OP Sheet #9 By Shadi Jarrar

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OP Sheet #9 By Shadi Jarrar

Post by Sura on 15/12/2011, 12:10 am

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Re: OP Sheet #9 By Shadi Jarrar

Post by Shadi Jarrar on 23/12/2011, 9:20 pm

Odontomes & odonto-genic tumours


Definition: Odontomes are non-neoplastic, developmental anomalies or malformations that originate from odontoginic tissues and contain enamel and dentine. They represent hamartomas and not neoplastic structures.



Types: 1)Invaginated odontome(IO): which in turn is divided into coronal type and radical type. 2)Evaginated odontome (EO).



1)Invaginated odontome(IO):Coronal IO: (Dens invaginatus) Although coronal invaginations may involve any type of tooth, the lingual side of the upper lateral incisor is the most common site where you can see a very deep cingulum pit which can be a common place to find caries. It’s rare to find this in lower and primary teeth.



This is called Dens invaginatus -due its dense appearance in the radiographs-and is often bilateral. It is variable in degree involving three degrees. It’s called dilated, conical or gestant odontome because the tooth shows dilated appearance in the radiographs.(fig. 1)



Fig. 1:

a radiograph of upper lateral incisor shows invagination lined by enamel continuous with surface.

(star)
















Diagnosis: Clinically, It is asymptomatic anomaly. But because it represents a common area for caries where bacteria can easily get into, it can represent signs and symptoms of caries and pulpitis.

Radiographically, it shows what u can see in Fig. 1 which looks like a small tooth inside a larger one.. this is why it’s also called dense in dente.



Degrees of severity: Type one: invoving the crown only.

Type two: if it exceeded the CEJ.

Type three : if it approaches the apex.



Histological appearance:It shows a tooth inside a tooth. It’s surrounded by defective hypo-mineralized enamel that is continuous with the surface. The dentine of the odontome can be commonly involved in the defect.



Pathogenicity : unknown, but they think that the milder forms represent

exaggeration of the formation of the cingulum pit, or active proliferation of epithelium within the lamina.






Radicular IO: It can be axial infolding mostly seen in lower second premolars and seems as if it makes separations in the roots lined by cemuntum, or saccular invagination that is less common(rare) and appears like a cyst in the roots lined by enamel.



Fig. 2: axial infolding (star)




2) Evaginated odontome(EO): (Dens invaginatus)It looks like an eagle's talon. They are outward enlargements or tubercles that are globular in shape most commonly seen in upper anterior teeth mainly central and lateral incisors on the palatal surfaces and premolars between buccal and lingual cusps on the occlusal surfaces. This can lead to fractures in the cusps and hence pulpitis follows. It occurs predominantly in peopleof Mongoloid stock.(fig. 3)

Fig. 3:

Talon cusp (star)















Enamel pearl (enameloma):



It represents a small a globular structure specially in bifurcation area.(fig. 4) It’s asymptomatic, even though, it accelerates periodontal pocketing causing periodontitis.





Fig. 4 : Enamel pearl












Histologically it can consist of enamel entirely, enamel and dentine inside or enamel, dentine and pulp inside.



Pathogenesis: budding of epithelial root sheath of heartwig forming enamel.






Compound & Complex Odontomes:

They reach a specific size then stop growing and surrounded by capsules. So they are not aggressive and their management is easy.

It is mostly seen in children and young adults 1st & 2nd decades of life( average age is about 14 years), and usually associated with permanent dentition.



According to radiographs they are divided into two types:

Compound: looks like a cyst of several tooth-like structures surrounded by radiolucent bar representing the capsule. Mostly seen in Intercanine area especially in the maxilla. (Fig. 5)

Fig. 5: Note the encircled area with the dotted line. Multible tooth-like structures is representative of a compound odontome.










Complex: A mass of a dense structure of haphazardly arranged enamel, dentine and cemuntum surrounded by radiolucent bar representing the capsule. Mostly seen in premolar and molar areas of the mandible.

(Fig.6)



Fig. 6:Note the encircled area with the dotted line. The amorphous mass is representative of a complex odontome.


_





















Diagnosis : it’s asymptomatic if it has no communication with the oral cavity or cause no bone expantion. If it undergoes eruption, it become infected and the patient starts to complain form pain and inflammatory symptoms.



In radiographs they appear either associated with crowns or replacing a missing tooth.



They initially appear as radiolucent area with deposited radiopaque material. But once fully formed:

-Compound odontomes: unilocular radiolucency containing multiple small denticles

-Complex odontomes: immature solid radiopaque mass with a radiolucent zone.



-Histologically: complex odontomes appear disorganized but well-formed mass of enamel ,dentine , cemuntum and pulp, unlike compound odontomes which represent well-organized denticles separated by fibrous tissue.



Again, these odontomes are easy to remove without reportd recurrence.




Odontogenic tumours




Introduction

First: Benign tumours: these tumers are either of epithelial origin only; without mesenchyme, or with odontogenic mesenchyme.

1. Without odontogenic mesenchyme

Most common is ameloblastoma. Others are:

Squamous odontogenic tumour.

Calcifying epithelial odontogenic tumour.

Adenomatoid odontogenic tumour.



