Rotary Instruments

NiTi Rotary Instruments

ByEman Helmy

NiTi Rotary Instruments Eman Helmy

INTRODUCTION

Endodontics can be considered a game, the degree and consistency of endodontic success depends on the vigilance and resolve with which the endodontic game is played.

Over the last few years endodontics has undergone a complete revolution with the introduction of the NiTi alloy for the manufacture of initially manual and then rotary endodontic instruments.

COMMON FEATURES OF NICKEL-TITANIUM FILES:

Manufacturers have placed great emphasis on various NiTi rotary design details but only two major factors have been identified that impact shaping potential:

1) Tip configuration and

2) Cross-sectional design.

1) Tip configuration :

Cutting Tip:

Transportation of canal in less experienced hands. Going long with it, creates an elliptical tear at the end of the root. Making apical seal and obturation difficult. Negotiating tip that cuts as it moves apically, following canal pathways and

minimizing stress.

Non-Cutting Tip:

Going long with it, creates a concentric circle at the end of the root. Making apical seal and obturation easier. Guides the instrument in the canal. Reduces the risk of ledging, scratching or gouging

2) Cross-sectional design:

File cross-sections. (A) K-file, RaCe. (B) ProFile, GT, LightSpeed. (C) Hero 642. (D) K3. (E) ProTaper,

Flexmaster. (F) ProTaper F3.

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3) Flute design:

A. Landed flute design (with radial lands):

- In which cutting edges had been flattened, named "radial lands" giving a U-file design.

- This flattening was necessary because every permanent rotating system has the tendency to screw into the canal.

- Prepare canals in a planning action and need to be advanced with light pressure in order to engage the perimeter of the canal and then cut the dentin there.

- Make preparation slower but safer.

- Increase strength and decrease flexibility.

Note:

- The flute of the file is the groove in the working surface used to collect debris removed from the wall of the canal.

- The land is the surface that projects axially from the central axis as far as the cutting edge between flutes.

- The land helps:

Centering the instrument in the canal. Preventing any binding or catching (screwing) into dentin. Adding peripheral mass increasing strength. Permitting easy smoothening of the canal walls. Supporting the cutting edge. Reducing the propagation of cracks inherent in the cutting edge.

- The landed flute design with radial land relief reduces friction on canal walls as in K3.

B. Non-landed flute design :

- Sharp cutting edges resulting from a triangular cross sectional design that cuts more rapidly but can lead also to preparation errors.

- Considered more efficient but require more operator skill to avoid procedural mishaps compared to radial-landed files.

- Prepare canals with more of a cutting action (aggressive cutting); their Should never be used long to avoid the occurrence of apical zipping, perforation or an elliptical shaped foramen that is difficult to obturate.

- More flexible.

C. Others .

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4) 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.

A. Positive rake angle: shave dentin.

B. Negative rake angle: scrape dentin.

C. Neutral rake angle: plan dentin.

PRINCIPLES OF NITI INSTRUMENTS

1. Should not be used as path finder

2. Should not be used to negotiate small calcified canals or curved canals because of its non cutting tip (i.e. C plus files are now invented to overcome that problem).

3. Should not be used to bypass ledges.

NiTi will face difficulty in entering the real canal & will extreme the ledge forming what we call a false canal.

4. Should not be applied with pressure.

5. Should not be used for estimating working length

Stainless steel instruments are more radiopaque than nickel titanium & show up better in tooth length measurements.

6. Need more flaring of access opening to decrease fatigue on file.

7. Must be used in a lubricated canal to reduce frictional resistance.

8. Should not be used in abrupt curves, S-shaped canals & canals that join.

9. When a NiTi file rotates inside a canal system, it becomes stressed & may subsequently wobble in the handpiece.

Once the instrument is removed, the file should be disposed off.

10. When Ni-Ti experiences any undue stress including cyclic fatigue, the metal undergoes a crystalline (microscopic) phase transformation & become structurally weaker.

Not rotating: Austenite phase (rest phase/ parent phase) (high-temperature phase) (hexagonal lattice).

Rotating: Martensite phase (daughter phase) (low-temperature phase) (a bodycentered cubic lattice).

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11. Cutting efficiency decreases with repeated sterilization:

Due to alteration in the superficial structure thus indicating weaker structure, possibly prone to fracture.

