Name the Odontogenic inflammatory cysts x 4

Radicular cyst (dental cyst)
- apical
- lateral
- residual
Paradental cyst


Name the non-odontogenic cyst of the jaw

Nasopalatine (duct) cysts/ incisive canal cysts


Name the non-epithelial-lined 'cysts' x 3

Stafne bone cyst (Staphne's idiopathic bone cavity)
Aneurysmal bone cysts
Solitary bone cyst


Soft Tissue cysts which may affect the head and neck x 5

Salivary mucoceles
Dermoid cysts
Epidermoid cysts
Lymphoepithelial cyst
Thyroglossal duct cyst
Nasolabial cysts


Name the ondontogenic developmental cysts

Dentigerous cyst /Eruption cyst
Odontogenic keratocyst (parakeratotic or orthokeratotic)
Lateral periodontal and botryoid odontogenic cyst
- Gingival cyst
- Glandular odontogenic cyst
Calcifying odontogenic cyst


Name the benign odontogenic tumours

Classified by tissue cell of origin

Ameloblastoma, unicystic type
Ameloblastoma, extraosseous/ peripheral type
Metastasizing (malignant) ameloblastoma
Squamous odontogenic tumour
Adenomatoid odontogenic tumour
Ameloblastic fibroma
Primordial odontogenic tumour
Odontoma, compound type
Odontoma, complex type
Dentinogenic ghost cell tumour
Odontogenic fibroma
Odontogenic myxoma/myxofibroma
Cemento-ossifying fibroma


Radicular Cysts - histopathology and facts

Most common jaw cysts (~75% all jaw cysts)
- apical (most commonly)
- lateral (formed at lateral canals)
- residual (following extraction of a tooth)
Arise from periapical granuloma from nectrotic remnants of dental pulp
Chronic inflammation (including cytokines and growth factors) stimulates cell rests of malassez - epithelial proliferation, followed by cyst development (due to degeneration of the central cells due to avascular necrosis or necrosis due to toxins) and then growth.
Fluid filled lesions, growth by osmotic pressure, cytokines and prostaglandins released by cells within the capsule causing local bone resorption.
Hydrostatic pressure in the cyst fluid as contents hypertonic compared with serum, so water drawn in along osmotic gradient.
Histologically - non-keratinised squamous epithelial-lined (wholly or in part), supported by chronically inflammed fibrous capsule. Can also get mucous cells (40%) or even cillated respiratory-type cells, and Rushton bodies - hyaline eosinophilic bodies in the lining. Cholesterol clefts may form in the cyst capsule and may produce a shimmering appearance to the fluid.
Can't tell if periapical granuloma or cyst from radiograph
Rate of expansion estimated at 5mm/year diameter
M>F (possibly due to less dental disease in F)


Radicular cysts - signs, symptoms, investigation and management

Possible pain and swelling if infected
Associated with a non-vital tooth
May find expansion, egg-shell crackling, if perforates the cortex - bluish fluctuant submucosal swelling
Investigations - vitality testing tooth and adjacent teeth
Radiographs, possibly CBCT if indicated
Radiographs - well defined unilocular radiolucency with possibly displacement of adjacent structures (e.g. roots/IDC),
Removal of causative tooth/extirpation of necrotic pulp
Small cysts may regress, others require enucleation. Could consider marsupilisation in immunocomprimised/ if large lesion. May consider prophylactic plating if seems high risk of mandibular fracture associated with treatment.


Paradental cysts

Paradental cysts are odontogenic, inflammatory cysts and occur buccally or distobuccally to a tooth affected by pericoronitis. Most commonly affect the mandibular third molar tooth
Radiographically - well defined radiolucency associated with the neck of the tooth and coronal third of the root
Histologically - resemble inflammatory radicular cysts


Dentigerous (and eruption) cysts
-Radiographic features
-Eruption cyst

Encloses all or part of the crown of an unerupted tooth
attached at the CEJ
Arises from the follicular tissues
M>F 2:1
Mandible>Maxilla 2:1
MTM>Maxillary canine>MaxillaryTM>mandibular premolar>supernumerary/complex/compound odontomes
Types - central, lateral, circumferential
Radiographically: unilocular, well defined radiolucency associated with the crown of unerupted tooth (which may be displaced). Suspect if follicular space >3mm
Adjacent teeth: displaced, reorbed in ~50%, enveloped by large cysts.
Eruption cysts - extra-alveolar so present as flutuant bluish swellings.
Pathogenesis - stimulus and mechanism of formation unclear
estimated 1% develop cysts
Histopath: Derived from the reduced enamel epithelium (REE)
Occasionally what appears to be ameloblastomous epithelium proliferates into cyst lumen - unicystic ameloblastoma
Lined by thin, non-keratinizing squamous epithelium; often shows mucous cell metaplasia


