RAD Ch. 21: Occlusal Films and Buccal Object Rule

1. RAD Ch. 21: Occlusal Films and Buccal Object Rule DA 118 Radiology

2. Purposes and Uses of Occlusal Film • Examine large areas of upper or lower jaw • Used in conjunction with periapical x-rays or bitewing x-rays • White side of film positioned toward PID • No film holder; film is stabilized when patients bites the film • Adult: Size 4; pediatric: Size 2

3. Edentulous Patient:Periapical and Occlusal X-Rays

4. Why use an Occlusal Film? • Locate retained roots of extracted teeth • Locate supernumerary, unerupted, or impacted teeth • Locate foreign bodies or salivary stones • Locate and evaluate extent of lesions (cysts, tumors) • Evaluate boundaries of the maxillary sinus • Evaluate fractures of maxilla or mandible • Examine area of cleft palate • Examination of patients with limited opening • Measure changes in size and shape of jaw

5. Maxillary Occlusal Films • Patient head position: maxillary arch is parallel to floor; midsagittal plane is perpendicular to floor • Topographic Projection • Lateral Projection • Pediatric Projection

6. Maxillary Topographic Projection Palate and anterior teeth CR = +65 Size 4 film

7. Maxillary Lateral Projection • Palatal roots of the molars • Locate foreign bodies or lesions in the posterior maxilla • CR =+60 • Size 4 film

8. Pediatric Projection • Anterior teeth of the maxilla • Recommended for ages 5 and under • CR = +60 • Size 2 film

9. Mandibular Occlusal Films Position patient: • Occlusal plane is perpendicular to floor OR • Occlusal plane is parallel to floor • Topographic Projection • Cross-Sectional Projection • Pediatric Projection

10. Topographic • Anterior teeth of the mandible • CR = -55 • Size 4 film

11. Cross-Sectional Projection • Buccal and Lingual aspects of the mandible • Locate foreign bodies or salivary stones in the region of floor of the mouth • CR = 90 (0) • Size 4 film

12. Pediatric Projection • Anterior teeth of the mandible • Recommended for use in children ages 5 years and under • CR = -55 • Size 2 film

13. Localization Techniques • Used to locate the position of a tooth of object in the jaws • X-ray is a 2-dimensional image of a 3-dimensional structure; does not show the depth of the structure 1.Buccal-Object Rule 2.Right-angle Technique

14. Buccal Object Rule • Governs the orientation of structures portrayed in two radiographs exposed at different angulations • One periapical or bite-wing film is exposed using proper technique and angulation • A second periapical or bite-wing film is exposed after changing the direction of the x-ray beam • TWO PERIAPICAL FILMS

15. Buccal Object aka “SLOB Rule” • S = SAME • L = LINGUAL • O = OPPOSITE • B = BUCCAL • IF the structure or object seen in the 2nd x-ray appears to move in the same direction as the PID, item is positioned on the lingual • If the structure or object seen in the 2nd x-ray appears to move in the opposite direction as the PID, item is positioned on the buccal

16. Same * Lingual Opposite * Buccal

17. SLOB Rule • When two radiographs are compared, the object that lies to the lingual appears to have moved in the same direction as the PID, and the object that lies to the buccal appears to have moved in the opposite direction as the PID.

18. Right-angle Technique • Another method to determine orientation of structures. • One PA x-ray: • exposed using proper technique and angulation • shows the position in the superior-inferior, anterior-posterior relationship • One occlusal film: • exposed directing CR at right angle to the film; • shows the object in the buccal-lingual and anterior-posterior relationships • Primary use: locate objects in the mandible

19. Right-Angle Technique Example • PAx-ray shows that there is an object located between the first premolar and the canine, subgingivally • Occlusal film indicates that the object is on the lingual aspect of the mandible

20. Exercises # 11-14

21. Exercise #15