2. A well circumscribed lesion derived from odontogenic epithelium that usually occurs around the crowns of unerupted anterior teeth of young patients and consists of epithelium in swirls and ductal patterns interspersed with spherical calcifications
3. The adenomatoid odontogenic tumour usually presents during the second and third decades of life. The majority of tumours arise in the anterior part of the maxilla, especially in the canine areas, and there are usually few symptoms apart from a slowly enlarging swelling.
4. On radiographs it usually appears as a well- defined radiolucency but in some cases calcification within the tumour may produce faint radiopacities. The lesion is often associated with an unerupted tooth and may simulate a dentigerous cyst.
5. Histologically, the lesion is well encapsulated and may be solid or partly cystic; in some cases the tumour is almost entirely cystic. It consists of sheets, strands, and whorled masses of epithelium which in places differentiates into columnar, ameloblast-like cells. The columnar cells form duct or tubule-like structures (hence adenomatoid) with the central spaces containing homogenous eosinophilic material
6. They are thought to represent abortive attempts at enamel organ formation. There is very little supporting stroma. Small foci of calcification are scattered throughout the tumour and occasionally tubular dentine and enamel matrix may be seen.
7. The nature of the lesion is uncertain and it may be hamartomatous rather than truly neoplastic. It must be differentiated from ameloblastoma.
8. The adenomatoid odontogenic tumour is readily enucleated and does not recur: it does not require radical excision.
9. The calcifying epithelial odontogenic tumour is a rare, benign epithelial neoplasm. It occurs over a wide age range and is about twice as common in the mandible as in the maxilla. Most of the tumours arise in the molar or premolar area and about half are associated with the crown of an unerupted tooth. Although most tumours arise within bone, extraosseous lesions have been reported.
10. Radiographs of intraosseous tumours show an irregular radiolucent area which may or may not be clearly demarcated from the surrounding normal bone. The radiolucency contains varying amounts of radiopaque bodies due to calcification within the tumour.
11. Histologically, the tumour consists of sheets and strands of polyhedral epithelial cells with abundant eosinophilic cytoplasm lying in a fibrous stroma. The epithelial cells often show prominent intercellular bridges and marked nuclear pleomorphism but the latter is not indicative of malignancy.
12. A characteristic feature is the presence within the sheets of epithelial cells of homogeneous, amyloid-like material which may become calcified. The calcifications are concentric laminated structures that may fuse into complex masses. The nature of the amyloid-like material is uncertain but is probably derived from products synthesized by the epithelial cells.
13. Although the tumour is generally regarded to be locally invasive it appears to be less aggressive than the ameloblastoma.
14. Sheets of polyhedral epithelial cells withprominent intercellularbridges and nuclear pleomorphism in aCEOT
15. The calcifying cystic odontogenic tumour is a grossly cystic odontogenic tumour and may be a hamartoma rather than a true benign neoplasm. The dentinogenic ghost cell tumour is histologically very similar except that it is a solid lesion. It was originally considered to represent the solid variant of the calcifying cystic odontogenic tumour.
16. However, as more cases are reported there is increasing evidence that the dentinogenic ghost cell tumour is a distinct pathological entity and is a true benign neoplasm. Both present mainly as central lesions within the jaws but peripheral, gingival lesions also occur.
17. The calcifying cystic odontogenic tumour occurs over a wide age range but is usually seen below 40 years of age. About 75 per cent are intraosseous and either jaw may be involved. The majority, including those located in the gingival or alveolar soft tissues, arise anteriorly to the first permanent molar tooth. The lesion usually presents as a slowly enlarging but otherwise symptomless swelling.
18. Radiographically, the lesion appears as a well-defined unilocular or multilocular radiolucent area containing varying amounts of radiopaque, calcified material. It may be associated with the crown of an unerupted tooth.
19. Histologically, the cyst is lined by epithelium which shows a well-defined basal layer of columnar, ameloblast-like cells and overlying layers of more loosely arranged cells that may resemble stellate reticulum.
20. A characteristic feature is the presence within the lining of masses of swollen and keratinized epithelial cells which are usually referred to as ghost cells since the original cell outlines can still be discerned.
21. The ghost epithelial cells may calcify. Breakdown of the epithelium may release keratinous debris into the supporting connective tissue resulting in a prominent foreign-body, giant-cell reaction. Irregular masses of dentine-like matrix material (dentinoid) are frequently found in the supporting fibrous tissue in direct contact with the basal layer of the epithelium.
22. Less commonly, more extensive formation of dental hard tissues is seen, including enamel, producing a structure similar to a complex or compound odontome as an integral part of the lesion. Calcifying cystic odontogenic tumour associated with odontomes tend to occur in a younger age group and most have presented in the anterior maxilla.
23. The dentinogenic ghost cell tumour is a predominantly solid lesion which comprises the same epithelial, keratinized ghost cells and dentinoid components as the calcifying cystic odontogenic tumour, but as a disorganized mass.
24. Ittends to occur in an older age group than the calcifying cystic odontogenic tumour. Like the calcifying cystic odontogenic tumour some respond well to conservative treatment. However, others pursue a more aggressive course and, like the ameloblastoma, are locally invasive neoplasms.
25. Odontomas are mixed odontogenic tumors in which both the epithelial and mesenchymal components have undergone functional differentiation to the point that both enamel and dentin are formed. The most common of the odontogenic tumors, odontomas are believed to be hamartomatous rather than neoplastic in nature.
26. The compound odontoma is a lesion in which all the dental tissues are represented in an orderly fashion so that there is at least superficial anatomic resemblance to teeth.
27. In a complex odontoma, on the other hand, although all the dental tissues are represented, they are formed in such a rudimentary fashion that there is little or no morphologic similarity to normal tooth formation.
