file. They have the ability to cut
more efficiently, aggressively and tendency to
straighten the canal curvature.
Passive Instruments : These instruments have a
radial land between cutting edges and flute. The
radial land touches the canal wall on its entire
surface, guiding the instrument – stable and
balanced with in the canal.

Active Instruments Passive
Instruments

Profile RaCE

GT files Hero642

Light speed K3

Flex master

Protaper


ROTARY SHAPING GUIDELINES
Rotary shaping instruments are introduced into the canal
only after the confirmation of straight-line access and the
canal been scouted by a small hand instruments.
small flexible, stainless steel, ISO 0.02 tapered hand files
confirm straight line access, cross sectional diameter
and canal anatomy giving the clinician the idea to
introduce the rotary instrument into the canal.
There certain standards or guidelines that has to be
followed or kept in mind before and during use of the
rotary instruments.


 1.Straight line access : “on – off” position of
handle of the file to be corrected.

 2.Cross-Sectional diameter: To be confirmed
with hand instruments, sufficient space to guide
the rotary instruments is must.

 3.Root canal system Anatomy: curvature,
recurvature, dilaceration, dividing, merging.


 4.Speed and sequencing: Rotary
instruments experience less breakage
when used with gear reduction electric
motors, also using larger taper instruments
first and then small tapers reduces
breakage.
 5.Lubrication and the “light-touch”: Always
introduce the rotary instrument in a
lubricated canal, that will avoid friction. The
pressure that is given on the rotary
instrument should be equivalent to the
pressure when writing with sharp lead
pencil.

CORONAL TWO THIRD ROTRARY SHAPING
TECHNIQUE.
a) Root canal first scouted with small number
hand file.
b) Rotary instrument that fits passively with in
the canals orifice is selected.
c) Regardless the name and brand of the rotary
system to be used, crown down technique to be
followed.
d) When used properly, the instrument will pass
passively and progressively into the canal
according to the canal’s cross sectional
diameter, curvature and anatomic form but
never deepen the instrument into the canal
which has not been scouted.

 e) When the rotary files ceases to move,
then the cutting is stopped immediately and
the file is withdrawn from the canal to check
for the debris accumulation along the cutting
blades.

 f) At this stage the dentist should decide to
use either one size larger or one size smaller
file to reduce dangerous taper lock.

 g) Clearing debris from the instrument allows
close inspection of the cutting blades for
evidence of stress, strain or frank
deformation.

 h) after each Niti rotary, the clinician
should passively irrigate , recaptuvate
with a small clearing file to move debris
into the solution and then irrigate to flush
out debris and clear the canal.
 i) when a confirmed glide path through
the coronal two thirds of a canal, the
clinician should either reintroduce the
same rotary instrument to see if it will
passively move deeper into the canal or
proceed to the next small file.


The rule is, “take what the canal will
give” and not try to force the instrument
letting the preparation evolve to its
optimal shape.
 j) In more calcified or anatomically
difficult canals, it may be necessary to
recapitulate through a portion or the
entire instrument series a second or
third time to create a clean, smooth,
flowing coronal two thirds of the canal.


Apical one third rotary shaping
technique
a) Rotary NiTi instruments can be used to complete the
apical one third after a no.15 hand file can be pushed
apically a few mms to the terminus.
b) Any given series of files, regardless of the difference in
geometries among various instrument lines, can create
a variety of apical-third tapers based on its method of
use.
c) Rotary NiTi shaping files are best used starting with the
larger instruments and working through with smaller
instruments in a crown down manner.


d) Theoretically a Rotary niti file is designed to follow a
canal length as its non-cutting, most flexible working
end is guided by the pilot hole of circumferential
dentin. If a portion of the file extends beyond the
foramen, esp. in the curved canal, then there is no
pilot hole to guide the instrument that, with its rapidly
increasing taper and stiffness only leads to probability
of iatrogenic mishaps.

e) Each instrument is rotated at the recommended RPM
And passively directed apically.


e) When the rotating instruments resists apical movement,
the clinician should irrigate, recapitulate and irrigate to
confirm the glide path way and canal patency.

f) Then the canal prepartion is continued either by using
the same file or the next smaller one.

g) Even in the presence of smooth and glided path care
must be taken at the terminal 1-2 mm of canal to
prevent instrument breakage. Best way to avoid this
breakage is “thinking of shaping instruments as
disposable items”

h) If the rotary shaping instrument used to finish the apical
third of a canal have sufficient taper, preparation is
automatically gauged, tuned and ready to pack.

