Radiology sheet # 5 -Shadi Jarrar

by **Shadi Jarrar** 9/11/2012, 4:57 pm

Oral Radiology
Sheet # 6

In this lecture we will talk about 2 topics:

1) Bone diseases manifested in the jaws.

2) Trauma

Bone diseases manifested in the jaw:

They look very similar to the manifestations of systemic diseases in the jaws.

First group is fibro-osseous lesions:

1- Fibrous dyslplasia.

2- Cemento-osseous dysplasia.(2 types: periapical and florid)

3- Cemento-ossifiying fibroma.

Fibrous dysplasia: (FD)

A congenital disease due to a mutation in GNAS1 gene which is responsible for bone repair à

an abnormality in bone turnover à

replacement of the normal bone with abnormal haphazard bone à Clinically: Unilateral asymmetry and facial swelling.

It can be mono-ostotic -involving one bone- or poly-ostotic.

( if the patient suffers from endocrine diseases and skin pigmentation (café au lait) beside the polyostotic FD; the three together constitute McCune-Albright syndrome. These endocrine diseases include precocious (early) puberty. If the patient doesn’t suffer from any endocrine abnormality, this is called Gaffe syndrome)

FD is one of the few things that present in the maxilla more than the mandible.

It mostly present bilaterally and in the posterior part.

Radiographic presentation:

-FD first appears as a radiolucent lesion then becomes mixed and finally gets radiobaque.(it’s appearance is sometimes called orange peal, granular, ground glass or cotton wool appearance)

-Ill defined borders.

-Hypercementosis is common in FD.

-In some cases, radiolucent lesion appears in side the mature radiopaque lesion. This is due cystic formation inside the radiopaque lesion.(Trumatic bone cyst)

Osseosarcoma and chondrosarcoma both appear radiobaque in the posterior part of the jaw, and affect the same age group affected by FD. So that, they should be considered in the differential diagnosis of FD lesions.

Remember that this FD doesn’t appear as a pushing mass like tumors, it’s just abnormal bone.

In the early radiolucent stage, parathyroidism can be included in the differential diagnosis. While in the late radiobaque stage, paget disease should be considered.

(the position, age and ethnicity can lead to the definitive diagnosis here.. because while FD affects younger patients bilaterally, paget disease affect older anglo-Saxonians unilaterally)

“”FD presents clinically as unilateral expansion””

Periapical cemento-osseous dysplasia: (PCOD):

It has the same pathophesiology of FD but around the root tips of the teeth(periapical) not generalized as FD.

Mostly is seen in middle African specially mostly in the anterior area.

Radiographic presentation:

It starts as a radiolucent lesion in periapical areas; so it should be differentiated from inflammatory periapical lesions by doing vitality test where the teeth should be vital if the lesion is PCOD.

As in FD, PCOD early lesion becomes mixed and finally radiobaque. (But it doesn’t fully radiobaque)

Unlike FD, PCOD does not “respect” the boundaries of the sinuses; it bushes the boundaries of the nearby sinuses.

We will talk about 3 diseases that are histopathologically similar:

1- CGCG (central giant cell granuluma)

2- Anurysmal bone cyst.

3- Chirubism.

Although they are similar from the histopathological point of view, they are totally different clinically.

CGCG is a reactive lesions affects children mostly in front the first molar. It crosses the midline and have well defined peripheries.

Differential diagnosis:

1- Ameloblastoma.

2- Myxoma.

3- Aneurysmal bone cyst.

4- Simple bone cyst.

5- Brown tumor.

6- Cherubism.

3,5,6 are similar to CGCG under the microscope.

4 is similar to CGCG because they both affect small children.

“Wispy” septations are typical for CGCG; They are narrow poorly defined septations appear in the lesion with 90 degrees to the borders.

Aneurismal bone cyst : It appears clinically as expansion especially in the posterior area( while CGCG appears mostly in the anterior area)

It’s painful and unilateral affecting young people.

It’s treated with complete enucleation.

Cherubism:

affects very young patients (ex: 4 years) bilaterally.

So that, anterior teeth displacement is common in these patients as they are affected while teeth development.

