**Introduction to Rotary NiTi Instruments** The University of Western Australia, School of Dentistry Dr Mostafa Elkholy, BDS, MSc, Phd University of Western Australia logo # **Introduction to Rotary NiTi Instruments** The University of Western Australia, School of Dentistry Dr Mostafa Elkholy, BDS, MSc, Phd > [!note] Lecture Overview > This lecture provides an overview of rotary Nickel-Titanium (NiTi) instruments, covering their evolution, key features, and the proper techniques for their use. The goal is to equip clinicians with the necessary skills and knowledge for clinical practice. The discussion will begin with the foundational objectives of canal preparation and the limitations of traditional instruments, leading into the history and metallurgical evolution of NiTi files, and concluding with modern instrument design and kinematics. **Mechanical Objectives** 1. Continuously tapering funnel from the apex to the access cavity. 2. Cross-sectional diameter should be narrower at every point apically. 3. The root canal preparation should flow with the shape of the original canal. 4. The apical foramen should remain in its original position. 5. The apical opening should be kept as small as practical. Schilder, 1974 # **Mechanical Objectives** 1. Continuously tapering funnel from the apex to the access cavity. 2. Cross-sectional diameter should be narrower at every point apically. 3. The root canal preparation should flow with the shape of the original canal. 4. The apical foramen should remain in its original position. 5. The apical opening should be kept as small as practical. *Schilder, 1974* **Biological Objectives** 1. Confinement of instrumentation to the roots themselves. 2. No forcing of necrotic debris beyond the foramen. 3. Removal of all tissue from the root canal space. 4. Creation of sufficient space for intra-canal medicaments. Schilder, 1974 # **Biological Objectives** 1. Confinement of instrumentation to the roots themselves. 2. No forcing of necrotic debris beyond the foramen. 3. Removal of all tissue from the root canal space. 4. Creation of sufficient space for intra-canal medicaments. *Schilder, 1974* 3D anatomical model of a hand with highlighted vascular structures, labeled "Anatomical Challenges". University of Western Australia logo present. **Mechanical Limitation** 5/9/2011 mag HV WD spot HFW det 12:32:57 PM 500 x 30.00 kV 10.3 mm 4.0 597 µm LFD THE UNIVERSITY OF WESTERN AUSTRALIA Microscopic image of a material surface showing layered structure with scale bar indicating 200 µm. # **Mechanical Limitation** > [!warning] Limitations of Stainless Steel > Traditional stainless steel hand instruments present significant mechanical limitations, particularly in anatomically complex canals. > - ==**Stiffness**==: While small-diameter stainless steel files are flexible enough to be pre-bent, larger files become increasingly stiff. > - ==**Straightening Effect**==: As the file diameter and core material increase, the instrument tends to straighten itself inside a curved canal. This 5/9/2011 mag HV WD spot HFW det 12:32:57 PM 500 x 30.00 kV 10.3 mm 4.0 597 µm LFD Diagram illustrating two cross-sectional views of a root canal, with red arrows indicating direction of force or movement along the canal walls. Series of microscopic images with labeled parts showing cell morphology Single object labeled "LEDGE" with The University of Western Australia logo Diagram showing a cross-section of a biological structure with a red pathway and spiky black entities along a pink inner lining, possibly indicating a process or infection pathway. # Problems with curved root canals - Transportation - Zip formation - Elbow formation - Perforation - Strip perforation - Ledging Schäfer & Dammaschke, (2006) Endodontic Topics, 15, 75–90. Diagrams and radiographs illustrating the problems with curved root canals. # **Problems with curved root canals** > [!failure] Iatrogenic Mishaps > The stiffness of stainless steel instruments poses a major challenge in curved canals, often leading to iatrogenic mishaps that compromise the mechanical objectives of treatment. > - ==**Transportation and Zipping**==: The tendency of a stiff file to straighten can cause it to preferentially cut the outer wall of the canal at the apex and the inner wall coronally. This alters the original canal anatomy, leading to transportation or, in severe cases, a - Transportation - Zip formation - Elbow formation - Perforation - Strip perforation - Ledging *Schäfer & Dammaschke, (2006) Endodontic Topics, 15, 75–90.