**Endodontic Instruments**
![]()
Endodontic instruments and root canal treatment radiographs.
# **Endodontic Instruments**
**Preparation Appointment**
* **Local Anaesthesia**
* **Rubber Dam**
* **Access**
* **Establish “working length”**
* **Prepare / instrument the canal**
* **With anti-bacterial irrigation**
* **Medicate the canal**
* **Temporary restoration**
## **The Preparation Appointment**
- Local Anaesthesia
- Rubber Dam
- Access
- Establish “working length”
- Prepare / instrument the canal
- With anti-bacterial irrigation
- Medicate the canal
- Temporary restoration
> [!note]
> The primary focus of this lecture is on establishing the working length and the process of preparing and instrumenting the canal.
**Preparation Appointment**
* Local Anaesthesia
* Rubber Dam
* Access
$\Big{\{} $
* **Establish “working length”**
* **Prepare / instrument the canal**
* With anti-bacterial irrigation
$\Big{\}} $
* Medicate the canal
* Temporary restoration
**Root Canal Preparation**
**Aims**
* To remove all of the canal contents, organic or otherwise, that may lead to the growth of micro-organisms or the breakdown of toxic products and their release into the periapical tissues
* To remove the irregularities of the canal walls including obstructions such as calcifications, etc.
* To prepare the canal for its disinfection and to develop a shape that permits a simple and effective root canal filling to be placed.
## **Aims of Root Canal Preparation**
- To remove all of the canal contents, organic or otherwise, that may lead to the growth of micro-organisms or the breakdown of toxic products and their release into the periapical tissues
- To remove the irregularities of the canal walls including obstructions such as calcifications, etc.
- To prepare the canal for its disinfection and to develop a shape that permits a simple and effective root canal filling to be placed.
> [!note]
> Root canal preparation is a mechanical procedure with both biological and mechanical objectives. The mechanical objectives are designed to facilitate the achievement of the biological goals.
**Root Canal Preparation**
**Aims**
$\diamond$ Biological objectives
$\diamond$ **Mechanical objectives**
The aims of root canal preparation can be divided into two categories:
- Biological objectives
- **Mechanical objectives**
**Biological Objectives**
* **Remove all tissue and other debris**
* **Avoid periapical irritation**
* **Create sufficient space within the canal for intracanal medication**
### **Biological Objectives**
# **Biological Objectives**
* Remove all tissue and other debris
* Avoid periapical irritation -
* **Confine instruments to the canals**
* Create sufficient space within the canal
for intracanal medication
**Biological Objectives**
$\diamond$ **Remove all tissue and other debris**
$\diamond$ **Avoid periapical irritation -**
* **Confine instruments to the canals**
* **Do not force debris through the ap. foramen**
$\diamond$ **Create sufficient space within the canal**
**for intracanal medication**
# **Biological Objectives**
* Remove all tissue and other debris
* Avoid periapical irritation -
* Confine instruments to the canals
* Do not force debris through the ap. foramen
* **Measure & prepare canals at the same visit**
* Create sufficient space within the canal for intracanal medication
- Remove all tissue and other debris
- Avoid periapical irritation
- Confine instruments to the canals
- Do not force debris through the ap. foramen
- Measure & prepare canals at the same visit
> [!warning] Note
> To minimize errors in measurement, it is crucial to **measure and prepare the root canals in the same appointment**. Relying on measurements from a previous appointment increases the risk of error due to variations in reference points and operator positioning.
- Create sufficient space within the canal for intracanal medication
**Mechanical Objectives**
* Leave the ap. foramen in its original position
* Keep the ap. foramen as small as is practical
### **Mechanical Objectives**
## **Mechanical Objectives**
* **Leave the ap. foramen in its original position**
* **Keep the ap. foramen as small as is practical**
* **Create a continuously tapering conical shape**
* **Create a shape that is easy to fill**
**Mechanical Objectives**
* Leave the ap. foramen in its original position
* Keep the ap. foramen as small as is practical
* Create a continuously tapering conical shape
* **Narrow apically, tapering to wide orifice**
* **Narrowest point at the apical constriction**
* **Conical preparation must exist in multiple planes**
* Create a shape that is easy to fill
- Leave the ap. foramen in its original position
- Keep the ap. foramen as small as is practical
- Create a continuously tapering conical shape
- Narrow apically, tapering to wide orifice
- Narrowest point at the apical constriction
- Conical preparation must exist in multiple planes
- Create a shape that is easy to fill
> [!example] Analogy
> An analogy for the ideal prepared shape is the **Washington Monument** or the state war memorial in Kings Park, which has an even greater taper. The shape features a narrow apical point (apical seat) and a continuous flare towards the coronal end.
