Radiopacities

Question 1

Why do radiopacities occur on radiographs?

Answer 1

Increase in tissue or of an object (thickness) in the line of the X-ray beam

Increase in density of the soft tissue (which is of a normal thickness)

Question 2

List some of the causes of radiopacities on radiographs

Answer 2

The various causes can be divided into-

Artefacts

Normal anatomy

Dental tissue origin

Bony origin
Increased thickness of bone (due to developmental, inflammatory or neoplastic processes)
Increased density of bone (due to inflammatory or dysplastic processes)

Soft tissue origin (antral lesion, soft tissue calcification)

Foreign body, external to the normal tissue

Question 3

List some artefacts that appear radiopaque on a radiograph

Answer 3

Copper dot (circular radiopacity, occurs when the phosphor plate has been used in the back to front position and as a result the copper dot on the film is projected as a radiopaque circle on the image)

Foreign objects (e.g. glasses)

Cervical spine shadow (occurs due to incorrect patient positioning, as a result of the patient being in a slumped position during OPT scanning)

Ghost shadow of the mandible (an artefact that is inherent to the OPT imaging technique, a ghost shadow of the mandible is a normal radiopaque feature of an OPT)

Question 4

List some normal anatomical radiopacities

Answer 4

Zygomatic buttress (can obscure PA tissues surrounding posterior teeth)

Coronoid process (on a PA film, we would see a bony projection coming from the inferior aspect of the film)

Lower lip

Nose (anterior PA)

Question 5

List the abnormalities of teeth that can present as radiopacities

Answer 5

Retained roots

Unerupted or ectopic teeth

Supernumeraries

Abnormality of tooth development

Odontomes

Hypercementosis

Question 6

What is a pulp stone?

Answer 6

Calcification within the pulpal tissues (pulp space/root canal)

Question 7

How do pulp stones arise?

Answer 7

Can occur as idiopathic calcifications in pulpal tissues

Or may be related to longstanding local irritation e.g., from caries or as a result of trauma

Sometimes associated with various syndromes such as dentinogenesis imperfecta or dentinal dysplasia

Question 8

What is an enamel pearl?

Answer 8

1/5 types of odontomes (abnormal growths of tooth forming tissues).

Essentially an extra growth of enamel, usually at the furcation region of a multi-rooted tooth. Tends to affect the maxillary molars

Question 9

How does an enamel pearl present on a radiograph?

Answer 9

Will see an extra radiopacity of a similar density to the enamel around the crown.

Will be situated in the coronal third of the root, often in the furcation region of a multi-rooted tooth

Question 10

What is hypercementosis?

Answer 10

Excessive deposition of cementum on roots of teeth

Question 11

Describe the features of hypercementosis

Answer 11

Excessive deposition of cementum on roots so the roots will be quite bulbous

Asymptomatic

On an X-ray, we will see a smooth widening of the roots that is slightly less radiopaque than the adjacent dentine (but still a radiopacity)

The PDL and lamina dura will continue all the way around the outside of the more bulbous root form/cementum

Question 12

What is an odontome?

Answer 12

Abnormal growth of tooth forming tissue

Benign hamartoma (a disorganised mass of tooth forming tissue, native to its normal anatomical location)

Question 13

What is a compound odontome?

Answer 13

An abnormal growth of tooth forming tissue which is made up of lots of little denticles (small tooth like structures which have all of the layers of a tooth in correct formation i.e., root canal centrally, surrounded by dentine and then enamel on the outside).

Will look like a little collection of small malformed teeth / mass of tiny teeth

Often associated with failed eruption

Question 14

What is a complex odontome?

Answer 14

An abnormal growth (disordered mass) of tooth forming tissue

Won’t have normal ordering of the dental tissues. Very irregular mass, where we can’t differentiate between the root canal, enamel and dentine.

Often associated with failed eruption

Question 15

Describe the features of a cementoblastoma

Answer 15

Benign neoplasm (new growth of tissue occurring outside of the normal homeostatic mechanisms)

Rare

Tend to be seen in the mandibular premolar/molar region

On an X-ray, we will see a circular radiopacity of an abnormal structure of cementum at the apex of a tooth. Usually these lesions will have a radiolucent periphery and be more radiopaque centrally.

Can have sclerotic margins around the outside

Can be quite expansile, often displacing the lower border of the mandible

Often associated with root resorption

Question 16

Describe the radiographic features of a cementoblastoma

Answer 16

On an X-ray, we will see a circular radiopacity of an abnormal structure of cementum at the apex of a tooth. Usually these lesions will have a radiolucent periphery and be more radiopaque centrally.