* I think I should do something I think I should do something Nickel Titanium for the Naval Ordinance Laboratories **NiTinol** 1960 Naval ship at sea with University of Western Australia logo # **Nickel Titanium for the Naval Ordinance Laboratories (NiTinol)** 1960 > [!info] Discovery and Early Use > - ==**Discovery**==: In the 1960s, a metallurgist named Bueller at the U.S. Naval Ordnance Laboratory was investigating a non-magnetic, salt-resistant alloy for military use. He discovered an alloy of nickel and titanium, which he named **Nitinol** (an acronym for **Ni**ckel **Ti**tanium **N**aval **O**rdnance **L**aboratories). > - ==**Early Use**==: The first dental application of Nitinol was in orthodontics, where its superelastic properties were ideal for archwires used with brackets to facilitate tooth movement. 0099-2399/88/1407-0346/$02.00/0 **JOURNAL OF ENDODONTICS** Copyright © 1988 by The American Association of Endodontists Printed in U.S.A. Vol. 14, No. 7, July 1988 # An Initial Investigation of the Bending and Torsional Properties of Nitinol Root Canal Files Harmeet Walia, BDS, MDS, MS, MS, William A. Brantley, BS, MS, PhD, and Harold Gerstein, BS, DDS 0099-2399/88/1407-0346/$02.00/0 JOURNAL OF ENDODONTICS Copyright © 1988 by The American Association of Endodontists Printed in U.S.A. VOL. 14, No. 7, JULY 1988 **An Initial Investigation of the Bending and Torsional Properties of Nitinol Root Canal Files** Harmeet Walia, BDS, MDS, MS, MS, William A. Brantley, BS, MS, PhD, and Harold Gerstein, BS, DDS Figure showing bending moment vs angular deflection for Size No. 15 Nitinol and Stainless Steel files. Figure 6: Clockwise torsion test results for the size #15 Nitinol and stainless steel files. Figure showing counterclockwise torsion moment vs angular deflection for Size No. 15 Nitinol and Stainless Steel files. # **An Initial Investigation of the Bending and Torsional Properties of Nitinol Root Canal Files** *Harmeet Walia, BDS, MDS, MS, MS, William A. Brantley, BS, MS, PhD, and Harold Gerstein, BS, DDS* *JOURNAL OF ENDODONTICS, Vol. 14, No. 7, July 1988* # Superelasticity **Austenite** → **SIM** → **Deformed martensite** - **Stress** (applied to Austenite) - **Unloading** (from Deformed martensite) - **Spring-back** (returns to Austenite) *Zupanc et al 2018* University of Western Australia logo # **Superelasticity** > [!info] > Superelasticity (also known as pseudoelasticity) is a defining characteristic of conventional NiTi alloys. > - ==**Crystalline Structure**==: At room temperature, standard NiTi exists in a stable, ordered cubic crystal structure known as the **Austenite** or **Austenitic phase**. > - ==**Stress-Induced Transformation**==: When the instrument is stressed (e.g., by being inserted into a curved canal), the atomic lattice transforms into a more flexible state called the **Martensite** or **Martensitic phase**. This is a **Austenite** → **SIM** → **Deformed martensite** - **Stress** (applied to Austenite) - **Unloading** (from Deformed martensite) - **Spring-back** (returns to Austenite) *Zupanc et al 2018* Businessman in suit interacting with futuristic digital interface displaying data and graphs, with the word "Advantages" prominently overlaid. **Flexibility** Three dental X-ray images showing root canal treatments with varying degrees of flexibility in the instruments used. # **Flexibility** > [!tip] Primary Advantage > The primary advantage of NiTi files is their exceptional flexibility, which allows for the safe and effective preparation of curved root canals while minimizing the risk of transportation and preserving the original canal anatomy. Time An antique-style alarm clock with Roman numerals, placed on a textured surface. Time **Comparative study of six rotary nickel–titanium systems and hand instrumentation for root canal preparation** Guelzow et al, Int Endod J 38, 743–752, 2005 **Table 6** Time