Dental Radiography: Bisecting Technique

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Questions and Answers

What principle does the bisecting angle technique rely on?

Drawing a line that bisects a triangle (correct)

Running the x-ray beam parallel to the tooth

Aligning the film and teeth perfectly

Directing the beam away from the long axis of the teeth

What is the recommended angulation for maxillary incisors when using the bisecting technique?

-15 degrees

+40 degrees (correct)

+20 degrees

+75 degrees

What is considered an advantage of the bisecting technique?

More complex film holders

Higher radiation exposure

Increased image distortion

Comfort for the patient (correct)

Which of the following is a potential disadvantage of the bisecting technique?

Distortion of the image Signup and view all the answers

What does horizontal angulation in bisecting technique involve?

Direction of the central ray horizontally Signup and view all the answers

What can result from incorrect horizontal angulation?

Overlapped contact areas Signup and view all the answers

What is the purpose of the aiming rings in bisecting angle instruments?

To dictate proper PID angulation Signup and view all the answers

Which of the following indications is appropriate for using the bisecting technique?

High lingual frenum Signup and view all the answers

What is the effect of incorrect horizontal angulation when examining interproximal areas of teeth?

It causes overlapping contacts. Signup and view all the answers

In the paralleling technique, how should the central ray be directed?

Perpendicular to the film and the long axis of the tooth. Signup and view all the answers

What happens to the image when vertical angulation is too steep?

The image is foreshortened. Signup and view all the answers

Which radiographic technique determines the vertical angulation based on an imaginary bisector?

Bisecting technique. Signup and view all the answers

What is the purpose of a premolar bite-wing radiograph?

To assess incipient carious lesions in the interproximal area. Signup and view all the answers

What is a consequence of using too flat vertical angulation?

The image appears elongated. Signup and view all the answers

Which method is used for object localization in the jaws?

Clark's rule / SLOB technique. Signup and view all the answers

What is the result of using correct vertical angulation?

The image is the same length as the tooth. Signup and view all the answers

Study Notes

Bisecting Technique

The bisecting technique is based on bisecting the angle formed by the long axis of the tooth and the long axis of the film.
The x-ray beam is directed perpendicular to the bisecting angle.

Projections

The bisecting technique uses different vertical angulation for different teeth.
Incisors: +40 degrees for maxillary, -15 degrees for mandibular
Canines: +45 degrees for maxillary, -20 degrees for mandibular
Premolars: +30 degrees for maxillary, -10 degrees for mandibular
Molars: +20 degrees for maxillary, -05 degrees for mandibular

Indications

The bisecting technique is indicated for patients with:
- Shallow palates
- Palatal tori
- Tongue tie or high lingual frenum

Advantages

Comfort: The technique is generally comfortable for patients.
Snap-A-Ray film holders: These holders are easy to use and accommodate film placement.

Disadvantages

Distortion of image: The bisecting technique can result in image distortion.
Positioning error / operator error: Proper positioning is crucial for accuracy, and errors can lead to inaccurate images.
Film movement by patient: Patient movement can also cause image distortion.

PID Angulations: Bisecting Technique

Horizontal angulation: Remains the same for both the bisecting and paralleling techniques.
- The central ray is directed perpendicular to the curvature of the arch and through the contact areas of the teeth.
- Incorrect horizontal angulation leads to overlapped contact areas, hindering examination of interproximal areas of the teeth.
Vertical angulation: Determined by the imaginary bisector, with the central ray directed perpendicular to it.
- Correct vertical angulation produces an image the same length as the tooth.
- Incorrect vertical angulation leads to either elongated or foreshortened images.
  - Elongation: Occurs when vertical angulation is too flat, resulting in an image longer than the actual tooth
  - Foreshortening: Occurs when vertical angulation is too steep, resulting in an image shorter than the actual tooth.

Purpose and Use

The bisecting technique is used to:
- Detect incipient carious lesions in the interproximal area.
- Detect crestal bone loss.

Bite-Wing Radiographs

The film is positioned parallel to the crowns of both upper and lower teeth, and the central ray is directed perpendicular to the film.
The bite-wing radiograph should include:
- Distal half of the crowns of the cuspids
- Both premolars
- The first molars on both the maxillary and mandibular arches.
The molar film should be centered over the second molars.

Object Localization

Clark's rule / SLOB technique (Tube shift technique): A method to locate the position of a tooth or an object in the jaws.
Right angle technique for mandible: Another method to locate objects in the jaws.

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Description

Explore the bisecting technique used in dental radiography, including its applications, projection angles for different teeth, and advantages and disadvantages. This quiz will test your knowledge on the specifics of this essential dental imaging method.