Optimizing Dental Radiography for Extractions

Optimizing Radiographic Imaging for Extractions

Panoramic Radiographs: Preparation

  • Removal of Removable Items:
    • Patients must remove any removable items from the head and neck region before a panoramic radiograph. This includes:
      • Jewelry and piercings
      • Removable partial dentures
      • Hearing aids
      • Glasses
  • Ghost Images:
    • Leaving these items in place can cause radiation to bounce off them, creating ghost images on the panoramic radiograph.
    • A ghost image is a distorted, radiopaque representation of the item in a different area of the image, obscuring underlying structures.

Focal Trough Optimization

  • Focal Trough Definition:
    • The focal trough is a U-shaped area where the patient's jaw should ideally be positioned to achieve optimal image clarity.
  • Analogy to Camera Focus:
    • If the patient is positioned too close or too far from the focal trough (similar to being out of focus in a camera), the resulting image will be unclear.
  • Adjustable Settings on Modern Machines:
    • Modern panoramic machines allow for adjustments to the focal trough based on arch shape and patient size.
    • Settings include:
      • Square arch
      • Triangular arch
      • Incisor proclamation adjustment
      • Patient size (child, average adult, larger adult)

Patient Positioning in the Panoramic Machine

  • Frankfurt Horizontal Plane:
    • Use laser levels to align the patient's face, ensuring the Frankfurt horizontal plane (from nose to ear) is level.
  • Downward Tilt:
    • If the Frankfurt plane is angled too far downwards:
      • Incisors may appear shorter than normal.
      • The mandible may appear V-shaped.
  • Upward Tilt:
    • If the Frankfurt plane is angled upwards:
      • A reverse smile line may appear, with incisors curving upwards towards the molars.
      • The hard palate may obscure the apices of maxillary teeth.
  • Bite Stick Positioning:
    • Patients should bite on the bite stick, aligning their incisors with the groove to position them in the center of the focal trough.
    • Incorrect positioning:
      • Too far forward: Incisors appear narrow and distorted.
      • Too far back: Incisors appear wide and blurry.
  • Neck Extension:
    • Patients should extend their necks as much as possible to stretch out the cervical vertebrae, reducing radiopacity in the anterior region.
  • Lead Apron Placement:
    • Ensure the lead apron does not obstruct the image, creating a white triangle in the anterior portion.
    • Consider placing the apron on the patient's back "like a cape" as the beams may come from the back (depending on the machine).

Palatoglossal Space

  • Definition:
    • The palatoglossal space is a dark space visible when the patient does not have their tongue pressed against the roof of their mouth.
  • Impact on Image Clarity:
    • If the tongue is not in the correct position, it can be difficult to identify periapical pathology around the maxillary teeth due to superimposition.

Periapical Radiographs: Achieving Optimal Images

  • Parallelism:
    • Aim for the image to be as parallel as possible to the tooth.
    • Assessment: Only one set of cusp tips visible indicates good parallelism.
    • Steep Angulation: Two distinct sets of cusp tips indicate a steep angulation, leading to distorted roots and inaccurate depth perception.
  • Sensor Placement in Maxilla:
    • Position the sensor in the deepest part of the palate to maximize parallelism.
  • Ring Systems:
    • Use ring systems to align the x-ray cone and sensor for consistent parallelism.

Techniques for Gagging Patients

  • Sensor Size and Orientation:
    • Use a smaller size sensor (e.g., size one instead of size two) and orient it vertically to minimize discomfort.
  • Breathing Technique:
    • Have the patient take a full breath in, place the sensor, and have them exhale continuously until the image is exposed. Exhaling inhibits the gag reflex.

Bisecting Angle Technique

  • Description:
    • Compromise when parallel image is not possible due to patient anatomy.
    • Angle the sensor and x-ray beam to bisect the angle between the tooth and sensor.
  • Limitations:
    • Not as accurate as parallel technique but may provide an acceptable image.

SLOB Rule (Same Lingual, Opposite Buccal)

  • Purpose:
    • To determine the relative position of roots or objects (e.g., broken bur tip) in the bucco-lingual dimension, especially in multi-rooted teeth.
  • Procedure:
    • Take an initial periapical radiograph.
    • Shift the x-ray cone mesially or distally while keeping the sensor in the same position.
    • Compare the second image to the first.
  • Interpretation:
    • Same Lingual: If the object moves in the same direction as the cone shift, it is located on the lingual aspect.
    • Opposite Buccal: If the object moves in the opposite direction of the cone shift, it is located on the buccal aspect.