2. Introduction
• A cyst is an epithelium lined sac containing
fluid or semifluid material
• The epithelial cells first proliferate and later
undergo degeneration and liquefaction
• Grow by expansion, causing displacement of
adjacent teeth
3. Odontogenic cysts
• Originate from residues of the tooth-forming organ
• Derived from 3 origins:
- epithelial rests of Serres: odontogenic keratocyst,
developmental lateral periodontal and gingival
cysts
- reduced enamel epithelium : dentigerous,
eruption and paradental cyst
- rests of Malassez : radicular cysts
4. Radicular Cysts
•Subdivided into :
Apical
Lateral
Residual
•Causes:
Develops from a preexisting periapical granuloma,
Related to the apex of a nonvital tooth
5. Clinical features
• High incidence in anterior maxillary teeth
• Usually symptomless
• When enlarged cause expansion of the
alveolar arch and may discharge through a
sinus
• The rate of expansion 5mm/year in diameter
6. Histopathology
• Lined by non-keratinized stratified squamous
epithelium
• Chronically inflamed fibrous tissue capsule
• Newly formed cysts have irregular epithelial lining
with variable thickness. Becomes regular and even in
thickness
7.
8.
9.
10.
11. • The connective tissue capsule becomes more fibrous, less
vascular, and with less inflammatory cells
• Metaplasia of epithelial lining may give rise to mucous cells,
and rarely ciliated respiratory epithelium
• In some cases the lining contains hyaline eosinophilic bodies,
Rushton bodies
• Common cholesterol crystals deposits, which form clefts.
• Cholesterol crystals result from hemorrhage and breakdown
of RBCs
12.
13.
14.
15. Radiographic features
• Round radiolucency at the root apex
• Well defined, surrounded by radiopaque
margin
• 40 % of apical radiolucencies are cystic
16. Contents
• Hypertonic fluid containing:
-breakdown products of epithelial,
inflammatory, connective tissue elements
-serum proteins (5-11 g/dl), Igs higher than
serum
-water and electrolytes
-cholesterol crystals
17.
18. Residual cyst
• It is a radicular cyst that is retained after the
extraction of the related tooth
• May continue growth causing significant bone
resorption
19. Dentigerous cyst
• Encloses part or all of the
crown of an unerupted tooth
• Develops from proliferation
of the reduced enamel
epithelium
• Eruption cyst arises in an
extra-alveolar location
20. Radiographic examination
• Well-defined, unilocular, radiolucent, related
to the crown
• Associated with impacted or delayed eruption
(most commonly lower 8, upper 3)
21.
22. Clinical features
• Twice as common in males
• Twice as common in mandible
• Usually asymptomatic
• Large cysts tend to expand the outer plate
23. Histopathology
• Lining is a thin, regular, 2-5 cells thick, non-
keratinized, stratified squamous or cuboidal
• Fibrous CT capsule free from inflammatory
cell infiltration
• Occasional cholesterol clefts
24.
25.
26. Odontogenic keratocyst
• uncommon
• 2nd
to 3rd
decades, or fifth decade
• More common in males
• Asymptomatic
• Multiple cysts are associated with naevoid
basal cell carcinoma syndrome (Gorlin
syndrome)
27. Radiographic features
•3rd
molar and ramus of mandible area favored
•Well-defined radiolucency
•Can displace and resorb teeth
•Uni or multi locular
28.
29. Histopathology
• wall is thin, regular, 5-10 cells thick stratified
squamous epithelium
• Characteristic folded wall
• Basal cell layer is well defined, contains
columnar or cuboidal cells
• Sudden transition between stratum spinosum
and surface cells
30.
31. Histopathology
• Thin fibrous capsule free from inflammatory
cells
• High recurrence due to rupture
• Cyst contains keratinous debris, white cheesy
material, protein level 4 g/dl
35. Gingival cyst
• Common in neonates
• Also knows as Bohn’s nodules or Epstein pearls
• Disappear by 3 months of age
• Arise from remnants of dental lamina, form
keratinizing cysts
36.
37. Developmental lateral periodontal cyst
• Uncommon
• Canine and premolar region of the mandible
• Derived from either reduced enamel
epithelium or rests of dental lamina
• Occasionally multi locular
38. • Radiographically: well-defined radiolucency
• Large cysts can displace teeth and cause
expansion
• Histologically: Lined by non-keratinized
squamous or cuboidal epithelium
39. Paradental cyst
• Arises alongside an unerupted third molar
involved with pericoronitis
• Radiographically: well-defined radiolucency
related to the neck of the tooth
• Inflammatory origin stimulating proliferation
of reduced enamel epithelium
40.
