1. The document discusses various aspects of root canal instrumentation including the goals, hand vs rotary instrumentation, nickel-titanium files, file design features, and advances in endodontic motors. 2. Key aspects of file design discussed include taper, cross-section, lands, flutes, helical angles, pitch, and tip design. Qualities of different file types like ProTaper, K3, and GT files are compared. 3. The document also covers generations of endodontic motors from first to fourth generation and features like torque control, auto-reverse, and apex locators that improve safety and outcomes.

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Dr. Abdalazim Badraldin
Sudanese Dental Center
November 2017

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4. The two primary goals for root canal
instrumentation
are:
1. To provide a biological environment
that is conducive to healing
2. To provide a canal shape that is conformable
to sealing.
John T. McSpadden

5. Rotary Instrumentation
V/S
Hand instrumentation
-- Ability to collect and remove debris
from the canal system
-- Mechanical rotation provides a more
constant movement inside the canal
respecting and following the canal anatomy
reducing the incidence of ledging , perforation
or canal transpotation
-- Less time

6. NiTi Endodontic Rotary Files
The greatest innovation in the
manufacturing of endodontic rotary files
in twentieth century ( 1960)
Why Nickel – Titanium ( NiTi) Files
NiTi V/S SS
-- NiTi endodontic rotary files are entirely fabricated
by machining process in contrast to twisting process
of stainless steel files
-- The widespread popularity of nickel-titanium
(NiTi) rotary instruments arises from the relatively
low elastic modulus of the nickel titanium alloy,
which permits use of these instruments in curved
root canals that would present considerable
difficulty for stainless steel instruments .
-- The NiTi file comes back to its original straight form
without showing any sign of lasting deformation .
This is called shape memory.

7. Why Nickel – Titanium ( Nitti) Files
NiTi V/S SS
-- The ability of resisting stress without permanent
deformation and going back to the initial lattice
form is called super elasticity
-- Super-elasticity and shape memory of NiTi alloy
is because of phase transformation in their
crystal structure. The alloy exists in two
crystallographic forms i.e. parent Austenitic phase
which is stronger and stable than the daughter
Martensitic phase. On heating the alloy undergoes
transformation from the Austenitic,stronger and
stable phase to the Martensitic phase weaker phase,
and on cooling it reverts back to Austenitic phase.
A similar phase change occurs when the alloy is
stressed during root canal treatment. On release of
stress, the structure reverts back
to Austenite.

8. Why Nickel – Titanium ( Nitti) Files
NiTi V/S SS
-- Cutting efficiency of NiTinol is only 60% than
that of matching S.S. file.
-- NiTi Does not give any signs of fatigue
before they fracture.
-- More expensive

9. 1)M-wire NiTi –
Developed by Dentsply Tulsa Dental Specialties
(Tulsa, OK, USA)
Advantage:
This material has greater flexibility and an
increased resistance to cyclic fatigue when
compared to
traditional NiTi alloys
2) R-phase NiTi –
Developed by SybronEndo (Orange, CA, USA)
Advantage:
Files have reduced stiffness and more fracture
resistance compared to standard NiTi files.
3) Controlled-Memory (CM) NiTi
Advantage:
Files have superior cyclic fatigue resistance and
increased torque strength over traditional NiTi
files.
Advances in Nickel-Titanium Metallurgy

10. Original recommendation by Ingle for
standardized instruments
INSTRUMENT DIAMETER
AND TAPER
Cutting blades 16 mm in
length
2 % Taper.
The diameter of the
instrument at tip (D1) is
determined by size in
hundredths of millimeters.
Diameter 2 (D2) is uniformly
0.32 mm greater than D1.
Length- 21, 25, 31 mm.

11. Two modifications were
made in Ingle’s original
proposed recommendation -
additional measurement at
D3, 3 mm from tip/ D1, and
specification for shapes of
the tip: 75 degrees, ± 15
degrees.

12. .

14. Core
It is the cylindrical center part of the
file having its circumference outlined
and bordered by the depth of the flutes.
Significance :The flexibility and
resistance to torsion is partially
determined by the core diameter.

15. Flute
It is the groove in the working surface used to
collect soft tissue and dentin chips removed from
the walls of the canal. The effectiveness of the flute
depends on its depth, width, configuration, and
surface finish.
A progressively larger distance between flute space
and blade is required so as to avoid any compaction
of debris and also provides an effective channel for
its removal.

16. Cutting edge:
-- The surface with the greatest diameter
-- The blade of the file.
Significance : The cutting edge forms and deflects
chips from the wall of the canal and cut or snags
soft tissue. Its effectiveness depends on its angle of
incidence and sharpness.