28. compound odontomas have a propensity for occurrence in the canine and incisor region, being found more often in the maxilla than in the mandible, whereas complex odontomas show a predilection for occurrence in the posterior jaws.
29. Compound odontomas have been reported by Slootweg as having a mean age of occurrence of 14.8 years compared to 20.3 years of age for complex odontomas, possibly because the odontogenic tissue in the anterior jaws where the compound odontoma predominantly occurs has finished. its differentiation earlier than tissues in the posterior part of the jaw."
30. Althoughodontomas are usually asymptomatic, they may be the cause of noneruption or impaction of teeth and retained primary teeth.
31. Odontomas are most commonly found on routine radiographic examination, presenting as an irregular radiopaque mass or as small, toothlike structures.
32. The recommended treatment for an odontoma is conservative surgical excision, with care taken to remove the surrounding soft tissue. No propensity for recurrence has been noted.
33. Invaginated odontomes (dens invaginatus) arise as a result of invagination of a portion of the enamel organ into the dental papilla at an early stage in odontogenesis, before the formation of calcified dental tissues. The majority of invaginations originate in the coronal part of the tooth but radicular invaginations also occur.
34. Although coronal invaginations may involve any type of tooth, including supernumerary teeth, the permanent maxillary lateral incisors are the teeth most frequently affected. The anomaly is often bilateral. The condition is uncommon in mandibular teeth and cases reported involving the primary dentition are exceedingly rare. The prevalence of dens invaginatus varies in different series from less than 1 to about 10 per cent, based on studies of extracted maxillary permanent lateral incisors, or on radiographic surveys.
35. Thedegree of invagination varies but three main types are identified: type 1, where the invagination is confined to the crown of the involved tooth; type 2, where the invagination extends into the root; and type 3, where the invagination extends through the root apex.
36. In the permanent maxillary lateral incisor the invagination arises from the cingulum pit or, in the case of peg-shaped lateral incisors, from the incisal tip. Where the invagination is of a minor degree the tooth may be of normal appearance, but with the more extensive forms the crown, and particularly the root, may be considerably dilated. The terms dilated or gestant odontome are sometimes applied to describe such anomalies
37. Radiographs reveal an invagination lined by enamel which is continuous with the normal enamel covering of the tooth. The appearances may resemble a tooth within a tooth, hence the term dens-in- dente.
38. Key points - Invaginated odontome · mainly permanent maxillary lateral incisors · enamel-lined invagination on radiograph · extent of invagination varies · enamel and dentine in the base of the invagination often defective in quantity and/or quality · pulpitis and sequelae common · abnormalities of crown/root morphology
39. Evaginated odontomes (dens evaginatus) are uncommon and are characterized by extra cusp-like tubercles which usually arise from the occlusal surfaces of premolars or the palatal surfaces of the maxillary central or lateral incisors. The anomaly presents as an enamel-covered, teat-like tubercle projecting from the occlusal surface of an otherwise normal premolar. The evagination is easily fractured resulting in exposure of the pulp and its sequelae.
40. Evaginated odontomes involving the occlusal surfaces of premolars occur predominantly in people of Mongoloid stock. Those involving the anterior teeth, predominantly the permanent maxillary lateral incisors, originate from the palatal cingulum. They are usually referred to as talon cusps because of their resemblance to an eagles talon.
41. The enamel pearl presents as a small droplet of enamel on the root of a tooth and is found most frequently near or in the furcation of the roots of maxillary permanent molar teeth. Most arise close to the amelocemental junction but they are occasionally found near the root apex.
42. The lesion is symptomless and is discovered as an incidental finding on radiographs or when the tooth is extracted. Microscopically, some consist entirely of enamel but others contain a core of dentine and even a small amount of pulp tissue . The anomaly is thought to arise as a result of a growth disturbance of Hertwigs sheath resulting in budding of the sheath followed by differentiation of ameloblasts and amelogenesis.
43. Thecomplex odontome is A Developmental tumour- Like Mass Consisting Of Disorderly arranged dental tissues.
44. The complex odontome occurs predominantly in the second and third decades of life and the majority arise in the molar region of the mandible. They are often associated with the crowns of unerupted teeth and occasionally may take the place of a tooth.
45. For these reasons they may be discovered, when small, as incidental findings when investigating a patient with a tooth missing from the dental arch. As the lesion enlarges it usually presents as a painless, slow- growing expansion of the jaw, but may become infected and present with pain, particularly if it communicates with the mouth. Multiple odontomes are rare. In some cases complex odontomes develop in association with calcifying odontogenic cysts .
46. Radiographically, a fully formed complex odontome appears as a radiopaque lesion, sometimes with a radiating structure , but in the developing stages it shows as a well- defined radiolucent lesion in which there is progressive deposition of radiopaque material as calcification of the dental tissues proceeds. The mature lesion is surrounded by a narrow radiolucent zone analogous to the pericoronal space around unerupted teeth.
47. Histologically, the fully developed complex odontome consists of a mass of disorderly arranged, but well-formed enamel, dentine, and cementum.
48. Key points - Complex odontome · developmental lesion resulting in disorganized mass of dental tissues · 2nd/3rd decade; predominantly molar region mandible · may overlie/replace a tooth · radiolucent/radiopaque depending on maturity · dentine forms bulk of lesion
49. Key points - Compound odontome · developmental lesion resulting in the formation of a bag of discrete denticles · 1st/2nd decade; predominantly anterior maxilla · often overlies the crown of an unerupted tooth · separate denticles identifiable on radiograph · denticles comprise enamel, dentine, cementum, and pulp in their normal anatomical relationship