Paget disease of the bone:

It’s a radiobaque problem affects Anglo-Saxonians because of a defect in the metabolism of bone. à the bone enlarges abnormally à that can lead to compression of some vital structures (the british anglo-Saxonians affected with this abnormality used to change their hats several times to fit with their heads sizes!) – [I don’t know why that was mentioned!]

It differs from FD in 2 main features: Bilaterality(it’s always systemic) and the age of the affected patients(it affected older patients than those affected with FD)

It presents with cotton wool appearance.

Alkaline phosphatase level is increased in the blood in this disease.

Hypercemetosis in this disease makes teeth extraction sth to worry about.

Langherhan cell histocytosis:

It’s classified into:

1- Letterer-siwe disease.(acute and not compatible with life)

2- Hand-Schuller- Christian.(a chronic type): it results is polyostotic lesions in the bone, diabetes insipidus(due to kidneys problem) and exophthalmia.

One variant of the disease is eosinophilic granuloma. It’s characterized by scoped bone lesions (as ice-cream scopes) and we may see floating teeth.

This disease is an aggressive disease, that we can notice it with periostial reaction.

( periostial reaction usually appears with malignant lesions or inflammatory lesions)

Truama:

To confirm fractures radiographicly, we always need 2 radiographs with different angulations.(1 radiograph is not enough as the overlap between the fractured parts hide the fracture line- and u r expected to know the modalities of cephalic imaging)

Trauma to the tooth can be associated with mobility or not. If no mobility; this is called concussion. It’s often not seen radiographicly and just needs follow up after 6 months and then after one year from the date of trauma.

When the tooth is displaced from its position, this is called luxation(subluxation: the tooth is just minimally mobile(loose) but is not displaced , intrusion: the tooth is displaced in, extrusion: displaced out, avulsion : the tooth is out and not in the socket anymore)

Avulsion obviously does not need radiographs unless the tooth is missing; if the tooth is missing, chest X-rays are required to exclude aspiration.

Also, trauma can be associated with a fracture or not, the fractures can affect the crown or the root or both.

When the fracture goes beyond the tooth to alveolar bone we should splint the bone and follow the tooth up for endo prespective.

Mandibular fracture is the second most common maxillofacial fracture(the most common is the nasal.). the most common site to be fractured in the mandible is the angle followed by the body.

Any fracture can be classified to simple or compound; the simple is closed and not communicating with outside, e.g: if there is communication between the fracture and the periodontal ligament, this a compound fracture. Compound fractures need antibiotic coverage.

Fracture can be also classified to greenstick and comminuted fractures; comminuted fractures smash the bone into multiple pieces. [And I suppose greenstick fractures to include only to pieces]

When we diagnose these fractures we follow a systematic method for fracture evaluation(the 4 “S” approach; A general and useful approach to the evaluation of the facial bone series following trauma):

1- Symmetry

2- Shrpness.

3- Sinus.

4- Soft tissues.[especially important in mid-face fractures]

The fracture line can be either black or obaque.

Undisplaced fractures are difficult to see in radiographs. While displaced fracutures can be seen as radiolucent or radiopaque(due to overlap) with steps in the cortical border.

We can also check for air and fluid level inside the sinus in cases of facial trauma.

Nasal fractures are the most common.(can be seen by lateral nasal radiographs)

The best modality for mid-facial trauma imaging is CT scan.

Considering zigomatic fractures, you should look where the zygomatic arch is fused to other facial bones[zygomaxillary suture, zygomaticotemporal suture and zygomaticofacial suture] they can result in tripod fracture:

1- Limited mouth opening due to compression on the condoyles.

2- Periorbital bruising.

3- Bleeding nose.

4- Flattened cheeks.

5- Hemorrhage to the eyes.

Tripod fractures are best seen by CT scans

Mid-face fractures are classified according to Le Ford classification(depends on the level of fracture):

Le Ford 3 : It separates the middle face from the cranium.

Le Ford 2 : Pyramidal fractures in the nasal and frontal bones that detach the maxilla form the base of the skull.

Le Ford 1 : Horizontal fracture causing deattachmant of alveolar bone from the maxilla.

Sometimes only the zygomatic arch get fractured. This is best viewed by submentovertex projections.

The end

Shadi B. Jarrar