14. Diseases of the facial bones and joints Flashcards
What are the 4 layers in the structure of bone?
Outer, dense compact bone
Trabecular or cancellous bone
Central medullary cavity
Periosteum
Where is marrow found and what types can it be?
In the medullary cavity
Red or yellow marrow
What are the 2 layers of the periosteum?
Fibrous layer
Cellular layer
What does fibrous periosteum contain?
Sharpey’s fibres that anchor down into the bone and attach the periosteum to the bone
What is bone composed of?
Osteoid- Type 1 collagen that becomes mineralised.
Cells- osteoblasts, osteocytes, osteoclasts
What are the 2 types of bones?
Mature lamellar
Woven bone
What gene does osteogenesis imperfecta affect?
Type 1 collagen genes
COL1A1 COL1A2
What genes do the 4 rare types of osteogenesis imperfecta affect?
CRTAP
LEPRE1
What is the clinical presentation of osteogenesis imperfecta?
Brittle bones
Deafness- ear ossicles deformation
Ligament laxity
Thin aortic and heart valves
Blood vessel fragility
Short stature
What is the pathogenesis of osteogenesis imperfecta?
Amino acid substitution in the triple helix (glycine).
What are the types of osteogenesis imperfecta?
Type 1- common, mildest, AD, deafness, bone fragility, blue-grey sclera +-DI
Type 2- in utero fractures, respiratory dys, fatal, AD and AR
Type 3- rarers, progressive bone deformities, DI
Type 4- White sclera, same as type 1
What gene causes opalescent teeth in osteogenesis imperfecta?
COL1A
What gene causes dentinogenesis imperfecta?
DSPP
What are the features of dentinogenesis imperfecta?
Opalescent Amber teeth
Affects primary more than secondary
Normal colour
Short roots/obliterated canals
Decreased caries
Increased attrition
Decreased dentinal tubules or atubular
What is cleidocrania dysplasia due to?
Mutation in RUNX2 gene- controls osteoblast differentiation
Autosomal dominant
What are the symptoms of cleidocranial dysplasia?
Aplasia of clavicles
Frontal bossing- delayed ossification of fontanelles
Short stature
Hypertelorism
Delayed eruption of secondary teeth
Supernumerary teeth
Prognathism
What occurs in osteopetrosis?
Reduced bone resorption and diffuse symmetric skeletal sclerosis
What is the inheritance of osteopetrosis?
2 modes
Autosomal dominant more rare than autosomal recessive
Autosomal recessive is fatal if untreated
What is the pathogenesis of osteopetrosis?
Defect in carbonic anhydrase 2
Mutation in CLCN7- proton pump/gene defect
Causes defect in osteoclastic function and so failed remodelling
What are the general symptoms of osteopetrosis?
CN palsy- sclerosis of foramina at base of skull compresses nerves
Enlarged spleen
Anaemia
Increased fracture
Recurrent infection
What are the dental symptoms of osteopetrosis?
Malformed short roots and unerupted teeth
Osteomyeleitis after extractions
Delayed eruption
Root and bone fractures
Unusual dentition
What are the radiographic findings of osteopetrosis?
Abnormally dense bones
Chalky white appearance
Reduced marrow spaces
What is the treatment for osteopetrosis?
Bone marrow transplant
What is the genetic reason for achondroplasia?
Mutation in fibroblast growth factor receptor 3 gene
Abnormal cartilage formation which affects endochondral ossification
What disease is achondroplasia associated with?
Mutations of the FGRF3 also associated with Crouzon syndrome
Which type of achondroplasia is fatal?
Homozygous form
What are the features of achondroplasia?
Normal sized head, trunk
Protuberant abdomen
Short limbs
Retrusive middle third of face- due to lack of development of the base of skull
Severe Malocclusions
What are the treatment for achondroplasia?
Surgery for cleft palate
Orthodontics
What are the symptoms of cherbusim?
Individuals appear normal at birth AD
2-4- painless symmetrical swelling of mandible, and sometimes maxilla
7- lesions become static or regress
Chubby face
Rim of sclera visible underneath iris
Puberty onwards see improvement but cosmetic surgery may be necessary
What gene does cherubism involve?
Mutation in SH3BP2- function unclear thought to be involved in cell signalling in bone remodelling
What do you see in radiographs of cherbusim?
Multiocular radiolucencies
Thinning or perforation of cortical bone
What are the dental anomalies of cherubism?
Early loss of deciduous teeth
Displacement
Abnormal unerupted permanent teeth
What is the histology of cherubism?
Cellular and vascular fibrous tissue
Focal collections of multinucleated giant cells
Haemosiderin
Metaplastic bone
How does Gardner’s syndrome occur?
Autosomal dominant- APC gene
Recessive form- MUTYH gene
What are the symptoms of Gardners syndrome?
- Multiple polyposis of the large intestine- premalignant
- Osseous anomalies
- Dental anomalies- supernumerary, odontome, impacted
- Epidermoid cysts of skin- scalp and back
- Desmoid tumours
What osseous anomalies are seen in Gardner’s syndrome?
Hazy sclerosis of jaw bones
Dense bone islands of jaw bones
Osteomas of the bones. Jaw and skull/long bones
How does fibrous dysplasia occur?
Somatic mutation in GNAS1 gene- G protein that regulates cAMP formation
Overproduction of cAMP leads to overexpression of c-fos, a protooncogene responsible for regulating proliferation and differentiation of osteoblasts
What are the clinical forms of fibrous dysplasia?