17. Land or Marginal width
The surface that projects axially from the central
axis as far as the cutting edge between the flutes.
Functions :
-Prevents screwing in of the file
- Supports the cutting edge
- Limits the depth of cut
- Maintains the file in the
Centre of root canal
Relief Area
A reduce surface area of the land
Function
reduce friction resistance

18. Helix Angle
The angle formed by the cutting
edge with the long axis of the file.
Helps in removing debris collected
in the flute from the canal

19. PITCH
The pitch of the file is the
distance between a point
on the leading edge and the
corresponding point on the
adjacent leading edge.
The number of the flute per
unit length
The smaller the pitch
the shorter the distance between corresponding points
more spirals the file will have greater the helix angle
Most files have a variable pitch, that changes along the
working surface.
The result of a constant pitch
and constant helical angles is a
“thread-in” or “sucking down”
of file within the canal.

20. Rake Angle :
is the angle formed by the leading
edge and the radius of the file when
the file is sectioned perpendicular to
its long axis.
If the angle formed by the leading
edge and the surface to be cut is
acute, the rake angle is said to be
negative or scraping
Most conventional endodontic files
utilize a negative or “substantially
neutral” rake angle.
NEGATIVE RAKE ANGLE
PROTAPER

21. Rake Angle :
If the angle formed by the
leading edge and the surface to be
cut is obtuse, the rake angle is said
to be positive or cutting. Positive
rake angles will cut more efficiently
than neutral rake angles, which
scrap the inside of the canal.
K3
positive angle

22. Tip design can affect file control, efficiency,
and outcome in the shaping of root canal
systems.
Instrument tips have been described as
cutting, noncutting, and partially cutting,
The specific design features of the tip,
such as tip angle, tip length,
cross-section , and tip
geometry ,significantly effect
the cutting efficiency of the
file and play the important
role in Controlling the
movement Of the file inside
the root canal

23. The instrument tip has two functions: to
enlarge the canal and to guide
the file through the canal.
If the canal is smaller than the file, a
cutting tip would be more efficient.
If the canal is larger than the tip,
using a less effective cutting tip can help in
preventing transportation.
Powell et al pointed out that when this tip
“angle” is reduced, the file stays centered
within the original canal and cuts all sides
more evenly

24. Depend on :
--- Canal Anatomy
configurations, size of the
canal, degree of curvature
--- File Design
--- Experience and skill of the practitioner

25. :
File Tip --- Cutting or non-cutting
Cutting Tip
A gressive file –efficient and quick
cutting process.
Caution --- not to be stay in the
working length more than one second
-- must reach the WL only one time .
-- Create an elliptical tear upon retraction
and this is very difficult to repair and obturate
ProTaper – Race systems
Non-cutting Tip
Safe & create a concentric circle
at the end of the root. These are easily
filled with a non-standardized cone.
Guiding the file inside the root canal.
ProFile—K3---GT—M3 M3 noncutting tip

26. :
File Taper---
== File with constant - graduating Taper
0.02—0.04– 0.06 -0.05—0.08 – 0.010– 0.012
-- File has a progressive – variable taper a long its
the shank
Graduating Taper
each successive file
is only engaging a minimal aspect of the canal wall
Therefore, frictional resistance is reduced
and requires less torque to properly run the file.
Profile-K3-Race-GT-M3
Progressive Taper
One of the benefits of such a design,
according to the manufacturer, is reduced torsional loading
ProTaper

27. :
Files have a :
-- Radial Land ,
-- Radial with Relief Area
-- Non- Radial Land
Radial land file ( landed file)
- The combination of
a non-cutting tip and radial land that keeps a file centered
in the cana
- radial land supported and strength the blade
inside the canal, prevent the transportation
- increase frictional resistance

28. :
Files have a :
-- Radial Land ,
-- Radial with Relief Area
-- Non- Radial Land
Landed File with Relief Area
- all the benefits of the landed file
- decrease frictional resistance
- increase the property of dentine chips canal debrise
K3

29. :
Files have a :
-- Radial Land ,
-- Radial with Relief Area
-- Non- Radial Land
Non-Landed File
- decrease frictional resistance
- sucking of the file inside the
canal when combining
with a cutting tip
- transportation of the canal
ProTaper

30. :
Ranke Angles
It is the angle formed by the cutting edge
and a radius when the file is sectioned
perpendicular to the cutting edge. Positive
rake angles will cut more efficiently than
neutral rake angles, which scrap the inside
of the canal. Most conventional endodontic
files utilize a negative or “substantially
neutral” rake angle.
The ProTaper has a negative rake angle but
due to its modified blade and progressive
taper, the instrument cuts very effectively.
many practitioners believe the ideal rake
angle is, in fact, slightly positive but not
overly positive. An overly positive rake
angle will result in digging of the dentin
This can lead to separation.