to complete root canal preparation (s) | System | *n* | Mean | SD | |---------------------|-----|--------|--------| | FlexMasterA | 21 | 102.9 | 46.3 | | System GTA | 20 | 93.5 | 34.0 | | HERO 642B | 20 | 186.1 | 92.0 | | K3C | 20 | 114.2 | 40.8 | | ProTaperB | 18 | 152.0 | 46.8 | | RaCeB | 21 | 207.6 | 223.9 | | Manual techniqueD | 20 | **1179.8** | 536.6 | A,BMeans with the same letters are not significantly different. # **Comparative study of six rotary nickel–titanium systems and hand instrumentation for root canal preparation** *Guelzow et al, Int Endod J 38, 743–752, 2005* > [!note] > NiTi instruments offer a significant advantage in clinical efficiency. A 2005 study comparing six rotary NiTi systems to manual stainless steel instrumentation demonstrated a dramatic reduction in preparation time. ## **Table 6: Time to complete root canal preparation (s)** | System | *n* | Mean | SD | | :--- | :--- | :--- | :--- | | FlexMasterA | 21 | 102.9 | 46.3 | | System GTA | 20 | 93.5 | 34.0 | | HERO 642B | 20 | 186.1 | 92.0 | | K3C | 20 | 114.2 | 40.8 | | ProTaperB | 18 | 152.0 | 46.8 | | RaCeB | 21 | 207.6 | 223.9 | | Manual techniqueD | 20 | **1179.8** | 536.6 | A,BMeans with the same letters are not significantly different. > [!success] Clinical Implication > The study found that manual instrumentation could take up to **ten times longer** than some rotary NiTi systems. This time saved during gross shaping can be reallocated to more thorough irrigation and disinfection, improving the biological outcomes of treatment. Deep Shape Three red V-shaped diagrams with circles labeled "25" at the bottom, each with a percentage below: 2%, 4%, and 6% respectively. Deep Shape # Tip design Scanning electron microscope image of a microtip with labeled parameters: tilt 0.0°, det ETD, date 2/24/2020, time 1:36:57 PM, WD 10.4 mm, mag 500x, HV 20.00 kV, HFW 829 µm, scale bar 300 µm, source British University in Egypt (BUE). # **Tip design** Man in orange shirt pointing to two different drill bits, one silver and one gold with red accents, against a green background. Evolution of lighting: candle, oil lamp, incandescent bulb, CFL, LED bulb # First Group - **Radial Land** - **Passive Cutting Edge** Microscopic view of a tool's cutting edge with labeled features. # **First Group** > [!note] > The first generation of rotary NiTi files, introduced in the early 1990s, had distinct design features: - **Radial Land** - **Passive Cutting Edge** > [!warning] Design Flaw > The cutting edges were not sharp, based on the theory that this would lead to more conservative preparation. However, this design caused the files to grind rather than cut, leading to inefficiency and increased stress. **First Group** - **Fixed Taper (4%, 6%...)** - **Numerous files/kit** LightSpeed, Quantec, ProFile, System GT dental files arranged in groups with labels - **Fixed Taper (4%, 6%...)** - **Numerous files/kit** - **Example**: The **Lightspeed** system, which resembled a Gates-Glidden bur with a short cutting head designed only for apical preparation. These systems are now considered historical. Second Group **Active Cutting Edge** Microscopic image of a cutting tool edge, showing detailed surface texture and geometry. # **Second Group** > [!note] > The second generation introduced significant improvements that became the foundation for modern file systems. - **Active Cutting Edge** - **Removal of Radial Lands**: The radial lands were eliminated to reduce friction and improve cutting. **Second Group** - **Variable Taper** - **Lesser Files** - **Alternating Cutting edge** - **Electropolishing** **ProTaper** - SX - S1 - S2 - F1 - F2 - F3 **RaCe** - **Variable Taper** - **Lesser Files** - **Alternating Cutting edge** > [!info] RaCe System > Some systems, like the **Race** system (Reamers with Alternating Cutting Edges), featured a design with alternating twisted and straight sections to reduce the - **Electropolishing** > [!warning] > This was a process used to smooth the file surface and remove microscopic cracks from the milling process. However, it was found to reduce cutting efficiency and create other surface irregularities. ## **Examples** - **ProTaper** > [!example] ProTaper Universal > This