Wk 2 Intraoral Radiography PDF

Film holding devices ForAnteriorteeth Forposterior teeth  The x-rays pass through the contact areas of the premolars because the central ray is directed through the contacts and perpendicular to the film.  The Bisecting Technique The bisection of th...

Film holding devices ForAnteriorteeth Forposterior teeth  The x-rays pass through the contact areas of the premolars because the central ray is directed through the contacts and perpendicular to the film.  The Bisecting Technique The bisection of the angle technique is based on a geometric principle of bisecting a triangle (bisecting means dividing into two equal parts). The angle formed by the long axis of the teeth and the film is bisected, and the x-ray beam is directed perpendicular to the bisecting line. Perpendicular means at a right angle to the film. Bisecting angle technique CENTRAL RAY BISECTOR LONG AXIS OF THE TOOTH LONG AXIS OF FILM  Principle The x-ray beam is directed perpendicular to an imaginary line which bisects the angle formed by the long axis of the tooth and the long axis of the film. v  Projections Teeth Maxilllary Mandibular Incisors +40 -15 Canines +45 -20 Premolars +30 -10 Molars +20 -05  Indications Shallow palate Palatal tori Tongue tie/ high lingual frenum  Advantages Comfort Snap –A-Ray film holders- easy to use Easy film accommodation  disadvantages Distortion of image Positioning error/ operator error Film movement by patient PID Angulations: Bisecting Technique In the bisecting technique, the angulation of the PID is critical. Angulation is a term used to describe the alignment of the central ray of the x-ray beam in the horizontal and vertical planes. Angulation can be changed by moving the PID in either a horizontal or vertical direction. The bisecting angle instruments (BAI) with aiming rings dictates the proper PID angulation. Horizontal Angulation Horizontal angulation refers to the positioning of the tubehead and direction of the central ray in a horizontal, or side-to-side, plane. The horizontal angulation remains the same whether you are using the paralleling or bisecting technique. Correct Horizontal Angulation With correct horizontal angulation, the central ray is directed perpendicular to the curvature of the arch and through the contact areas of the teeth. Incorrect horizontal angulation results in overlapped (unopened) contact areas. A film with overlapped contact areas cannot be used to examine the interproximal areas of the teeth. Correct horizontal angulation. Incorrect horizontal angulation. Overlapped contacts. v Vertical Angulation Vertical angulation refers to the positioning of the PID in a vertical, or up-and-down, plane. The vertical angulation differs according to the radiographic technique being used: With the paralleling technique, the vertical angulation of the central ray is directed perpendicular to the film and the long axis of the tooth. With the bisecting technique, the vertical angulation is determined by the imaginary bisector; the central ray is directed perpendicular to the imaginary bisector. Correct Vertical Angulation Correct vertical angulation results in a radiographic image that is the same length as the tooth. Incorrect vertical angulation results in an image that is not the same length as the tooth being radiographed. The image appears either longer or shorter: Elongated Foreshortened  Foreshortening A- If the vertical angulation is to too steep, the image on the film is shorter than the actual tooth. B- Foreshortened images. Elongation A- If the vertical angulation is to too flat, the image on the film is longer than the actual tooth. B- Elongated images.  Purpose and use To detect incipient carious lesions in interproximal area To detect crestal bone loss  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 premolar bite-wing radiograph should include the distal half of the crowns of the cuspids, both premolars, and often 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) Right angle technique for mandible Method to locate the position of a tooth or an object in jaws