Bones and joints

Question 1

What is the composition of bone

Answer 1

Non-cellular matrix:
ECM: type 1Collagen associated with calcium hydroxyapatite , regulatory proteins & growth factors

Cellular matrix:
- Osteoblasts, osteocytes, osteoclasts

Question 2

What is the function of bone?

Answer 2

-Protection
-Haematopoesis
- support
-Lipid and mineral storage

Question 3

What is the function of osteoblasts

Answer 3

Secrete uncalcified/ unmineralised extracellular matrix (known as osteoids) which is later mineralised

• regulate bone resoprtion: rich in APL
  -Synthesis matrix
• express receptors for PTH, Glucortocioids, vit D, Oestrogen (influence remodelling)

Question 4

What is an osteoid

Answer 4

Unmineralised extracellular matrix

Question 5

What is an osteocytes function

Answer 5

Osteoblast that is entomed in lamella in lacunae- mineralises osteoids

Question 6

What is the function of osteoclasts

Answer 6

Monocyte derivatives, resorb bone via secretion of H+ and lysozyme enzymes

Question 7

What are the phases of bone formation

Answer 7

Woven:
- embryo/ fracture
- full of osteoids (unmineralised ecm)
- collagen randomly arranged

Lamella:
- Compact/ spongy

Question 8

What is meant by ‘Compact bone’

Answer 8

Type of lamella bone
- dense rigid
- found in outerbone

Contains:
Haversian canal- nerve & lymphatic vessels

Volkmans canal- Horizontally connected- transmit blood

Cannalculi = osteocytes between laemalla and connect by interconnecting tunnels

Question 9

What is meant by spongy bone

Answer 9

• interior of bone
• Honeycomb texture
• Light and porous
• non structural fill

Question 10

How are osteoblasts activated

Answer 10

hormone/ damage

Question 11

What affects bone formation

Answer 11

• PTH
• Vitamin D
• Calcitonin
• (BMP) Bone morphogenic proteins

Question 12

What is the effect of PTH

Answer 12

Regulated by blood calcuium, vitamin D and phosphate levels

1. Increases intestinal transport of CA & phosphate
2. Removal of calcium from bone
3. Increases absorption of vitamin D in upper small intestine

Question 13

What is the role of calcitonin

Answer 13

Opposes action of PTH
-Lowers blood calcium levels
- deposits calcium in bones

Question 14

What are the stages of fracture healing

Answer 14

1. Fracture: inital haematoma: formed with granulation tissue- results in inflammation causing immune response
2. Proliferation stage: macrophages move in and devour debris & dead cells

• proliferation of fibroblasts
  -differenation of osteoclasts and osteoblasts

3.Bone callus: primary callus, osteoids replace with mature bone & becomes mature callus (6 weeks- 3months+) new bone is liad down along lines of stress,

4. Remodelling:
   reduces size of bone callus, bone ends rejoin so now a whole bone
   - bone marrow cavity is restored, new bone is laid down along lines of stress

Question 15

What is osteogenesis imperfecta & signs and symptoms

Answer 15

Autosomal dominant
collagen defect (affect 1-5)

signs & symptoms:
- blue sclera, bruising easily, deafness, loose joints/ tendons
- +/- cardiac complications
- short stature
- multiple fractures

Question 16

How does osteogenesis imperfecta affect dentistry

Answer 16

• Caution with XLA
  -GA risk: chest defomity/ cardiac issues
• Brown/ blue/ pruple/ soft dentine teeth

Question 17

What is cleidocranial dysplasia & its presentations

Answer 17

Autosomal domiant- defect of skull & clavicle

Presentations:
- clavicles absent/ defective
- brachycephalic: broad short skull
- hypoplastic midface: mandibular protrusion
- +/- clefts

Question 18

How does cleidocranial dysplasia affect dentistry

Answer 18

• Hypodontia
• supernumeraries
  -Retained decidious dentition
• abnormaltieis with dentition: root formation, cysts

Question 19

What is osteopetrosis & how does it present

Answer 19

Excessive bone density due to defect in osteoclastic activity & remodelling
- risk of fracture for bones but normal healing

clinical presentations:
- incidental radiographically
-bone pain, fractures, osteomyelitis
- +/- anaemia
- susceptible to infections : RISK OF SEPSIS

Question 20

How does ostepetrosis affect dentistry

Answer 20

• fractures of jaw
• osteomyelitis (surgical complications)
• if infection confirmed it is difficult to eradicate
  -consider abx

Question 21

What is rickets

Answer 21

acquired childhood disease due to lack of vitamin D/ calcium:

• fish & eggs

Question 22

How does rickets affect dentistry?