system, developed by clinicians in 2006, became a market leader due to its innovative **variable taper**. Instead of a fixed taper along the entire cutting length, the taper changes multiple times. This design ensures that when a file is inserted to the working length, only a specific portion of the instrument engages the canal wall. The shaping files (S1, S2) engage the coronal and middle thirds, while the finishing files (F1, F2, etc.) primarily shape the apical third. This creates a progressive, crown-down preparation even as each file is taken to the full working length, minimizing stress on the instrument. - SX - S1 - S2 - F1 - F2 - F3 - **RaCe** **Third Group** **Change in Metallurgy** Image showing two dental endodontic files with logos for "m-wire® nickel titanium" and "TF®". The University of Western Australia logo is also present. # **Third Group: Change in Metallurgy** > [!info] > To overcome the limitations of conventional NiTi, such as low resistance to cyclic fatigue, manufacturers began developing new alloys through thermal processing. Room Temp. Lattice structure with blue nodes and red connecting lines, arrow indicating direction, labeled "Room Temp." Room Temp. Room Temp. Lattice structure with blue spheres connected by red lines, arrow indicating direction, labeled "Room Temp." Room Temp. Room Temp. Lattice structure diagram with blue nodes and red connecting lines, labeled "Room Temp." Room Temp. **Austenitic NiTi Alloy** ## **Austenitic NiTi Alloy** > [!note] > This is the traditional, superelastic NiTi alloy, stable at room temperature. While flexible, its strong Grid of blue circles connected by red lines, representing a network or lattice structure. High temperature Diagram showing a central lattice structure labeled "High temperature" with arrows pointing from four surrounding distorted lattice structures towards it, illustrating a process or transformation. High temperature # Shape Memory Effect **Austenite** → **Cooling (Ms)** → **Twinned martensite** → **Stress (MR)** → **Deformed martensite** **Heating (Af)** ← Zupanc et al 2018 University of Western Australia logo # **Shape Memory Effect** **Austenite** → **Cooling (Ms)** → **Twinned martensite** → **Stress (MR)** → **Deformed martensite** **Heating (Af)** ← *Zupanc et al 2018* **Martensitic NiTi Alloy** ## **Martensitic NiTi Alloy** > [!note] > This is a more ductile, heat-treated phase of NiTi. A file in the Martensitic phase is soft and can be easily bent. It does not spring back to its original shape at room temperature. Phase transformation diagram showing austenite and martensite fractions versus temperature in °C, with labeled cooling and heating paths and transformation points (Ms, Mf, As, Af). # Austenitic NiTi - Af temperature is at or below room temp. - Superelastic. - High cutting efficiency. - High torque resistance. - Low cyclic fatigue resistance. Illustration of dental files with colored handles and a single file with a blue handle and red/blue band. # **Austenitic NiTi** - Af temperature is at or below room temp. - Superelastic. - High cutting efficiency. - High torque resistance. - Low cyclic fatigue resistance. - thermomechanical processing - unique nanocrystalline martensitic microstructure - austenite finish temperature of M-wire was found to be around 43–50° - phases that are in both the deformed and microtwinned martensitic, R-phase, and are austenite whilst maintaining a pseudoelastic state - thermomechanical processing - unique nanocrystalline martensitic microstructure - austenite finish temperature of M-wire was found to be around 43–50° - phases that are in both the deformed and microtwinned martensitic, R-phase, and are austenite whilst maintaining a pseudoelastic state > [!info] M-Wire > This was one of the first thermo-mechanically treated alloys. It is created through a special heat treatment process that results in a unique microstructure containing both Martensite and Austenite at room temperature. It offers improved cyclic fatigue resistance over conventional NiTi but is now considered a somewhat outdated technology. > - **Example**: ProTaper Next ProTaper Next® dental instrument with m-wire® nickel titanium branding, highlighting higher