口腔顎顏面放射線學會 專科醫師繼續教育課程 Buccal Object Rule 從X光片辨識物體位置 2011/11/05 陳玉昆副教授: 高雄醫學大學 口腔病理科 07-3121101~2755 yukkwa@kmu.edu.tw

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

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 rule is: When two different radiographs are made of a pair of objects, the image of the buccal object moves, relative to the image of the lingual object, in the same direction that the X-ray beam is directed. * 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.

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

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.

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 Front Right Left Same Lingual Opposite Buccal SLOB (遠方) (近方) Ref. 2

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

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

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

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

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

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

Summaries http://www.unc.edu/~jbl/

Summaries http://www.unc.edu/~jbl/

Summaries http://www.unc.edu/~jbl/

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