An image showing widening of the root canal.
An image showing widening of the root canal.
![]()
Photograph and model of the Washington Monument, referenced in "Endodontics" by Ingle, 1976
![]()
Three obelisks located in Kings Park (Perth), Nadi (Fiji), and Alice Springs (NT)
# **Preparation Techniques**
* **Hand files** - Stainless steel
* **Rotary files** - Nickel Titanium (NiTi)
* Many different techniques for each are described in books, journals, lectures
## **Preparation Techniques and Instruments**
### **Overview of Techniques**
- **Hand files** - Stainless steel
- **Rotary files** - Nickel Titanium (NiTi)
- ==Flexible instruments used in a special low-speed, torque-controlled motor at speeds around 200 RPM.==
- Many different techniques for each are described in books, journals, lectures
> [!tip]
> While this lecture focuses on hand files, it is essential to master their use before progressing to rotary systems, as hand files are still required for initial canal negotiation and establishing working length even when using rotary techniques.
**Some Hand File Techniques**
* Non-serial
* Step-back
* Step-down
* Double-flared
* Crown-down pressureless
* Balanced forces
* Canal Master
* Hybrid techniques
* Continuous wave
* Dr. XXXX's technique
* Dr. AAAA's technique
* Etc, etc, etc.
### **Examples of File Techniques and Systems**
#### **Hand File Techniques**
- Non-serial
- Step-back
- Step-down
- Double-flared
- Crown-down pressureless
- Balanced forces
- Canal Master
- Hybrid techniques
- Continuous wave
- Dr. XXXX's technique
- Dr. AAAA's technique
- Etc, etc, etc.
> [!tip] Guiding Principle
> However, the most important principle is to base the technique on the instrument's design.
**Some Rotary NiTi File Systems**
| File systems | Handpiece systems |
| :--- | :--- |
| **Quantec - SC, LX** | **TriAuto ZX** |
| **Axxess Flare** | **ProFile High Torque** |
| **Profile - 29, GT, .04, .06** | **ATR Tecnika Motor** |
| **ProTaper** | **Nouvag TCM Endo Motor** |
| **ProSystem GT** | **K³ etcm Motor + H/P** |
| **K³** | **Rotary Master Endo H/P** |
| **Lightspeed** | **Endo-Pro Micromotor** |
| **Herodent** | **Endo Gripper H/P** |
| **ENDOflash** | **M4 Safety Handpiece** |
| **Navi Flex** | **Tardie CS** |
| **NT McXim** | **Titan 3** |
| **NiTi Roto 360** | **Sprint TCM** |
| **NiTi Flex** | **Kavo ENDOflash** |
| **Microtitane** | **Herodent** |
| **Onyx-R File** | **Canal Finder** |
| **SureFlex** | **Canal Master** |
| **HyFlex** etc, etc, etc | **Cursor** etc, etc, etc |
#### **Rotary NiTi File Systems**
> [!info]
> There are approximately 80 different rotary file systems available worldwide. These systems come and go from the market frequently. While students will gain experience with specific rotary systems in later years, the foundational knowledge of hand instrumentation is paramount.