Can also have sclerotic margins around the outside

Can be quite expansile, often displacing the lower border of the mandible

Often associated with root resorption of the affected tooth

Question 17

Describe the features of a calcifying epithelial odontogenic tumour (Pindborg tumour)

Answer 17

Benign swelling or excessive growth of tissue

Rare

Affects the mandible more than the maxilla

Often associated with an unerupted tooth (particularly L8s)

2/3rds of these tumours will have a mixed density, but will become increasingly more radiopaque/dense with age)

Usually have a scalloped margin

Can be expansile

Question 18

List the soft tissue radiopacities that may present in the maxillary antrum/sinus

Answer 18

Inflammatory change that has caused mucosal thickening of the sinus mucosa

Benign antral cyst/retention pseudocyst

Question 19

How does a benign antral cyst/retention pseudocyst present on a radiograph?

Answer 19

Well defined, non-corticated, smooth, dome shaped radiopacity in the antrum

Antral floor will be intact

Question 20

On an X-ray, you observe a well defined, non-corticated band of radiopaque soft tissue that is parallel to the bony outline of the antral/sinus floor. The cortical line of the antral/sinus floor and walls is intact. The patient reports a dull throbbing pain from the UR6. What is the likely diagnosis of the radiopacity observed in the sinus?

Answer 20

Inflammatory change that has caused thickening of the paranasal sinus mucosa

Inflammatory thickening can be related to dental infection. As the patient reports pain from the UR6, it may be that the inflammatory thickening of the sinus mucosa has occurred in response to the PA infection in this tooth

Question 21

Some radiopacities in the antrum are a cause for concern and require further investigation or referral. What are the red flag signs and symptoms we should look out for?

Answer 21

Signs on imaging-

Bone erosion (absence of corticated margins surrounding the antrum/sinus, indicates that the bone has been eroded by the radiopacity)

Corticated border around the outside of the soft tissue (around the dome shaped benign antral cyst, for example)

Displacement of the antral/sinus boundaries

Symptoms-

Epistaxis (nose bleed)

Unilateral nasal obstruction

Dys- or paresthesia (altered sensation or loss of sensation in the region of the cheek)

Facial swelling (non-odontogenic origin)

Question 22

List some examples of soft tissue calcifications

Answer 22

Pulp stones

Ligaments e.g. stylohyoid (with age, ligaments can begin to calcify)

Lymphoid tissue/tonsils (tonsilloliths)

Salivary glands (sialolith)

Blood vessels (phleboliths)

Antrum (antrolith)

Nose (rhinolith)

Skin (calcinosis cutis)

Muscle/subcutaneous tissues

Question 23

Describe tonsilloliths

Answer 23

Little stones within the palatine tonsils, which can project over the ramus of a mandible on an OPT

Question 24

Describe a sialolith

Answer 24

Stone within a salivary gland

Mainly seen in the floor of the mouth as a radiopacity on a lower occlusal radiograph

May project over the mandible on an OPT

Parotid stones are relatively rare but can be seen along the occlusal plane on an OPT

Question 25

Describe phleboliths

Answer 25

Little calcifications that occur within blood vessels of a vascular malformation The blood in these regions won't be moving very quickly and due to that slow flow, we can get little stones forming Tend to have a targetoid appearance (central radiopaque area, with a layer of radiolucency surrounding it and possibly another radiopaque area around that) Generally a few of these stones will be clustered together

Question 26

How can we localise a radiopacity?

Answer 26

The easiest way of localising is by taking another type of radiograph at a right angle to the first one (PA/OPT paired with a lower occlusal) If this is not achievable, we can localise by using a different angle for the same type of radiograph and employing the PARRALLAX technique / SLOB rule

Question 27

What is a dense bone island?

Answer 27

A localised growth of compact bone which extends from the inner surface of the bony cortex Normal variation of bone More common in the mandible than in the maxilla Also known as idiopathic osteosclerosis

Question 28

What is another term for a dense bone island?

Answer 28

Idiopathic osteosclerosis

Question 29

What is a tori?

Answer 29

Overgrowth of bone (bony extoses) (primarily compact bone) Developmental abnormality In the mandible, tend to develop on the lingual surfaces, usually in the premolar region In the maxilla, tend to develop centrally or either side of the midline in the posterior hard palate Will present as bright radiopacities

Question 30

Inflammatory change in the bone in response to infection can produce radiopacities. List some examples

Answer 30

Sclerosing osteitis (PA radiopacity, very localised to the source of the infection, occurring in response to a low grade chronic infection of the pulp) Osteomyelitis Osteoradionecrosis MRONJ

Question 31

What is sclerosing osteitis?