12. Ni-Ti file may disarticulate without any warning especially if not properly used.

13. Each instrument should not be used more than 5-10 seconds only.

FRACTURE PREVENTION OF NITI ROTARY INSTRUMENTS:

1- Use only torque controlled electric handpiece for these instruments.

2- Proper glide path must be established before using rotary files, i.e getting the canal to at least size 15 before using them.

3- Use crown-down method for canal preparation. By this apical curves can be negotiated safely.

4- Frequent cleaning of flutes should be done as it can lessen the chances that debris will enter the micro-fractures and resulting in propagation of original fracture and finally the separation.

5- Do not force the file apically against resistance. Motion of file going into canal should be smooth, deliberate with 1-2 mm deep increments relative to the previous instrument.

6- Remove the maximum possible pulp tissue with broach before using rotary files.

7- Canals should be well lubricated during cavity preparation.

8- Dentin mud collected in the canal increases the risk of fracture; it should be cleared off by frequent irrigation.

9- Discard the file if it is bent, stretched or has a shiny spot.

10- Do not use rotary nickel-titanium files to true working length especially in teeth with S-shaped canals, canals with multiple and sharp curves and if there is difficult access of orifice because it can place stresses on the instrument which will cross the breaking torque value.

In such cases apical portion of canal should be prepared by hand files.

11- File should be considered disposable when:

A. It has been used in curved canals.

B. Despite of existence of excellent glide path, if it does not cut dentin properly.

12- Frequently inspect file flutes under magnification.

Note:

- The two most important causes that contribute to NiTi rotary instrument breakage are “method of use” and “multiple uses” of files.

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- Recently, the US Patent 7,198,486 - Rotary dental files were introduced by Dr. Duane E. Cox (date: 4/3/2007).

They have a safe breakage point "Break R-Way" upgrade which presents a new approach for solving NiTi rotary separation. It is an annular groove made up at the SSP (safe separation point) 1-2 mm. from where the shaft meets the handle for maximum ease of removal.

Other files presents with the "Break R-Way" upgrade:

3GEN Reamer/RSS (Rapid Safe Shaping) Series 29 F3 ProTaper

TYPES OF ROTARY INSTRUMENTS ACCORDING TO TAPERING:

The taper is usually expressed as the amount the file diameter increases each millimeter along its working surface from the tip toward the file handle.

1) Tapered:

Examples

K3/ QuantecProtaper and ProfileProsystem GTRaCe SystemSafeSider EndoexpressQuantec systemHero 642 Also see Hero shaper and Hero apical Twisted File with phase from Sybron Librator from Miltex Endodontics

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Note:

Tapering:

i. Constant: e.g: Profile; The diameter of the instrument increases 0.02 (or 0.06, 0.08…) mm for every millimeter of length

ii. Progressive (multi-taper): e.g: Protaper; the diameter of the instrument increases in a progressive manner.

iii. Variable: e.g: Protaper; whether increases in a variable manner (S1, S2) or increases then decrease (SX, Finishing files).

2) Non-tapered:

Examples

LSX-Non tapered rotary system (a system really different).

Note:

1. If any NiTi rotary instrument ceases to advance deeper into a canal, withdraw it, and recognize the four factors that typically prevent the file from passively moving in an apical direction:

1) Insufficient canal diameter.2) Intracanal debris.3) Intrablade debris.4) Root canal anatomy.

2. In order to obtain the maximum efficiency without risks there should be a correct balance between two important parameters adjusted in the motor to be used:

i. Speed.ii. Torque.

3. NiTi instruments usually results in a round preparation and smear layer formation. Therefore, the cleaning efficacy of NiTi rotary instruments was questioned, especially in oval canals such as mandibular incisors and distal roots of mandibular molars.

4. NiTi rotary instruments must not remain stationary within the canal. Once the maximum working depth for that instrument is reached one must remove it immediately.

5. No one knows the maximum or ideal number of times that a nickel-titanium file can be used; it depends on the case and method of use.

6. In order 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.

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7. Gates Glidden drills might be used after initial instrumentation depending on the degree of calcification (i.e. G.G usage prior to instrumentation will invariably lead to blockage or canal misdirection).

