L14 Bone lesions affecting the jaws Flashcards
What are the 3 broad groups that bone lesions can be categorised into?
- Lesions of the jaw bones as part of a systemic bone diseases (most, if not all, bones affected e.g. osteogensis imperfecta)
- Localised bone disease occuring in the jaws (may affect almost any bone, including the jaws, e.g. osteomyelitis)
- Lesions occuring only in the jaw bones (e.g. dental cyst, ameloblastoma)
How can a surgical sieve be used to diagnose/differentiate between bone lesions?
Give examples of reactive processes, degenerative conditions and metabolic/endocrine deficiencies that can cause bone lesions.
Describe torus palatinus.
- Slow growing, sessile exostosis in the midline of the vault of the palate
- Symptomless, usually flat but may be lobular if large
- Overlying mucosa may become ulcerated by trauma
- Don’t typically require treatment
What is the inheritance pattern of torus palatinus?
Simple autosomal dominance
F:M (2:1)
When may torus palatinus be removed?
If they interfere with insertion of a denture
What type of bone is present in torus palatinus and mandibularis?
- Cortical bone on the surface
- Normal lamellar (cancellous) bone in the centre
Describe torus mandibularis.
- Exostosis on the lingual aspect of the mandible in the premolar region
- Broad base with smooth or lobular surface
- Bilateral in 80% ofcases, can present more prominently on one side compared to the other
- Affects 7% of Caucasion population
What is the inheritance pattern of torus mandibularis?
Autosomal dominant with 100% penetrance in females, 70% in males.
What is osteogenesis imperfecta?
- Hereditary disease: usually autosomal dominant, recessive forms and spontaneous cases occur
- Characterised by defects in type I collagen synthesis (25% chace of dental presentation)
What are the clinical features of osteogenesis imperfecta?
- Generalised osteoporosis with slender bones, vulnerable to fracture
- Long bones have narrow, poorly formed cortices composed of immature woven bone
- Skull is thin, may be wormian bones in the skull (supernumerary)
- Jaws are rarely affected
- Sclera appear blue
- Deafness due to distortion of ossicles
- Joint hypermobility with lax ligaments
- Translucent skin
- Heart valve defects
What are the oral manifestations of osteogensis imperfecta?
- 25% of cases are associated with dentinogenesis imperfecta, especially in primary dentition
- Increased tendency to class III occlusion and impacted molar teeth
- Dentinogenesis imperfecta: short roots, obliterated pulp chambers
List inflammatory conditions that can affect the jaws.
- Fracture
- Healing extraction socket
- Dry socket
- Chronic periodontal disease
- Osteomyelitis
- Actinomycosis
- Syphilis
- Osteoradionecrosis
Describe the stages of tooth socket healing following extraction.
1) Socket fills with blood, blood clots
2) Blood clot is organsied to form granulation tissue (macrophages remove clot at periphery, fibroblasts migrate into clot, endothelial ells produce new thin walled BVs)
3) Osteoclast resorption of crestal bone and spicules of bone detached during extraction
4) Gingival epithelial proliferation and migration across the defect, by 6 weeks the epithelium is normal thickness
5) Osteoblasts at the base of the socket replace granulation tissue with woven bone, by 6 weeks the socket is filled with woven bone
6) Remodelling of woven bone and removal of lamina dura of tooth socket
What is the prevalence of acute alveolar osteitis?
- 1-3% of all extractions
Most common in: - Molar teeth
- Mandible
- Local anaesthetic cases rather than GA
- Complex extractions
- Most commonly associated with lower 3rd molar extraction
What is acute alveolar osteitis?
- Dry socket
- Localised inflammation of bone following failure of blood clot to form, or premature loss/disintegration of clot
- Bone is exposed to saliva, food debris and bacteria
- Bone becomes necrotic with inflammation in adjacent bone
- Healing is slow; necrotic bone is gradually seperated by osteoclasts and bony sequestra form
Name the various types of osteomyelitis.
What does the term osteomyelitis mean?
Inflammation of the bone
Describe acute suppurative osteomyelitis.
- Usually due to spread of local infection (e.g. from periapical infection)
- Occassionally due to haematogenous spread
- Relatively rare condition
- Predisposing factors: reduced host resistnace, virulent bacteria
Why is acute suppurative osteomyelitis more common in the mandible than the maxilla?
- Mandible has thicker bone trabeculae and cortical plates
- Therefore the blood supply is more easily compromised
Describe the radiology of acute and chronic osteomyelitis.