strength, wear resistance, and fatigue resistance. University of Western Australia logo present. **R-Phase** R-phase P3- Crystal structure of R-phase with blue and grey spheres representing atoms, labeled with crystallographic directions [100], [010], and [001]. # **R-Phase** > [!info] > The R-Phase is an intermediate crystalline phase between Austenite and Martensite. R-phase P3- R- Phase Austenite → R- Phase → Martensite Diagram showing the phase transformation from Austenite to R-Phase to Martensite, with lattice structures depicted. ## **R-Phase Transformation** > [!tip] > By carefully controlling the cooling process of the alloy, manufacturers can create a file that incorporates the R-Phase. This phase provides increased ductility and fatigue resistance. Files can be manufactured by twisting the wire blank while it is in the R-phase. Austenite → R- Phase → Martensite R-Phase Austenite → R-Phase Twisting → Martensite Diagram showing phase transformation from Austenite to Martensite via R-Phase Twisting, with lattice structures depicted. Austenite → R-Phase Twisting → Martensite Image of a rotary endodontic file labeled with "R-Phase" and indicating "lower shear modulus", with logos including "TF" and The University of Western Australia. **R- Phase** **K3XF™** a post-machining R-phase heat treatment THE UNIVERSITY OF WESTERN AUSTRALIA Diagram showing a circular cross-section with a dark central region and a lighter outer layer, marked with red crosshairs and directional arrows indicating treatment or measurement zones. ## **R-Phase Example: K3XF™** - a post-machining R-phase heat treatment # R-Phase - Superior fatigue resistance - Less stress needed to SIM transformation - Superior flexibility University of Western Australia logo # **R-Phase Properties** - Superior fatigue resistance - Less stress needed to SIM transformation - Superior flexibility # Austenitic NiTi - Conventional NiTi - Electropolished NiTi - M-wire - R-phase University of Western Australia logo # **Types of Austenitic NiTi** - Conventional NiTi - Electropolished NiTi - M-wire - R-phase Diagram illustrating two cross-sections of a tooth root canal, showing the effect of instrumentation with red arrows indicating direction of force or debris movement. Citations are listed below the diagrams. # Martensitic NiTi - Ductile - Easily deformed Two dental endodontic files with colored handles # **Martensitic NiTi** - Ductile - Easily deformed # Shape Memory Effect **Austenite** → *Cooling (Ms)* → **Twinned martensite** → *Stress (MR)* → **Deformed martensite** → *Heating (Af)* → **Austenite** Zupanc et al 2018 # **Shape Memory Effect** **Austenite** → *Cooling (Ms)* → **Twinned martensite** → *Stress (MR)* → **Deformed martensite** → *Heating (Af)* → **Austenite** *Zupanc et al 2018* > [!tip] Clinical Application > This property is characteristic of Martensitic files. > - ==When a Martensitic file is bent, it remains in that shape.== > - ==It will only return to its original, straight form when heated above a specific # CM-Wire - The first thermomechanically treated NiTi alloy that does not possess superelastic properties at neither room nor body temperature. - CM Wire instruments **do not** tend to fully straighten during HyFlex™ CM logo and image of a dental instrument being held by gloved hands # **CM-Wire** > [!note] > CM-Wire (Controlled Memory) was the first thermomechanically treated NiTi alloy to fully utilize the properties of the Martensitic phase at room temperature. - The first thermomechanically treated NiTi alloy that does not possess superelastic properties at neither room nor body temperature. - CM Wire instruments **do not** tend to fully straighten during > [!tip] Properties > These files are extremely flexible, have no shape memory at room temperature, and exhibit high resistance to cyclic fatigue. They can be pre-bent and will passively follow the canal's curvature. > - **Example**: HyFlex CM # CM-Wire - austenite finish temperature of CM Wire instruments is around 47–55 °C - mixture of austenite and martensite structure with small amounts of the R-phase at room temperature. Graph showing phase transformation of HyFlex™ CM wire with temperature, indicating cooling and heating