| File systems | Handpiece systems |
| :--- | :--- |
| **Quantec - SC, LX** | **TriAuto ZX** |
| **Axxess Flare** | **ProFile High Torque** |
| **Profile - 29, GT, .04, .06** | **ATR Tecnika Motor** |
| **ProTaper** | **Nouvag TCM Endo Motor** |
| **ProSystem GT** | **K³ etcm Motor + H/P** |
| **K³** | **Rotary Master Endo H/P** |
| **Lightspeed** | **Endo-Pro Micromotor** |
| **Herodent** | **Endo Gripper H/P** |
| **ENDOflash** | **M4 Safety Handpiece** |
| **Navi Flex** | **Tardie CS** |
| **NT McXim** | **Titan 3** |
| **NiTi Roto 360** | **Sprint TCM** |
| **NiTi Flex** | **Kavo ENDOflash** |
| **Microtitane** | **Herodent** |
| **Onyx-R File** | **Canal Finder** |
| **SureFlex** | **Canal Master** |
| **HyFlex** etc, etc, etc | **Cursor** etc, etc, etc |
# **Preparation Techniques**
$\diamond$ *The technique used should depend on the:*
* **Instruments used -**
$\rightarrow$ Design of the cutting blade
### **Factors Influencing Technique Choice**
**Preparation Techniques**
- ***The technique used should depend on the:***
- **Instruments used -**
$\rightarrow$ Design of the cutting blade
- **Root filling technique used -**
$\rightarrow$ e.g. Lateral compaction, vertical compaction, etc.
**Preparation Techniques**
$\diamond$ *The technique used should depend on the:*
* **Instruments used -**
$\rightarrow$ Design of the cutting blade
* **Root filling technique used -**
$\rightarrow$ e.g. Lateral compaction, vertical compaction, etc.
* **Operator -**
$\rightarrow$ Skill, preference, experience
The technique used should depend on the:
- **Instruments used -**
- Design of the cutting blade
- **Root filling technique used -**
- e.g. Lateral compaction, vertical compaction, etc.
- ==A lateral compaction technique requires a different preparation than a vertical compaction technique, which needs a larger canal size.==
- **Operator -**
- Skill, preference, experience
**Endodontic Hand Instruments -**
**ISO Specifications**
![]()
A diagram illustrating the dimensions of an endodontic hand instrument according to ISO specifications.
## **Endodontic Hand Instruments**
**Endodontic Hand Instruments -**
**ISO Specifications**
| Colour | Size | D1 |
|---|---|---|
| White | 15 | 0.15 mm |
| **Yellow** | 20 | **0.20 mm** |
| **Red** | 25 | **0.25 mm** |
| **Blue** | 30 | **0.30 mm** |
| **Green** | 35 | **0.35 mm** |
| **Black** | 40 | **0.40 mm** |
# **Endodontic Hand Instruments -**
# **ISO Specifications**
<table>
<thead>
<tr>
<th>Colour</th>
<th>Size</th>
<th>D1</th>
</tr>
</thead>
<tbody>
<tr>
<td>White</td>
<td>45</td>
<td>0.45 mm</td>
</tr>
<tr>
<td><span style="color: yellow;">Yellow</span></td>
<td>50</td>
<td><span style="color: yellow;">0.50 mm</span></td>
</tr>
<tr>
<td><span style="color: red;">Red</span></td>
<td>55</td>
<td><span style="color: red;">0.55 mm</span></td>
</tr>
<tr>
<td><span style="color: blue;">Blue</span></td>
<td>60</td>
<td><span style="color: blue;">0.60 mm</span></td>
</tr>
<tr>
<td><span style="color: green;">Green</span></td>
<td>70</td>
<td><span style="color: green;">0.70 mm</span></td>
</tr>
<tr>
<td>Black</td>
<td>80</td>
<td>0.80 mm</td>
</tr>
</tbody>
</table>
<table>
<thead>
<tr>
<th>Colour</th>
<th>Size</th>
<th>D1</th>
</tr>
</thead>
<tbody>
<tr>
<td>White</td>
<td>90</td>
<td>0.90 mm</td>
</tr>
<tr>
<td><span style="color: yellow;">Yellow</span></td>
<td>100</td>
<td><span style="color: yellow;">1.00 mm</span></td>
</tr>
<tr>
<td><span style="color: red;">Red</span></td>
<td>110</td>
<td><span style="color: red;">1.10 mm</span></td>
</tr>
<tr>
<td><span style="color: blue;">Blue</span></td>
<td>120</td>
<td><span style="color: blue;">1.20 mm</span></td>
</tr>
<tr>
<td><span style="color: green;">Green</span></td>
<td>130</td>
<td><span style="color: green;">1.30 mm</span></td>
</tr>
<tr>
<td>Black</td>
<td>140</td>
<td>1.40 mm</td>
</tr>
</tbody>
</table>
<table style="width:100%; border-collapse: collapse;">
<thead>
<tr>
<th style="border: 1px solid black; padding: 8px;">Colour</th>
<th style="border: 1px solid black; padding: 8px;">Size</th>
<th style="border: 1px solid black; padding: 8px;">D1</th>
