Bone Disorders

24 June 2025

Name the types of bone cells

1. Osteocyte

2. Osteoblast

3. Osteogenic cell

4. Osteoclast

What

What is an osteocyte responsible for

Maintaining bone tissue

What is an osteoblast responsible for

Forming bone matrix

What is an osteogenic cell responsible for?

Stem cell

What is an osteoclast responsible for?

Bone resorption

Name some fibro-osseous lesions

1. Fibrous dysplasia

2. Cemento-osseous dysplasia (COD)

What is fibrous dysplasia?

A tumor-like condition, characterized by replacement of normal bone by fibrous connective tissue intermixed with abnormal bone

What does dysplasia in bone look like?

Disorganized growth that is not malignant

What kind of a condition is fibrous dysplasia?

A sporadic condition resulting from a postzygotic mutation

Depending on when the mutation in fibrous dysplasia takes place, what processes can be involved?

• One bone (monostotic)

• Multiple bones (polyostotic)

• Skin

• Endocrine system

What does polyostotic fibrous dysplasia mean?

Isolated or with syndrome

What are syndromes involved with polyostotic fibrous dysplasia?

1. McCune-Albright Syndrome

2. Jaffe-Lichtenstein Syndrome

3. Mazabraud Syndrome

What is McCune-Albright Syndrome?

A syndrome of polyostotic fibrous dysplasia that is Polyostotic FD + café au lait + endocrinopathies*

What is Jaffe-Lichtenstein Syndrome?

A syndrome of polyostotic fibrous dysplasia that is Polyostotic FD + café au lait

What is Mazabraud Syndrome

A syndrome of polyostotic fibrous dysplasia that is Polyostotic FD + intramuscular

What gender does Monostotic Fibrous Dysplasia affect the most?

M = F

What age group does Monostotic Fibrous Dysplasia affect the most?

Teenage years (2nd or 3rd decade)

Where would you find Monostotic Fibrous Dysplasia?

Affects the maxilla more than mandible, monostotic accounts for 80% of all cases

What is the most common feature of Monostotic Fibrous Dysplasia?

Painless, slowly-growing swelling of affected area

What does fibrous dysplasia look like on a radiograph?

In the early stages, the lesion may be radiolucent but with time it becomes radiopaque

What are some characteristics of fibrous dysplasia on a radiograph?

• “Ground-glass” opacification

• Not well demarcated, blend

• Narrowing of PDL with an ill-defined lamina dura

• Expansion of both buccal and lingual plates

• Obliteration of maxillary sinus

Fibrous Dysplasia Clinical and Radiographic Image

What is the involvement of polyostotic fibrous dysplasia?

Two or more bones; can involve up to 75% of skeleton

Who does polyostotic fibrous dysplasia mainly affect?

Children before 10 years old

What can happen if the jaw is involved in polyostotic fibrous dysplasia?

Facial asymmetry may result

What are some other features of polyostotic fibrous dysplasia?

• Pain due to pathologic fracture of the long bones is common

• Leg length discrepancy (hockey stick deformity)

What are some endocrinopathies seen in McCune Albright Syndrome in polyostotic fibrous dysplasia?

• Sexual precocity (early puberty)

• Pituitary adenoma

• Hyperthyroidism

What is Neurofibromatosis 1 (NF1)?

• Café au lait spots are smaller and higher in #

• Borders are smooth and ovoid shape (coast of California)

• Cross the midline

Cafe au lait spots in McCune Albright Syndrome

• Café au lait spots are larger and fewer in #

• Borders are jagged and irregular (coast of Maine)

• Found in midline and does not cross the midline

What is the treatment for fibrous dysplasia?

• Varies, medication, pain management, physical therapy and surgery as resection

• Disease tends to stabilize and stop growing at skeletal maturity

• Up to 50% recurrence

What is the most common fibro-osseous lesion encountered in clinical practice?

Cemento-osseous dysplasia (COD)

Where would you find cemento-osseous dysplasia?

In tooth-bearing areas of the jaws

In which demographic does cemento-osseous dysplasia show up?

Middle aged females, AA

What are the types of cemento-osseous dysplasia?