paths, and marking Ms, Mf, As, Af points on the Austenite/Martensite transition curve. - austenite finish temperature of CM Wire instruments is around 47–55 °C - mixture of austenite and martensite structure with small amounts of the R-phase at room temperature. # CM- Wire - harden the surface of the NiTi file - improved fracture resistance - superior cutting efficiency Diagram illustrating HyFlex™ EDM process, showing machining tool, dielectric liquid, cross sections of raw wire and machined NiTi instrument, and workpiece. - harden the surface of the NiTi file - improved fracture resistance - superior cutting efficiency > [!info] Manufacturing: Electric Discharge Machining (EDM) > HyFlex files are often manufactured using **Electric Discharge Machining (EDM)**. This is a non-contact process where electrical sparks are used to shape the file from a wire blank, creating a unique, hardened surface without the machine grooves and microcracks associated with traditional grinding. Golden and blue glitter textures side by side Product comparison of VortexBlue, Reciproc Blue, and VDW.Rotate rotary files against a blue glitter background. - Af is around 38°C, Ms around 31°C. - Mainly contain martensite and R-phase under clinical conditions - Postmachining heat treatment - Af is around 38°C, Ms around 31°C. - Mainly contain martensite and R-phase under clinical conditions - Postmachining heat treatment - Af of is around 38°C, Ms around 31°C. - Postmachining heat treatment - Greater amount of stable martensite - Ductile - Af of is around 38°C, Ms around 31°C. - Postmachining heat treatment - Greater amount of stable martensite - Ductile Golden glitter background with three dental file products: ProTaper Gold, WaveOne Gold, and Maillefer TruNatomy. ○ Af of is around 50°C. ○ mainly contain martensite and R-phase under clinical conditions ○ Postmachining heat treatment - Af of is around 50°C. - mainly contain martensite and R-phase under clinical conditions - Postmachining heat treatment Scanning electron micrograph (SEM) image labeled 'A', showing a cross-section of a material with a distinct layered structure. The image includes a scale bar (100 µm) and acquisition parameters (date, time, magnification, voltage, etc.) at the bottom. SEM micrographs of a layered material: (A) tip view showing striations, (B) cross-section revealing internal layering and defects. Scale bars: 100 µm and 200 µm respectively. SEM micrographs of a blade edge showing surface striations and a crack; labeled A, with scale bars and imaging parameters. SEM micrograph showing a cracked surface with layered structure, scale bar 40 µm, captured at 4000x magnification by British University in Egypt (BUE). Enhanced flexibility and fatigue resistance compared with Au NiTi Gold glitter background with a dental endodontic file illustration Enhanced flexibility and fatigue resistance compared with Au NiTi ### **Blue, Gold, and Max-Wire Files** > [!note] > Further advancements in post-machining heat treatment led to: > - ==**Blue Files**==: These files are coated with a layer of titanium oxide, which gives them a blue appearance and increases cyclic fatigue resistance. (e.g., VDW Rotate, Reciproc Blue) > - ==**Gold Files**==: These files undergo a proprietary heat treatment that modifies the crystal structure, resulting in significantly increased flexibility and fatigue resistance compared to their predecessors. (e.g., ProTaper Gold, WaveOne Gold, ProTaper Ultimate) > - ==**Max-Wire**==: This unique alloy exhibits both shape memory and superelasticity depending on the temperature. - **Martensitic (20 °C), austenitic (35 °C)** - **Superelastic + shape memory effect** - **Martensitic (20 °C), austenitic (35 °C)** - **Superelastic + shape memory effect** > [!tip] How Max-Wire Works > - ==At room temperature (~20°C), it is in the soft, ductile **Martensitic phase**.== > - ==At body temperature (~35°C), it transforms into the stronger, superelastic **Austenitic phase**.