Odontogenic Keratocyst (Prev OKT)
-Clinical Features
-Radiographic features

Peak incidence 2-3 decades
Mandible>maxilla (70-80% : 20-30%)
>50% cases mandibular third molar region, ascending ramus, almost all posterior to first premolars
Expansion predominantly in anterior-posterior direction hence few clinical signs - often incidental finding
Multiple cysts associated with Gorlin-Goltz Syndrome
Radiographically - uni/multilocular, well defined, scalloped margin.
(Differential - ameloblastoma/dentigerous cyst if associated with the crown of an unerupted tooth, lateral periodontal cysts.)
May displace adjacent roots
Pathogenesis - Aetiology still speculative. May arise from primordial epithelia (remains of dental lamina) or from the enamel organ before tooth formation, Cell rests of Serres instead of a normal tooth developing - hence sometimes a tooth is missing from the series.
Evidence suggesting PTCH-gene not a significant factor in sporadic OKC
More proilferative than mucosal epithelium. Active epithelial growth more important than osmotic pressure, hence growth pattern and probably affects keratocystic recurrence. Bone resorbing factors produced by the cysts. Cyst has extension of proliferating areas along cancellous spaces.
2 types - Parakeratotic (usually multilocular, more likely to recur) and Orthokeratotic (monolocular)
Recurrence 3-60% - due to friable cell wall, projections into cancellous spaces and satellite cysts
Histology - thin cyst wall, often foldered and lined by regular continuous layer of stratified squamous epithelium 5-10 cells thick. Fibrous capsule thin and tears easily.
Satellite cysts - (often microscopic) known as daughter cysts, involved in recurrance

If secondarily inflamed then may be difficult to differentiate from radicular cyst histologically.


Gorlin-Goltz Syndrome

Autosomal dominant
Also known as Naevoid basal cell carcinoma syndrome
-facial features - frontal & parietal bossing, broad nasal root
-skin - multiple BCCs unrelated to sun exposure (90% of cases) (earlier onset, slower growth)
-oral - multiple OKCs (90% of cases)
-skeletal - rib anomalies , vertebral deformties, polydactyly (more fingers), cleft lip/palate (~5%)
-CNS - calcified falx cerebri (fold of dura mata), brain tumours
Caused by mutation of tumour suppressor gene on chromosome 9q termed patched (PTCH) gene, probably acting as a tumour supressor
PTCH encodes for a protein which represses transcription of the hedgehog signalling network
Severity of expression varies/ which areas involved.
Mutations in PTCH also reported in sporadic odontogenic keratocysts.


Odontogenic Keratocyst Management

Preferably diagnosis prior to definitive treatment - rule out ameloblastoma and other differentials depending on location - incisional biopsy
Complete enucleation required, or marsupulisation followed by enucleation/resection.
Resection - lowest recurrence but morbidity so not usually advocated. Consider on case by case basis depending on size of OKC
Carnoy's fluid improves results of enucleation - but no longer available due to being banned by FDA
Some advocate peripheral ostectomy or cryotherapy with liquid nitrogen.
Optimal treatment modality not yet identified - ? medical management in future to manage tumour suppresant gene?
Need follow up with regular radiographic examinations due to risk of recurrence 1.5-4 years in some studies


Nasopalatine (duct) cyst (incisive canal cyst)
-Clinical features
-Radiographic findings

Arise from the epithelial remnants of the nasopalatine duct.
Present 3-5th decade. Uncommon.
Asymptomatic/occasional salty discharge/pain if inflamed. Slow-growing.
Most occur in most inferior aspect of the canal or occasionally completely within the soft tissue.
Radiographically - well defined, round, ovoid or heart-shaped radiolucency. Usually in the midline, but may be displaced to one side or another.
If radiolucency at incisive foramen >6mm then consider cystic change.
Histopath - epithelial lined (stratified squamous. pseudostratified cilated columnar (repiratory), often containing mucous cells), supported bu connective tissue campsule. Collections of mucous glands and chronic inflammatory cell infiltrate frequently seen.
Treatment - enucleation - do not recur. On enucleation, may contain the neurovascular bundle.


Staphnes / Static Idiopathic Bone Cyst
Non-epithelial cysts ('pseudocysts')

Non-epithelial lined
Incidental radiographic finding of well circumscribed radiolucency with sclerotic margins in area of second or third molar teeth, beneath the inferior dental canal.
Not a true cyst, but an invagination of the medial aspect of the mandible usually containing salivary tissue (or can be lymphoid tissue)
CBCT indicated to confirm diagnosis, but biopsy and exploration not indicated.