ProFile 0.04 and 0.06 Taper and
ProFile Orifice Shapers


System GT


Canal Preparation
 According to the manufacturer, the ProFile GT
technique can be broken down into three steps:
1) Step-down with ProFile GTs
2) Then step back with ProFile 0.04 taper files
3) Then GT file to create final canal shape.
 As in all rotary techniques, a step-down approach is used
once initial negotiation is completed with hand files and
lubricant.
 Standard GT files (0.12, 0.10, 0.08, and 0.06 tapers)
are then used in a step-down manner at 150 to 300
rpm, allowing each to cut to their passive lengths.


 Working length should be determined once the GT file has
reached two-thirds of the estimated length of the canal.
 In some cases, the 0.06 taper will reach full length. Since the
standard GT files all have a 0.20 mm tip diameter, the 0.08
and 0.10 taper files should easily go to length if a 0.08 or 0.10
taper is desired for that particular canal.
 Rather than using the GT file to the apical terminus, a
variation of the technique involves the creation of an
apical taper. ProFile 0.04 taper instruments, usually sizes
25 to 35, can be used in a step-back fashion, starting
about 2 mm short of working length


 The standard GT files can then be used in a step-down
fashion again to create the final canal shape right to
working length, or, if preferred, hand instruments may be
used to shape the apical 2 mm of the canal.
 If additional coronal flare is needed, an appropriate GT
accessory file can be used.
 Speeds must be kept constant, a light touch must be used,
the GT files should not be used in a canal more than
4 to 6 seconds, and irrigation and lubrication must be
continually used throughout the procedure


Small canal
Small roots include
mandibular incisors,
buccal roots of maxillary
molars and mesial roots
of mandibular molars.
Use yellow-banded 20
series in these cases.


Medium canal
Medium roots are often the
maxillary premolars,
mandibular premolars and
sometimes mandibular
anteriors.The blue-banded
30 series may be most
appropriate here.


Large canal
Large roots will
generally be found in
maxillary anteriors,
mandibular cuspids,
some mandibular single-
canal premolars, and
palatal roots of
maxillary molars and
distal roots of
mandibular molars. The
black-banded 40 series
of instruments was
designed to handle
these cases

ProTaper
(Progressively
Tapered) nickel
titanium rotary
files are specially
designed to
instrument
difficult, highly
calcified, and
severely curved
root canals.


The ProTaper technique
1 Explore the root canal with
a stainless steel 10K hand file
using a small reciprocating
back and forth motion. Work
passively and progressively
until it is a few millimeters
short of the estimated working
length. Fill the pulp chamber
full with (NaOCl) for all initial
negotiation procedures.


•2 start the ProTaper
sequence with Shaping file
N° 1 which has purple ring.
The S1 is carried into the
canal and moved apically to
just short of the depth of the
hand files. In more difficult
canals, one or two
recapitulations may be
necessary to enlarge the
coronal two thirds of the
canal. Irrigate and go back in
with 10K hand file to break
up debris and then re-irrigate


3 The SX (no colour ring) is
then used with a brushstroke
action to selectively remove
dentine, relocate the canal away
from furcal danger and achieve
straight line radicular access.
With improved access, the SX is
passively fit a little deeper into
the canal until it encounters light
resistance. Bounce off this
resistance and brush out of the
canal in an apical to coronal
direction. Continue with the SX
until about two thirds of the
overall length of its cutting
blades are below the orifice.
www.indiandentalacademy.com irrigate.
Don’t forget to

•4 Once the pre-enlargement
procedure is finished with
excellent coronal two thirds
access, use a precurved 10K
hand file to negotiate the rest
of the canal, establish patency,
and confirm working length.
When working length is
confirmed and a smooth
GLYDE path to the terminus is
verified, use Shaping file N° 1
to length


•5 Following the use of S1,
irrigate and use Shaping file
N° 2 which has a white ring on
its handle. This file will
typically go to full working
length on the first pass.
Following its use, irrigate


•6 .When the coronal two
thirds of the canal has been
prepared, the apical one third
can be finished. The
Finishing file N° 1 has a
yellow ring (ISO 020) and with
the canal flooded with irrigant,
carefully take the F1 to
working length and
immediately withdraw.