8. Techniques that might be used for rotary instrumentation includes:

A. Crown-down technique:

Starting with larger sized instruments in a crown-down manner, where each instrument enters to a specific length (till resistance) inside the canal.

B. Modified crown-down technique:

Starting with larger sized instruments, where each instrument is taken to the full working length.

Using the Peeso or Gates to open up the coronal end of the canal to let the subsequent endodontic instruments do their job more easily.

C. Graduating taper technique:

Starting with smaller tapered instruments, where each instrument is taken to the full working length and then proceeding with larger tapers (tip size is constant).

D. Step-back technique:

Starting with smaller sized instruments in a step-back manner by decreasing 1mm for each increased size after the master is being reached.

E. Modified step-back technique:

As in LSX modified step back technique.

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LIGHTSPEED(LIGHTSPEED ENDODONTICS)

Introduced in the early 1990's. it has a very unique design unlike any other instrument in the market and has the following characteristics:

1. Similar in design to the Gates Glidden drills, only the tip of the instrument cuts.

2. Minimal incidence of fracture and when fracture occurs it occurs high on the shank of the instrument so it is easy to remove.

3. The predecessor of this instrument was called canal master U system, they were made out of stainless steel.

4. The most recent light speed instrument is called light speed LSX.

5. Has short cutting blades that only bind at their tips, thus:

- Increasing the accuracy of the tactile feed back.- Result in rounded and centered apical preparation.

6. U-blade design cross section with three flat radial lands.

7. Neutral rake angles.

8. Non-cutting pilot tip.

9. The shank is thinner than the cutting head and very flexible, it is not conical and with increasing instrument size the diameter of shaft also increases.

10. The shank is marketed with rings indicating distances from the instrument tip.

11. The set of instruments consists of ISO sized rotary files from size 20 through 160, including nine half sizes ranging from 22.5 through 65.

CANAL PREPARATION

Four methods could be used:

1) Zurich light speed technique:

Three special instruments should be singled out while using this technique:

i. The initial apical rotary (IAR): the first light speed instrument which begins to cut canal walls at the working length.

ii. The master apical rotary (MAR): the last instrument to form the apical preparation, may be 6-12 light speed sizes larger than the (IAR).

iii. The final rotary (FR): the last step-back instrument and completes the step-back procedure.

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Divided into four steps:

Step 1: Access and coronal preflaring.Step 2: Determine working length and the IAR.Step 3: Determine the MAR.Step 4: Completes the step-back and recapitulation.

2) Manufacturer's recommended light speed technique:

Similar to the Zurich technique but with some different terms, calculations and number of steps.

3) New crown-down LS technique:

Using:

A. Light speed CRX / Coronal third shaping:

Reduces the number of instruments. A uniquely designed blade creates a similar shape as 3 Gates Glidden drills.

B. Light speed MRX / Middle third shaping:

Creates a customized tapered preparation. An extended non-cutting pilot and shortened tapered blade design that flares

the canal, yet limits cutting to the middle third.

C. Light speed LSX / Apical third shaping:

Has a built-in safety factor. When extreme force and torque are exerted onto the instrument, the shaft is

designed to separate at the handle instead of at the tip, greatly reducing the risk of irretrievable separation.

4) Hybrid technique (light speed technique combined with tapered technique):

- In which crown-down technique is performed using .04, .06 tapered rotary instruments to the working length for coronal and middle third preparation (only to size 20) then light speed instruments complete the apical and middle thirds of the canal (5-8 mm.).

- The hybrid concept combines the best features of different systems for safe, quick, and predictable results.

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ProFile system (Dentsply Maillefer)

This was one of the first rotary nickel-titanium instruments, it was introduced in 1996 and has the following characteristics:

- U-file cross-section with radial lands that provide a contact with the canal wall at only 3 zones.

- non-cutting blunt tip - Central parallel core that may account for the enhanced flexibility.- A negative rake angle.- Constant taper.