Aneurysmal bone cyst
Non-epithelial cysts ('pseudocysts')

Benign intra-osseous blood filled cavities; most commonly found in long bones.
Unknown aetiology, essentially a vascular malformation
Adolecents/ young adults.
Primary (70%) - no associated previous lesions
Secondary (30%) - history of previous lesions such as fibrous dysplasia or dentigerous cyst
Clinical features - firm, painless, slowly expanding swelling. Sudden expansion suggests bleeding within lesion (often following minor trauma). Pain in 50% presentations
Can cause root resorption.
Radiographically - unilocular or multilocular radiolucencies, with irregular outline. Differential - keratocyst or ameloblastoma
Histologically - multiple blood filled spaces separated by septa with scattered multi-nucleate giant cells.
Treatment - simple curettage - sometimes complicated by severe bleeding. Can recur.


Solitary bone cyst
(simple bone cyst, traumatic bone cyst, haemorrhagic bone cyst, latent bone cavity)

Non-epithelial lined space that may contain small amount of straw-coloured fluid/no fluid
Most often found in the long bones, rare in the jaws
trauma proposed aetiology with clot formation which is followed by clot degredation, but no subsequent bone formation. The clot is thought to liquify, producing a gas - the oxygen being absorbed, and the nitrogen remaining, which can be found on analysis.
Painless swelling/ incidental radiographic finding. Expansion in around 25%
F>M 3:2
Radiographically - radiolucency extending between roots of involved teeth, well defined, scalloping, commonly in the premolar and molar region of the mandible. Maxillary lesions rare.
? spontaneous resolution after adolescence


Radiological description of jaw lesions

Site/anatomical position
Shape (unilocular, multilocular, psuedolocular, round, oval scalloped, undulating, irregular, regular)
Outline (smooth, punched out, corticated, sclerotic, encapsulated, signs of invasion or blending with normal anatomy)
Relative radiodensity and internal structure (uniform, mixed, radiopaque, ground glass, cottonwool patches, honeycomb appearance, bony septa, identifiable dental tissue)
Effect on adjacent surrounding structures (resorption, displacement, delayed eruption, dirupted development, loss of lamina dura, increased pdl space, alteration of size of pulp chamber, hypercementosis, expansion, ragged destruction, increased density, sclerosis, subperiosteal new none formation, irregular bone remodelling)
Time present (if known)


Location of odontogenic/non-odontogenic lesions

odontogenic - above IDC
non-odontogenic - below IDC


Differential diagnosis radiolucencies of the jaw

?normal or abnormal?
?pathological? (congenital/developmental/acquired)


Lateral Periodontal Cysts
and variants

Rare, developmental cyst. Thought to develop from either cell rests of dental lamina, or remains of the REE on the lateral surface of the root.
Site -lateral surfaces of the roots of vital teeth, lower canine/premolar/upper lateral incisors
less than 1cm diameter
smooth, well defined and corticated, uniformly radiolucent.
If cyst becomes large, may rarely resorb adjacent teeth. Buccal expansion if large.
Differentials - lateral radicular cyst (inflammatory) or odontogenic keratocyst.
Responds well to enucleation.

Occasionally multilocular - described as botryoid as they resemble a bunch of grapes (even more rare than lateral periodontal cysts) - more likely to recur.

Glandular odontogenic cyst - v rare, associated with lateral periodontal cysts
multilocular, pools of mucin and micous cells in epithelium. Strong tendency to recur.


Gingival cysts

Common in neonates, often referred to as epsteins pearls or Bohn's nodules.
Most disappear spontaneously by 3/12
Arise from remnants of the dental lamia proliferating to form karatinising cysts (cell rests of serres)

In adults - rare - likely represent developmental lateral periodontal cysts in an extra-alveolar location. Can cause bony resorption, resulting in saucer-like defects in the alveolus. Unlikely to recur after enucleation.


Calcifying odontogenic cyst (previously classifed as an odontogenic tumour, reclassified 2017)

Rare, affects any age.
Affects anterior maxilla or mandible.
Unilocular, well defined and corticated radiolucency, calcifying as it matures. Adjacent teeth usually displaced and/or resorbed. 1/3 associated with unerupted tooth.
Intra-osseous or extra-osseous eroding the jaw
Initially may have little calcification, but increasing calcification leads to differentials including odontome or calcifying odontogenic tumour.
Benign, but may recur and can be aggressive.
Enucleation and curettage is treatment of choice.


Nasolabial cysts

4-5th decade, F>M 4:1
swelling at nasal fold causing distortion to alar base
can cause local resorption of the maxilla
Treatment - excision
lined by squamous or respiratory epithelium
Aetiology unknown


Dermoid Cysts

Sublingual - found in midline beneath tongue and as far down as hyoid
Developmental - believed to arise from epidermal cell rests resulting from the fusion of embryonal processes.
Deeply placed, filled with keratin, giving firmer feel compared to a ranula.
If above mylohyoid - present as a swelling in FOM
If below mylohyoid - present as swelling in the neck
Treatment - excision

Dermoid cysts can arise in the skin of the H&N and can arise from trauma where skin is driven into subepithelial layers. Treatment - excision.


