Brd Rev Buccalobject

8/8/2019 Brd Rev Buccalobject

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Welcome. In navigating through the slides, you

should click on the left mouse button when (1), you

see the mouse holding an x-ray tubehead (seebelow), (2) you are directed to click for the next

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The following slides describe

Object Localization, including the

Right Angle Technique and the

Tube Shift Technique.

Object Localization


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A periapical film will identify the location of an object

vertically and in a horizontal (mesiodistal) direction.

However, we cannot tell where the object is located

buccolingually, since the periapical film is two-

dimensional. Therefore we need another method for

locating objects in a buccolingual direction. The twoprimary methods of determining the buccolingual

location of objects are:

Right-Angle Technique (Occlusal projection)

Primarily identifies buccolingual location, but may

also confirm mesiodistal location seen on periapical

Tube-shift Technique (SLOB rule, Clarks rule)

Utilizes two films with different horizontal or vertical

angulations

Object Localization


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Right Angle (Occlusal) technique

Right Angle Technique

Once you have identified an object on the periapicalfilm, you can take an occlusal film with the beam at a

right angle (perpendicular) to the direction of the beam

for the periapical. The beam may also be perpendicular

to the film, especially in the mandible. The occlusal film

below shows that the impacted canine is linguallypositioned.


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Tube-Shift Localization (Clark)

SLOB RuleSame Lingual Opposite Buccal

The SLOB rule is used to identify the buccal orlingual location of objects (impacted teeth, root

canals, etc.) in relation to a reference object

(usually a tooth). If the image of an object moves

mesially when the tubehead is moved mesially(same direction), the object is located on the

lingual. If the image of the object moves distally

when the tubehead moves mesially (opposite

direction), the object is located on the buccal.


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For the SLOB rule to work, there must be a

change in the horizontal or vertical

angulation of the x-ray beam as the tubeheadis moved. This change in angulation will alter

the relationship between the object of

interest and the reference object, allowing

you to determine the buccal or linguallocation.

The closer the object to be localized is to thereference object, the less the amount of

movement of the image of the object in

relation to the reference object.


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In the diagram at right, the

tubehead is moved, but there is no

change in direction of the x-ray

beam, which results in no change

in location of the object of interest

in relation to reference object (see

below). Moving the tubehead

without changing the beam

direction would often result in a

cone cut , depending on how far

the tubehead is moved (see below

right).


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When using the SLOB rule, the direction of the beam

must be opposite to the way the tubehead is moved.

Horizontal Tube Shift: When the tubehead is moved

mesially, the beam must be directed more distally (from

the mesial). If the tubehead is moved distally, thedirection of the beam must be more towards the mesial

(from the distal).

Vertical Tube Shift: The SLOB rule also works for

movement of the tubehead in a vertical direction.Downward movement of the tubehead requires that the

beam be directed upward and when the tubehead is

moved upward, the beam must be directed downward.


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Moving the tubehead mesially or distally and changing the

direction of the x-ray beam (as described in the previous slide) will

result in the movement of the object of interest on the film in

relation to the reference object. In the diagram below, the tubeheadis moved distally with the x-ray beam directed more mesially (from

the distal). The object of interest, located lingual to the first molar,

moves distally, in the same direction as the tubehead movement.

(Objects closer to the film move less distance than objects farther

from the film; in the example shown below, both the tooth and

object move forward on the film, but the lingual object , being

closer to the film, moves less and appears to move distally in

relation to the tooth).


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incisors

canine

premolar

molar

Horizontal movement of the tubehead and x-ray beam

In moving from the incisor film to the canine film, the canine

film to the premolar film and the premolar film to the molar

film, the tubehead moves distally and the beam is directedmore mesially. There is not much change in angulation from

the premolar to the molar film; the normal situation would

be that the beam is directed slightly more from the distal (or

to the mesial) as the tubehead is moved distally for the

molar projection.


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In the diagram at left, the

buccal (yellow) and lingual

(red) objects of interest are

superimposed on each other

because the beam is directedperpendicular to both of them

and they are in the same

relative position mesiodistally

and vertically. Both images arelocated above the second

molar.

mesial

distal

mesialdistal

Horizontal movement


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tubehead is moved distallyand the beam is directed

mesially. On the radiograph,

the buccal object of interest

(yellow) moves mesially(opposite to tubehead

movement) in relation to the

second molar and the lingual

object of interest (red) moves

distally (same direction astubehead) in relation to the

second molar.

mesialdistal

mesial

distal

Horizontal movement


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In the diagram at right, thetubehead is moved mesially

and the beam is directed

distally. On the radiograph, the

buccal object of interest

(yellow) moves distally

(opposite to tubehead


second molar and the lingual

object of interest (red) movesmesially (same direction as

tubehead) in relation to the

second molar.

mesial

distal

mesialdistal

Horizontal movement


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buccal (yellow) and lingual

(red) objects of interest are

superimposed on each other

because the beam is directedperpendicular to both of them

and they are in the same

relative position mesiodistally

and vertically. Both images are

superimposed over the

mandibular second premolar.

