HyFlex CM File

HyFlex CM

2. Introduction

One of the primary goals of endodontic therapy is the
complete debridement of pulp tissue from the canal, coupled
with shaping of the root canal system.

The ability to enlarge a canal without deviation from the
original canal curvature is a primary objective in endodontic
instrumentation.

Standard Nickel Titanium rotary endodontic
files, because of their shape memory
property and larger tapers can often not serve
well for complicated cases such as those with
very fine and curved canals.

3. NiTi is a shape-memory alloy also commonly referred to by the
name Nitinol, derived from its place of discovery, the Nickel
Titanium Naval Ordinance Laboratory. William Buehler, along
with Frederick Wang, discovered its properties during research
in 1962.

The discovery of the shape-memory effect dates to 1932, when
Swedish researcher Arne Olander first observed the property in
gold-cadmium alloys. The material, if deformed while cool,
returns to its undeformed shape when warmed.

4. How does Nitinol work?

Nitinol shape-memory alloys undergo a phase transformation in
their crystal structure when cooled from the stronger, high
temperature form (austenite) to the weaker, low temperature form

(martensite).*

Figure 1

Twinned
Martonste

*Austenite: itis quite strong and hard.
Martensite: it is soft and ductile, and it can be easily deformed.
Stress-induced martensite (superelastic): it is highly elastic (rubber-like).

5. This inherent phase transformation is the basis for the
unique properties of these alloys-in particular, shape
memory and super elasticity.

6. HyFlex CM file

Eventually a concept emerged which revolutionized the
technology of rotary endodontic files, which was based
on ‘Controlled memory’ in contrast to the classical
‘Shape memory’ one.

A new Nitinol rotary instrument files with controlled
memory (HyFlex® CM, Coltene) was introduced by
Riacrdo Caiecedo & Stephen Clark in 2011, which was
machined from a wire termed (CM-wire) previously
subjected to a proprietary, novel, thermomechanical
processing procedure. Clinical and experimental studies

7. The Controlled memory effect helps the file to retain the
shape of the canal even when it is out of the canal. This
property is responsible for avoiding procedural errors
such as ledge formation, transportation, perforations
etc.

The extreme flexibility and lesser taper of these files
make them very advantageous in curved canal cases.

8. File Design

+ ISO color coded on handle-indicates size of file, diameter [mm]
at the tip, assortment (19mm, 21mm, 25mm, 31mm lengths).

* Printed number indicates degree of taper.

* Accelerated flute design provides excellent flexibility, tip
strength and debris transportation.

Positive Negative
rake angle rake angle

* Positive rake angle* (except for
orifice opener neutral) for efficient ve j
cutting properties. >

N

rake angle is the angle between the leading edge of a cutting tool and perpendicular
to the surface being cut.

9. Non-active tip of file.

2 cutting blades.

Sizes of files have 3 tapers 0.04, 0.06, 0.08

Cross section was double fluted Hedstroem design, 2 cutting
blades.

Double fluted hedstroem design

10. Features of File

1. Unique NiTi wire treatment that controls the material’s
memory makes the file extremely flexible without rebound
providing superior canal tracking thus virtually eliminates these
typical problems with other files such as:

/

TRANSPORTATION

HYFLEX CM

11. Superior Flexibility + No Rebound = Superior Tracking

Standard NiTi File Material Hyflex CM NiTi file Material

12. 2. Unique NiTi wire treatment controls the material’s memory
making the file Up to 339% higher fatigue resistance than

standard NiTi files
Benefits
+ Virtually eliminates 183.2
instrument separation. CYCLIC sm

FATIGUE TEST

+ File unwinds before it
separates, this provides
a clear visual warning
to remove.

99.8
Product A
80 71.6
60 Product B

3
S
S
$
3
2
El
à
2
2
E
=

41.7
40

20} |
— | | | | L

* Source: In-house tests, at 300 rpm simulated 30 degree root canal

13. 4. Controlled Memory (HyFlex CM) files , retain their
shape in curved canals and do not possess the ‘Spring
back action’, thereby avoiding any perforation.