Lymphoepithelial cysts (?prev classified as Branchial cysts)

?Arise from incomplete obliteration of branchial clefts
lateral aspect of the neck, anterior to SCM. Unusually presenting in the oral cavity - generally FOM.
Rarely present with acute infection.
Age of presentation - children, young adults - if over 40 consider base of tongue SCC and cystic metastases
MRI indicated and excision of the branchial cyst tract.
Histologically - lined by stratified squamous epithelium with well-organised lymphoid tissue. Probably arise from salivary epithelium that becomes entrapped by lymphoid tissue.
Lymphoepithelial cysts found in FOM and posterior tongue epithelial inclusion within lymph nodes


Thyroglossal duct cysts

arise from thyroglossal duct, which should break down after migration of the thyroid from the foramen caecum.
Present as midline swelling anywhere along line of migration of gland. Usually asymptomatic
Attached to hyoid bone and tongue so move on swallowing and tongue protrusion.
MRI scan and FNA.
Sistrunk procedure - excision of cyst and central portion of hyoid


Ameloblastoma types x 5

- Ameloblastoma - conventional
- Unicystic ameloblastoma
- Extra-osseous/peripheral ameloblastoma
- Metastasizing (malignant) ameloblastoma
- Ameloblastomastic carcinoma


Treatments - Marsupulisation

Aims to initially decompress the cyst or tumour to allow shrinkage and bone deposition around the periphery of the cyst/tumour
Minimises surgical defect as a result of enucleation and results in a thickened cyst lining which may facilitate its removal when subsequently enucleated.
Cyst is de-roofed and the lining sutured to the mucosa then the defect repeatedly packed, or a tube secured in situ to hold the cyst open (with the patient irrigating the area). The cyst is left open for 2-3 months prior to definitive enucleation.
If a drain is used this will probably spontaneously exfoliate in 1-2 months


Treatments - Intra-lesional adjunctive therapy: Chemical fixation

Carnoys advocated by some as a chemical fixative. Now banned by the FDA as it contains chloroform (and is therefore thought to be possibly carcinogenic to humans - animal studies only)
Can be used on the cyst itself prior to enucleation, or after removal to fix the bony cavity - 5 min application penetrates to a depth of 2-3mm
Performed by packing ribbon gauze into the cavity with gauzes to protect surrounding tissue. Syringe used to administer Carnoy's solution for 5 mins while minipulated within cavity to access all walls. Then removed and cavity irrigated with copious saline.
Minimises recurrance


Treatments - Intra-lesional adjunctive therapy: Cryotherapy

1 minute freeze procdues depth of bone necrosis of 1-3mm depending on technique
- cryoprobe with jelly (non-uniform) - repeat x3
- liquid nitrogen (uniform) - 3 thaw cycles using funnel and altering operating position to enable access to all areas of the cyst cavity


Treatments - Resection

Consider for large primary or recurrent benign tumours and malignant tumours.
Composite, segmental or marginal resection


Treatments - Reconstruction

Ideally - immediate reconstruction
- non-vascularised autogenous bone grafts from illiac crest
- microvascular free flap - fibula, illiac crest, radial forearm, scapula - good for larger defects greater than 6-9cm
Aim - to re-establish mandibular continuity
Vasularised bone grafts have a better success rate compared to non-vasular grafts, and on average require fewer operations.


Ameloblastomas - presentation

(Benign Odontogenic Tumour - Epithelial Origin)

Most common odontogenic neoplasm (excluding odontomas)
Ameloblasts thought to be the cell of origin
Symptoms - slow-growing submucosal mass, loose teeth, malocclusion, paraesthesia, pain. (~35% may be asymptomatic)
Median age - 35
80% in mandible, usually ramus. Often associated with molar teeth.
More common in people of african decent, in this population may be more common anteriorly.
Radiographically - multilocular radiolucency (occasionally unilocular in early stages), rarely honeycomb or soap-bubble type.appearance. Well defined, well corticated, smooth scalloped outline. Displacement and resorption of adjacent teeth. Expansion in all directions. Can extend into adjacent structures (maxillary lesions - paranasal sinuses, orbit, base of skull)


Ameloblastomas - histology

Distinctive histological appearance - columnar, basally staining cells palisaded pattern along basement membrane


Ameloblastoma - treatment

'radical' enucleation followed by resection of surrounding margin or bone, or cyrotherapy, or carnoy's solution, or resection (local or radical) and reconstruction.


Unicystic Ameloblastoma

(Benign Odontogenic Tumour - Epithelial Origin)

5-15% of all ameloblastoma
Unilocular radiolucency with either the crown of an unerupted tooth (early presentation - peak at 16yrs) or at the apices of teeth - resembling a radicular cyst.
Can mimic other types of cysts - so should be considered in differential diagnoses
Histologically - ameloblastoma - predominently fluid filled.
Treatment - same as ameloblastoma, but responds better to simple enucleation and currettage. Recurrance rates less than ameloblastoma.