31. :
Ranke Angles
The K3 file can have a positive rake
angle (red line angle)
The K3 is the only third generation
file to feature a slightly positive
rake angle. This results in
optimum cutting efficiency

32. :
Helical Angles
Files with a constant helical flute angle allow debris to
accumulate, particularly in the coronal
part of the file. beside that the file will be more
susceptible to the effect of “screwing in” forces.
-- By varying the flute angles, debris will
be removed in a more efficient manner and the
file will be less likely to screw into the canal.
K3 -- RaCe file, is unique and utilizes an
“alternating helical design” that reduces rotational
torque by using spiraled and non spiraled portions
Along the working length) .This design feature
also reduces the tendency of the file to get
“sucked into” the canal
Is the angle that the cutting edge makes
with the long axis of the file

33. :
Ranke Angles
It is the angle formed by the cutting edge
and a radius when the file is sectioned
perpendicular to the cutting edge. Positive
rake angles will cut more efficiently than
neutral rake angles, which scrap the inside
of the canal. Most conventional endodontic
files utilize a negative or “substantially
neutral” rake angle.
The ProTaper has a negative rake angle but
due to its modified blade and progressive
taper, the instrument cuts very effectively.
many practitioners believe the ideal rake
angle is, in fact, slightly positive but not
overly positive. An overly positive rake
angle will result in digging of the dentin
This can lead to separation.

34. :
Pitch --- Pitch is the number of
spirals or threads per unit length.
--- Variable Pitch
or
--- Constant Pitch…. Screws
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
instrumentation when using files
with a constant taper.
Variable Pitch -- Increase the safety
movement of the file into the canal by prevent
the Pulling or sucking down
ProTaper… wave one …K3

35. Does the quality of manufacturing
make much difference?
The quality of manufacturing
is the most basic consideration for
determining the success or failure of files
independent of its composition or design.
Less than ideal manufacturing quality controls
result in the formation of micro-cracks
and defects along the surface of a file.

37. .

38. 1. Assess case difficulty
2. Provide adequate access…. Straight line access
3. Prepare with hand files up to size #20 prior
to rotary use--- glide path
4. Use light touch and low rpm --don’t force the file
5. Proceed with crown-down sequence preparation
6. Replace rotary instruments frequent
to avoid overuse

39. 7. Avoid Cutting With the Entire Length of File—the more file
engaged in the root canal, the higher potential for instrument
fracture. This total or frictional fit of the file in the canal will
cause taper lock and fracture.
8. Don’t Start and Stop—sudden changes in the direction of a
rotary caused by the operator must be avoided. A smooth
gentle reaming motion is most efficient; rotaries should be
inserted and withdrawn from a canal while rotating.
9. Length Control is Critical—working length should be well
established
10. Don’t rotate a file inside a dry canal

40. GENERATIONS OF MOTORS
a) First generation motor without torque control.
b) Second generation motor with torque limiter.
c) Third generation motor with simple torque control.
d) Forth generation motor with apex locator and torque
control
A rotary endodontic system incorporates three key
elements into its operation:
1) torque-sensing, which monitors how much
twisting force the file is encountering
2) auto-reversing, which will reverse the rotation of
the file if the file exceeds the torque limit
3) constant file rotational speed, which many file
manufacturers recommend.

41. First-generation motor
without torque control
second-generation motor
with sensitive torque limiter.
Third-generation simple
torque-controlled motor
Forth-generation motor with
built-in apex locator and torque control

43. Speed reverse
Torque Gear
Program Memorize
auto reverse Power

44. Speed reverse
Torque Gear
Program Memorize
auto reverse Power

45. Speed reverse
Torque Gear
Program Memorize
auto reverse Power
Importance of Speed
Speed refers to revolutions per minute -- r.p.m.
In endodontics, speed varies from
150-40,000 rpm Greater the speed
, more the cutting efficiency.
But at higher speed, there are more
disadvantages such as :
1) loss of tactile sensation
2) breakage of instruments preceded
by flute distortion
3) change in anatomical curvature of
canal
4) loss of control

46. Speed reverse
Torque Gear
Program Memorize
auto reverse Power
Torque
Torque is a measure of how much a force acting on an object
causes that object to rotate.
Factors affecting the torque of
a rotary file are the speed ,
axial pressure, contact area
and presence of lubricants.

47. Speed reverse
Torque Gear
Program Memorize
auto reverse Power
Auto reverse
During root canal preparation all the instruments are
subjected to different levels of torque. If the level of the
torque is equal or greater than the torque at deformation
or at separation, the instrument
will either deform or separate.
With low torque control motors
, the motor will stop rotating
and can even reverse the direction
of rotation when the instrument
is subjected to torque levels equal
to the torque values set on the motor.

48. Speed reverse
Torque Gear
Program Memorize
auto reverse Power
Gear
Electric motors with gear
are more suitable for rotary
NiTi systems because they
ensure a constant rpm level
however, they also deliver
torques much higher than
those required to break tip

51. These instruments deliver an irrigant which is usually
sodium hypochlorite into canal space while cleaning and
shaping are carried out by a vibrating K-file

53. An electronic apex locator is an electronic
device used in endodontics determine the
position of the apical constriction and thus
determine the length of the root

54. An electronic apex locator is an electronic
device used in endodontics determine the
position of the apical constriction and thus
determine the length of the root