</tr>
</thead>
<tbody>
<tr>
<td style="border: 1px solid black; padding: 8px;"><strong>Pink</strong></td>
<td style="border: 1px solid black; padding: 8px;"><strong>6</strong></td>
<td style="border: 1px solid black; padding: 8px;"><strong>0.06 mm</strong></td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;"><strong>Grey</strong></td>
<td style="border: 1px solid black; padding: 8px;"><strong>8</strong></td>
<td style="border: 1px solid black; padding: 8px;"><strong>0.08 mm</strong></td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;"><strong>Purple</strong></td>
<td style="border: 1px solid black; padding: 8px;"><strong>10</strong></td>
<td style="border: 1px solid black; padding: 8px;"><strong>0.10 mm</strong></td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;">White</td>
<td style="border: 1px solid black; padding: 8px;">15</td>
<td style="border: 1px solid black; padding: 8px;">0.15 mm</td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;"><strong>Yellow</strong></td>
<td style="border: 1px solid black; padding: 8px;"><strong>20</strong></td>
<td style="border: 1px solid black; padding: 8px;"><strong>0.20 mm</strong></td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;"><strong>Red</strong></td>
<td style="border: 1px solid black; padding: 8px;"><strong>25</strong></td>
<td style="border: 1px solid black; padding: 8px;"><strong>0.25 mm</strong></td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;"><strong>Blue</strong></td>
<td style="border: 1px solid black; padding: 8px;"><strong>30</strong></td>
<td style="border_1px solid black; padding: 8px;"><strong>0.30 mm</strong></td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;"><strong>Green</strong></td>
<td style="border: 1px solid black; padding: 8px;"><strong>35</strong></td>
<td style="border: 1px solid black; padding: 8px;"><strong>0.35 mm</strong></td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;"><strong>Black</strong></td>
<td style="border: 1px solid black; padding: 8px;"><strong>40</strong></td>
<td style="border: 1px solid black; padding: 8px;"><strong>0.40 mm</strong></td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;">White</td>
<td style="border: 1px solid black; padding: 8px;">45</td>
<td style="border: 1px solid black; padding: 8px;">0.45 mm</td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;"><span style="color: yellow;">Yellow</span></td>
<td style="border: 1px solid black; padding: 8px;">50</td>
<td style="border: 1px solid black; padding: 8px;"><span style="color: yellow;">0.50 mm</span></td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;"><span style="color: red;">Red</span></td>
<td style="border: 1px solid black; padding: 8px;">55</td>
<td style="border: 1px solid black; padding: 8px;"><span style="color: red;">0.55 mm</span></td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;"><span style="color: blue;">Blue</span></td>
<td style="border: 1px solid black; padding: 8px;">60</td>
<td style="border: 1px solid black; padding: 8px;"><span style="color: blue;">0.60 mm</span></td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;"><span style="color: green;">Green</span></td>
<td style="border: 1px solid black; padding: 8px;">70</td>
<td style="border: 1px solid black; padding: 8px;"><span style="color: green;">0.70 mm</span></td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;">Black</td>
<td style="border: 1px solid black; padding: 8px;">80</td>
<td style="border: 1px solid black; padding: 8px;">0.80 mm</td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;">White</td>
<td style="border: 1px solid black; padding: 8px;">90</td>
<td style="border: 1px solid black; padding: 8px;">0.90 mm</td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;"><span style="color: yellow;">Yellow</span></td>
<td style="border: 1px solid black; padding: 8px;">100</td>
<td style="border: 1px solid black; padding: 8px;"><span style="color: yellow;">1.00 mm</span></td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;"><span style="color: red;">Red</span></td>