Peripheral Ameloblastoma (extraosseous)

(Benign Odontogenic Tumour - Epithelial Origin)

Rare - present in gingival or soft tissue without involving bone
May arise from the basal cell layer of oral epithelium or extraosseous rests of dental lamina
Much less invasive than intraosseous tumours - less drastic surgery required.
Histologically - resemble intra-osseous type ameloblastomas


Squamous odontogenic tumour

(Benign Odontogenic Tumour - Epithelial Origin)

Well-circumscribed radiolucency with sclerotic border associated with the roots of teeth.
Histology - irregularly-shaped islands of differentiated squamous epithelium in a stroma of mature fibrous tissue. Thought to be derived from the rest cells of malassez


Calcifying epithelial odontogenic tumour
(Pindborg tumour)
(Benign Odontogenic Tumour - Epithelial Origin)

Mandible>Maxilla 2:1
20-60yrs old
Most arise in molar or premolar area and about half are associated with the crown of an unerupted tooth, particularly MTMs
Most occur within bone, rare cases of extraosseous lesions reported.
Radiographically - variable definition, and cortication, sometimes irregular radiolucency not clearly demarcated from surrounding normal bone, but can be unilocular or multilocular. Varying amounts of radiopaque bodies due to calcification with the tumour. 'driven snow' appearance.
Adjacent teeth can be displaced or resorbed, and expansion seen
Histologically - a characteristic feature is presence within the sheets of epithelial cells of homogenous amyloid-like materia, which may become calcified.
Less aggresive than the ameloblastoma


Adenomatoid odontogenic tumour (AOT)

(Benign Odontogenic Tumour - Epithelial Origin)

Presents 2-3rd decade
Majority arise in anterior maxilla, particularly the canine region. Present as slowly enlarging swelling.
Radiographically - well defined radiolucency - some cases calcification within tumour may produce faint radiopacities. Often associated with an unerupted tooth and may simulate a dentigerous cyst.
Histology - well encapsulated, solid or partly cystic. Consists of sheets, strands and whorled masses of epithelium which in areas differentiates into columnar, ameloblast-like cells. Must be differentiated from ameloblastoma as less aggressive treatment is required as it does not recur following simple enucleation


Ameloblastic fibroma

(Benign Odontogenic Tumour - Epithelial - Mesenchymal Origin)

Rare, presents in young people, rare over age of 21.
Well circumscribed lesion, needs to be differentiated from ameloblastoma as less invasive treatment required. Recurrance around 20%.
Radiographically - well-defined, usually unilocular radiolucency. May be associated with an unerupted tooth and mimic a dentigerous cyst.
Histology - proliferating strands or odontogenic epithelium in fibroblastic tissue resembling the dental papilla of the developing tooth. Epithelial component has layer of cuboidal or columnar cells - cimilar to ameloblastoma, but stellate cells much less abundant


Primordial odontogenic tumour

(Benign Odontogenic Tumour - Epithelial - Mesenchymal Origin)

Added to WHO classification in 2017
Mixed odontogenic tumour, very rare.
Composed of variable cellular loose fibrous tissue.
Affects young patients in the mandible, presenting as a well-circumscribed peri-coronal radiolucencies.
No recurrence following conservative surgery.


- compound
- complex

(Benign Odontogenic Tumour - Epithelial - Mesenchymal Origin)

Compound - made up of several small tooth-like denticles, none of which resemble normal tooth morphology, but contain organised pulp, dentine and enamel. Occur in 1st-2nd decades and majority in anterior maxilla associated with an unerupted tooth.
Complex - irregular disorganised mass of dental tissues - not in the shape of a tooth with a clear surrounding radiolucent line. 2-3rd decades. Molar region of the mandible. Often associated with crowns of unerupted teeth. Composed mainly of dentine.

Speculative relationship between developing odontomas and ameloblastic fibromas/ ameloblastic fibrodentinomas and ameloblastic fibro-odontomas : as pre-cursors of odontomas.


Dentinogenic ghost cell tumour

(Benign Odontogenic Tumour - Epithelial - Mesenchymal Origin)

The tumour is a relatively rare type of ghost cell lesion characterised by ameloblastoma-like islands of epithelial cells in a mature connective tissue stroma with accumulation of ghost cells.
Radiologically - radiolucent or mixed radiolucent and radiopaque with unilocular, well circumscribed borders.
Recommended surgical treatment is segmental resection because of the high recurrence rate and local invasive nature of the tumour


Odontogenic Fibroma

(Benign Odontogenic Tumour - Mesenchymal Origin)

Arise in relation to the root of a tooth, crown of an unerupted tooth or may take the place of a tooth missing from the arch. (depending if from periodontal ligament, dental follicle and dental papilla - all mesenchymal tissues)
Uncommon, well demarcated and readily enucleated.
Histologically - cellular fibrous tissue with varying amounts of inactive odontogenic epithelium.
Central - in the bone
Peripheral - fibrous epulis