• Focal

• Periapical

• Florid

Focal cemento-osseous dysplasia

Periapical cemento-osseous dysplasia

Florid cemento-osseous dysplasia

Features of periapical cemento-osseous dysplasia

• Located near periapical region of the anterior mandible

• Multiple foci are usually present

• Teeth are invariably vital and asymptomatic

• Early lesions are circumscribed areas of RL involving the apex of a tooth

• looks identical to that of a periapical granuloma or cyst

• The PDL will be intact; the lesion will NOT fuse to the tooth

• Lesion is typically non-expansile self-limiting

Stages of periapical cemento-osseous dysplasia

• Early stage: Radiolucent (RL) lesions

• Mixed stage: RL-RO appearance

• Late-stage: Densely RO with a RL rim

In which demographic would you see periapical cemento-osseous dysplasia

• 90% are female

• 70% in African Americans

• Middle age (40s)

In which demographic do you see focal cemento-osseous dysplasia?

90% occur in females, AA

Middle age

What is the most common location of focal cemento-osseous dysplasia?

Posterior mandible

What are some clinical features of focal cemento-osseous dysplasia?

• Single lesion

• Asymptomatic

• Lesions are smaller than 1.5cm

• Radiolucent to radiopaque

• Occurs in the tooth-bearing areas of the jaws

• Well-defined rim during mixed stage

What can cemento-osseous dysplasia potentially be confused with?

Hypercementosis

What is the difference between cemento-osseous dysplasia and hypercementosis?

Cemento-osseous dysplasia is not within the PDL space whereas in hypercementosis, the radiodensity is all within the PDL

In which demographic do you see florid cemento-osseous dysplasia?

• 90% are female

• 90% are African American

• Middle aged or older adults

Where might you find florid cemento-osseous dysplasia?

• Multiple focal involvement not limited to the anterior mandible

• Patients may just have lesions in the posterior jaws but many patients have lesions throughout

What is a marked tendency of florid cemento-osseous dysplasia?

Bilateral and symmetrical, but teeth are vital and asymptomatic

What is the treatment for cemento-osseous dysplasia?

• Periapical or florid COD, diagnosis can be made from the distinctive clinical & radiographic findings – do NOT need biopsy

• Biopsy of florid COD may lead to necrosis due to the hypovascularity

• Focal COD may require surgical investigation because the features are less specific

• Follow up

• Management: AB if osteomyelitis is present

Differential diagnoses of radiopaque lesion at apex

What are some radiographic features of focal COD

Rim is prominent during the mixed phase

What are some radiographic features of cementoblastoma (benign neoplasm of cementum)

Radiolucent rim is contiguous with PDL and PDL is not intact at the involved portion of the root, effacement of root

What are some radiographic features of condensing osteitis (focal sclerosing osteomyelitis)?

No radiolucent rim, borders blend with surrounding trabeculae due to pulpal involvement

What are some radiographic features of idiopathic osteosclerosis, dense bone, enostosis, bone scar?

No radiolucent rim, borders blend with surrounding trabeculae

Name some hereditary bone disorders

1. Osteogenesis Imperfecta (OI)

2. Osteopetrosis

3. Cleidocranial Dysplasia

4. Cherubism

What is another name for osteogenesis imperfecta?

Brittle bone disease

What is the cause of osteogenesis imperfecta?

Mutation in type 1 collagen

What is the mode of inheritance for osteogenesis imperfecta?

• Autosomal dominant (AD = 90%)

• Autosomal recessive (AR = 10%)

• Some are sporadic

In which demographic does osteogenesis imperfecta show up?

Gender: M=F

Age: Infant, young children

Where would you find osteogenesis imperfecta?

Bone, teeth, ligament, skin, sclera

What is the prevalence of osteogenesis imperfecta?

Most common inherited bone disorder

What condition is a blue sclera associated with?

Osteogenesis Imperfecta

What are some clinical features of osteogenesis imperfecta?

• Osteopenia (low bone density)

• Short stature/bowing of legs/pathologic fractures

• Irregular skill (Wormian skull)

• Hearing deficit

What are some craniofacial features of osteogenesis imperfecta?

Triangular face, maxillary hypoplasia, Class III malocclusion

What are some dental features of osteogenesis imperfecta?

