L14 Working Radiography for Endo_formatted_text

Principles of Radiography¹

Lecture Focus

==This lecture revisits key radiographic principles, particularly as they apply to endodontics. The primary focus is on

Positioning Devices

Info

Standard positioning devices, such as Rinn or Neoss holders, are essential for diagnostic and follow-up radiography when a rubber dam is not in place. However, during endodontic treatment, several factors make these devices impractical:

1. ==Rubber Dam: The dam obstructs normal placement.==
2. ==Rubber Dam Clamp: The clamp prevents the patient from biting down on a holder.==
3. ==Endodontic Instruments: Files or filling materials protrude from the tooth, preventing the patient from closing their mouth on a holder.==

Tip

Alternative methods for holding the film or sensor are therefore required for working radiography.

• Nygaard-Östby Frame

• Rinn XCP Endodontic Film Holder

• EndoRay® II Film holder

Radiographic Interpretation²³⁴

Info

Accurate interpretation is crucial, especially when using tube shift techniques to visualize complex anatomy. The lecture emphasizes understanding how different angles project three-dimensional structures onto a two-dimensional image.

Tube Shift Techniques⁵

Info

Tube shift techniques are essential in endodontics for separating superimposed anatomical structures, such as multiple canals within a single root, and providing a pseudo-three-dimensional view.

Vertical Shift⁶

Note

Vertical tube shifts have limited diagnostic value, with one important exception.

• Increased angle
• Decreased angle

Decreased Angle⁷

Warning

==A decreased vertical angle is not recommended as it causes image distortion, specifically elongation of the tooth, which compromises diagnostic accuracy.==

• → elongates the image
• NO diagnostic value
• NO practical value

Increased Angle⁸

Modified Parallel Technique

==An increased vertical angle of approximately 15 degrees is a core component of the modified parallel technique. This technique should be used for all intraoral radiographs (endodontic, restorative, periodontal) to produce the most geometrically accurate images with minimal distortion.==

• → 15º vertical shift

  • Modified parallel technique
  • Provides more apical detail and definition

• → Occlusal views

  • Esp. useful for trauma diagnosis

    Root Fractures & Lateral Luxation

Horizontal shift^910111213

• Mesial

• Distal

• Used to separate objects that are otherwise superimposed over each other

• Can help to indicate the “3rd dimension”

SLOB Rule¹⁴

• SLOB rule: Same Lingual Opposite Buccal

Explanation

==This means that the object (e.g., canal) that is on the lingual (or palatal) side will appear to move in the same direction as the x-ray tube head. The object on the buccal (or labial) side will appear to move in the opposite direction. The key takeaway is to remember **

Views

• Straight View

• Canals are often superimposed. In an upper molar, the palatal root typically appears between the two buccal roots.

  • Film
  • Bu
  • Li
  • Li
  • Bu
  • CR

• Mesial

• The x-ray beam is directed from a more mesial angle.

  • ==The lingual/palatal canal or root will appear more mesial on the radiograph.==
  • ==The buccal/labial canal or root will appear more distal on the radiograph.==

  • Clinical Clue

  For a posterior radiograph, the canine may become visible on the image.

  • Film
  • Li
  • Bu
  • M
  • Li
  • Bu
  • CR

• Distal

• The x-ray beam is directed from a more distal angle.

  • ==The lingual/palatal canal or root will appear more distal on the radiograph.==
  • ==The buccal/labial canal or root will appear more mesial on the radiograph.==

  • Clinical Clue

  For a posterior radiograph, the most distal molar will be more fully visible, and the canine will likely be absent from the image.

  • Bu Li
  • Film
  • M
  • Li
  • Bu
  • CR

Straight View

Mesial

Distal

Radiographs showing Mesial and Distal views.

Mesial

Distal

Endodontic “Working” Radiography^15161718

General Techniques

Info

Successful working radiography depends on managing access and stabilizing the film/sensor.

Importance of the Rubber Dam Frame

Recommended Frame

• ==A plastic, full-circumference frame like the Nygaard-Ostby frame is ideal.==
  • ==It should be placed underneath the rubber dam sheet.==
  • This setup allows a corner of the frame and dam to be easily lifted for sensor placement without the entire assembly collapsing.

Not Recommended

• ==Placing the frame on the outside of the dam severely restricts access.==
• Three-sided or metal frames are problematic. Metal frames must be removed to prevent superimposition on the image, and three-sided frames tend to collapse when a corner is released.

Film/Sensor Holding Methods

Lower Posterior Teeth

Technique

• ==Device: A pair of straight artery forceps is used to grip the film/sensor. (If using a sensor, protect it with a cardboard sleeve from the forceps’ grip).==
• ==Patient Positioning: The patient is instructed to create a

Three images showing techniques for taking radiographs during endodontic procedures, with the top and bottom left images depicting proper methods and the bottom right image showing an improper technique (marked with a red X).

Upper Posterior Teeth¹⁹

Technique

• ==The patient holds the film/sensor in place with their index finger.==
• The rubber dam clamp can help to position the film and keep it relatively parallel to the tooth.
• The patient applies light pressure against the clamp and the palate.