Odontogenic myxoma/myxofibroma

(Benign Odontogenic Tumour - Mesenchymal Origin)

2-4th decade
Rare - but 3rd most common odontogenic tumour.
Occurs in posterior mandible or posterior maxilla. Variable size, but becomes large when untreated.
Multilocular radiolucency - soap bubble/honeycomb. Fine intermal radiopaque seta sometimes described asresembling the strings of a tennis racket, or the letters X & Y.
Causes tooth displacement and occasionally root resorption. Extensive bucco-lingual/palatal expansion. May occur in place of a missing tooth.
Occasionally unilocular. appearance with well defined margin. Non-encapsulated with infiltrative pattern of growth
Histologically - stellate and spindle-shaped cells in myxoid or mucoid extacellular matrix - originates from odontogenic connective tissue of the developing tooth germ.



(Benign Odontogenic Tumour - Mesenchymal Origin)

Mean age 20 yrs, but wide range.
Occurs at apex of mandibular first permanent molars, occasionally pre-molars. Exceptionally associated with primary dentition. Up to 2-3cm diameter
Radiographically - well defined, 'golf ball' appearance radiopacity attached to a tooth root. Thin radiolucent line. Often surrounded by diffuse sclerotic bone.
May cause localised expansion.
Tooth involved vital. Root usually shows resorption.
Histology - mass of calcified cementum-like tissue.
If incompletely removed, may recur.


Bone-related lesions
- Giant cell lesions x 3
- Osseous dysplasias x 4
- Other x 3

Giant Cell Lesions
- Central giant cell lesion (granuloma)
- Brown tumour in hyperparathyroidism
- Cherubism
- Aneurysmal bone cyst
Osseous Dysplasias (previously known as fibro-cemento-osseous lesions)
- Periapical osseous dysplasia
- Focal osseous dysplasia
- Florid osseous dysplasia
- Familial gigantiform cementoma
Other Lesions
- Fibrous Dysplasia
- Simple bone cyst
- Stafne's bone cavity


Central Giant Cell Lesions (Granuloma)

(Giant Cell Lesions)

Osteolytic proliferation
Fibrous tissue with haemorrage and haemosiderin deposits with osteoclast-like giant cells and reactive bone formation producing buccal or lingual expansion.
Age - can affect all ages, usually young adolescents and adults under 30 yrs.
Radiographically - multilocular, or honeycombed well defined radiolucency generally well corticated, with internal septa affecting all parts of the mandible particularly premolar/molar region.
Can be aggressive - rapidly growing and destructive or non-aggressive with slow growing, benign behaviour.


Brown Tumours and Hyperparathyroidism

(Giant Cell Lesions)

Hyperparathyroidism caused by hyperplasia or adenoma of parathyroid glands (primary hyperparathyroidism), or secondary hyperparathyroidism caused by kidney disease - due to hypocalcaemia.
Most commonly affects post-menopausal women.
Both result in the increased secretion of parathyroid hormone (PTH), which leads to osteopenia, bone pain, pathological fracture, and raises plasma calcium levels.
Other findings:
- browns tumours: cyst-like lesions in the mandible localised - histologically and radiographically indistinguishable from central giant cell lesions.
- Peripheral giant cell lesions - cyst like swelling. If originating from the periosteum rather than the gingivae, may cause bone resorbtion - can also be due to trauma.
- skull vault osteopenia results in stippled pattern to the bone - 'pepper-pot skull'
- osteopenia in the mandible produces a fine trabecular pattern - 'ground glass' appearance and loss of the lamina dura surrounding all the teeth and thinking or loss of cortical bone of the lower border of the mandible.
Alveolar bone may also be resorbed, but reforms after treatment.
Treatment - of cause (removal of parathyroids, or treatment of renal failure). Bone lesions may respond to vit D.
Hyperparathyroidism - bloods - raised calcium, low phosphorus, raised PTH, raise Alk Phos



(Giant Cell Lesions)

Rare, inherited disease, usually autosomal dominant, can occur spontaneously.
Weaker penetrance of trait in F, so M>F 2:1
Gene for cherubism - 4p16.3.
Seen worldwide, but rare in Japan.
Age 2-6 years
Extensive expansion seen angle/posterior mandible, bilaterally (occasionally maxilla). Variable size, may fill whole jaw, swelling, which can affect the speech, swallowing or even breathing. Growth is rapid for a few years, then slows until puberty, and usually there is slow regression until, by adulthood normal facial contour is restored - the radiolucencies in the bones are still evident however.
Causes gross displacement of teeth which can be resorbed or exfoliated early.
Maxillary disease rare, but if affected then eyes appear to be turned heavenward. This with plumpness of face gives rise to term Cherubism.
Radiographically - resemble closely other giant cell - containing lesions,- multilocular, smooth outline which is well defined and well corticated. Radiolucent with internal septa.
Histologically - multinucleated giant cells, over time these become fewer and there is bony repair of the defect.
Management - occasionally debulking may be indicated, but preferably after growth.