TWO TYPES:

i. Profile 29 series: o Has a progressive 29 % increase in diameter size at D0 (transition between sizes

is enhanced by a more gradual increase in diameter by 29 %).o The first eight files replace the 11 files necessary with the traditional size 10

through 60 files.o The first five profile 29 instruments exhibit narrower diameters at D0 compared

with traditional files.

ii. Profile .02, .04, .06 tapered instruments: o Profile 02-series: used for preparing curved terminal part (carry

1colored ring).

o Profile 04-series: - Initially designed for carrier based obturation technique.- Used for preparing the terminal part of the canal, small canals or apical region.- Carry 1 colored ring.

o Profile 06-series: -initially designed for those clinicians who preferred a fuller canal preparation than that obtained by .04 taper.- Used for preparing the median canal zone, distal roots of mandibular

molars and palatal roots of maxillary molars.- Carry 2 colored rings.

o Profile orifice shapers (O.S.): -taper 5-10 %, numbering 1-6 (20-80).- With different color/size match than in other instruments as follows:

1 = white # 20/.052 = yellow # 30/.063 = red # 40/.064 = blue # 50/.075 = green # 60/.086 = black # 80/.08

Used for: preparing the coronal section, removing gutta percha and sealer for retreatment and Decreasing tension on files to be used next to it by orifice flaring.

-carry 3 colored rings.

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Greater Taper (Dentsply Maillefer)

The original Greater-Taper or GT Rotary instrument set derives from Buchanan (1996), and was available commercially from the Tulsa Dental Company.

After the merge of the Tulsa Dental and Dentsply companies in 1998, GT rotary instruments and ProFile 0.04 taper and 0.06 taper with International Standards Organization (ISO)-sized tips were marketed.

The greater taper rotary instruments have the following characteristics:

1. U-file cross-sectional design.

2. An inactive Bat non-cutting tip.

3. constant taper.

Note:

- In medium, large straight canals, it is common that single 0.10 or 0.08 tapered files will cut to the full length in one or more cutting cycles (preparing with only one file).

In small, narrow curved canals, it will require more than just the 0.10 or 0.08 tapered files to cut to the full length (requires stepping down to 0.06 or 0.04 tapered files).

- Recent developments:

1) The creation of the 13 mm. instruments for easy introduction in posterior teeth.

2) The introduction of the GT series-X which is the next generation of the well known system GT files:

A faster cutting instrument with increased flexibility to follow curved canals.

Flexibility not only comes from how they built but also from what they are built from:

M-wire TM NiTi which is flexible and resistant to cyclic fatigue (the leading course of file separation).

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Quantec System (SybronEndo)

Introduced by Dr. Mc Spadden, and have the following characteristics:

1. Asymmetrical cross-section with wide lateral radial lands behind sharp edges,

(designed asymmetrical to be an effective trough for channeling debris in a coronal direction).

2. Available in a non cutting (LX Non-Cutting) and a cutting (SC Safe-Cutting) tips.

3. Available with Axxess handle which is shorter by 4 mm. providing easier access when vertical space is limited.

4. A positive rake angle cutting dentin more effectively.

. 5. Comes in a series of sixteen instruments with its own color code system and different sizes and tapers.

Note:

The order in which the Quantec files are used is directly related to the type root canal filling technique that is planned:

- Lateral condensation, microseal : Graduating taper technique.

- System B, warm vertical condensation: crown-down or modified crown-down.

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The K3 (SybronEndo)

Introduced in 2002 by Dr. John Mc Spadden.

The instrument has a complicated design and comes from a line of instruments designed by Dr. Mc Spadden the Quantec 2000, Quantec SC, Quantec LX and finally the K3 instrument.

It has the following characteristics:

1. Bullet head non-cutting tip.

2. The instrument core thickness is variable making it stronger at the apical part.

3. Constant taper.

4. Has asymmetric cross-section design (triple fluted).

Two radial lands have been partly reduced, called radial land relief which:

- Reduces friction on the canal wall.

- Help to control the depth of cut protecting the file from over-engagement and separation (breakage).

Third radial land which:

- Stabilize instrument.

- Prevent file from screwing.

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- Much more control of instrument.

- Prevent over-flaring of canal by centering and stabilizing the instrument.

Note:

Without relief, the following might occur:

- Over engagement.

- Apical blocking.

- Instrument failure.

5. Has a slightly positive rake angle.

6. An ‘‘Axxess’’ (shorter) handle design.

Canal preparation:

- 0.012, 0.010, 0.08 tapers are used successively in the coronal third (in small canals 0.08 is the first to be used then 0.12 and then 0.10).