Answer 31

Inflammation of the bone that has led to bone hardening (sclerosis) in response to a low grade chronic infection of the pulp. Proliferative reaction following pulpal necrosis Occurs in a very localised area, next to the source of infection (PA tissues adjacent to infected tooth)

Question 32

What is osteomyelitis?

Answer 32

Spreading, progressive inflammation of bone in response to infection This can be acute or chronic Affects the mandible more often than the maxilla (potentially due to the maxilla’s better blood supply)

Question 33

Describe the radiographic features of sclerosing osteitis

Answer 33

Sclerotic bone surrounding the apex of a non-vital tooth (deep caries, RCT/crown, large filling, history of trauma) Widening of the PDL

Question 34

Describe the radiographic features of osteomyelitis

Answer 34

Poorly defined moth-eaten appearance of the bone Subperiosteal bone formation (inflammation of the periosteum leads to the layering of new bone at the periosteum. This deposition of new bone causes the bone to expand. These bone layers can form parallel to each other and parallel to the cortical surface on a radiograph. As a result, we may observe an onion skin appearance of the layers of new bone) Sequestra of necrotic bone (section of necrotic bone which is no longer attached to the adjacent normal bone, will work its way towards the surface as the body tries to expel the area of necrotic tissue) Sclerosis (hardening/proliferation) of surrounding bone

Question 35

What is subperiosteal bone formation?

Answer 35

Where there is infection of the bone, the periosteum can become inflamed. The inflammation of the periosteum can lead to the layering of new bone at the periosteum (healing inflammatory response to infection). This deposition of new bone causes the bone to expand These bone layers can form parallel to each other and parallel to the cortical surface on a radiograph. As a result, we may observe an onion skin appearance of the layers of new bone

Question 36

What is a sequestra of necrotic bone?

Answer 36

Section of necrotic bone which is no longer attached to the adjacent normal bone Will work its way towards the surface as the body tries to expel the area of necrotic tissue

Question 37

What is osteoradionecrosis?

Answer 37

Radiation induced damage resulting in bone necrosis Bone death following radiotherapy Clinically seen as an area of exposed bone in a location that has either been treated with radiotherapy or been within the radiotherapy field. Affects the mandible more than the maxilla

Question 38

Describe the radiographic features of osteoradionecrosis

Answer 38

Similar appearance to osteomyelitis but without a periosteal reaction (less likely to see a periosteal reaction as there isn't as much of a healing inflammatory response) Poorly defined, moth eaten area of bone with irregular margins. Bone sequestra (areas of dead bone breaking away from adjacent normal bone) Pathological fracture (due to weakening of the bone) Prominent bony sclerosis Can resemble bone destruction by a maligned neoplasm (always worth considering whether it could be a recurrent malignancy or a primary malignant tumour as opposed to osteoradionecrosis. Will need a biopsy to confirm this)

Question 39

What is MRONJ?

Answer 39

Necrosis of the bone arising from complications of medications which reduce bone metabolism e.g. bisphosphonates Clinically, we observe exposed bone (following XLA/trauma) Affects the mandible more than the maxilla

Question 40

Describe the radiographic features of MRONJ

Answer 40

Resembles osteoradionecrosis/osteomyelitis Poorly defined, moth eaten appearance Bone sequestra (areas of dead bone breaking away from adjacent normal bone) Widening of the PDL spaces of adjacent teeth Prominent bony sclerosis Delayed non-healing sockets (couple of months after XLA with no evidence of bony infill following XLA) Reduced periosteal reaction (less likely to see a periosteal reaction as there isn't as much of a healing inflammatory response)

Question 41

Describe the features of an osteoma

Answer 41

Arise on the cortical surface of bone as a pedunculated mass (mushroom like) Usually asymptomatic, although patient may be aware of a lump Usually a single/lone mass Multiple jaw osteomas are a feature of Gardner syndrome

Question 42

Describe the radiographic features of an osteoma

Answer 42

Well defined radiopacity with a smooth outline, arising from the cortical surface of bone Pedunculated (almost looks like a mushroom coming out of the bone surface) Homogenous radiopacity On a PA it will present as a homogenous radiopacity overlying the teeth

Question 43

Multiple (5 or more) jaw osteomas are a feature of which syndrome? What other symptoms may be observed in patients with this syndrome?

Answer 43

Gardner syndrome Other associated symptoms include- Multiple polyps in the colon Epidermoid cysts Fibromas Multiple supernumerary teeth in the jaws etc.