Osseous Dysplasias - General

Skeletal disorders where bone is replaced by fibrous tissue, which is then is replaced by bone or mineralised tissue to varying degrees.
Therefore - Intially radiolucent, then mixed radiopacity - mixed with patchy opacities. Late stage - densely radiopaque with a think radiolucent line.


Periapical Osseous Dysplasia

Osseous Dysplasias

Age - middle age
F>M typically black women.
affects apices of vital lower incisors - small - usually up to 5-6mm dia, round unilocular, often multiple with outline which is poorly defined and not corticated.
Intially radiolucent, then mixed radiopacity - mixed with patchy opacities. Late stage - densely radiopaque with a think radiolucent line. No expansion or displacement/resorption of adjacent teeth. Lamina dura may be discontinuous however.


Florid osseous dysplasia

Osseous Dysplasias

Age - middle age - typically black women
widespread osseous dyplasia lesions up to around 2cm dia, moderately well defined but irregular, occasionally corticated.
ntially radiolucent, then mixed radiopacity - mixed with patchy opacities. Late stage - densely radiopaque with a think radiolucent line.
Occasionally may cause expansion, but teeth are generally vital and not resorbed or dysplaced.
Can be associated with low grade osteomyelitis.


Osteogenesis imperfecta
(brittle bone syndrome)

Heterogeneous group of related disorders
mutations of gene that codes for type-1 collagen leading to failure of osteoblasts to form adequate amounts of bone.
generalised osteoporosis
slender bones
marked tendency to fracture
narrow long bones with poorly formed cortices - immature, woven bone. Healing usually normal, but callus may form
Sclerae appear blue
FH of deafness caused by distortion of ear ossicles
Also may have joint hypermobility, lax ligaments, think translucent skin and heart valve defects.
Often also associated with dentinogenesis imperfecta, particularly in deciduous dentition.
Thought that defects carried by separate but related genes.
Type I - (classic type) - autosomal dominant, blue sclera, premature deafness, with or without osteogenesis imperfecta
Type II - (perinatal lethal) - autosomal dominant
Type III - (progressively deforming) - autosomal dominant, recessive, severe osteoporotic bone, progressive deformity, dentinogenesis imperfecta
Type IV - autosomal dominant. Like type I but more servere - white sclera, with or without dentinogenesis imperfecta.



Otherwise known as marble bone disease
Excessive bone denisity - obliteration of bone marrow cavities and consequent secondary anaemia. Liver and spleen take on blood cell formation.
Defect in osteoclastic activity - but normal bone deposition, which leads to excessive formation of bone which is weak and fractures easily.
Delayed eruption of teeth.
Osteomyelitis common with tooth extraction, prevention of infections important.
Radiographically - no distinction between cortical and medullary bone.
Jaw involvement variable. Affects mandible more commonly than maxilla. May cause compression of cranial nerve canals and deficits or pain can result.
BMT main hope for treatment.


Cleidocranial dysplasia (cleidocranial dysostosis)

Autosomal trait. Abnormalities of many bones, particularly skill, jaws and clavicle. 1:1,000,000
Dental abnormalities including delayed or non-eruption are common due to multiple impactions. Supernumeraries and dentigerous cysts also common. Roots tend to be thinner and cementum absent or sparsely present
Skull - fontanelle and sutures fail to fuse or fuse late and skull appears flat with prominent frontal, parietal and occipital bones. Nasal bridge depressed.
Clavicle - partial or complete absence.
Maxilla - underdeveloped with high, narrow arched palate.



Autosomal dominant - can be inherited or as a result of a spontaneous mutation
Most common form of dwarfism - abnormality in endochondral ossification - absence or defect in the zone of provisional calcification in the epiphyses and base of skull, resulting in a normal sized trunk and head, but excessively short limbs and retrusive mid face due to defective growth of skull base, as a result, severe malocclusion common.



Uncommon, recessive genetic disorder.
Early onset - rickets-like skeletal disease with defective mineralisation. Defective cementogenseis resulting in premature tooth loss. Alk Phos low, urinary phosphoethanolamine raised.
Late onset - dominant trait, main manifestation os fragility of the bones.


Sickle cell anaemia and thalassemia major
(relating to bone)

Bone changes uncommon.
When severe these conditions can cause rarely causes bone malformation in the maxillofacial region, in particular thalassemia. Expanded erythropoiesis causes thickening but also osteoperosis of the skull.