== > - ==This allows the file to be inserted passively into the canal and then become more active as it warms up, theoretically allowing for Close-up of a dental procedure showing a tooth with a labeled "Palatal Canal" under a dental dam, with tools in use. **Martensitic NiTi** - High cyclic fatigue resistance - Shape memory - Lower cutting efficiency - Lower torque resistance # **Martensitic NiTi Properties** - High cyclic fatigue resistance - Shape memory - Lower cutting efficiency - Lower torque resistance **Austenitic** **Martensitic** Low cyclic fatigue resistance High cyclic fatigue resistance Super elastic (Spring back action) Shape memory High cutting efficiency Lower cutting efficiency High torque resistance Lower torque resistance # **Austenitic vs. Martensitic NiTi** <table style="width:100%;"> <tr> <th style="text-align:left;">Austenitic</th> <th style="text-align:left;">Martensitic</th> </tr> <tr> <td>Low cyclic fatigue resistance</td> <td>High cyclic fatigue resistance</td> </tr> <tr> <td>Super elastic (Spring back action)</td> <td>Shape memory</td> </tr> <tr> <td>High cutting efficiency</td> <td>Lower cutting efficiency</td> </tr> <tr> <td>High torque resistance</td> <td>Lower torque resistance</td> </tr> </table> > [!note] > Manufacturers now often create alloys that blend these properties to achieve a balance, aiming for the Phase transformation diagram showing austenite to martensite during cooling and reverse during heating, with key temperatures labeled (Ms, Mf, As, Af) and percentage of austenite on y-axis versus temperature in °C on x-axis. Diagram comparing Austenitic NiTi and Martensitic NiTi with subcategories listed under each. **Fourth Group** **Change in Kinematics** doi:10.1111/j.1365-2591.2007.01351.x **CLINICAL ARTICLE** **Canal preparation using only one Ni-Ti rotary instrument: preliminary observations** **G. Yared** 102-83 Dawson Road, Guelph, ON N1H 1 B1, Canada Int Endod J, April 2008 # **Fourth Group: Change in Kinematics** ## **CLINICAL ARTICLE** **Canal preparation using only one Ni-Ti rotary instrument: preliminary observations** **G. Yared** 102-83 Dawson Road, Guelph, ON N1H 1 B1, Canada *Int Endod J, April 2008* *doi:10.1111/j.1365-2591.2007.01351.x* > [!info] Reciprocation > Developed by Dr. Ghassan Yared, this involves an **unequal bidirectional movement**. > - ==The file rotates in a larger cutting direction (e.g., clockwise) and then reverses in a smaller, non-cutting direction (e.g., counter-clockwise).== > - ==The cutting motion engages dentin, while the reverse motion disengages the file, relieving stress and helping to auger debris coronally.== > - ==This motion allows for the entire canal to be shaped with a single file.== Fourth Group **Change in Kinematics** ◆ **Change in Kinematics** Image showing three dental instruments labeled RECIPROC® blue and WaveOne® Gold, with text indicating "Fourth Group Change in Kinematics" and "Change in Kinematics". **Fourth Group** **Change in Kinematics** <div style="text-align: center; background-color: #555; color: white; padding: 5px; margin: 10px 0;"> UNIQUE MOVEMENT </div> Illustration of a dental handpiece with a rotating drill bit, labeled "Unequal bidirectional movement" below. <div style="text-align: center; background-color: #555; color: white; padding: 5px; margin: 10px 0;"> UNIQUE MOVEMENT </div> **WaveOne® Gold** **The Protocol** **Shaping** Image showing a dental instrument being used on a transparent block, with a blue background. Image of a gold-colored dental shaping tool with red bands. ## **WaveOne® Gold** ### **The Protocol** ### **Shaping** **Fifth Group** **Change of Rotation Mass** 3D object with a blue circle highlighting a section containing a cross symbol # **Fifth Group: Change of Rotation Mass** > [!info] Mechanism and Purpose > This group involves files designed with an off-center mass of rotation. > - ==**Mechanism**==: Instead of rotating symmetrically around its central axis, the file has an eccentric or # Fifth Group **ProTaper Next®** **REVO-S™** **MAILLEFER** **TruNatomy™** Image of ProTaper Next® dental file with a gold handle, red collar, and silver twisted tip. Image of REVO-S™ dental file with a gold handle, red collar, black section, and silver twisted tip. Image of TruNatomy™ dental file with a black and silver handle, red collar, and gold twisted tip. ## **Examples** - **ProTaper Next®** - **REVO-S™** - **MAILLEFER** - **TruNatomy™** Fifth Group Diagram