牙科放射線學 (1)

1. 牙科放射線學(1) Buccal Object Rule 從X光片辨識物體位置 陳玉昆副教授: 高雄醫學大學 口腔病理科 07-3121101~2755 yukkwa@kmu.edu.tw

2. Introduction Understandbuccal object rule Assessment of the impacted maxillary canine tooth position Conclusions References: 1. White & Pharoah: Oral radiology: principle & interpretation, 5th edition, Chapter 5, p. 91-93 2. Eric Whaites: Essentials of dental radiography & radiology, 3rd edition, p.7, 8, 113, 279-283 學 習 目 標

3. Introduction * In 1909, Clark [1] reported a radiographic procedure for the localization of impacted teeth. * The Buccal Object Rule is a method for determining the relative location of objects hidden in the oral region. * The initial concepts of the procedure were reported in 1952 & 1953 [2, 3] & since that time the procedure has been developed to its present state of refinement & usefulness. [1] CLARK C A. A method of ascertaining the relative position of unerupted teeth by means of film radiographs. Royal Society of Medicine Transactions 3:87-90, 1909-1910. [2] RICHARDS AG. Roentgenographic localization of the mandibular canal. Journal of Oral Surgery 10:325-329, 1952. [3] RICHARDS AG. The Buccal object rule. Journal of the Tennessee State Dental Association 33:263- 268, 1953.

4. Lingual Buccal object rule Mesial shift Tube shift technique 同方向移動 Clake’s rule (1910) Zygomatic process 往mesial方向移 (與X-ray beam相反方向移動) Buccal Distal shift Zygomatic process Mesial shift 相反方向移動 Direct orientation Understand buccal object rule X-ray beam X-ray beam Ref. 1

5. Assessment of the impacted maxillary canine tooth position • Parallax in the horizontal plane • Parallax in the vertical plane • A vertex occlusal • A true PA and lateral skull views • (two views at right angles) *Impacted maxillary canine teeth occur in about 2% of the population.

6. Left Right Front Opposite Buccal Same Lingual 1. Parallax in the horizontal plane Principle of parallax: The apparent displacement of an object due to different positions of the observer Object moves in different direction SLOB (近方) (遠方) Ref. 2

7. Position 2- distal shift Position 2 11 Position 1- centrally oriented Position 1 (遠方-palatal side) Same Lingual 12 1. Parallax in the horizontal plane Ref. 2

8. 12 22 22 12 11 21 21 Opposite Buccal Same Lingual 1. Parallax in the horizontal plane Choice (近方) (遠方) Ref. 2

9. Opposite Buccal Same Lingual 1. Parallax in the horizontal plane Choice (近方) (遠方) Crown Apex Ref. 2

10. Unerupted mesiodens Upper occlusal Panorex Crown portion (遠方-palatal side) SLOB Apex portion (近方-labial side) Opposite Buccal Same Lingual 2. Parallax in the vertical plane Ref. 2

11. 3. A vertex occlusal Not recommended due to high radiation dose Vertex occlusal Ref. 2

12. Similar images PA view PA view Mass of head in a different position & different shape Similar images Lateral view Radiodense object 4. A true PA and lateral skull views (two views at right angles) Ref. 2

13. Conclusions http://www.unc.edu/~jbl/

14. Conclusions http://www.unc.edu/~jbl/

15. Conclusions http://www.unc.edu/~jbl/

16. Summaries Knowing : Understand Clake’s rule Assessment of the impacted maxillary canine tooth position

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