Oral Radio Lec 4 Final

7/30/2019 Oral Radio Lec 4 Final

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Occlusal technique

-The occlusal technique is a method used to examine large areas ofthe upper or lower jaw.

."occludes" or bite on the filmThe film is so named because the patient-

intraoral film is used in the occlusal technique.Size 4-

-The occlusal radiograph is not common.

- When there is difficulty in making periapical radiograph, I can make anocclusal one, useful in very young children who cannot keep periapical

film in place.

-It is also used to localize an object in three dimensions. Because the

periapical and bitewings are 2-D radiographs. Whi le the occlusal

radiograph shows us:

1-mesiodistal dimension

2 occlusoapical dimension

)occlusal radiographonly seen in theBuccolingual dimension (-3


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Maxillary occlusal projections:

1. Maxillary topographic (also called standard cross sectionalradiograph in UK):

-it is used to examine the palate and the anterior teeth of the maxilla by

using size 4 film and Angulation +65

2. Maxillary pediatric radiograph: used to examine the anterior teeth of

the maxilla and use for children 5 years old or younger. (Size 2 film).Angulation +65

3. Maxillary lateral (right or left) (also called oblique in UK):

- used to examine the palatal roots of the molar teeth from one side only.

-It may also be used to locate foreign bodies or lesion on the posterior

maxilla by using Size 4 film and Angulation +60

*Mandibular occlusal projections:-Here you ask the patient to tilt his head so that the mandible will be

parallel with the floor. (About 45 degrees backward tilt).

1. Mandibular topographic: is used to examine the anterior teeth of the

mandible. (Size4 film)


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2. Mandibular cross sectional projection: used to examine the buccal

and lingual aspects of the mandible. And it is used to locate foreign

bodies or salivary stones in the region of the floor of the mouth. (Size 4

film)

3. Mandibular pediatric: used to examine the anterior teeth of the

mandible and use for children 5 years old or younger. (Size 2 film)

* The occlusal radiograph includes:

1. Localization of roots, impacted teeth, un-erupted teeth, foreign bodies,

and salivary stone.

2. Evaluation of size of lesion, boundaries of maxillary sinus, nasal fossa

and jaw fracture.

3. Examination of patient who cannot open their mouths.

4. Measurement of changes in size and shape of jaws.

*Note: To detect mandibular salivary gland:--Anterior 2/3 we can use occlusal radiograph

2-Posterior 1/3 we can use panoramic radiograph or lateral oblique

technique


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*Exposure & Technique Errors

Exposure errors which include:

1) Unexposed Film: Film appears clear. This is caused by failure to turn

on the X-ray machine. Or you press the exposure button without waiting

to listen the audible sound.

2) Film exposed to light: Film appears Black (very dark film) & this iscaused by accidentally exposing the film to white light so the film gets

burned. We have to protect the film & we shouldnt un-wrap it in a room

with white light.

3) Overexposed: Film also appears dark but NOT darker than Film

exposed to light. This is caused by increasing exposure time, Kilovoltage, Milliampere or a combination of these factors.

4) Underexposed: Film appears Light & this is caused by inadequate

exposure time, Kilo voltage, Milliampere or a combination of these

factors.


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**Periapical Film ErrorsTechnique Errors which include:

1) Periapical Film errors: these include

a) Film Placement errors: Film should be placed parallel to the teeth

and it should be positioned 2 mm beyond the apex & 1/8 inch beyond the

incisal/occlusal surface. A correct periapical film placement demonstrates

the entire tooth, including the apex and surrounding structures.

*Incorrect film placement:

1-Absence of apical structures.

- Dropped film corner: when the occlusal plane is slanted/tilted due to the

film not placed parallel to incisal-occlusal surfaces of the teeth.

*To avoid this you have to instruct your patient to hold the film firmly in

place, and you have to be very quick so that you wont initiate gagging

reflex for your patient.


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b) Angulation errors which include:

*Angulation:is a term used to describe the alignment of the central ray

(the x-ray beam) in the horizontal and vertical planes.

