CHAPTER 16 ORAL RADIOGRAPHY

Intraoral Radiographs Latent Image: invisible image on the film, only visible after processing the film Types of Intraoral Radiographs: Periapical, Bite-wing, Occlusal (Table 16-1, pg. 236) Film Packet: consists of the outer wrap, lead foil, black paper, one or two films. (Fig. 16-1, pg. 236)white side is always placed toward the patients cheek/tooth, raised dot aids in mounting x-ray, black paper protects the film, lead foil absorbs the x-rays that pass through the film Double Film Packets: two pieces of film,, produces a duplicate of the image taken, mainly for insurance and referring out to a specialist X-Ray Film: semiflexible, coated on both sides with an emulsion containing x-ray sensitive crystal bromide, silver halide, silver iodine embedded in gelatin, size of the crystals determine the film speed, Fig. 16-2, Table 16-2 (pg. 237)

Film Storage: manufactures storage recommendations, protect from light, heat, moisture, chemicals, scatter radiation, Film Care During Exposure: dispense before procedure begins, place on clean towel, never leave films inside the room where films are being exposed Infection Control: Box 16-1, pg. 237, saliva is on the film from placing in and out of the patients mouth, use barriers and protective measures, See Procedure 16-1 (in lab) Periapical Radiographs: two techniques ( the paralleling technique, and bisecting angle technique Paralleling Technique: preferred and provides more accurate image of the teeth and surrounding tissues Bisecting Angle Technique: supplemental technique (fig. 16-4, pg. 239

Paralleling Technique Two Basic Principles: (1) film is placed parallel to the long axis of the teeth being radiographed (2) x-ray beam is directed at the right angles (perpendicular) to both the film and the long axis of the tooth Fig 16-4, b (pg. 239) Landmarks of the face for Xrays: Ala of the nose, Tragus of the Ear, Corner of the Eye

Film Holding Instruments: to place and keep the film packet in its proper position in relation to the tooth, paralleling technique requires the use of these instruments Fig. 16-5, pg. 239 Various ones Rinn XCP: common device to hold film, (extension cone paralleling), Fig. 16-6, pg. 239 these increase accuracy and reduces the need for retakes Procedure 16-2 (in lab) Factors for exposing Periapical Film: dental chair position, film position/placement, point of entry of the x-ray beam, vertical and horizontal angulation, use of film holding instrument Dental Chair Position: patients head is to be straight, upright position, occlusal plane is parallel to the floor Film placement and Position: film is placed in a vertical position for anterior and in a horizontal position for the posterior , film is held by the patient closing on bite-block or other film holding device

Film Placement and Position Cont: raised dot toward the occlusal surface, facing PID. Film position must be parallel to the entire mouth, not just to the crown. (because of tilting) Fig. 16-7, To achieve parallelism between the long axes of the teeth an film, film must be placed slightly away from the teeth toward the midline of the oral cavity. Films placed to close to the teeth may not record enough tissue in the area of the root apex. Film must be positioned away from the teeth , biting near the anterior edge Point of Entry: position on the patient’s face at which the central xray beam is aimed, completely covering the film Vertical Angulation: movement of the tubehead in and up/down direction Fig. 16-8, pg. 240, in paralleling technique the vertical angulation must be perpendicular to the film and to the long axes of the teeth or images will be elongated, foreshortented Fig. 16-9, 16-10, pg. 240,241

Horizontal Angulation: movement of the tubehead in a side to side direction Fig. 16-11, pg. 241 in the paralleling technique, the horizontal angulation of the x-ray beam must be directed through the contacts of the teeth and be perpendicular to the horizontal plane of the film if possible, failure to do this will cause overlapping of proximal contacts, fig 16-12, pg. 241 Bisecting Angle Technique: can be used in some special cases, ex. Difficult/unusual anatomy, patients with a shallow palate or short lingual frenum, or mandibular tori (boney masses) Basic Principles: based on the geometric principle of bisecting a triangle, two equal parts. Fig 16-13, pg. 242, angle is formed by the long axis of the teeth and the film is bisected and the beam is directed at the right angle to the bisecting line, film is placed close to the crowns of the teeth to be radiographed, extends at an angle into the palate floor of the mouth

Patient Positioning: midsagittal plane should be perpendicular to the floor, upright. Upright for the maxillary film and back slightly for the mandibular film. No. 2 size film is used for both anterior and posterior, only 3 films are need in the maxillary anterior region Beam Alignment: beam is directed to pass between the contacts of the teeth being radiographed in the horizontal dimension, just as it does in the paralleling technique. Vertical angle must be directed 90 degrees to the imaginary bisecting line, too much vertical angulation will produce images that are too short, to little vertical angulation will produce images that are to long. Always center beam, prevents cone cutting Table16-3, pg. 243

Full-Mouth Radiographs-(FMX): specified number of periapical and bite-wing x-rays. 10-18 films may be present for the set, Film to be used depends on, dentist instruction, number of teeth present, size of oral cavity, anatomic structures, age of patient, level of patient cooperation Fig 16-14 Bite Wings: Procedure 16-4, pg. 265 Occlusal Technique: procedure 16-5, pg. 267 Exposure and Technique Errors: diagnostic quality radiographs one that is properly placed, exposed, and processed, Errors Table 16-4, pg. 244 Infection Control: procedure 16-6, 16-7, pg. 268-269

Developer Solution: first step in processing, softens the emulsion, films are then rinsed in water, films must not be exposed to light or films will turn black Fixer Solution: second step in processing, removes the unexposed silver halide crystals and creates white to cleat areas on the radiographs, after fixed the film is washed, then dried Care and Maintenance of Solutions: Table 16-5, pg. 245 Manual Processing: Procedure 16-8, pg. 271 Dark Room: Fig.16-15