- K3 files are then introduced in a crown-down fashion with one of two sequences:

1) Varies the tip size (VT):

With subsequently smaller K3 tip sizes of the same taper.

2) Varies the tip size, varies the taper size (VTVT):

Mixing the tapers of the instruments as the tip size diminishes.

N.B:

Variations on the standard K3 technique: (K3/ Light speed Hybrid technique)

Advantages of K3:

1. Efficiency: K3 files have been found to leave less smear layer in the apical portion of the canal than some other files.

2. Unparalleled debris removal (benefit to the practitioner).

3. Excellent cutting characteristics.

4. Robust sense of tactile control.

5. Excellent fracture resistance.

6. Negotiates canals with ease and without undue force.

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HERO (Micro-Mega)

The HERO 642 instruments has the following characteristics:

1. Positive rake angle.

2. Triangular cross section with a close resemblance to an H-file and three edges for better force balance and better cutting as a curette (pumping motion).

3. Non-cutting tip.

4. constant taper (6%, 4%, 2%)

5. High level of flexibility and hence its name HERO.

7. Anti breakage control: the instrument "unwinds" to prevent the risk of fracture.

8. Big inner core for excellent resistance to breakage.

9. Newer version called the HERO Shaper instruments are better manufactured and have slight design improvements:

It prevents instrument binding. Reduce instrument fractures. Reduce number of instruments used to prepare the canal (no 0.02 taper).

Also HERO apical has been introduced lately to be used after canal preparation following the normal sequence when we need to enlarge the apical third (ideally with hero shaper).

Canals are classified as easy, average or difficult:

Easy canals: straight and curved < 5° (Blue sequence). Canals of average difficulty: curved > 10° and < 25° (Red sequence) Difficult canals: curved > 25° (Yellow sequence).

Note:

Sequences are named according to the file that we begin with

HERO Shaper

Easy sequence (Blue):

Two instruments:

0.06 n º 30-21 mm.

0.04 n º30-25 mm.

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Medium sequence (Red):

Three instruments:

0.06 n°25-21 mm.

0.04 n°25-25 mm.

0.04 n°30-25 mm.

Difficult sequence (Yellow):

Four instruments:

0.06 n°20-21 mm.

0.04 n°20-25 mm.

0.04 n°25-25 mm.

0.04 n°30-25 mm.

HERO Apical

Two instruments are offered:

0.06 n°30 HERO Apical.

0.08 n°30 HERO Apical.

Advantages (HERO Apical):

Efficient enlargement of the apical zone.

Respect of the initial canal path.

Respect of the apical constriction.

Complementary to HERO Shaper and R-Endo systems.

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A short cutting part (4 mm) connected to the handle through a fine, smooth and flexible shank. Thus the stress on the active part of the instrument which prepares the apical third is reduced.

A high flexibility to follow the canal without slipping.

Avoids any screwing effect (short cutting part).

A long pitch increases the cutting action and the debris evacuation.

Great strength thus avoiding breakage.

A reversed taper of the non-active part which avoids the risk of sudden bending behind the cutting part.

Improve the root canal sealing by elimination of the superficial dentine layers that are in the process of mineralization.

Significant reduction of risk of gutta percha extrusion beyond the apical limit.

Uses:

1) To enlarge the apical third.

2) If there is Root canal infection, in order to eliminate the dentin layers contaminated with bacteria and also enable antiseptic solution or temporary medication to be applied.

3) To make root filling, sealing easier.

4) For easier penetration of the plugger in the apical third, particularly for heated vertical condensation techniques.

Note:

In case of thin and curved roots, it might be necessary to use HERO Apical® in step back technique. So the progressively tapered canal does not weaken the root.

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ProTaper (Dentsply Maillefer)

The ProTaper is one of the most readily available and widely used nickel-titanium instruments today; the following innovations characterize the ProTaper system:.

1. Progressive/ variable taper.

2. Modified guiding tip (rounded, non-cutting and parabolic shaped tip):

3. Varying tip diameters.

4. New cross-section of the instruments (Convex triangular):

Note:

Regarding instrument geometries, only F3 has a reduced cross section with a U-file design to facilitate higher degree of flexibility.

.

