Bone Pathology Flashcards
What are the components of compact bone?
Compact bone- made up of osteons (Haversian system)
Haversian canal- centre of osteon, inside this we have blood vessels, bone is laid down around canal as concentric lamellae
Osteoblasts form bone- after formation they go into lacunae and become osteocytes
Interstitial lamellae
Volkmans canals allow communication of HS
Canals between osteocytes allow information exchange about environment and stimuli affecting formation
What is the periosteum and what does it contain?
Soft tissue overlying bone
-> contains pain receptors, blood vessels, osteo-progenitor cells
What is found in woven bone?
Osteoblasts- oval in shape, sit in rows over the bone (once they have formed bone and become surrounded they become cytes
Osteoclasts (multinucleated)- break down bone to release calcium if required
-> sit on surface of bone in howship lacunae
What factors affect bone remodelling?
Mechanical stimuli- muscular loading, orthodontic forces (resorption and deposition)
Hormones- most have some effect on bone metabolism (direct or indirect)
-> PTH, Vit D3, Oestrogen
Cytokine
-> IL-1 and IL-6 are released in response to inflammation and can activate osteoclasts and cause bone resorption
What is the issue with biopsying bone, what tends to be done instead?
Difficult access/Difficult healing
-> Use special tests- bone biochemistry
What are the different bone biochemistry tests and their normal ranges?
Blood calcium (2.20 to 2.60 mmol/L)
Osteoblast activity (bone formation)
-> serum alkaline phosphatase (30 to 130 U/L)
-> Osteocalcin (Vit K dependent) (< 15 ng/L)
Osteoclast activity (bone resorption)
-> collagen degradation urine & blood
Parathyroid hormone (1.6 to 7.5 pmol/L)
Vitamin D assays (>50 nmol/L adequate)
What is a torus?
Developmental exostosis
What are the types of Tori?
Torus palatinus- midline of palate
Torus mandibularis
-> bilateral on lingual aspect of mandible at premolar region (can meet at midline)
What are the issues with Tori?
Can impede flanges of dentures due to lack of space
May get trauma to them from denture or eating causing discomfort
What is a potential cause of torus formation?
Clenching- increased bone pressure could be leading to increased bone thickness
What are the features of Tori when seen on CBCT?
- Found incidentally
- Found in body of mandible as bony protuberances (not growing into bone, growing off of it)
- Cortical bone- solid
- In palate- seen as dense lump of bone in midline (flat normally)
What type of Osteogenesis imperfecta is related to dentinogenesis imperfecta?
Type 3
What is the most severe type of OI?
Type 2- tend to die young
What types of OI are related to blue sclera?
Type 1 and 3
What are some of the implications of OI?
Weak bones- prone to fracture
Lasting scarring can occur after fractures
Patient may be wheel chair bound
What is achondroplasia?
Issue with formation of long bones (defect in endochondral ossification)
-> Shorter limbs, normal head and thorax (dwarfism)
What pattern of inheritance does Achondroplasia follow?
Autosomal dominant
What is Osteopetrosis?
Lack of osteoclast activity (resorption failure) with excess osteoblast activity leading to denser bones
-> marrow can become lost (obliterated) and can lead to anaemia
What are the dental implications of Osteopetrosis?
Difficult to extract teeth due to bone density
Delayed healing- lack of blood supply
What causes fibrous dysplasia?
Gene defect
What occurs in fibrous dysplasia?
Slow growing swelling in bone- bone is replaced by fibrous tissue
Stops when patient stops growing (treat after this finishes)
Serum biochemistry is normal
What is the difference between monostotic and polystotic Fibrous Dysplasia?
Monostotic- single bone (more common)
-> can affect head- maxilla > mandible
-> increasing facial asymmetry occurs
Polyostotic- many bones (usually part of Albrights syndrome)
What are some of the other features of Polystotic fibrous dysplasia (Albright’s)?
Melanin pigmentation
Precious puberty (may start at age 2-3)
What are the radiographic features of Fibrous Dysplasia?
Ground glass/orange peel appearance
Amorphous- loss of trabecular pattern
Base on clinical presentation and fact that it looks abnormal
Margins are poorly defined (helps distinguish from other fibro-osseous lesions)
Becomes more radiopaque as it matures
Bone maintains approximate shape initially
On OPT it may be seen as bulging of alveolar crest that drops below opposite side (enlarged tuberosity with loss of trabeculae)
Usually no root resorption of displacement of teeth (can happen as it progresses)
Secondary lesions can occur- Solitary bone cysts
What are the histological features of Fibrous dysplasia?
Fibro-osseus appearance- cellular fibrous tissue background with bone within it (usually woven and as it matures can increase in size)
Metaplasia- spicules of bone present
No capsule- not separated from surrounding normal bone (nothing present to demarcate it from bone)
What is the treatment if Fibrous dysplasia is not deemed to be too deforming?
Leave it and do nothing
What is rarifying osteitis?
Process rather than pathology- localised loss of bone in response to inflammation
Bone breaks down leaving area without bone or less mineralised bone (radiolucent on radiographs)
What pathologies is rarifying osteitis be associated with?
PA abscess, granuloma, periodontitis
-> seen in failed RCT
What is sclerosing osteitis?
Abnormal hardening- increase in bone density in response to low grade inflammation
How does scleroisng osteitis appear radiographically?
- Seen as radiopacity
- Poorly defined
- May form alongside rarefying
- Increased density in trabeculae
- Tends to occur alongside non-vital teeth
What is Idiopathic osteosclerosis?
Localised increase in bone density of unknown cause
-> Seen as island of Dense bone
What are the features of idiopathic osteosclerosis?
- Commonly occurs in premolar region of mandible
- Always asymptomatic- if any issues this is not diagnosis
- No expansion
- No displacement of teeth or canal (shows it is not a bony tumour)
How is Idiopathic osteitis distinguished from sclerosing osteitis?
Carry out sensibility tests on teeth involved- if tooth NV its likely to be SO
What is the technical term for Dry Socket?
Alveolar osteitis
What are the risk factors for dry socket?
Mandible
Further back in mouth
Difficult extractions
Female sex
Smokers
OCP use
What is thought to occur which results in Dry socket?
Clot is lost from socket too soon (loss of temporary plug)- perhaps by rinsing too soon (tell patient not to brush?)
-> Patient may say it is sorer than toothache they were experiencing
How is dry socket managed?
LA
-> try and create new clot by gently traumatising
Irrigate with saline
Apply packs with medicament to socket
-> helps stop pain but can delay healing process