Dr Khin Soe

Department of Oral Medicine

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

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.

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.

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

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.

The nature of the lesion is uncertain and it

may be hamartomatous rather than truly

neoplastic.

It must be differentiated from

ameloblastoma.

The adenomatoid odontogenic tumour is

readily enucleated and does not recur:

it does not require radical excision.

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.

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.

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.

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.

Although the tumour is generally regarded to

be locally invasive it appears to be less

aggressive than the ameloblastoma.

Sheets of polyhedral epithelial cells with

prominent intercellular

bridges and nuclear pleomorphism in a

CEOT

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.

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.

The calcifying cystic odontogenic tumouroccurs 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.

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.

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.

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.

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.

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.

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.

It tends 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.

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.

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.

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.

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.

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."

Although odontomas are usually

asymptomatic, they may be the cause of

noneruption or impaction of teeth and

retained primary teeth.

Odontomas are most commonly found on

routine radiographic examination, presenting

as an irregular radiopaque mass or as small,

toothlike structures.

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.

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.

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.

The degree 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.

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

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'.

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

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.

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 eagle's

talon.

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.

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 Hertwig's sheath

resulting in budding of the sheath followed

by differentiation of ameloblasts and

amelogenesis.

The complex odontome is A Developmental

tumour- Like Mass Consisting Of Disorderly

arranged dental tissues.

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.

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 .

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.

Histologically, the fully developed complex

odontome consists of a mass of disorderly

arranged, but well-formed enamel, dentine,

and cementum.

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

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