HyFlex NiTi File

Conventional NiTi file

14. 3. Additional file features:
+ Accelerated Flute Design (Variable pitch)*.

* Increasingly wider flutes provides efficient debris
transportation & prevents file from “screwing” into the canal.

*Absence of radial lands allows the instrument to be sharper and
consequently more efficient.

*Pitch is the distance between a point on the leading edge and the corresponding point
on the adjacent leading edge.

15. * The conventional NiTi files have another drawback of not
giving a ‘warning sign’ before breakage (unlike stainless steel
files, which show such signs in the form of unwinding of
flutes, or presence of a shiny spot on the file, indicating that
the file should be discarded). HyFlex files have overcome this
problem with the unique characteristic of rewinding of the file
after autoclaving.

«If the file does not
rewind, it indicates that it

needs to be discarded. [EEE SÁ A
This is a very useful

criteria for the clinician [PI Ri
to decide when to discard

- — — x Rewound
the file. SS ; (discard)

A eee T4 New file

After
autoclaving

16. Figure 3: Reverse-form adaptation sequence

| a __

Figure 3A: Instrument prior to use

Figure 3B: Instrument after use with debris

Figure 3D: After sterilizing the file, the instrument is
back to the original shape after heat treatment

17. Visual Functionality Verification

HyFlex® CM™ files respond to excessive resistance with straightening of the
spirals. This feature provides a clear visual opportunity to verify safe continuation of
file use. The file can continue to be used, provided it has not started to rewind in the
opposite direction. Option: During treatment place file in a glass bead sterilizer (Not
for sterilization but for heat treatment) for 10 seconds and file will regain shape.

x

SS E mm

Care has to be taken if the spiral of the instruments start to wind in the opposite
direction during use, the files should be discarded. The file above should
be discarded

Regains shape after sterilization = Multi-Use

owe aS Se E

18. The following are general recommendations for
the instrumentation process:

* Sterilize files prior to use.
* Operate the handpiece at 500 rpm. Recommended torque setting
is up to 2.5 N.cm.

¢ Instruments need to be inspected before and after use.

+ Recapitulate between each step with the patency file.

» Irrigate/lubricate the canal frequently when using the files.
* Clean file flutes after each insertion into the root canal.

+ The number of times the instruments can be reused is
dependent on treatment and procedure.

19. Coronal Patency: After gaining a straig

STEP 1 + Start w

20. STEP 3 - Inse file for apical enlargement to the
forward without pr n a pecking motion, If resistance
step. Use an 02/20 hand file to check patency. Irrigate and lubrica

s file can also dx
n a pecking motion. If

atency

STEP 5 - se 04
f

0 file to working length. Move slowly forward without
f resistance occurs, go back to the previous step. Use an
atency. Imgate and lubricate

21. STEP 1 .08/25 STEP 2 .04/20 STEP 3 .04/25
Orifice Opener Apical Enlargement, Working Length Apical Enlargement, Working Length
NOTE: If Working
Length ts reached, it
may be possible to
go to Step 4.

STEP 4 .06/20 STEP 5 .04/30 STEP 6 .04/40

Middle Part Shaping, Working Length Apical Enlargement, Working Length Apical Enlargement, Working Length

22. CROWN-DOWN TECHNIQUE STEP BY STEP CARD

Depending on the clinical situation, the numbers of files can be reduced.

SMALL CANALS
os | [25
04 | (85)
04 | Bo
04 | ES
04 | 20
04 4/15

MEDIUM CANALS

25
04 | 60
04 | 50
04 | [45
04 | EN]
04 y 5)

LARGE CANALS

06
06
06
06
06

SHEE EE
o

23. Some of studies on HyFlex CM file

Fatigue Resistance:
» HyFlex CM showed the highest resistance to fracture than
ProTaper Universal and ProTaper next.

Apical Extrusion of Debris:

* Reciprocating files (WaveOne and RECIPROC) had more
extrusion than HyFlex CM.

+ HyFlex CM had significantly less debris extrusion than the
ProTaper Next.

Dentinal Cracks:
+ HyFlex CM had less dentinal crack than the ProTaper Universal