Answer 22

fractures

Question 23

What is osteoporosis
- How is it diagnosed

Answer 23

Demineralised bone mass
Low bone density
Results in fragile bones

affects: 1 in 3 women

diagnosed: FRAX tool, DEXA scan

Question 24

What are the signs and symptoms of osteoporosis

Answer 24

asymptomatic until fracture- back pain, reduced height overtime with stooped posture

Question 25

How does osteoporosis affect dentistry

Answer 25

Patients are on bisphosphonates- risk of MRONJ - Pt weaker bones fractures

Question 26

How is osteporosis managed

Answer 26

Exercise Ca, Vit D supplements HRT +/- Bisphosphonates Medications: hormone replacement, bisphosphonates, PTH, fluoride, vitamin D, calcitonin

Question 27

What is the mechanism of bisphosphonates

Answer 27

1. Attach to hydroxyapatite binding sites Particularly on surfaces that are actively resorbing 2. Impairs osteoclastic ability to bind to the bony surface & inhibit resorption - Reduce osteoclast activity by promoting osteoclast apoptosis & inhibit new osteoclast developing

Question 28

What is fiborous dysplasia

Answer 28

benign, chronic fibro-osseous lesions in craniofacial region - monostoic/ polystoic - chronic disorder: scar tissue grows in place of normal bone - fiborous tissue weakens bone overtime Linked with Albrights syndrome: bone, skin, endocrine tissues

Question 29

How does a pt with fibrous dysplasia present & how is it diagnosed

Answer 29

Firm swelling in maxilla Diagnosis: Imaging: appear dense ground glass, poorly defined margins raised APL & urinary hdroxyproline biospy

Question 30

What is pagets disease

Answer 30

Common in 40 years old, unknown aetiology, change in balance of remodelling of bone

Question 31

What are the signs and symptoms of pagets disease & how is it diagnosed

Answer 31

Bone pain, no symptoms in early stages, systemic effects - Enlargement of maxilla -bulging zygomatic area - hypercementosis of teeth Diagnosis: radiographs shows lysis and sclerosis - raised ALP - normal Ca, PO

Question 32

What is the tx for pagets disease

Answer 32

bone bisphosphonates - calcitonin: pain relief

Question 33

What are the systemic effects associated with pagets disease

Answer 33

Musculoskeletal: - bone pain, bone deforbity, fractures, osteoarthritis, spinal stenosis Neurological: Tinnitus, cranial nerve, basilar impressions, hearing loss, cardiovascular: - congestive heart disease, increase CO, aortic stenosis, generalised atheroscleoriss metabolic: hypercalcaemia, immboilsation neoplasia: - sarcoma, giant cell tumour

Question 34

How does PTH work

Answer 34

- acts on kidneys : increases renal reabsorption -reabsorption of phosphate - increases absoprtion of calcium in gut - promote osteoclastic bone resoprtion: rise in calcium plasma levels & ALP

Question 35

What is primary hyperparathyroidism

Answer 35

too much PTH - associated with adenoma

Question 36

What are the signs and symptoms of primary hyperparathyroidism

Answer 36

- Associated with renal tones - Hypercalcemia - Bone pain - Fractures -Pathological fractures -Giant cell tumours -peptic ulcers - pancreatitis - hypertension

Question 37

How does hyperparathyroidism affect the hesd and neck

Answer 37

- Local swelling in mandible - corneal calcification - thinning bone trabeculae - Develop bony lesions - jaw/ skull lesions - pepperpot skull - fibrous replacement of reabsorbed bone- osteitis fibrosa cystica

Question 38

What is the tx for hyperparatyrodisim

Answer 38

Surgical removal of adneoma post-op issue with hypocalcemia

Question 39

What is secondary hyperparathyroidism caused by

Answer 39

Response to persistently low calcium: - chronic renal failure - malabsoprtion

Question 40

How does secondary hyperparathyroidism affect dentistry

Answer 40

- Giant cell lesions - Brown tumourd -GC lesions - Other systemic issues