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Introduction

Orthopantomogram   (OPG)

Also known as an "orthopantogram" or "panorex", is a panoramic scanning dental X-ray of the upper and lower jaw. It shows a two-dimensional view of a half-circle from ear to ear.

Diagnostic uses

OPGs are used by Dentists to provide information on:

Impacted wisdom teeth

Periodontal bone loss

Finding the source of dental pain

Assessment for the placement of dental implants

Orthodontic assessment

The most common use is to determine the status of wisdom teeth.

Principal of orthopantomography

Orthopantomography (OPG) provides a complete view of the teeth and jaws in one image.

The following regions can be represented with this technique:

The dentoalveolar region of both jaws

The osseous structure of the maxilla

The osseous structure of the mandible

Odontogenic myxoma

The odontogenic myxoma is an odontogenic tumor arising from the dental papilla. It is more common

in young adults and affects the mandible more than the maxilla. Usually, the odontogenic myxoma is

painless but can cause a swelling. On radiographs, it appears as a multilocular radiolucency (dark

area) with short, straight trabeculae. As a result, this appearance is usually described as

"honeycomb-like".

Odontogenic tumor

A odontogenic tumor is a neoplasm of the cells or tissues that initiate Odontogenic 

processes. An example is ameloblastoma.

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Anatomy

Orthopantomogram: Mixed dentition

This   x-ray   scan   illustrates the maxilla   and   mandible , all the   teeth including the " wisdom teeth ," the frontal, nasal and   maxillary   sinus   air spaces and the   temporomandibular joint   complex or "TMJ".

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Case report

Odontogenic myxoma

This 31-years old man presented with a gradual increasing swelling of the right lower jow. So, he come for checking the problem that he had.

Image modality

Using The OPG it shows a trabeculated, expansile lesion. Dental panoramic radiography equipment

consists of a horizontal rotating arm which holds an X-ray source and a moving film mechanism

(carrying a film) arranged at opposed extremities.

Technical detail

X-ray machine The patient's skull sits between the X-ray generator and the film. The X-

ray source is collimated toward the film, to give a beam shaped as a

vertical blade having a width of 4 – 7 mm when arriving on the film, after

crossing the patient's skull. Also the height of that beam covers

the mandibles and the maxilla regions. The arm moves and its movement may

be described as a rotation around an instant center which shifts on a

dedicated trajectory.

The manufacturers propose different solutions for moving the arm, trying to

maintain constant distance between the teeth to the film and generator. Also

those moving solutions try to project the teeth arch as orthogonally as possible.

It is impossible to select an ideal movement as the anatomy varies very much

from people to people. Finally a compromise is selected by each manufacturer

and results in magnification factors which vary strongly along the film (15% -

30%). The patient positioning is very critical in regard to both sharpness and

distortions.

Cassette size There are two kind of film moving mechanisms one using a sliding flat cassette which holds the film and another

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using a rotating cylinder which has the film wound around. There are two standard sizes for dental panoramic films 30cm x12cm (12"x 5") and 30cm x 15cm (12"x6"). The smaller size film involves 8% less of X-ray dosage.

Exposure factor kVp The kvp range from 70 to 80

mAs Exposure time varies from 10 to 20 second

Grid It using grid

Source image Follow the height of patient distance (SID)

Projection done The whole this meant that from posterior to anterior

Patient position Stand or seat

Part position When positioning a patient for a panographic view of the mandible. The patient’s spine must be straight, with the hips slightly forward; the head should not lean forward. The patient should rest the chin on the chin rest. The height of the chin rest must then be adjusted so the infraorbitomeatal line is parallel with the floor; the occlusal plane will slant 10o from posterior to anterior.

In evaluation of the finished radiography, the entire mandible, booth TMJs ( temporomandibular joint ), and the inferior portions of the nasal fossae and maxillary sinuses should be demonsrated with the upper and lower teeth slightly seperated. The density should be uniform across the entire mandible, with no density loss near mentum. Because it cannot be used to describe the position of fracture fragment. It also can be use for a general survey of dental abnormalities.

Cassette position The position of cassette must be crosswise

Beam direction and Vertical blade beam with entering the patient skull and for center centring point must include mandibles and the maxilla regions.

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Protection Lead gown is used

Instruction given The patient should be instructed to close the mouth, bite on a spacer , and hold the tongue againt the roof of the mouth during the exposure.

An OPG-Unit

Orthopantomogram (O.P.G) X-ray

Orthopantomogram (O.P.G) X-ray machine to take the full mouth x-ray of all the teeth and surrounding bone in one go.

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Finding

OPG shows a trabeculated

CT showed an enhancing

Indeterminate

Discussion

The case described here however shows features reasonably typical of this neoplasm. On histopathology, the lesion was shown to be an odontogenic myxoma. This is a mesenchymal odontogenic tumor, which is difficult to diagnose pre-operatively.

So, next he do CT scan that contrast-enhanced CT showed an enhancing, solid lesion with trabeculations. Then, he goes for diagnosis of a lesion such as this is indeterminate to see the lateral position.

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Conclusion

Using the OPG as the basic for dental diasease that patient had and can be cantinue to other scaning for more clear on part of that diasease for example using CT scan and MRI as the other way. The treament for this case is:

Small tumors Currettage

Large tumors Enucleation with currettage of surrounding bone Resection may be considered

Reference

file:///D:/Dental%20x-ray/Odontogenic%20Myxoma.htm

file:///D:/Dental%20x-ray/Odontogenic%20myxoma%20- %20Wikipedia,%20the%20free%20encyclopedia.htm

file:///D:/Dental%20x-ray/Odontogenic%20tumor%20-%20Wikipedia,%20the%20free%20encyclopedia.htm

file:///D:/Dental%20x-ray/Orthopantomogram%20-%20Wikipedia,%20the%20free%20encyclopedia.htm

file:///D:/Dental%20x-ray/science.htm

file:///D:/Dental%20x-ray/Spot%20Diagnosis%20%20Orthopantomogram%20(OPG).htm

file:///D:/Dental%20x-ray/Technology.htm

Radiographic anatomy Positioning ( Andrea Gautbier Cornuelle, Diane H. Gronefeld )