41. Glandular odontogenic cyst
• Rare
• occur in the anterior part of the mandible
• Slow growing, painless
• Histology: lined by varying thickness of
epithelium
• Potentially aggressive, locally invasive with
tendency to recur
43. Odontomes
• Definition: non-neoplastic developmental
anomaly or malformation that includes enamel
and dentine
• Types:
1.Invaginated
2.Evaginated
3.Enamel pearl (enameloma)
4.Double tooth
5.Complex odontome
6.Compound odontome
44. Invaginated odontome
• Invagination of the enamel organ into the
dental papilla early in odontogenesis
• Permanent maxillary lateral incisor
• Three main types:
1: confined to the crown
2: extends into the root
3: extends through the
root apex
45. Histopathology
• Enamel and dentin lining the cavity are often
defective and poorly mineralized
• The cavity is occupied with food debris and
bacteria
49. Complex odontome
• Disorderly arranged dental
tissues
• Limited growth potential
• 2nd
and 3rd
decades, in the
molar region of the
mandible
• Painless, slow-growing
52. Compound odontome
• Consists of numerous small denticles
• 1st
and 2nd
decades of life and in anterior maxilla
• Less growth potential than the complex type
54. Ameloblastoma
• Rare
• Benign, locally invasive
• Derived from odontogenic epithelium
• More common in africans
• Two variants: unicystic
peripheral
• 80% occur in mandible
56. Histopathology
• 2 patterns:
• Follicular: epithelium arranged into discrete
follicles resembling tooth germ
• Plexiform type: epithelium is arranged in
tangled network and irregular masses
57.
58.
59. • The ameloblast-like cells express amelogenin,
however, enamel and dentine are not formed
• Behavior: locally invasive, infiltrate cancellous
bone without bone destruction initially
• High recurrence rate
60. Unicystic ameloblastoma
• Occur at younger age than other variants
• Mainly in mandibular third molar region
• Histologically: ameloblastomatous lining with
reversed polarity nuclei
61.
62. • Radiographically: unilocular radilucency, usually associated
with an unerupted tooth
• distinguishable from dentigerous cyst on by
histopathological examination
63. Squamous odontogenic tumor
• Rare
• Radiographically: well-circumscribed
radiolucency
• Sclerotic border associated with roots of teeth
• Histologically: irregularly shaped islands of
well-differentiated squamous epithelium in a
stroma of mature fibrous tissue
• Derived from epithelial cells of Malassez.
64. Calcifying epithelial odontogenic
tumour
• Rare
• Benign
• Wide age range
• Mandible > maxilla
• Mostly seen in molar and premolar region
• 50% associated with an unerupted tooth
• Some extraosseous case have been reported
65. Radiographic features
• Irregular radiolucent area
• May or may not be clearly demarcated
• Contains radiopaque bodies due to
calcification
• Less aggressive than ameloblastoma
67. Adenomatoid odontogenic tumour
• Presents usually in 2nd
or 3rd
decades
• Majority in the anterior maxilla
• Slowly growing swelling
68. Radiographic features
• Well defined radiolucency
• Faint radiopacities due to calcifications
• May simulate a dentigerous cyst _often
associated with an unerupted tooth
69. Histopathology
• Well encapsulated lesion
• Maybe partly or wholly cystic
• Central spaces contain eosinophilic material
• Small foci of calcification
72. Histopathology
• Proliferating strands of odontogenic
epithelium in highly cellular fibroblastic tissue
with peripheral layer of columnar cells
• Appearance similar to ameloblastoma
73. Calcifying cystic odontogenic tumour
• Grossly cystic
• Mostly intraosseous
• Radiographically: well-defined, uni or multi
locular, radiolucent, with radiopaque areas
74. Histopathology
• Basal layer of ameloblast-like cells, masses of
swollen keratinized epithelial cells (ghost cells)
75. Odontogenic fibroma
• Derived from mesenchymal dental tissues
• 2 types:
• Central type: uncommon, well demarcated,
cementum-like and dentine-like foci
• Peripheral type: fibrous epulis, fibrous tissue
with cementum or dentinoid material
76. Odontogenic myxoma
• Locally invasive
• More common than odontogenic fibroma
• Radiographically:
Multilocular (soap-bubble appearance)
Well defined
Roots show resorption
78. Cementoblastoma
• Mostly patients under 25 years of age
• Usually molar and premolar area of mandible
• Attached to the root of the tooth - vital
• Slowly enlarging, sometimes causing pain
79. • Radiographically: well demarcated
mottled, radiopaque
radiolucent margin, root resorption
• Histologically: cementum-like tissue,
surrounded by sheets of uncalcified matrix