•7 Gauge the size of the foramen by
placing a 20 K hand file to length. If snug at
working length then the canal is prepared
and ready to obturate. If it is loose, use
Finishing file N° 2 (red ring ISO 025).
Irrigate and carry the F2 to length and
gauge the size of the foramen by placing a
25 K hand file to length. If snug at length
then the canal is prepared and ready to
obturate. If it is loose use Finishing file
N° 3 (blue ring ISO 030) and carefully carry
it to length.


Quantec System and
Graduating Taper Technique


Canal Preparation
 The Graduating Tapers technique involves a
modified step-down sequence, starting with a larger
tapered file first and progressing with files of lesser taper
until working length is achieved.
 The technique involves canal negotiation, canal
shaping, and, finally, apical preparation.
 As in all instrumentation techniques, straight-line
access to the canal orifices must be made first,
followed by passive negotiation of the canal using
No. 10 and No. 15 0.02 taper hand files.


 A Quantec No. 25, 0.06 taper, 17 mm in length,
is passively used. In most cases, this
instrument should approach the apical third of
the canal; at this point, the working length must
be established.
 A “Glide Path” is now established for all
subsequent Quantec files by working No. 10
and No. 15 0.02 taper files along with sodium
hypochlorite to the established working length.
 During the shaping phase, each Quantec file,
progressing sequentially from a 0.12 taper down to a
0.03 taper, is passively carried into the canal as
far as possible


 In all cases, light apical pressure, using a light
pecking motion and never advancing more
than 1 mm per second into the canal.
 Each instrument time - 3 to 5 seconds.
 The sequence is repeated until a 0.06 or 0.05
taper reaches the working length.
 The apical preparation can then be deemed
complete or further enlarged by using the
Quantec standard 0.02 taper No. 40 or No. 45
rotary instruments or hand files.
 With the Quantec series, the correct amount
of apical pressure must be maintained at all
times; the continuously rotating instrument
should either be inserted or withdrawn from
the canal while allowing for its slow apical
progression www.indiandentalacademy.com

 The instrument, however, should be withdrawn
after the desired depth has been reached and
not left in the canal for an extended period of
time, potentially causing canal transportation,
ledge formation, and instrument separation.

 Thus, to reduce procedural problems, there
should always be a continuous apical/coronal
movement of the instrument, and, if the rotating
file begins to make a clicking sound (file
binding), one should withdraw the file and
observe for instrument distortion


LIGHT SPEED


Canal Preparation
Proper coronal access, pre glaring with GG,
working length confirmed with15 size k file.
 Prior to using the LightSpeed in the handpiece,
the clinician should first select and hand-fit a No.
20 LightSpeed instrument that binds short of the
working length.
 Once fitted, that LightSpeed instrument is now
inserted in the gear-reduction, slow-speed
handpiece

There are two recommended motions with
LightSpeed:
(1) If no resistance is felt, the
LightSpeed is gently advanced to the
desired length and withdrawn
(2) If resistance is felt, a very light
apical pecking motion (advance and
withdraw motion) should be used until
working length is attained


 Increasingly larger LightSpeed instruments
are used to the working length, never skipping
sizes, including the half-sizes.
 Irrigation should occur at least once after every
three instruments
 Once the apical stop has been established, the
LightSpeed should never be forced beyond this
point.
 If forced, buckling along the shaft may occur,
potentially leading to fatigue and instrument
separation


