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Diagnostic radiology
Lec. 22
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Object localization
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Localization techniques can be used to obtain the
dimensional information , so we can use it to locate
the following :
1.Foreign bodies .
2.Impaction teeth .
3.Unerupted teeth .
4.Salivary stones .
5.Retained roots .
6.Broken needles .
Types of localization techniques :
1.Right angle technique .
2.Tube shift technique
3.Stereo radiography .
4.Radiopaque media technique .
The first two techniques are the more used because of
there simplicity and accuracy .
Right angle technique .
This technique involve the use of at least two films
taken in at right angle to each other .
A. One periapical film is exposed using the proper
technique and angulations to show the position of
the object in a superior inferior and anterior
posterior relation .
B .An occlusal film is exposed directing the central
ray at right angle to the film .
The occlusal film show the object in a bucco- lingual
and anterior posterior relationships .
After the two films have been exposed and
processed , the radiographs are compared together to
locate the object in three dimensions .
This technique is mainly used to detect object in
the mandible . On a maxillary occlusal projection
the superimposition of features in the anterior part of
the skull may frequently obscure the area of
interest.
The periapical radiograph shows impacted canine
lying apical to roots of lateral incisor and first
premolar .
Occlusal view shows that the canine lies palatal to the
roots of the lateral incisor and first premolar.
Tube shift technique :
This technique is also called Buccal object rule or
Clarks rule .This rule governing the orientation of
structure portrayed in two radiographs exposed at
different angulations .
One periapical or bite wing film is exposed using
proper technique and angulations .
A second periapical or bite- wing film is then exposed
after changing the direction of the x ray beam
, a different horizontal or vertical angulations is
used .
When the dental structure or object seen in the second
radiograph appears to have moved in the same
direction as the shift of the tubehead ,
the structure or object in question is positioned to the
lingual .
An object on the lingual surface of the mandible may
appear apical to the second premolar .
The object appears to have moved mesially with
respect to the second premolar apex .
When the dental structure or object seen in the second
radiograph appears to have moved in the direction
opposite the shift of the tube .
the structure or object in question is positioned to the
buccal .
An object on the buccal surface of the mandible may
appear apical to the second premolar .When another
radiograph is made of this region angulated from the
mesial .
The object appears to have moved distally with respect
to the second premolar apex .
SLOB
Same = Lingual
Opposite = Buccal
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