Editor's Notes
-By definition, a cyst is an epithelium lined sac containing fluid or semisolid material, which has not been created by the accumulation of pus
-During formation the epithelial cells first proliferate and later undergo degeneration and liquefaction
The liquefied material exerts equal pressure on the walls of the cysts
Definition: cysts whose epithelial lining originates from residues of the tooth-forming organ
Derived from 3 origins:
epithelial rests of Serres persisting after dissolution of the dental lamina, these give rise to odontogenic keratocyst, developmental lateral periodontal and gingival cysts
- reduced enamel epithelium which is derived from the enamel organ. The dentigerous and eruption and paradental cyst are derived from this tissue
- rests of Malassez : formed by fragmentation of the epithelial Hertwig’s root sheath. all radicular cysts are derived from these residues
Apical radicular cysts are the most common, comprising 75% of all radicular cysts
And they are the Most common cystic lesion of the jaw comprising about half of all jaw cysts
Develops from a preexisting periapical granuloma, which is a chronically inflamed granulation tissue
they are associated with apices of non-vital teeth
Can arise at any age and any tooth after eruption, particularly High incidence in anterior maxillary teeth. And rare in deciduous dentition
Usually symptomless, unless there is acute exacerbation leading to abscess formation
When enlarged cause expansion of the alveolar arch and deformity leading to the clinical sign of “oil can bottoming” or “egg shell crackling” and
may discharge through a sinus or perforate the cortex presenting as a bluish fluctuant swelling
The rate of expansion has been estimated as 5mm/year in diameter
The mechanism of development is unclear but persistence of chronic inflammation and bacterial endotoxin is essential for stimulation of proliferation
Lined by non-keratinized stratified squamous epithelium , supported by a chronically inflamed fibrous tissue capsule
Periapical granuloma containing proliferating arcades of squamous epithelium, showing early cystic breakdown
This is the previous section magnified, showing the early microcyst, associated with epithelial breakdown within the lesion
This is an early radicular cyst showing the long anastomosing cords of epithelium and the variation in the thickness of the epithelial lining. As the cyst grows it becomes more regular like the next slide
this is a section in an established cyst showing the thin and even epithelial lining
skip
Breaks in the epithelial lining are common we can see it in the (top right)
Sometimes the lining contains hyaline eosinophilic bodies, called Rushton bodies of varying sizes and shapes
Deposits of cholesterol crystals are common within the capsule, probably derived from the breakdown of red blood cells. They are usually associated with haemosiderin deposits
Could become ill-defined if infected
it cannot be reliably determined if the radiolucency represents a granuloma or cyst by radiography only
serum proteins (5-11 g/dl), most are inflammatory exudate, Igs higher than serum which reflects local production by plasma cells inside the capsule_
Clinically, its appearance varies from Watery, straw-colored, to semi-solid brown
Shimmering appearance due to cholesterol
A cyst that Encloses part or all of the crown of an unerupted tooth
Develops from proliferation of the reduced enamel epithelium, and is Attached to amelocemental junction
Radiographic appearance of a dentigerous cyst
Wide age range
As we can see in the photo Eruption cyst is Fluctuant, bluish, and might have haemorrhage into cavity after trauma
skip
Lining is a thin, regular, 2-5 cells thick, non-keratinized, stratified squamous andsometimes cuboidal
Mucous cell metaplasia is common with frequent epithelial breaks
Fibrous CT capsule free from inflammatory cell infiltration
It has Occasional cholesterol clefts
This is a section showing an eruption cyst just below the mucosa
We can see the Fibrous connective tissue capsule free from inflammatory cell infiltration
_ it is uncommon but is interesting due to its unusual growth pattern and tendency to recur
3rd molar and ramus of mandible area are favored
It is a Well-defined radiolucency
Can displace and resorb adjacent teeth
May present as Uni locular or multi locular lesion
Enlarge in anterior posterior direction to large sizes without causing bony expansion
skip
Here we can see the wall is thin, regular, 5-10 cells thick stratified squamous epithelium
Characteristic folded wall