<td style="border: 1px solid black; padding: 8px;">110</td>
<td style="border: 1px solid black; padding: 8px;"><span style="color: red;">1.10 mm</span></td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;"><span style="color: blue;">Blue</span></td>
<td style="border: 1px solid black; padding: 8px;">120</td>
<td style="border: 1px solid black; padding: 8px;"><span style="color: blue;">1.20 mm</span></td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;"><span style="color: green;">Green</span></td>
<td style="border: 1px solid black; padding: 8px;">130</td>
<td style="border: 1px solid black; padding: 8px;"><span style="color: green;">1.30 mm</span></td>
</tr>
<tr>
<td style="border: 1px solid black; padding: 8px;">Black</td>
<td style="border: 1px solid black; padding: 8px;">140</td>
<td style="border: 1px solid black; padding: 8px;">1.40 mm</td>
</tr>
</tbody>
</table>
- ==**File Size (D1 Diameter):** The size of a file is determined by its diameter in hundredths of a millimeter at **D1**, which is 1 mm from the instrument's tip. For example, a size 25 file has a diameter of 0.25 mm at D1.==
- ==**Size Increments:** Sizes increase by 0.05 mm from size 15 to 60. After size 60, they increase by 0.10 mm (e.g., 60, 70, 80).==
**Endodontic Hand Instruments -**
**ISO Specifications**
| Colour | Size | D1 |
|---|---|---|
| **Pink** | **6** | **0.06 mm** |
| **Grey** | **8** | **0.08 mm** |
| **Purple** | **10** | **0.10 mm** |
![]()
Endodontic hand instruments (files) in pink, grey, and purple, corresponding to sizes 6, 8, and 10 and D1 diameters.
### **ISO Specifications**
> [!note]
> To standardize instruments across manufacturers, the International Standards Organization (ISO) established specifications for hand files in the late 1960s.
**Endodontic Hand Instruments -**
**ISO Specifications**
***
Taper:
**0.02 mm / mm**
![]()
Diagram showing the dimensions of an endodontic hand instrument, including the distance d1, the 16 mm working portion length, the shaft, and the overall length of the working portion.
- **Taper:**
- **0.02 mm / mm**
- ==**Cutting Blade Length:** The fluted or cutting portion of all hand files is a standard **16 mm**.==
**Endodontic Hand Instruments -**
**ISO Specifications**
**21 mm**
**25 mm**
**28 mm**
**31 mm**
- **Lengths:**
- **21 mm**
- **25 mm**
- **28 mm**
- **31 mm**
- ==The clinic primarily stocks **25 mm** and **31 mm** files.==
- ==**Rubber Stoppers:** These silicone markers can be moved along the file's shaft to mark the working length, preventing over-instrumentation.==
<div style="background-color: blue; color: yellow; text-align: center;">
# **Endodontic Hand Instruments -**
# **ISO Specifications**
</div>
<div style="text-align: center;">
# 25 mm
# 31 mm
</div>
![]()
Endodontic Hand Instruments with measurements
**Endodontic Hand Instruments - Types of Files**
| Hedströmfile | File | Reamer |
|---|---|---|
| | | |
| Instrument | Cross-Section Shape |
|---|---|
| TRIOCUT™ | Three-lobed |
| HEDSTROEM FILE | Circle |
| UNIFILE® | S-shape |
| K-FILE | Square |
| K-FLEX® | Diamond |
| REAMER | Triangle |
![]()
A diagram illustrating the Hedström file's cross-section (circle) and blade shape.
![]()
A diagram illustrating the K-file's cross-section (square) and twisted shape.
![]()
A diagram illustrating the Reamer's cross-section (triangle) and twisted shape.
### **Types of Files**
**Endodontic Hand Instruments -**
**Types of Files**
| Instrument | Cutting Angle | Cross-Sectional Shape |
|---|---|---|
| H-File | $90^{\circ}$ | Circle with a leaf-like inner shape |
| K-File | $60^{\circ}$ | Square |
| Reamer | $60^{\circ}$ | Triangle |
| Instrument | Cross-Section Shape | Cutting Angle |
|---|---|---|
| HEDSTROEM FILE / H-File | Circle / Circle with a leaf-like inner shape | $90^{\circ}$ |
| K-FILE | Square | $60^{\circ}$ |
| REAMER | Triangle | $60^{\circ}$ |
| TRIOCUT™ | Three-lobed | |
| UNIFILE® | S-shape | |
| K-FLEX® | Diamond | |
**Hedström Files**
![]()
A diagram illustrating the cutting action of an H-file and a photograph of a physical Hedstrom file.