Rapid Body Shapers, Rotary Reamers,
and Pow-R Rotary Files
 Rapid Body Shaper (RBS) (Moyco/Union Broach;
Bethpage, N.Y.) consists of a series of four nickel-
titanium rotary engine reamers.
 These instruments feature the patented
nonledging Roane bullet tip and allow the
practitioner to rapidly shape the body of the
canal without the problems that can occur
using Gates-Glidden drills


Canal Preparation
 Prior to using RBS, the apical region of the canal must be
prepared with a minimum No. 35 ISO instrument to
within 0.5 mm of the apex.
 The No. 1 RBS is then placed in a gear-reduction, slow-
speed handpiece at 275 to 300 rpm and allowed to track
down the canal 2 to 3 mm.
 Constant and copious irrigation is necessary at all times.
 The RBS is removed to clean the fluting and is
reinserted to track another 2 to 3 mm down the
canal.


 This sequence is repeated until the No. 1 RBS is
within 4 mm of the apex.
 The No. 2 RBS is then used like the No. 1, also to
within 4 mm or shorter from the apex.
 The No. 3 RBS, followed by the No. 4 RBS, is used to
within 7 mm of the apex, completing the body
shaping.
 The No. 1 RBS will feel very aggressive, whereas the
No. 2 through 4 RBS feel almost passive in
comparison.
 Apical refinement is subsequently completed
by hand instruments or via Pow-R nickel-
titanium rotary instruments

Pow-R
 owing to their taper design, allow the
practitioner to clean and shape the middle
and apical regions of the canal in a
conservative manner.
 These instruments come in standard ISO
instrument sizes as well as in half sizes 17.5,
22.5, 27.5, 32.5, and 37.5 for more precise
apical refinement.


HERO 642
A crown down technique is recommended with an
apical preparation of at least size no:30
Despite its aggressive design the instrument is
easy to operate, with no higher apparent fracture
risk than other rotary instruments.
 Easy canals can be cleaned with 3 instruments

 Difficult canals with 5 or 6 - less than with other
NiTi techniques!


K3 Rotary NiTi system
Coronal third and middle third management :
After canal orifices have been located and enlarged with
a)

K3 enhanced-tapered body shapers, coronal third
enlargement in larger canals will be done with .12, medium
canals 0.10 and smaller canals accessed with 0.08 tapers.
b)      K3 body shaper is used to light resistance, which is
usually about 3 to 4mm down the canal, with EDTA gel and
canal debris washed with 5.25% sodium hyperchlorite.
c)      Body shaper files can be used as MAF after sufficient
scouting of canals with stainless steel files or if they slide
easily in a canal.

 d) The initial chosen body shaper is followed by
successively smaller tapered body shapers( using
crown down technique). Used in succession these
three body shaping files alone may take the
operator to the junction to the middle and apical
third or further.
 e) Taking rotary files into the apical third without
prior exploration with K files will increase chance
that the canal will be blocked with dentinal mud, a
ledge created wore of all separation of the
instrument.


f) After middle third scouting with K files, if the0.06 K3

with a tip size of 35 (or appropriate body shaper) will
not progress to the desired level( the jn. Of middle and
apical third) then a 0.063 K3 with a tip size of 30,25,20
or 15 can be employed.
g) Recapitulation and irrigation should be frequent
ideally after every file.

Apical third management and deep body shape :

a) Deep body shape refers to the final and ideal shape
of a prepared canal at the junction of the middle and apical
thirds. This space might be considered as ‘Gate keeper” to
the apical third.

b) After apical third is opend, it must be explored with
hand instruments beginning with 6 to 10 k files,
operator shoul slowly and gently attempt to reach the
estimated working length. After a 10 or 15 hand file
reaches the working length, confirmation with
radiographs and apexlocator is carried out.

c)After true working length s reliably established and
the glide path is created, K3 files are introduced with
larget to smaller tip sizes used in coronal to apical
direction until true working length is reached.


