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1. Buccal Object Rule
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2. 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
Conclusions
學 習 目 標
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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.
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5. Tube shift technique
Buccal object rule
Clake’s rule (1910)
Lingual
Mesial shift
同方向移動
Buccal
Mesial shift 相反方向移動
X-ray beam
X-ray beam
Ref. 1
Distal shift
Zygomatic process
往mesial方向移
(與X-ray beam相反
方向移動)
Direct
orientation
Zygomatic
process
Understand buccal object rule
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6. Assessment of the impacted
maxillary canine tooth position
1. Parallax in the horizontal plane
2. Parallax in the vertical plane
3. A vertex occlusal
4. A true PA and lateral skull views
(two views at right angles)
*Impacted maxillary canine teeth occur in about 2% of the population.
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7. 1. Parallax in the horizontal plane
Front RightLeft
Principle of parallax: The apparent displacement of
an object due to different positions of the observer
Opposite BuccalSame Lingual SLOB
Object moves in different direction
(遠方) (近方)
Ref. 2
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8. Position 1-
centrally
oriented
Position 2-
distal shift
Same Lingual
(遠方-palatal side)
11
12
1. Parallax in the horizontal plane
Ref. 2
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9. 1. Parallax in the horizontal plane
Opposite BuccalSame Lingual
(遠方) (近方)
22
21
12
1112 22
21
Choice
Ref. 2
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10. 1. Parallax in the horizontal plane
Opposite BuccalSame Lingual
(遠方) (近方)
CrownApex
Choice
Ref. 2
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11. Panorex
Upper occlusal
Unerupted
mesiodens
Crown portion
(遠方-palatal side)
Apex portion
(近方-labial side)
SLOB
Same Lingual
Opposite Buccal
2. Parallax in the vertical plane
Ref. 2
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12. Vertex occlusal
Not recommended
due to high radiation
dose
3. A vertex occlusal
Ref. 2
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13. 4. A true PA and lateral skull views
(two views at right angles)
Lateral view
Similarimages
Radiodense objectRef. 2
Mass of head in a different
position & different shape
Similar images
PA view
PA view
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14. Conclusions
http://www.unc.edu/~jbl/
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15. Conclusions
http://www.unc.edu/~jbl/
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16. Conclusions
http://www.unc.edu/~jbl/
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17. Summaries
Knowing :
Understand Clake’s rule
Assessment of the impacted
maxillary canine tooth position
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