5. a positive rake angle

6. New shorter handle of the file.

7. Work longer in a super elastic phase than do instruments with a U-file design, allowing for high performance and less risk.

8. the instrument comes in 6 sizes (3 Shaping files and 3 Finishing files):

a. SX File (auxiliary shaping file):

- Tip size = 0.19 mm.

- Taper = D0 to D9: taper increase from 0.19 mm. to 1.1 mm.

D9 to D14: a reduction in taper to increase flexibility.

- Color Code = No (golden).

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- Designed to:

Relocate the canal away from the external root concavities (e.g. Dangerous zone of lower molars: mesial surface of mesial root).

Shaping the coronal aspect of canals with large roots.

Shaping Canals of teeth with short roots.

Claimed to provide the advantages of Gates Glidden drills and orifice shapers.

b. S1 File:


- Taper = D0 to D14: taper increase from 0.185 to 1.2 mm. variably along the length of the file (increasingly larger taper).

- Color Code = Purple.

- Designed to: prepare the coronal 1/3 of the canal.

c. S2 File:


- Taper = D0 to D14: taper increase from 0.20 to 1.1 mm. variably along the length of the file (increasingly larger taper).

- Color Code = White.

- Designed to: enlarge and prepare the middle 1/3 in addition to the critical coronal region of the apical 1/3.

d. F1 File:


- Taper = D0 to D3: taper increase equal to 0.07 mm./mm.


- Color Code = Yellow.

- Designed to:

Primarily to finish the apical 1/3 of the canal.

Expand the middle 1/3 of the canal.

Plane away the variations in canal diameter after shaping.

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e. F2 File:




- Color Code = Red.

- Designed to: as F1

f. F3 File:




- Color Code = Blue.

- Designed to: all finishing files are designed for the same purposes but used according to canal morphology, size and needs.

(I.e. for severely curved canals F1 is only used while in less curved canals F1, F2, F3 could be used).

Note:

In addition to the previous finishing files there are F4 and F5 with double black, and double yellow identification rings on their handles corresponding to D0 diameters and apical tapers of 40/06, and 50/05 respectively.

Protaper instruments are not used in a pecking motion, but lightly pressed forward in the canal selectively (in a brushing motion).

After each instrument irrigation, establishing patency and reirrigation is of extreme importance to achieve perfect cleaning and shaping objectives.

ProTaper instruments can be helpful in re-treatment cases to remove gutta-percha using (D1, D2, D3 … instruments); then the finishing files are useful For reshaping the canal anatomy.

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Advantages (Benifites):

1) Patented progressive (multiple) taper design improves flexibility and cutting efficiency, especially in tighter or more curved canals.

2) Fewer files are needed to achieve a fully tapered canal exhibiting uniform shape over length.

3) Convex triangular cross section:

Increase the cutting efficiency.

Increase tactile sensation.

Decrease the lateral contact area between the file & dentin & so

Decreasing torsional load, file fatigue & breakage.

4) Both shapers & finishers remove debris & soft tissue from the canal & finish the preparation with smooth continuous taper.

5) The modified guiding tip can easily follow a prepared glide path without gouging side walls.

6) A progressively changing helical angles and balanced pitches:

Stabilizing each instrument.

Aiding in debris removal.

Effectively reducing threading (screwing, grabbing and taper lock).

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RaCe(Brasseler)

(Rotary Alternating Cutting Edge)

- RaCe is the new Brasseler design set of alternating sharp cutting edges standing for reamer.

- The result is a rotary endodontic file with the following advantages and characteristics:

1. Alternating cutting edges

(Has twisted areas alternating with straight line areas)

2. Triangular cross-section and sharp cutting edges:

3. Non cutting safety Unique spade shaped tip

4. Electro-chemical treatment (Electro-polishing):

Better resistance to torsion and metal fatigue. Reduce breakage by eliminating micro-scarring of the instrument. Glossy surface of the metal (mirror-like).

5. Constant taper.

Types:

For retreatment:

D-Race: DR1, DR2

For shaping, cleaning:

Race is available in four sets with different sizes and shapes to be used with different techniques (crow-down, step-back) for canal preparation:

1) Pre-Race and Race.

2) Easy Race.

3) Xtreme Race.

4) Bio Race.