### **Hedström Files**
- ==**Manufacture:** Ground from a round stainless-steel wire blank, creating a series of sharp, spiraled cutting edges.==
- ==**Properties:** Very efficient at cutting on the pull stroke. More flexible than K-files due to the round cross-section. These are the files used in the clinic.==
**Hedström Files**
**Mechanism of Use**
Based on the overall design
of the file and its cutting edges
![]()
Two diagrams depicting the design of a Hedstrom file, one showing a cross-section and the other a magnified view of the cutting edge and its 90-degree angle.
**Hedström Files**
**Mechanism of Use**
Based on the overall design
of the file and its cutting edges
- ***Three actions used simultaneously:***
1. **Slight Rotation to Engage** (⅛ turn)
2. **Push-Pull**
3. **Circumferential Filing**
![]()
A depiction of a file's cross-section and a close-up of a file tip with a 90° angle indicated.
**Hedström Files**
**Slight Rotation to Engage**
![]()
Diagram showing the rotation of a Hedström file to engage in the canal, indicating a rotation of 1/8th of a turn.
**Slight Rotation to Engage**
**Hedström Files**
**Push-Pull action**
![]()
Showing the cross-section and cutting angle of Hedström files with Push-Pull action arrows.
**Push-Pull action**
**Hedström Files**
**Circumferential filing**
![]()
A central illustration displaying a cross-section of a root canal with surrounding dentin, showing the concentric removal of material, flanked by two inset diagrams.
**Circumferential filing**
![]()
Circumferential filing process with anatomical cross-sections indicated by arrows
**Hedström Files**
**Circumferential filing**
![]()
A diagram illustrating circumferential filing motion with circular arrows for rotation.
**Circumferential filing**
![]()
A flowchart illustrating the process of circumferential filing and its resulting radiographic images.
**Hedström Files**
**Mechanism of Use**
Based on the overall design
of the file and its cutting edges
- **Three actions used simultaneously:**
1. **Slight Rotation (⅛) → To engage dentine**
2. **Push-Pull**
3. **Circumferential Filing**} **Use together - to enlarge & flare**
![]()
Green circle with irregular shape inside.
![]()
Diagram illustrating a file cross section and a 90 degree angle.
#### **Mechanism of Use**
Based on the overall design of the file and its cutting edges.
- **Three actions used simultaneously:**
1. **Slight Rotation (⅛) → To engage dentine**
- ==A **maximum 1/8th of a turn** clockwise is used to engage the file's cutting flutes into the dentin wall.==
> [!danger] Caution
> Over-rotation, especially the 1/4 turn often cited for K-files, can cause the file to lock and break.
2. **Push-Pull**
- ==The primary cutting action occurs on the **pull (withdrawal) stroke**. The push stroke is passive. This motion shaves dentin from the canal wall.==
3. **Circumferential Filing**
- ==Because most canals are oval or irregular, the file must be moved around the entire periphery of the canal. After each push-pull stroke, the instrument is repositioned against an adjacent part of the wall. This action ensures the entire canal is cleaned and shaped, maintaining its original cross-sectional form while enlarging it.==
- These actions are used together to enlarge & flare.
**Action of Files in Canals**
**Passive**
**Pull**
![]()
Diagram illustrating the passive and pull actions of files within the root canal, showing areas of engagement indicated by arrows and stars.
### **Action of Files in Canals**
- **Passive**
- **Pull**
**Action of Files in Canals**
$\diamond$ **Canal Transportation**
$\diamond$ ***Strip perforation***
![]()
A descriptive image showing cross-sections of a tooth before and after canal preparation, illustrating canal transportation and a radiograph showing a strip perforation.
#### **Potential Complications**
- **Canal Transportation**
- ==The inherent stiffness of a file causes it to try and straighten itself within a curved canal. This can cause the file to preferentially cut the outer wall of the curve apically and the inner wall of the curve coronally,
**Action of Files in Canals**
$\diamond$ Pre-curve $\underline{ALL}$ files prior to use
- $\triangleright$ $>$ **95% of canals are curved $>$5$^\circ$**
- $\rightarrow$ **Reproduce the canal's curve**
![]()
Diagram of pre-curved files entering a curved canal
#### **Pre-curving Files**
- Pre-curve **ALL** files prior to use
> [!tip]
> Over 95% of root canals have some degree of curvature. Therefore, it is safest to assume **all canals are curved** and to **pre-curve files** before insertion.