Considering keratinazing cystic odontogenic tumor, it’s considered as tumor here but as you can remember, we talked about it in cystic lesions in the oral pathology 1 course. Even some scientists don’t agree to include it within tumors, it’s considered as a tumor because it has highly proliferative ability.



2. With odontogenic mesenchyme : it includes:

Ameloblastic fibroma

Ameloblastic fibro-dentinoma & fibro-odontoma

Odontoameloblastoma

Calcifying cystic odontogenic tumour



Some classifications include Complex & compound odontomes within this category.



Second: Malignant tumours: They can be carcinomas or sarcomas:



Odontogenic carcinomas:

Malignant ameloblastoma

Primary intraosseous squamous cell carcinoma

Malignant variant of other epithelial tumours

Clear-cell odontogenic carcinoma

Malignant change in odontogenic cysts

Odontogenic sarcomas:

Ameloblastic Fibrosarcoma

Ameloblastic fibro-odontosarcoma





  • Ameloblastoma



A benign locally aggressive neoplasm derived from odontogenic epithelium.

It’s most common odontogenic tumor representing about 10-15% of all odontogenic tumers. Even though, it’s rare tumor.



It’s more common in black race.



Age group of most presentation : 20-50 years.



Signs:

Most common site of presentation is posterior mandible where we can see swelling. It can keep expansion until it perforates the bone through the soft tissues which complicate the clinical situation.



In the affected area, we can see displacement in the teeth, teeth mobility and resorption in the roots. In some cases we can see impacted teeth inside the ramus of the affected side.



In radiographs, multilocular radiolucency is most common presentation, but unilocular rasiolucency can be seen in some cases.



This presentation resembles multiple rooms occupied with soft tissues.



Treatment : surgical resection is the most definitive treatment, sometimes we need to undergo a surgical resection for the whole mandible! Followed by bone grafting.



Histopathology:

We have several histological patterns(discussed below), but they are not important clinically; as clinical signs are to clear and definitive for diagnosis.



1- follicular pattern: follicles of columnar or cuboidal cells -with reversed polarity- peripherally and angular stillate cells centrally.. this pattern resembles enamel organ in the dental formative organ. These follicles are surrounded by fibrous connective tissue.



The peripheral cells are called preameloblasts.. because they represent ameloblasts precursors and are not able to produce enamel yet.



The angular stillate cells can regenerate to produce the cysts we notice in the radiographs.. so that, these cysts are not formed in the connective tissue, but inside the follicles.



These angular cells sometimes undergo metaplasia to squamous cells and produce keratine. This is a subtype of the follicular pattern but with metablasia of the central cells into squamous cells. It has clinical significance due its relatively lower recurrence rate.



Sometimes these cells undergo metablasia into granular cells -like granular cell tumor- with large eosinophilic cytoplasm with granules and small nucleolus.



2- Fishnet pattern: in which less amount of stillate cells is found so that no cystic changes are detectable inside the follicles but outside tem in the connective tissue. But still they share the same arrangement of cells with the follicular pattern.

3- Desmoblastic variant(rare): with less epithelial cells and dense connective fibrous tissue resembling a scar tissue. The amont of stillate cells is less than the follicular pattern here as well.

4- Basal variant (rare) resembles basal cell carcinoma.



Pathogenesis: Some scientists believe that enamel organ is the source of this tumor. But still this is uncertain ; because the affected people with this tumor are usually adults rather than small children, and it’s unjustifiable why enamel organ cells doesn’t proliferate until the patient enters his adulthood. Other scientists believe that ruminants of dental lamina can be the source of such a tumor.



Recurrence:

It’s common, so affected patients need long follow up period.

In rare cases, this ameloblastoma can be detected in the lungs! This is called malignant ameloblastoma.. actually this was found to be related to surgical resection due to aspiration of ameloblastoma’s neoplastic tissues.(so this is not true malignancy)




Another case of surgical interest is unicystic ameloblastoma, which looks unilocular in radiographs and more common in young patients mostly in wisdom tooth area(posterior mandible).

This type can be confused with keratocysts and dentigerous cysts.



According to the site of proliferation in unicystic ameloblastomas, they can be devided into: 1) luminal unicystic ameloblastoma with proliferation in the lumen of the cyst 2) intraluminal unicystic ameloblastoma with proliferation into inside the lumem. 3) mural unicystic ameloblastoma with proliferation into outside the lumen.. last one of these three types is the most dangerous due high recurrence rate.



Histologically, it looks like cysts composed of dense fibrous connective tissue surrounding fluid-filled cavity. But with higher magnifications, we see columnar cells surrounding stillate cells..(in case of keratocysts, we see squamous cells instead)






Peripheral ameloblastoma

Unlike the conventional multilocular ameloblastoma and unilocular ameloblastoma, peripheral ameloblastoma grows in the soft tissue[not inside the bone-not intraosseous]. So the most common site of peripheral ameloblastoma is the gingival tissues. Although, pressure in the bone caused by this tumor can cause some resorption in the bone. Its pathology does not differ from other ameloblastomas. As it’s surrounded by capsule, it has low recurrence rate.



Origin: either from the oral epithelium or from the dental lamina that gets outward from the bone into the soft tissues.
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Shadi Jarrar
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عدد المساهمات : 997
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تاريخ التسجيل : 2009-08-28
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الموقع : Amman-Jordan

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