-I ncorr ect Horizontal Angulation: overlapped contacts appear on thefilm.

This happens when the central ray is not directed through the

Inter-proximal spaces so as a result, the proximal surfaces of adjacent

teeth appear overlapped in the peri-apical film.

- I ncorr ect Verti cal Angulation: this results in an image that is not thesame length as the tooth. The image may be:

1) Foreshortened (When vertical angulation is too excessive or too

steep the image of the tooth is shorter than the actual tooth)

2) Elongated (when the vertical angulation is too

flat so the image of the tooth on the film is longerthan the actual tooth).

*Both of these errors are rare nowadays since we

use a film holder now instead of using fingers to

hold the film.


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c) Beam Alignment errors / PID alignment problems:

-Occur when the PID is misaligned & the x-ray beam is not centered over.a partial image onlythe film so the resultant radiograph is

-The PID or cone is said to cut the image. A cone-cut appears as a clear

unexposed area on a dental radiograph & may occur with either a

rectangular or a round PID.

-This can happen in 2 ways:

=> a clear, unexposed area appears onfilm holderWITHcut-Cone-1

the film due to PID not properly aligned with the periapical holder so the

x-ray beam did not expose the entire film.

=> a clear unexposed area appearsfilm holderWITHOUTcut-Cone-2

on the film due to PID not directed at the center of the film so x-ray beam

did not expose the entire film.

2) Bite-Wing Film errors:

a) Film Placement Problems

b) Angulation Problems

c) PID alignment Problems

a) Film Placement Problems: Correct placement for bite-wing films

shows equal areas of the maxilla & mandible, occlusal plane exactly in

the middle.


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- Incorrect Film Placement may result in an absence of specific teeth or

tooth surfaces on a film, tipped occlusal plane, overlapped inter-proximal

contacts or a distorted image. Such errors may render a bite-wing film as

non-diagnostic.

- The most common error students make is that when they want to film a

premolar they put the film exactly on the first premolar so sometimes half

of the 1st premolar is not shown. To avoid this we should place the film

in the middle of the canine!!!

* Same thinggoes for the Molar bite-wing; we should place the film in

the middle of second premolar. Also in Molar bite wing; 3rd molars

should be visible on the film. Even if the patient doesnt have 3rd molars

that area should be visible on the film. This mistake is very common as

well.

b) Angulation Problems:

-Incorrect Horizontal Angulation which causes overlapping.

-Incorrect Vertical Angulation causes distortion on the film.


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c) PID alignment Problems:

-If PID is misaligned & the x-ray is not centered over the film, a partial

image is seen on the radiograph, this partial image is called cone-cut. It

appears as a clear area with a curved outline. Again this happens in 2ways:

1- Cone-cut WITH film holder => Due to PID not properly aligned with

the bite-wing film holder so the x-ray beam did not expose the entire film.

A clear, unexposed area on the film is the result.

2- Cone-cut WITHOUT film holder => Due to PID not directed at the

center of the film so the x-ray beam did not expose the entire film. A

clear, unexposed area on the film is the result.

*Our last topic is Miscellaneous Technique Errors which include:

1) Film Bending = caused by excessive bending & this cause the image

of the film appear stretched, elongated & distorted. This is common

when using finger technique.


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2) Film Creasing = Due to the film being creased and the film emulsion

are on the resultantthin radiolucent linescracked. As a result,

radiograph. (Permanent force on it or very excessive bending or long

nails could cause this)

3) Phalangioma = Patients finger appears on the film.

4) Double Exposure = Film was exposed in the patients mouth twice. It

happens sometimes if the dentist takes the radiograph, puts it in his

pocket and forgets it. Then after a while he finds it & assumes he didnt

use it so he uses it again

5) Movement = Blurred/hazy images appear on the film due to

movement of the patient during the exposure of the film.


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6) Reversed Film = Film was placed in the mouth backward then

exposed causing he lead foil to appear in the image & it would be light

with a tire-track/ herringbone pattern or a fish-skeleton appearance.

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Oral Radio Lec 4 Final