Acute:
- Ragged, moth eaten radiolucency
- Subperiosteal bone formation
- May be sequestra
Chronic:
- Ragged, moth eaten radiolucency
- Sequestra present
- Sclerosis of surrounding bone
- Involucrum formation (layer of new bone growth)
Explain the pathogenesis of acute suppurative osteomyelitis.
- Infection of marrow leads to acute inflammatory reaction
- Tissue necrosis and suppuration follow
- Thrombosis may produce widespread necrosis of osteogenic tissues
- Inflammation, nerosis and suppuration extends through marrow spaces
- Pus reaches periosteum (which is elevated), reducing blood supply
- Pus may discharge through sinuses to mouth and skin
- Granulation tissue seen in marrow spaces beyond areas of necrosis, osteoclasts seperate off necrotic bone and form sequestrum
- New bone (involucrum) may form beneath the elevated periosteum
Describe the histological features of osteomyelitis.
- Loss of osteocytes
- Non-vital bone
- Fibrous replacement of bone marrow with mixed inflammation (PMNs and granulation tissue)
Describe radiation osteomyelitis and osteoradionecrosis.
- Radiotherapy involving the jaw causes ischaemia (lack of blood supply = lack of oxygen)
- Ischaemia is caused by proliferation of intima of BVs (endarteritis obliterans) which can occlude vessels
- Central mandibular artery may be occluded
- Ischaemic and possibly necrotic bone
- Bone now susceptible to infection from teeth, periodontium, XLA, mucosa
- Extensive painful necrosis of bone with sloughing of overlying mucosa exposing more bone to infection
Describe MRONJ.
- Medication related osteo-necrosis of the jaw
- Associated with bisphosphonates, antiangiogenic agents, RANKL inhibitors and m-TOR inhibitors (inhibit osteocalst formation and migration and reduce bone turnover)
- Increased risk with IV delivery
- Causes exposed bone, localised pain and failure of extraction socket to heal
How is MRONJ staged?
Stage 1 is asymptomatic.
What are the types of fibro-osseus lesions?
Describe the oral manifestations of fibrous dysplasia.
- Maxilla more commonly affected
- Gradually increasing painless swelling
- Produces facial asymmetry
- May cause tooth displacement
- Usually smooth surfaced
- More pronounced bucally than palatally
- Maxillary lesions may involve sinus, zygomatic process, floor of orbit
Describe the radiographic features of fibrous dysplasia.
- Localised lesion within normal bone
- Appearance varies depending on age of lesion
- Begin more radiolucent due to more fibrous tissue, gradually become more calcified with ground glass or orange peel effect
- Poorly demarcated, margins blend with normal bone
- Loss of lamina dura! (Key feature)
- Enlargement of bone
- Teeth displaced
- Antrum may be involved
Describe the histological features of fibrous dysplasia.
- Replacement of normal bone by fibrous tissue containing islands and trabeculae of metaplastic bone
- Fibrous tissue may be cellular
- Overtime fibrous contents decrease and amounts of bone increase
- Newly formed trabeculae are delicate and irregularly shaped, lace like
- Consist of coarse fibred woven bone
Describe the radiographic presentation of ossifying fibromas.
- Well defined radiolucency
- Islands of bone present
- Mixed pattern of radiolucent and radiopaque areas
- Root resorption occurs
- Can cause expansion of bone
Describe the histological presentation of ossifying fibromas/cemento-ossifying fibromas.
Cellular fibrous tissue containing trabeculae of bone.
Pattern of bone and cellularity is highly variable.
Cementoid like bodies present.
Summarise the differences between fibrous dysplasia and ossifying fibroma.
Describe the radiology of central giant cell granulomas.
- Well defined radiolucent area
- May be multilocular (small lesions may be unilocular)
- Thinning and often expansion of the cortex
- Involved teeth may be displaced
- Root resorption is common
Describe the histological features of central giant cell granulomas.
- Cellular stroma mostly composed of fibroblasts and macrophages
- Variable numbers of multinucleated giant cells
Describe primary hyperparathyroidism.
Describe Brown tumours.
What is a haemangioma of bone?
- Rare benign tumour
- More common in soft tissue than bone
- More common in mandible
- May produce swelling, but can also present as an incidental radiographic finding
- Osteolytic, often multilocular honey comb appearance
- Aspiration reveals fresh blood
- Extraction of teeth may produce severe haemorrhage!!
What is Langerhans cell histiocytosis?
Describe the radiographic appearance of osteosarcoma.
- Variable appearance dependent on amount of normal bone destroyed
- Elevation of periosteum
- Deposition of radiating trabeculae produces sunburst appearance