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Note:

- Pre-Race instruments have short working area for preparation of the coronal portion and

- Race instruments are used for preparation of the middle and apical portions of the canal (available in different sizes and tapers).

- The instruments have a triangular cross-section except the smallest instruments (.02 taper) having a square cross-section instead.

- RaCe system is recommended to be used with safety memory disks (SMD).

SMD Quantifies usage and stress to minimize overuse and metal fatigue. Each SMD has eight petals. Color coded to indicate the taper of the instruments. The SMD gauge helps to calculate the difficulty of the case with the aid of

the canals curvature on the X-ray.

A three step scale with simple (S), medium (M) and difficult (D) canals make the allocation of the degree of difficulty easy and determine the number of petals to be removed after file usage in the canal.

When superimposing the x-ray and the SMD gauge, look for the smallest radius in the canal.

Based upon the obtained value, the canal will be classified simple, medium, or difficult.

The adjacent SMD table (metal fatigue test table) act as a guide to the number of petals needed for treatment.

As the instrument limit is approached, minimize the risk of fatigue and select a new instrument.

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Revo-S (Micro-Mega)

A new developed NiTi file sequence. Its purpose is to simplify the initial endodontic treatment and to optimize the cleaning.

Has the following characteristics:

1. In-active tip.

2. Treatment with only 3 instruments (basic sequence):

- SC1, SC2, SU

- WORKING CYCLE

Cutting (using SC1: # 25, 6% taper/ asymmetrical cross section to the coronal two thirds of the working length).

Clearance (using SC2: # 25, 4% taper/ symmetrical cross section to the full working length).

Cleaning (using SU: # 25, 6% taper/ asymmetrical cross section to the full working length).

3. For a successful canal preparation an additional apical finishing might be performed if necessary with specific instruments: AS30, AS35, AS40 (6% taper/asymmetrical cross section to the full working length):

- enable efficient widening of the apical preparation to .06 taper respecting the preparation performed with SC1, SC2 and SU.

- Enables an improved flow of the irrigating solution promoting efficient disinfection and facilitated obturation.

Note:

In thin root canals or canals with marked curvatures. The apical finishing files are used in a step back technique (AS30 at WL, AS35 at WL – 1mm, AS40 at WL – 2 if necessary).

Advantages of the asymmetrical cross section:

1) Enables a better root canal penetration owing to a "Snake-like" movement (better guidance of the instrument up to the apical region of the root canal).

2) Facilitates the upward elimination of dentin shavings up to the coronal region owing to a bigger available volume (better cleaning).

3) Avoids flutes obstruction and therefore the zipping of the dentin debris beyond the instrument tip.

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4) Less stress on the instrument owing to the movement of the file along the root canal walls:

No screwing. More flexibility. Better ability to negotiate curves.

5) Offers a root canal shaping which is adapted to biological and ergonomic imperatives.

Note:

- The canal axis has 3 cutting edges located on 3 different radiuses: R1, R2 and R3.

- The smaller section allows more flexibility, and offers a better ability to negotiate curves.

- The asymmetrical cross section increases the available volume for upward debris elimination.

Advantages of the symmetrical cross section of SC2:

1) Brings strength.

2) Allowing better penetration with no zipping.

3) Perfect guidance of the instrument up to the apical region of the canal owing to the balance of the forces.

4) Enables the patency of the root canal until the apical constriction (or preparartion apical limit).

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Mtwo (VDW)

Characteristics:

1. "Italic S" cross section with two cutting blades.

2. Maximum space for removal of dentinal debris and minimum radial canal wall contact for a safe and fast preparation.

3. The cutting blades form long, almost vertical spirals ensuring better control of instrument progression.

4. Used in a simultaneous technique (graduating taper technique):

Since the apex is reached by every NiTi instrument at each step, which means that this is a technique from crown to apex but first using smaller instruments before using bigger ones .

5. In addition to the basic set of files, Mtwo A and Mtwo R are specifically designed for apical preparation and retreatment respectively.

6. Positive rake angle.

7. Mtwo instruments are constantly tapered except for the Mtwo A instruments which are variably tapered as they have an innovative feature of being highly tapered at the last apical millimeter while the rest of the coronal portion is 2% ISO taper for a good apical preparation.

To obtain this design, the apical millimeter of the instrument is not produced in a spiral but has two straight blades.