Vertical movement


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In the diagram at left, thetubehead is moved upward


downward. On the radiograph,


(yellow) moves down

(opposite to tubehead


second premolar and the

lingual object of interest (red)moves up (same direction as


second premolar.

Vertical movement


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In the diagram at left, thetubehead is moved downward


upward. On the radiograph,


(yellow) moves up (opposite

to tubehead movement) in

relation to the second

premolar and the lingual

object of interest (red) movesdown (same direction as


second premolar.

Vertical movement


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Usually when using the tube-shift method of

localization, two films are taken of the same areausing different beam angulations. However, this

localization technique will also work when

comparing films taken as part of a complete series

of radiographs. The only difficulty is determiningwhich way the beam was directed when

comparing the molar and premolar films. Usually

this can be done by comparing the relative

positions of anatomical structures (e.g., zygomatic

process in maxilla or mental foramen in mandible)or the angulation of the roots of the teeth.

(See following two slides).


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For the films above, we know that the tubehead was moveddistally from the premolar to the molar film. The zygomatic

process (red arrows) is located at the distal aspect of the 2nd

molar on the premolar film and it is located over the distal

aspect of the 1st molar on the molar film. This indicates that

it moved mesially as the tubehead moved distally. We know

that the zygomatic process is buccal to the teeth and, using

the SLOB rule, it follows that the x-ray beam was directed

more mesially on the molar film (Buccal object moved

opposite to tubehead movement).

premolar molar


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Richards Method of Object Localization

This method of determining the buccolinguallocation of objects was first suggested by

Richards. It utilizes similar ideas to Clarks

method, but it emphasizes beam direction instead

of tubehead movement. If the beam is directeddistally, buccal objects will move distally in

relation to the reference object; lingual objects

move mesially, or opposite to beam direction.

Although this method certainly works, I feel it iseasier to use tubehead movement (SLOB) for

object localization.


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On the following six pre-test slides, identify the

buccal or lingual location of the selected objects.

Each slide will be followed with a slide indicating

the correct response and a brief explanation.


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Is the composite restoration on tooth # 8 (arrows)

located on the buccal or lingual?

canine film incisor film1

The restoration is located on the buccal. The tubehead

moves mesially from the canine film to the incisor film

(x-ray beam projected more distally) and the composite

moves distally, which is the opposite direction.


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canine filmpremolar film

The arrow in the canine film is pointing to the gutta

percha in which canal of the maxillary first premolar?

2

The arrow identifies the lingual canal. The tubehead moves

mesially from the premolar film to the canine film (beam

directed more distally) and the gutta percha indicated by

the arrow also moves mesially. (See following slide).


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PID

lingual

buccal

When the tubehead is moved mesially, with the beamdirected distally, the two canals, which are initially

superimposed (premolar periapical above) will separate.

The lingual canal (red arrow) will follow the tubehead

movement and the buccal canal (blue arrow) will move in

the opposite direction, as seen on the canine film.


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The red arrow is pointing to the gutta percha in

which canal of this maxillary left first premolar?

This is the buccal canal. The tubehead goes

distally from the canine film to the premolar filmand the gutta percha moves mesially to be

positioned over the lingual canal which has the

threaded post.

The pink arrow points to a threaded post. In which

canal of this maxillary left second premolar is thepost located?

The post is located in the lingual canal. As the

tubehead moves distally from the canine film tothe premolar film, the post also moves distally

to cover the canal that has all gutta percha.

3


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Is the maxillary second

premolar (arrows)

displaced to the buccal

or the lingual?

premolar film molar film

premolar bitewing

4

The tubehead moves distally from

the premolar film to the molar film.

The second premolar also moves

distally, overlapping the first molar

more in the molar film. In movingfrom the premolar periapical to the

bitewing, the tubehead moves

down and the premolar also moves

down. The displacement is to the

lingual.


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incisor film canine film

Is the displaced incisor (arrows) located on the buccal

or the lingual?

5

The lateral incisor is displaced to the lingual. The

tubehead moves distally from the incisor film to the

canine film. The lateral incisor also moves distally,

covering half the canine on the canine film.


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film placement for canine filmfilm placement for premolar film

root tip


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7

The maxillary right lateral incisor is tilted out of position.

In which direction (buccal or lingual) is it tipped?

premolar film incisor film


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incisor film canine film8

The maxillary left canine is impacted. Is it located more

to the buccal or the lingual?


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premolar periapical film

premolar bitewing film

10

The mandibular second

premolar is tilted out of

position. In whichdirection (buccal or

lingual) is it tipped?


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premolar film molar film

12

Does the arrow point to the mesiobuccal or mesiolingual

canal?


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molar bitewing film

molar periapical film

13

The amalgam particle

indicated by the arrows

is located bucally or

lingually?


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Is the restoration

indicated by the red

arrows located on thebuccal or lingual of the

first premolar?

canine periapical film

premolar periapical film

premolar bitewing film14


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15

incisor film canine film

premolar film

The gutta percha root canal filling identified by the red

arrows is located in which canal?

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Brd Rev Buccalobject