showing a drill bit with a red wavy line indicating a specific feature, alongside a close-up circular inset highlighting a cross-section of the bit. A full-length view of the drill bit is shown to the right. [[R1 Introduction to Rotary NiTi Instruments.pdf#page=1|R1 Introduction to Rotary NiTi Instruments, p.1]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=2|R1 Introduction to Rotary NiTi Instruments, p.2]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=3|R1 Introduction to Rotary NiTi Instruments, p.3]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=4|R1 Introduction to Rotary NiTi Instruments, p.4]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=5|R1 Introduction to Rotary NiTi Instruments, p.5]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=6|R1 Introduction to Rotary NiTi Instruments, p.6]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=7|R1 Introduction to Rotary NiTi Instruments, p.7]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=8|R1 Introduction to Rotary NiTi Instruments, p.8]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=9|R1 Introduction to Rotary NiTi Instruments, p.9]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=10|R1 Introduction to Rotary NiTi Instruments, p.10]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=11|R1 Introduction to Rotary NiTi Instruments, p.11]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=12|R1 Introduction to Rotary NiTi Instruments, p.12]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=13|R1 Introduction to Rotary NiTi Instruments, p.13]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=14|R1 Introduction to Rotary NiTi Instruments, p.14]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=15|R1 Introduction to Rotary NiTi Instruments, p.15]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=16|R1 Introduction to Rotary NiTi Instruments, p.16]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=17|R1 Introduction to Rotary NiTi Instruments, p.17]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=18|R1 Introduction to Rotary NiTi Instruments, p.18]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=19|R1 Introduction to Rotary NiTi Instruments, p.19]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=20|R1 Introduction to Rotary NiTi Instruments, p.20]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=21|R1 Introduction to Rotary NiTi Instruments, p.21]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=22|R1 Introduction to Rotary NiTi Instruments, p.22]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=23|R1 Introduction to Rotary NiTi Instruments, p.23]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=24|R1 Introduction to Rotary NiTi Instruments, p.24]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=25|R1 Introduction to Rotary NiTi Instruments, p.25]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=26|R1 Introduction to Rotary NiTi Instruments, p.26]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=27|R1 Introduction to Rotary NiTi Instruments, p.27]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=28|R1 Introduction to Rotary NiTi 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Introduction to Rotary NiTi Instruments.pdf#page=38|R1 Introduction to Rotary NiTi Instruments, p.38]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=39|R1 Introduction to Rotary NiTi Instruments, p.39]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=40|R1 Introduction to Rotary NiTi Instruments, p.40]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=41|R1 Introduction to Rotary NiTi Instruments, p.41]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=42|R1 Introduction to Rotary NiTi Instruments, p.42]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=43|R1 Introduction to Rotary NiTi Instruments, p.43]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=44|R1 Introduction to Rotary NiTi Instruments, p.44]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=45|R1 Introduction to Rotary NiTi Instruments, p.45]] [[R1 Introduction to Rotary NiTi Instruments.pdf#page=46|R1 Introduction to Rotary NiTi Instruments, p.46]] [[R1 Introduction to Rotary NiTi 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