- **>** 95% of canals are curved **>**5°
- **Reproduce the canal's curve**
**Action of Files in Canals**
$\diamond$ Pre-curve **ALL** files prior to use
$\P$ **>** 95% of canals are curved **>**5°
$\rightarrow$ **Reproduce the canal's curve**
$\P$ **Can help by-pass obstructions**
![]()
Two manually pre-curved endodontic files (likely K-files), a diagram illustrating a cross-section of a curved canal and a file within it, and three diagrams showing the action and movement of a file inside a canal
- **Can help by-pass obstructions**
## **Action of Files in Canals**
* **Pre-curve $\underline{ALL}$ files prior to use**
* **But - curved files can $\underline{CAUSE \ PROBLEMS}$ if are rotated too much**
![]()
Demonstration of pre-curved files and the potential problems with rotation, showing two dental files with curved tips and a diagram illustrating the rotational effect within a canal.
- **But - curved files can CAUSE PROBLEMS if are rotated too much**
**Action of Files in Canals**
- **Canal Transportation $\rightarrow$ Apically**
- Apically
**Action of Files in Canals**
**Canal Transportation $\rightarrow$ Apically**
![]()
Diagrams illustrating different outcomes of file action in root canals: Transportation of apical foramen (red), Zip without perforation (cyan), and Zip with perforation (yellow).
- ***Strip perforation***
- ==In multi-rooted teeth (e.g., mandibular molars), canals are often located closer to the thin furcation side of the root. Excessive transportation towards this
**Action of Files in Canals**
$\diamond$ Ledging of canal
![]()
Illustration showing a file creating a ledge in a canal, indicated by a red arrow.
- Ledging of canal
- ==If a file is forced or rotated excessively when it meets resistance, it can dig into the canal wall, creating a
# **Action of Files in Canals**
$\large \diamond$ **Shortening of “working length”**
$\quad \large \blacksquare$ **Occurs as the canal curvature is reduced**
- **Shortening of “working length”**
- **Occurs as the canal curvature is reduced**
- ==A 10-degree curve can shorten the working length by approximately 0.5 mm. This must be accounted for by progressively shortening the instrumentation length for larger files.==
**Action of Files in Canals**
- File acts like a "plunger" or a piston
![]()
Dental file in a tooth canal showing the accumulation of debris at the apex.
- File acts like a
- ==Debris created during instrumentation can be packed into the apical third if not properly removed, creating a blockage. This can be prevented by always instrumenting to the full working length with each file, using copious irrigation, and pre-curving files.==
"plunger" or a piston
**Action of Files in Canals**
- File acts like a “plunger” or a piston
- **Can lead to a “false canal” or a perforation**
<img > </img>
- **Can lead to a “false canal” or a perforation**
**MUST** Irrigate Between Each File
### **Irrigation**
**MUST** Irrigate Between Each File
- ==The canal should be flushed with an irrigant (e.g., **EDTAC**) between every file.==
- ==The irrigant helps to float debris out of the canal, lubricate the instrument, and begin the disinfection process.==
- ==When instrumenting a multi-canal tooth, it is efficient to use the same size file in all canals before irrigating them all and moving to the next larger file size.==
**Gates-Glidden Burs**
<br>
$\diamond$ **Rotary instrument** - **for a low speed handpiece**
<br>
$\blacksquare$ **Made from: Steel or stainless steel**
<br>
<br>
## **Gates-Glidden Burs**
# **Gates-Glidden Burs**
- **Rotary instrument - for a low speed handpiece**
- **Made from: Steel or stainless steel**
- **Side cutting bur**
![]()
an image showing the tip of a gate glidden bur and a full bur
**Gates-Glidden Burs**
$\diamond$ Rotary instrument - for a low speed handpiece
* **Made from: Steel or stainless steel**
* **Side cutting bur**
$\rightarrow$ **End does not cut - only guides the instrument**
![]()
Close-up image of the tip and full view of the Gates-Glidden bur
**Gates-Glidden Burs**
* Rotary instrument - for a low speed handpiece
* **Made from:** **Steel or stainless steel**
* Side cutting bur
$\rightarrow$ End does not cut – only guides the instrument
* Six sizes – numbered 1 - 6
$\rightarrow$ Should NEVER use No. 1 - too fragile
![]()
A close-up view of the Gates-Glidden bur tip and the full instrument shaft, with red arrows pointing to the tip and the base of the shaft.