In Thalassemia - diploic spaces in the skull are enlarged due to marrow expansion - radiographically this give a hair-on end appearance radiographically and a thin cortex. The maxilla can be expanded causing malocclusion. Zygomatic bones pushed outwards and the nasal bridge depressed in severe cases.

Sickle-cell infarcts in the jaw bones can be painful, and can mimic osteomyelitis - appearing radiolucent initially then sclerotic and opaque.



(Metabolic Bone Disease)

Vit D deficiency during period of bone development causes rickets - defective calcification and development of the skeleton, but rarely teeth.
Renal rickets - due to defective calcium and phosphorous metabolism due to chronic renal disease.
Onset - infancy
Broadening of growing ends of bones, and prominent costochondral junctions due to epiphyseal defects. Weakened bones bend readily.
Skull changes - wide fontanelles, bossing of frontal and parietal eminences, thinning of back of skull.
Radiographs - wide, thick epiphyses and deformities. Alk Phos raised (due to low calcium and phosphate - resulting from vit D deficiency)
Path - trebeculae surrounded by newly formed, uncalcified osteoid matrix. Cartilage fails to mineralise and cartilage cells continue to proliferate - causing thickening of the episphyseal plate.
Dental changes: teeth have a priority over the skeleton from minerals - so dental defects rare. Hypocalcification of dentine with wide band of predentine and excessive interglobular spaces may be seen in severe rickets. Eruption of teeth may be delayed. These abnormalities do not lead to increased susceptibility to caries.
Treatment - Vit D replacement - 2000-3000iu daily
orthopedic treatment may be required to correct malformations.



Vit C deficiency - defective collagen formation and osteoid matrix. Amount of osteoid matrix formed is small, but highly calcified - ends of long bones sharply defined on radiographs. Weakness of connective tissue leads to haemorrhagic tendency (purpura) can cause bone pain and detachement of the periosteum by bleeding. Haematoma becomes calcified, leading to abnormal shaped bones.
Severe scurvy - swollen, bleeding gingivae and early tooth loss.
Largely historical interest but rarely seen in neglect.


Giantism and Acromegaly

Overproduction of pituitary growth hormone - usually adenoma.
If before epiphyses fuse (during growth) - leads to giantism with overgrowth of the whole skeleton.
If after fusion of the epiphyses then continued grown of mandibular condyle (prognathism) and soft tissue growth causing macroglossia, thickening of facial soft tissues (in particular the lips and the nose) and overgrowth of the hands and feet. Subperiosteal bone deposition. Teeth become spaced.
Headaches and visual disturbances due to adenoma common.
Rarely a growth-hormone producing pituitary tumour is part of MEN1 (multiple endocrine neoplasia syndrome)
Resection or irradiation of tumour indicated and patient may require orthognathic surgery.



Excessive fluoride ingestion, usually area specific.
Causes severe mottling of the teeth and sclerosis of the skeleton. Intrervertebral ligaments and muscle insertions calcify, causing stiffness of the back in particular, and pain.
Bone changes similar to those seen in Pagets.


Paget's disease of bone (Osteitis deformans)

Unknown cause - ? viral/genetic?
Causes distortion and weakening, particularly in the elderly
Most frequently affects sacrum, spine, skull, femora and pelvis. Disease may be widespread and usually symmetrical, but sometimes a single bone is affected.
Skull vault more commonly affected than the facial skeleton and Maxilla>Mandible. Narrowing of foramena can occasionally cause cranial nerve deficits.
If affected - alveolar processes grossly enlarged and generalised spacing of teeth. Hypercementosis, and ankylosis. Severe bleeding or osteomyelitis of ischaemic bone may follow dental extractions
Radiographic features - lower density in early stages and sclerosis in later stages, patchily distributed with loss of normal trabeculation - giving "cotton wool" appearance.
Path - bone resorption and replacement rapid, irregular, exagerated and purposeless.
Destruction and deposition of bone alternated rapidly, marked histologically by blue-staining reversal lines, giving a jigsaw-like appearance 'mosaic' to the bone.
Osteosarcoma - rare but recognised complication of paget's disease.
Treatment - calcitonin or bisphosphonates or both.


Fibrous Dysplasia

Bone Related Lesions

- Monostotic fibrous displasia - boney swelling typically starting in childhood and arresting in adulthood.
Painless, smoothly rounded swelling, usually maxilla, can cause displacement of teeth and malocclusion.
Radiographically - area of weak radiopacity with fine orange-peel like texture and egg-shell expansion of bone. Margins merge with surrounding bone. May have more radiolucent or sclerotic appearance.
- Polyostotic fibrous dysplasia - rare. Histologically similar lesions in several bones and skin pigmentation and endocrine abnormalities. F>M 3:1
(McCune-Albrights Syndrome - polyostotic fibrous dysplasia, skin pigmentation and sexual precocity. )
Disease usually self-limiting but grossly disfiguring lesions may necessitate removal. Small risk of sacromatous change.