 Varying tip sequence
 .12 ETBS to resistance ( coronal third)
 .10 ETBS to resistance ( coronal third)
 .08 ETBS to resistance ( coronal
third/middle third)
 .06 K3 35 to resistance (middle third)
 .06 K3 30 to resistance (middle third)
 .06 K3 25 to resistance (apical third)
 .06 K3 20 to resistance (apical third)
 .06 K3 15 to TWL
 .06 K3 25 to TWL


Variable Taper sequence.
.12 ETBS to resistance ( coronal third)
.10 ETBS to resistance ( coronal third)
.08 ETBS to resistance ( coronal/middle third)
.06 K3 40 to resistance ( coronal/middle third)
.04 K3 35 to resistance ( middle third)
.06 K3 30 to resistance ( Middle third)
.04 K3 25 to resistance (apical third)
.06 K3 20 to TWL
.04 K3 25 to TWL
.06 K3 25 to TWL


 Gauging the apex :
Before a master apical file can be selected, it is
important to gauge the apex, that is to asses till what
size the canal is patent. This technique is described
with an example.
If a size 25 K file slides to the true working
length and gives a resistance to apical displacement ,
then a K3 with a tip size of 30 or 35 with an
appropriate taper can be used to true working length
to create the shape above the working length to give
an acceptable cone fit. Gauging the apex allows
shape to be created above the foramen while
maintaining its size, location and patency.


RaCE FILES(Reamers with
alternating cutting edges)
The innovative design
guarantees being able to
work gently and maintains
tactile sense.
 Working speed (300-600
Rpm)
 Apical pressure applied
should be extremely gentle
 Working time (5- 10 sec per
instruments)

Orifice opener
Tip Diameter -40 Tip Diameter -35
Taper - .10 Taper - .08
Short shafts.
Canal Shapers
Tip diameter – 25 3 instruments
Taper -.02,.04,.06
Usual length files.


Each SMD® has eight petals corresponding
to a maximum of eight utilizations of the
instrument.


Hybrid canal shaping
technique
 Ideal preparation :
The ideal preparation for the hybrid
concept takes its pattern from the definition
by Herbert Schilder and is slightly modified : “
a three dimensional continuously tapering
cone in multiple planes with sufficient apical
enlargement preserving foramen position and
size.


a)      Access cavity
b)      Straight line access
c)      Working length determination
d)      Master apical file size determination
e)      Glide path creation
f)        Body shaping
g)      Apical preparation( apical pre
enlargement, apical enlargement ,apical light
speed instrumentation, apical finishing.)


SStraight line access :- a) removal of dentinal
overhangs in outer aspect of orifice and coronal third,
b)facilitate proper irrigation. C) decrease coronal
interference and easy passage for instrumentation.d)GG
burs.
Working length : out of the five methods (different
angulated radiographs, electronic apex locator, tactile
sense, paper point , patient sensation) combination of at
least the first two should be used.


Master Apical file size : should be based on original
canal diameter.
“the optimal enlargement of each canal should be
calculated.. based on its initial size of the file that binds
at the apical portion of the canal and the apex should
be enlarged at least three sizes greater than its original
diameter. The apical cross sections of most of the
roots are not round and consist of major and minor
diameter.
In determining the minor initial diameter the
use of Lightspeed instrument has been shown by Levin
et all, the more accurate than K file. Anatomic
investigations confirm that in many cases, the original
apical diameter is size 30 or 40 or even greater
More over there is currently no way to estimate the
major original canal diameter clinically.

GGlide Path:
- up to size 20 stainless steel hand k file.
- This will enhance the fragile tips of small-sized NiTi rotary instruments
to follow the path without exploring or cutting.

BBody Shaping :
Active instruments such as Protaper can perform this body shaping
removing coronal; and middle third of the canal effectively. The Protaper
shaping instruments SX,S1,S2 are ideal. They first shape the canal to a
flared form with more taper in coronal than apical area, then the taper is
moved down to the canal using the crown down technique which will
pave way for ideal access to apical preparation.