Upper Anterior Teeth²⁰

Technique

• The lower part of the rubber dam frame is lifted.
• ==The patient holds the film/sensor with their index finger.==
• Using the index finger is preferable to the thumb, as the thumb can apply excessive pressure, potentially bending the film or dislodging the rubber dam clamp.

Lower Anterior Teeth²¹

Technique

• The upper part of the rubber dam frame is lifted.
• ==The patient holds the film/sensor in place with their index finger.==

Specific Techniques for Each Tooth

Guiding Principle

==For all teeth, the starting point is the modified parallel technique, incorporating a +15 degree vertical angulation. The primary variable is the horizontal angle.==

Upper Incisors + Canines²²²³

• ==Standard View: A straight-on horizontal view is usually sufficient, as these teeth typically have one canal.==

• Vertical: 15° increase

  • i.e. Modified parallel technique

• Horizontal: only if a problem is suspected

  • e.g. perforation, extra canal
    • → Central incisors - Mesial shift
    • → Lateral incisors and canines - Distal shift

Info

This is due to the curvature of the arch, which makes positioning for a mesial shift difficult and can lead to image distortion.

Lower Incisors + Canines²⁴

Anatomy & Technique

• ==Anatomy: These teeth have a high probability (50-60%) of having two canals (labial and lingual). Always assume two canals exist until proven otherwise.==
• ==Standard View: A horizontal tube shift is mandatory to separate the potential labial and lingual canals.==
• ==Interpretation: Apply the SLOB rule to identify the lingual and labial canals and assess the working length for each.==

• Vertical: 15° increase

  • i.e. Modified parallel technique

• Horizontal:

  • Central incisors - Mesial shift
  • Lateral incisors and canines - Distal shift

due to the arch curvature.

Distal Mesial Distal

Upper & Lower Premolars²⁵²⁶²⁷

• Vertical: 15° increase

  • i.e. Modified parallel technique

• Horizontal:

  • Mesial shift

Lower Molars²⁸²⁹³⁰

• Vertical: 15° increase

  • i.e. Modified parallel technique

• Horizontal:

  • Mesial shift

Rationale & Interpretation

A distal shift is often difficult, especially for first premolars, because the curvature of the palate (upper) or mandible (lower) prevents proper anterior placement of the sensor.

Interpretation (Upper Premolars): You can use two methods to confirm which root is which:

1. ==Horizontal SLOB Rule: The palatal root will appear mesial on a mesial shift.==
2. ==Vertical Angulation Effect: With a modified parallel technique, the palatal root will always appear longer on the radiograph than the buccal root.==

• usually

Rationale

A distal shift can create distortion due to the flaring angle of the posterior mandible. A straight-on view is often non-diagnostic, as it superimposes the mesiobuccal and mesiolingual canals and can be misleading about the length of the file in the distal canal.

• Can do distal shift if necessary

Interpretation

• ==A mesial shift effectively separates the two mesial canals. Using the SLOB rule, the mesiolingual canal will be the one that appears more mesial on the image.==
• If two files in a root remain superimposed after a tube shift, it often indicates they are in a single, large, oval-shaped canal.

Pitfall

Be careful not to mistake the outline of the periodontal ligament (PDL) for a missed canal. A tube shift can make the PDL space on both the buccal and lingual aspects of the root visible as two separate dark lines. Attempting to instrument towards one of these lines can lead to a perforation.

Straight

Mesial

Upper Molars³¹³²³³

Complexity

These are the most challenging teeth to radiograph due to:

• Three roots (mesiobuccal, distobuccal, palatal) with different axial inclinations.
• High frequency of a second canal in the mesiobuccal root (MB2).
• Superimposition of the zygomatic bone.

• Vertical: 15° increase

  • i.e. Modified parallel technique
  • Sometimes also vary vertical angle for Pal. root

• Horizontal:

  • Distal shift - usually (for MB root)
  • Sometimes also need mesial shift (for DB root)

Standard Views & Strategy

==Often, two or even three radiographs are necessary to visualize all root apices clearly.==

1. ==Distal Shift (First Choice): This is the primary view taken because it is best for separating the MB2 canal from the MB1 canal in the mesiobuccal root.==

   • Problem

   The distobuccal root is often superimposed over the palatal root in this view.

2. ==Mesial Shift (Second View): This view is taken to visualize the distobuccal root, which will be projected distally and away from the other roots.==

   • Problem

   The mesiobuccal root is often superimposed over the palatal root in this view.

Interpretation

• Use the SLOB rule to identify the roots in each view.
• ==A distal shift moves the palatal root distally.==
• ==A mesial shift moves the palatal root mesially.==
• The presence of a periapical radiolucency can sometimes make the root apex easier to see by reducing the amount of overlying bone.
• By combining information from multiple angled radiographs, a complete picture of the working length in all canals can be established.

Straight

Distal

Mesial

Specific Techniques for Each Tooth³⁴³⁵

No discernible text is visible in the image.

t** Distal Mesial

Endodontic “Working” Radiography^15161718

Info

This section details the practical techniques for taking radiographs during treatment while a rubber dam is in place.

Outline³⁶³⁵

• Principles of Radiography
• Positioning Devices
• Radiographic Interpretation
• Tube Shift Techniques
• Endodontic “Working” Radiography
• Specific Techniques for Each Tooth

No discernible text is visible in the image.

Footnotes

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