Question 44

Describe the features of a cemento-ossifying fibroma

Answer 44

Composed of fibrocellular tissue and mineralising material Benign mixed density lesion which increases in density over time (more dense centrally with a more radiolucent soft tissue capsule at the periphery) Found in variable locations, but tends to be in the posterior mandible Can lead to displacement of adjacent structures Can lead to bony expansion

Question 45

Describe the radiographic features of a cemento-ossifying fibroma

Answer 45

Round, well defined, mixed density lesion that appears more radiopaque centrally and less radiopaque at the peripheries (where a soft tissue capsule forms) Adjacent bone may have a sclerotic margin Becomes increasingly more radiopaque over time Expansile lesion with the ability to displace associated structures

Question 46

Describe the features of an osteogenic sarcoma

Answer 46

Primary bone malignancy Rapidly destructive More common in other bones, but can occur in the jaws (more commonly in those aged 30-40)

Question 47

Describe the radiographic features of an osteogenic sarcoma

Answer 47

Early radiographic features are fairly non-specific. May present as a widening of the PDL space initially Mixed density lesion with a more radiopaque centre Classically has a sharp ‘sunray’ appearance as bony spicules project at 90 degrees to the bone surface The sunray appear spreads out from a central source Bony spicules can appear to extend into the soft tissues

Question 48

List the 3 subtypes of cemento-osseous dysplasias

Answer 48

Periapical Focal Florid All have similar features but vary in extent

Question 49

Describe the features of a periapical cemento-osseous dysplasia

Answer 49

Relatively common Idiopathic In the early stages, it appears as a radiolucent area at the apex of a vital tooth, unlike PA cyst or granuloma, which occur at the apex of non-vital teeth. Associated teeth won't have deep caries or large restorations. Clinically, they will have normal vital responses to sensibility testing Most commonly occur in the anterior mandible With maturation, the lesion becomes increasingly radiopaque due to central calcification Usually, no corticated border around the outside Most commonly affects Black, Middle aged women Often mistaken for non-vital teeth but as the associated teeth are vital, we should not start destructive intervention like RCT, need to consider all things holistically, are there symptoms or indications for loss of vitality alongside the initial radiolucency?

Question 50

Describe the features of a focal cemento-osseous dysplasia

Answer 50

Mixed radiolucent area associated with one tooth/area. Central radiopacity with a peripheral radiolucency As it is seen in one area, it is known as a 'focal' COD

Question 51

Describe the features of florid cemento-osseous dysplasias

Answer 51

A mixed density lesion in 3 or more quadrants is known as 'florid COD' Changes throughout the bone can be quite pronounced. Mixed density appearance with a central opacity and peripheral radiolucency in the PA regions. Can also get some expansion with these areas, unlike other types.

Question 52

Describe the features of fibrous dysplasias

Answer 52

Idiopathic Proliferation of fibrous tissue and resorption of normal bone causing painless enlargement Develops during childhood (lesions usually become static when skeletal growth stops) Can affect any bone including the jaws, tibias, femur etc. 70% of cases are monostatic (i.e. they'll only occur in one bone). Jaws are commonly affected, usually unilateral Maxilla more commonly affected than the mandible

Question 53

Describe the radiographic features of fibrous dysplasias

Answer 53

When fibrous dysplasias first develop, they will have a radiolucent appearance which becomes mottled and then radiopaque with time. At the mottled / radiopaque stage, the trabecular pattern of bone will appear altered within the affected bone. At these stages, we will see a glass or orange peel texture to the bone There will be no clear margin as the abnormal bone merges into the adjacent normal bone with a blended periphery (poorly defined) Can be expansile

Question 54

Describe the general features of Paget’s disease

Answer 54

Idiopathic Disease that affects the elderly Abnormal maintenance of the bone which presents as slow enlargement of the bones (hats and dentures will no longer fit) Tends to have a symmetrical pattern of involvement Jaws are commonly affected (1 in 5) Maxilla more commonly affected than the mandible Results in brittle bone, with an increased risk of pathological fracture Increased risk of osteogenic sarcoma

Question 55

Patients with Paget disease have an increased risk of which other diseases?

Answer 55

Osteogenic sarcoma Pathological fracture

Question 56

Describe the radiographic features of Paget’s disease

Answer 56

There will be a variation in the radiological appearance of these lesions with time. In the initial stages of the disease, there will be osteolytic areas and later, there will be bony deposition. In the mandible/maxilla, we would see areas of osteoporosis With time, the bone will increase in density in these regions, developing a cotton wool appearance Expansile, enlargement of affected bone Loss of lamina dura around all teeth located within the affected bone Hypercementosis