### **Properties**
- **Rotary instrument** - **for a low speed handpiece**
- **Made from: Steel or stainless steel**
- ==Steel versions are considered single-use.==
- ==They have a small, flame-shaped, side-cutting head on a long, thin shaft.==
- **Side cutting bur**
- **End does not cut - only guides the instrument**
- Six sizes – numbered 1 - 6
- Should NEVER use No. 1 - too fragile
- ==Sizes are identified by rings on the shaft (e.g., 3 rings = size #3). Sizes #2 and #3 are most common.==
# Gates-Glidden Burs
* Use “passively” only - i.e. **NO** pressure
* $\rightarrow$ Cut on withdrawal stroke only
### **Usage**
- Use “passively” only - i.e. **NO** pressure
- Cut on withdrawal stroke only
**Gates-Glidden Burs**
- Use “passively” only - i.e. **NO** pressure
- Cut on withdrawal stroke only
- Use as an orifice opener & to flare the coronal few millimetres of the canal
<?xml version="1.0" encoding="UTF-8"?>
<img > <p>Line drawing illustrating the use of a Gates-Glidden bur in a root canal.</p> </img>
- Use as an orifice opener & to flare the coronal few millimetres of the canal
- ==This creates a funnel shape for better access to the apical regions.==
<?xml version="1.0" encoding="UTF-8"?>
# **Gates-Glidden Burs**
- Use “passively” only - i.e. **NO pressure**
$\rightarrow$ Cut on withdrawal stroke only
$\rightarrow$ Use as an orifice opener & to flare the coronal few millimetres of the canal
$\diamond$ **NB - Will widen an existing hole but will not create a hole or opening that is not already there !!**
![]()
Diagram showing a Gates-Glidden bur inside a curved root canal, with an arrow indicating the withdrawal direction.
- **NB - Will widen an existing hole but will not create a hole or opening that is not already there !!**
**Gates-Glidden Burs**
- **Take care to avoid "strip perforations"**
![]()
A diagram illustrating the use of a Gates-Glidden bur in a tooth's root canal, pointing toward the canal thinning that could lead to a strip perforation.
### **Risks**
- **Take care to avoid
- ==Aggressive use or using too large a size can cause a strip perforation, especially on the thin furcation side of a root. Cutting should be directed away from this
"strip perforations"**
**Gates-Glidden Burs**
\
- **Take care to avoid “strip perforations”**
\
\
\
\
**- Designed to break at top of shaft**
**if too much pressure used**
\
\
\
\
> **But - does not always happen !!**
\
\
\
\
\
\
\
\
<img > </img>
- **Designed to break at top of shaft if too much pressure used**
- **But - does not always happen !!**
> [!danger] Risk of Fracture
> Although designed to break at the shaft, they can corrode if reused and break near the cutting head, making retrieval extremely difficult. For this reason, they should be treated as **single-use instruments**.
**Preparation Appointment**
**♦ Local Anaesthesia**
**♦ Rubber Dam**
**♦ Access**
$\left\{ \begin{array}{l} \text{\text{♦ Establish “working length”}} \\ \text{\text{♦ Prepare / instrument the canal}} \\ \text{\text{ \hspace{1em} \text{\text{\text{With anti-bacterial irrigation}}}}\end{array} \right\}$
**♦ Medicate the canal**
**♦ Temporary restoration**
# **Preparation Appointment**
- **Local Anaesthesia**
- **Rubber Dam**
- **Access**
- **Establish “working length”**
- **Prepare / instrument the canal**
- With anti-bacterial irrigation
- **Medicate the canal**
- **Temporary restoration*
- ==Ultimately, every clinician develops their own variation of a standard technique.==
*
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