• Blue/grey translucent (opalescent teeth)

• Different mutation to dentinogensis imperfecta

• Both dentitions affected

• Obliterated pulp chamber/ shell teeth

• Fracture of enamel and dentin

• Open bite, cross bite

• Vertical dimension decrease

Obliterated pulp in osteogenesis imperfecta

Shell teeth in osteogenesis imperfecta

What is the dental management for osteogenesis imperfecta

• Crown

• Crown/bridge

• Partial or complete denture

• Implants

• Orthognathic surgery

• Orthodontics

What is another name for osteopetrosis?

Albers-Schönberg Disease; Marble bone disease

What is osteopetrosis?

Inherited function of a decreased osteoclastic activity (greek: petros “rock”) can be AD or AR (fatal)

INCREASE in bone density

What are some clinical features of osteopetrosis?

Can show up anywhere and can be associated with anemia, pathologic fractures, infection, deafness, and blindness

In what demographic do you see osteopetrosis?

Juvenile vs adult

Gener: M=F

Age: infancy except adult form

Osteopetrosis can caused delayed tooth eruption

Osteopetrosis can cause osteomyelitis

What are some craniofacial features of osteopetrosis?

• Frontal bossing

• Hypertelorism

• Broad face

• Snub nose

What is the management of osteopetrosis?

• Bone marrow transplant

• Palliative

What is the prognosis of osteopetrosis?

Good for AD but fatal for AR

What is another name for cleidocranial dysplasia?

Cleidocranial dysotosis

What is cleidocranial dysplasia?

Syndrome complex characterized by dental and clavicle abnormalities

What is the mode of inheritance for cleidocranial dysplasia?

AD inheritance

What do you see in cleidocranial dysplasia?

• Bone defects chiefly affect skull and clavicles

• Usually, clavicles are present with hypoplasia

• Clavicles are absent in 10% of cases

• Unusual mobility of shoulders

Name the clinical features of cleidocranial dysplasia

• Big head

• Pronounced frontal bossing

• Ocular hypertelorism

• Broad base of nose

• Hypoplastic mid face

• Long neck

• Missing or hypoplastic clavicles

• Short stature; Scoliosis

• Delayed suture closure

• Wormian bone

What are the dental features of cleidocranial dysplasia

• Patients have a high-arched palate

• Increased prevalence of cleft palate

• Mandibular prognathism

• Prolonged retention of deciduous teeth

• Delay or failure of eruption of permanent teeth

• Abnormally shaped teeth

• **Numerous unerupted permanent and supernumerary teeth**

What is this a pano of?

Cleidocranial dysplasia

What is the mode of inheritance of cherubism?

Autosomal dominant inheritance

What mutation causes cherubism?

SH3BP2 chromosome #4p16

In which demographic do you see cherubism?

Gender: M=F

Age: 2-5 (children)

In which location does cherubism appear?

Bilateral posterior mandible (most common), maxilla

What are some characteristic features of cherubism?

• Clinical alterations progress until puberty, then stabilize and slowly regress, asymptomatic

• There is an “eyes upturned to heaven” appearance due to a wide rim of exposed sclera noted below the iris

What are the clinical features of cherubism?

• Mandibular lesions are painless, bilateral, posterior and expansile

• Maxillary involvement occurs posteriorly as well

• In severe cases, entire maxillary and mandible are involved

• Distortion of the alveolar ridges

• May lead to failure of tooth eruption

• Microscopic findings are identical to those found in central giant cell granulomas (CGCG)

What are some radiographic features of cherubism?

Multilocular, radiolucent, expansile

What is this a pano of?

Cherubism

What is this

Cherubism

What is the prognosis and management of cherubism?

• Unpredictable

• Usually, the lesions show varying degrees of remission & involution after puberty

• By age 30, most patient’s facial features are normal

• However, some patients are left with facial deformities

• Early surgical intervention with curettage has lead to both good results or rapid regrowth with worsening deformity; therefore, optimal therapy hasn’t been determined

• Radiation therapy is contraindicated due to risk of postirradiation sarcoma

What is another name for paget disease of bone?

“Osteitis Deformans”

What is paget disease of bone?

A metabolic bone disease characterized by abnormal resorption and deposition of bone of unknown cause (mainly osteoclast)

What is the cause of paget disease of bone?

30% hereditary, AD, sporadic, or paramyxovirus

In which demographic does paget disease of bone appear?

Gender: M (caucasian) > F

Age: Older adults (>45 years)

Where does paget disease of bone appear?

Affects more than one bone (polyostotic)