Monostotic- most common- frequent in jaws
Polyostotic
McCune-Albright Syndrome
What is McCune-Albright syndrome?
Polyostotic fibrous dysplasia
Cafe au lait spots in skin
Endocrine abnormalities such as precocious puberty, thyroidal cysts, pituitary adenoma, large hands and feet, cushing syndrome
What is the radiographic appearance of fibrous dysplasia?
Orange peel ground glass appearance
Blends
Goes from radiolucent to radiopaque
Expansile mass
What is the histology of fibrous dysplasia?
Bone replaced by cellular or collagenous fibrous tissue
Metaplastic bone (woven or osteoid) arranged in irregular trabecular pattern forming chinese characters
Fuses with the surrounding bone unlike cemento-ossifying fibroma
How does fibrous dysplasia present as?
Common in jaws
Swelling painless
Not well circumscribed
Lesions expand during skeletal growth then stop
Not radiosensitive- if irradiated can transform into sarcomas
Surgical treatment preferable after growth phase
What is the definition of osteitis?
Localised inflammation that does not spread through marrow spaces
What is the definition of osteomyelitis?
Extensive inflammation that does spread through marrow spaces.
What is periostitis?
Inflammation of periosteum
What is alveolar osteitis?
Localised inflammation that occurs in some extractions
What can alveolar osteitis be due to?
Failure of blood clot formation
Disintegration of blood clot
How can a blood clot fail to form in alveolar osteititis?
Osteopetrosis
Paget’s disease
Poor blood supply
Vasoconstrictor
Radiotherapy
How can a clot become disintegrated in alveolar osteititis?
Mouthwashes
Protelytic bacteria
Empty socket retains food and debris and becomes infected
Osteoclasts separate dead bone forming sequestra
Localised inflammation, slow healing, granulation tissue
What is the tx for alveolar osteititis?
Remove debris
Alveogyl
Irrigate with CHX
Sequestrum removal
What are the symptoms of alveolar osteitis?
Severe pain
Foul taste
Foul smell
Denuded bone may be visible
How does the socket heal after extraction?
Socket fills with blood
Formation of granulation tissue
Osteoclasts cause resorption of crestal alveolar bone
Gingival epithelium migrates across defect
10-14 days- formation of granulation tissue, and osteoblasts form woven bone
4-6 weeks- socket healed by repair, contains woven bone, outline of socket visible on rads
20-30 weeks- woven bone remodelled, formation of cortical cancellous bone, socket obliterated, alveolar bone reduces in height
What is focal sclerosing osteititis?
Sequelae of periapical inflammation
Mild irritation
Infection
High tissue resistance
What does focal sclerosing osteitits look like on radiograph?
Asymptomatic
Dense area at apex, but not attached to the tooth
What is the differential for focal sclerosing osteitis?
Sclerotic bone islands
What is the histology of focal sclerosing osteitits?
Plasma cells
Lymphocytes
Fibrous marrow tissue
Increase in thickness and number of bony trabaculae
What types of suppurative osteomyelitis are there?
Acute or chronic
Chronic lasts more than 1 month
Where does suppurative osteomyelitis occur most?
Mandible more common- occurs in areas with high blood supply
What are the causes for suppurative osteomyelitis?
Abscess
Fracture
Local trauma
Penetrating wounds
Extraction
What is the pathology of suppurative ostemyelitiis?
Microorganisms proliferative in bone marrow spaces
Acute inflammation
Tissue necrosis
Accumulation of pus
What happens after suppurative osteoymyeleitis?
Sequesterum- formation of necrotic bone surrounded by pus
Involucrum- formation of new bone outside the original
What are the clinical features of suppurative ostemyelitis?
Pain
Pyrexia
Paraesthesia of lip
Swelling
Trismus
Intra-oral and extra-oral sinus
Tooth mobility
What is the histology of suppurative ostemyelitis?
Necrotic bone surrounded by inflammatory cells and pus
Involucrum
What is the radiology finding of suppurative ostemyelitis?
Early stages- normal
10-14 days- irregular, moth-eaten radiolucency
What is diffuse sclerosing osteomyelitis?
Similar to focal sclerosing, but more generalised
Proliferative reaction in response to low grade infection
Occurs in older age group
What is chronic osteomyelitis with proliferative periostitis?
Occurs in mandible of children and young adults
Low grade apical inflammation reaching cortical bone
Periosteal reaction seen- thickening and swelling of bone- onion skin
What are the histological features of chronic osteomyelitis with proliferative periostitis?
Fibrous marrow
Chronic inflammatory cells
Parallel layers of woven bone
What is chronic periostitis associated with?
Hyaline bodies- pulse granulomas
Hyaline ring shaped material
Fibrous thickening of periosteum
Pus
May be due to vegetable material implanted through tooth socket, raised flap, traumatic ulceration, root canal
What is phosphorus necrosis?
White phosphorus P4O10 converts to bisphosphonates
Causes MRONJ
What is osteoradionecrosis?
Radiation causes proliferation of blood vessels intima- endarteritis obliterans
Reduction in blood supply, especially mandible, thrombosis
When does osteoradionecrosis develop?
Months or years after radiotherapy
What is osteoradionecrosis clinically similar to?
Osteomyelitis- pain swelling slow recovery, may be asymptomatic
What should you do to head and neck radiotherapy patients to avoid osteoradionecrosis?
Leave only sound teeth and remove others at least 2 weeks before treatment