_if inflamed, it loses its characteristic feature and looks more like radicular cyst_
Thin fibrous capsule free from inflammatory cells
High recurrence due to rupture because of the thinness of the capsule
Cyst contains keratinous debris, white cheesy material, protein level 4 g/dl _so there is little free fluid_
Parakeratinized epithelium lining
Basal cell layer is well defined, contains columnar or cuboidal cells
Sudden transition between stratum spinosum and surface cells
Small groups of epithelial cells resembling dental lamina rests, they are present in the capsule, these can give rise to independent satellite cysts, those can cause recurrence if not completely enucleated
this is one reason, and the other reason as we said is due to the thin capsule that is easily ruptured
In adults: rare, most frequently in females between mandibular premolars
Occur mainly in the canine and premolar region of the mandible, middle aged patients
must be distinguished from lateral radicular cyst associated with non vital tth and odontogenic keratocyst arising alongside the root_
Occasionally multi locular, and then can be described as botryoid odontogenic cyst- resembling a bunch of grapes
Radiographically: well-defined radiolucency area with sclerotic margin
Histologically: Lined by non-keratinized squamous or cuboidal epithelium, with focal thickenings
Maybe associated with teeth having enamel spur
Histology resembles that of radicular cyst
Paradental cyst, with a macroscopic section through the cyst
Rare
occur in the anterior part of the mandible
Slow growing, painless
Histology: lined by varying thickness of epithelium, superficial layer of columnar or cuboidal
Potentially aggressive, locally invasive with tendency to recur
Tumor like masses, considered as dental hamartoma
_Dens invaginatus_
Invagination of the enamel organ into the dental papilla early in odontogenesis _before formation of calcified dental tissues_
invagination is covered with enamel that is continuous with the outer enamel_
Enamel and dentin lining the cavity are often defective and poorly mineralized
The cavity is occupied with food debris and bacteria, therefore pulpitis is frequent
Ground section in a peg shaped lateral incisor, we can see the axial infolding lined by cementum _
It could be due to an exaggeration of normal folding in roots like premolars, could indicate an incomplete attempt at root bifurcation, as a result of invagination of Hertwig’s root sheath, followed by differentiation of ameloblasts and amelogenesis
Radiographic appearance of a dilated invaginated odontome
Arise from occlusal surface of premolars or palatal surface of incisors and then its called (talon cusp)
occur in premolars of mongoloid people_
Multiple odontomes : associated with calcifying odontogenic cyst
well-defined radiolucent lesion, and as calcification proceeds it looks as radioaque, radiating structure
When mature it is surrounded by a translucent zone
Do not resemble normal teeth but have normal tooth structure
Less growth potential than the complex type, so less expansion of the bone
This shows a more advanced level of differentiation than the complex type
80% occur in mandible, mostly molar region
Slow-growing, asymptomatic in early stages
As it enlarges causes facial deformity and expansion
Thinning of the overlying bone, at late stages causing perforation
Teeth in the area may become loosened
Follicular ameloblastoma showing islands of neoplastic epithelium, forming separate follicles
Plaxiform ameloblastoma showing complex pattern of interconnecting epithelial strands
thought to arise from remnants of dental lamina or other sources
Unicystic ameloblastoma with proliferation into the lumen
Nuclear pleomorphism, not indicative of malignancy
Amyloid like material, may become calcified
Majority in the anterior maxilla _canines_
Slowly growing swelling _otherwise symptomless_
Sheets and strands of epithelium, which differentiates into columnar, ameloblast-like cells in some areas
The columnar cells form duct-like structures _hence adenomatoid_
Little supporting stroma
No recurrence _no need for radical excision_
Does not require radical excision _because it is not invasive_
_resembling dental papilla
except having fewer stellate cells and unusual cyst formation
Slowly enlarging, otherwise symptomless
May arise in relation to the root or the crown
Derived from mesenchymal dental tissues _periodontal ligament, dental follicle, dental papilla_
This is an odontogenic myxoma (stained by Alcian blue) showing the abundance of glycosaminglycans in the stroma