8. These instruments are produced with an extended cutting portion of 21 mm as well as the conventional 16 mm cutting part, allowing the instrument to cut in the coronal portion of the canals, on the cavity access walls and where dentin interferences are often located, without unnecessarily weakening the tooth.

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Twisted Files (SybronEndo)

Rotary NiTi instrumentation revolutionized the twisted file (TF) .A new breakthrough technology that was introduced in 2008.

Characteristics:

1. 70% more flexible than traditional NiTi files.

- Unsurpassed strength and flexibility is related to the way of its manufacturing by twisting nickel-titanium while in the crystalline phase structure known as R-phase (intermediate phase between austenite and martensite)

- Heating, cooling and twisting TF at R-phase:

Overcomes limitations of ground file technology.(Micro cracks that act as a precursor of fracture)

Optimize properties of NiTi.

Maximize flexibility and resistance to breakage (can negotiate any curve).

Increase surface hardness.

2. Make the patient's experience more pleasant through:

- Reduced chair time.- Less fracture and iatrogenic events of all types.- Reproducible and ideal preparations that will enhance microbial control

through improved irrigation and debris removal.

3. Tf manufacture is finalized with a final deoxidation process that maintains the file's surface hardness and sharpness of the cutting edges.

4. Made from one piece of nickel-titanium, enhancing structural integrity and reducing much of the "wobble" that is associated with some other files.

5. Safe, fracture resistant, no screwing in, better cutting efficiency, creating continuous taper and channels the debris out of the canal.

6. Can be used in crown down and as a single file system.

7. Excellent tactile control and minimal learning curve.

8. Triangular cross-section, safe-ended tip.

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SafeSiders (EDS) essential dental system

SafeSiders are developed by Dr. Musikant.

They are a series of non-circular instruments that have a patented non-interrupted flat-sided architecture.

This flat:

• Reduces instrument engagement allowing faster advancement with less resistance.

• Creates space for dentinal debris that would otherwise clog thread lines of conventional reamers and files.

• Reduces compressive and tensile stresses during use enabling improved instrument durability.

• Increased flexibility without sacrificing strength.

• Eliminates separation anxiety.

Note:

o The safe siders Pleezers are used to deepen and flare the canal.

o To ensure practical instrumentation sharpness.EDS recommends discarding the SafeSiders after 6 uses

o Constant taper.

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Liberator (miltex)

Liberator nickel titanium rotary files incorporate a unique straight flute design and manufacturing process which eliminates the traditional helical flutes found on virtually all rotary endodontic files.

The result is that Liberator files will not self- thread into a canal, which is a major contributor to file separation.

(i.e. It does not have the “spiral” appearance of existing rotary NiTi files on the market)

Note:

Due to relatively high RPM, the abrasion of dentin results in very fine debris particles. This debris clings to the file and is easily removed by wiping.

Due to the safety and control that the Liberator™ file provides, torque control is not necessary.

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Path File (Dentsply Maillefer)

- A new approach in collaboration with Dr. Berutti, Dr. Cantatore and Dr Castellucci making the glide path accessible to every clinician.

- These instruments are Flexible and resistant to cyclic fatigue, they offer many advantages Compared to manual solutions:

No apical foramen transport when the working length is too long

No ledges when the working length is too short

- Step -by -step ins tructions for use of Path files:

(1) Establish a manual Glide Path with standard stainless steel K-File # 008, # 010.

(2) Identify the working length with the # 010 K-File in combination with an Apex Locator.

(3) Irrigate.

(4) Use the PathFile™ # 013 to working length.

(5) Irrigate.


(7) Irrigate.


(9) Irrigate.

(10) Before starting the canal shaping with NiTi ProTaper Universal files (or another system), confirm your working length with a K-File # 015 combined with an Apex Locator.

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Others- Endo-taper (Guidance Endo)

- Endo-Eze (Ultradent)

- Endowave (J Morita)

- Hornet files (Endo Solutions)

- Hygienic Hyflex X-file (Coltene Whaledent)

- Pow-R (Endo Solutions)

- MITY Roto 360 (JS Dental)

- Ti LOS (Ultradent)

- 10 Series (DS Dental)

- V-taper (Guidance Endo)

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Documents

Rotary Instruments