 Apical Preparation :
 This step is divided into 4 steps, ( apical pre enlargement,
apical enlargement ,apical light speed instrumentation, apical
finishing) but all these four steps may not be necessary for all
cases, because different canals require different approaches.

 a) Apical Pre enlargement :
The idea of apical pre enlargement is to cut quickly and
effectively the apical canal third to a size to which the canal at
working length can quickly and safely be enlarged.
Protaper finishing instruments F1 to F3 will leave an ideal
preparation form. only the 2 to 3 mm need to be enlarged. The more
difficult the case(more curvature, small radius) clinician should think
of using the passive instrument . in very difficult cases, NiTi rotary
instruments can also be used by hand.


b)Apical Enlargement : after pre enlargement the apex safely, it
often needs to be enlarged more based on the decision on which
size MAF should be used for individual canal.
Apical Enlargement can be done with Active or Passive
instrument depending on the difficulty of the canal curvature. After
having reached the working length with Protaper F3 instrument, it is
not difficult to enlarge the apex even wider because other NiTi
rotary instruments like FlexMaster or other active or passive tapered
instruments in sizes such as 40 with a 0.06 or 0.04 and even size
50 with .02 taper can be used subsequently with minimal coronal
interference, minimal cutting surface and there fore minimal torque
load.
The number of instruments for this step seems large, but
each instruments cut minimally and cutting action is accomplished
with 1 to 3 rotations. This process can easily be done using the
instruments by hand, and is safer and faster than changing files in a
motorized handpiece.


Apical Light Speed Preparation.
This is necessary when the desired MAF
size is bigger than a size that can be prepared
with tapered instruments in a curved canal.
The apex will be enlarged to the desired size
starting with a light speed instrument that is one
light speed larger than the last instrument that
previously reached the working length.
Step back is used with each increasing
LightSpeed instrument which will result in 0.05
taper, 1mm increment will give 0.025 taper and
will form a “pseudo-taper” which forms steps in
the canal making the irrigation solution and
gutta percha difficult to pass in the outer wall of
canal curvature.


Apical Finishing:

Apical finishing can be performed using the LightSpeed
MAF size instrument or other passive instrument in a 0.02 or
0.04 taper and a size that follows to working length easily. The
instrument will be forwarded to working length in a clockwise
rotation or a watch-winding motion one or two times by hand.
This smoothes the steps in the outer wall of the curvature and
merges the step back taper into the more coronally located
taper.

Limitations :
Coronally located canal curvatures, extremely severe
curvatures, s shaped, ribbon shaped, C- shaped canals, Apical
canal bifurcations, margining canals.


Hybrid Sequence over View
Easy cases Difficult cases

ProTaper Profile or GT

Flex master Profile LightSpeed
or RaCE or GT
or K3 LightSpeed or ProFile
or Hero or GT by hand


SOTOKAWA’S CLASSIFICATION OF
INSTRUMENT DAMAGE


Main Causes of Breakage
 Rotation at too high speed.
 Application of excessive pressure to the
files.
 Non-respect of the operating sequences
recommended by the manufacturer.
 Overuse of the instruments, causing
breakage because of fatigue.


Canal centering
It denotes the ability of the instruments to remain centered in the
canal.
Centering ratio :
The mean centering ratio is a measure of the ability of the
instrument to stay centered in the canal. A ratio of 1.0 would indicate
perfect centering.
Glosson et al and Esposito et al attribute the maintenance of the
original canal path to the property of NiTi alloy, claims that ProFile
instruments remain better centered in the canal and is also been
supported by Short et al who compared oi with stainless steel
instrument, but no difference was found when compared with other
NiTi rotary files.


 In a study conducted by Kuhn et al, it was
found that NiTi regardless of the tip design,
remained significantly more centered and
demonstrated less apical transportation than
stainless steel files at size 25.


Conclusion :
Many variable and interrelationships
influence the clinical performance of the new
generation super elastic NITI –rotary-shaping
instruments. Much of what is known about
NITI-shaping instruments has been learned in
clinical practice on patient’s record. Rotary
instruments are here to stay, they will
continue to improve , but they are not a
panacea. However they are an important
adjunct for canal shaping procedures.

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CLEANING AND SHAPING USING ROTARY ENDODONTIC INSTRUMENTS /certified fixed orthodontic courses by Indian dental academy

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