Buccal Object

8/3/2019 Buccal Object

1/46

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.


2/46

For the SLOB rule to work, there must be

a change in the horizontal or vertical

angulation of the x-ray beam as the

tubehead is 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 lingual location.

The closer the object to be localized is tothe reference object, the less the amount

of movement of the image of the object in

relation to the reference object.


3/46

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 changein 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).


4/46

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.


5/46

Moving the tubehead mesially or

distally and changing the direction of

the x-ray beam (as described in

previous slide) will result in themovement of the object of interest on

the film in relation to the reference

object. In the diagram at right, the

tubehead is 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.


6/46

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.


7/46

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


8/46


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


9/46

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


10/46

Maxillary PA

BW

Mandibular PA

Vertical movement of the tubehead and x-ray beam

In moving from the maxillary periapical to the bitewing

and from the bitewing to the mandibular periapical, the

tubehead moves down and the beam is redirected

upward (opposite direction; decreased vertical

angulation).


11/46


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


12/46

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


13/46

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


14/46

Usually when using the tube-shift method of

localization, two film 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).


15/46

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 tubehead was directed

more mesially on the molar film (Buccal object moved

opposite to tubehead movement).

premolar molar


16/46

premolar molar

Another way of determining the change in the directionof the beam is to look at the angulation of the teeth. In

the premolar film, the roots of the teeth are angled

distally, indicating that the beam was directed distally

(from the mesial). In the molar film, the roots are more

upright or angled slightly mesially, indicating the beamwas directed more mesially (from the distal). Therefore,

the tubehead shifted distally and the beam was angled

in the opposite direction, allowing the use of the SLOB

rule (These films were taken from Slide 3 in the review

films to follow).


17/46

On the following 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.


18/46

Is the composite restoration on tooth # 8 (red arrow)

located on the buccal or lingual?

canine film incisor film1


19/46

The restoration is located on the buccal. The tubehead

moves mesially from the canine to the incisor film (x-ray

beam projected more distally) and the composite moves

distally, which is the opposite direction.

canine film incisor film1


20/46

canine filmpremolar film

The red arrow in the canine film is pointing to the gutta

percha in which canal of the maxillary first premolar?

2


21/46

canine filmpremolar film

The arrow identifies the lingual canal. The tubehead

moves mesially from the premolar to the canine film

(beam directed more distally) and the gutta percha

indicated by the arrow also moves mesially.

2


22/46

PID

lingual

buccal

When the tubehead is moved, with the beam angulationredirected in the opposite direction, 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.


23/46

Is the maxillary second

premolar displaced to the

buccal or the lingual?

premolar film molar film

premolar bitewing

3


24/46


premolar bitewing

The tubehead moves distally from the

premolar film to the molar film. The

second premolar also moves distally,

overlapping the first molar more in themolar film. In moving from the

premolar periapical to the bitewing,

the tubehead moves down and the

premolar also moves down. The

displacement is to the lingual.

3


25/46

incisor film canine film

Is the displaced incisor (arrow) located on the buccal or

the lingual?

4


26/46


The lateral incisor is displaced to the lingual. The

tubehead moves distally from the incisor to the canine

film. The lateral incisor also moves distally, covering

half the canine on the canine film.

4


27/46

canine film

premolar film

Is the radiopaque object identified by the arrow located

on the buccal or the lingual?

5


28/46

canine film

premolar film

Lingual. The tubehead moves mesially from the premolar

film to the canine film. The object also moves mesially,starting out distal to the first molar on the premolar film and

ending up mesial to the first molar on the canine film. This

object is apparently located toward the center of the palate

because of the extreme movement from distal to mesial on

the films.

5


29/46

6

The maxillary right lateral incisor is tilted out of position.

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

premolar film incisor film


30/46

6

The tubehead moves mesially from the premolar film to the

incisor film. The lateral incisor also moves mesially,

starting out overlying the canine on the premolar film and

ending up over the central incisor on the incisor film. Since

the lateral moves the same direction as the tubehead, it is

tipped lingually.

premolar film incisor film


31/46

incisor film canine film7

The maxillary left canine is impacted. Is it located more

to the buccal or the lingual?


32/46

canine filmincisor film 7

The tubehead moves distally from the incisor film to the

canine film. The impacted canine also moves distally,

starting out overlying # 9 on the incisor film and ending up

over the lateral incisor on the canine film. The impacted

tooth is located on the lingual (palatal).


33/46

premolar bitewing film

8

The amalgam restoration

indicated by the arrow islocated on the buccal or

the lingual?

premolar periapical film


34/46

8

The tubehead moves downfrom the premolar

periapical film to the

bitewing film. The

restoration also moves

down, starting out abovethe two occlusal

restorations (red arrows)

on the periapical film and

ending up overlapping the

occlusal restorations onthe bitewing film. The

restoration (black arrow) is

located on the lingual.




35/46



9

The mandibular second

premolar is tilted out of

position. In whichdirection (buccal or

lingual) is it tipped?


36/46

9

The tubehead moves

down from the premolar

bitewing film to the

periapical film. Thesecond premolar also

moves down, indicating

that it is lingually tipped.




37/46

molar bitewing film

molar periapical film

10

The arrow points to a

retention pin. Is the

pin located in thebuccal or lingual

portion of the tooth?


38/46

10

The tubehead movesdown from the molar

bitewing film to the

periapical film. The

pin identified by the

arrows also movesdownward. Since the

movement of the pin

follows the direction

the tubehead was

moved, it is locatedtoward the lingual

aspect of the tooth.

molar bitewing film



39/46


11

Does the arrow point to the mesiobuccal or mesiolingual

canal?


40/46

11

The tubehead moves distally from the premolar film to themolar film. The canal indicated by the arrow also moves

distally to align with the other canal, which moves mesially

(The canals have to move in opposite directions in order to

be superimposed on each other). The indicated canal

(arrow) is located mesiolingually.



41/46

molar bitewing film


12

The amalgam particle

indicated by the arrows

is located bucally orlingually?


42/46

The tubehead moves down

from the bitewing film to the

mandibular periapical film.

The amalgam particle moves

upward (opposite direction),indicating that it is located

buccally.

12

molar bitewing film



43/46

Is the restoration

indicated by the red

arrows located on thebuccal or lingual of the

first premolar?

canine periapical film


premolar bitewing film13


44/46

The tubehead moves distally from

the canine film to the premolar

periapical. The restoration moves

mesially. From the bitewing to themandibular premolar periapical, the

tubehead moves down and the

restoration moves up. The

restoration is located on the buccal

of # 21.canine periapical film


premolar bitewing film13


45/46

14


premolar film

The gutta percha root canal filling identified by the red

arrows is located in which canal?


46/46

14


premolar film

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

then from the canine film to the premolar film, the

tubehead moves distally. The gutta percha (red arrow)

also moves distally in each case. Therefore, it is in the

lingual canal

Documents

Buccal Object