Oral surgery L2: Bone biology bone and calcium

Question 1

Q1: what percentage of bone composition is mineral?

Answer 1

60% mineral, largely hydroxyapatite

Question 2

Q2: what percentage of bone composition is organic?

Answer 2

25% organic (90% type 1 collagen)

Question 3

Q3: what percentage of bone composition is water? 15% water

Question 4

Q4: which bone supports the tooth?

Answer 4

Alveolar bone

Question 5

Q5: which bone takes the shape of the mandible/maxilla?

Answer 5

basal bone

Question 6

Q6: why is infiltration of lidocaine on the lower 6 hard to achieve anaesthesia?

Answer 6

The bone is very dense and thick in that region, which doesn’t allow diffusion of the anaesthetic.

Question 7

Q7: why is infiltration more appropriate in the maxilla compared to the mandible?

Answer 7

More trabecular bone present in the maxilla compared to the lower, this allows better diffusion of anaesthetic material through the bone.

Question 8

Q8: which region in the maxilla will you begin to find challenging to achieve anaesthesia through infiltration and why?

Answer 8

You would start to struggle to achieve anaesthesia in the upper 6, this is due to the presence of the zygomatic process, which is allot thicker.

Question 9

Q9: the lamina dura is also known as bundle bones due to the presence of bundle of collagen fibres. the lamina dura acts as a cribriform plate, this feature allows us to achieve anaesthesia by which technique?

Answer 9

Intraligamentary technique.

Question 10

Q10: where is the circumferential lamellae located.

Answer 10

Question 11

Q11: where is the concentric lamellae located.

Answer 11

Question 12

Q12: where is the interstitial lamellae located.

Answer 12

Question 13

Q13: cartilage –> calcified cartilage –>bone. What type of ossification is this?

Answer 13

Endochondral ossification.

Question 14

Q14: trapped osteoblasts are called what?

Answer 14

Osteocytes

Question 15

Q15: which two hormones help regulate calcium homeostasis?

Answer 15

Calcitonin and parathyroid hormone.

Question 16

Q16: which thyroid hormone increases plasma calcium levels?

Answer 16

Parathyroid hormone

Question 17

Q17: which thyroid hormone decreases plasma calcium?

Answer 17

Calcitonin

Question 18

Q18: which hormone acts on the kidneys to decrease Ca excretion?

Answer 18

Parathyroid hormone

Question 19

Q19: which hormone acts on the kidneys to increase Ca excretion?

Answer 19

Calcitonin

Question 20

Q20: if there is a decrease in plasma calcium levels, the parathyroid hormone acts to release calcium in the plasma. It can do this fast and slow, how do osteocytes help in fast deliverance of Ca2+ in the plasma.

Answer 20

Osteocytes are osteoclasts trapped in bone, which are surrounded by blood vessels. In the bone there are small labile pools of Ca2+, the osteocytes undergo osteocytic osteolysis, which breaks down the small amount of bone and due to the proximity of the blood vessels, it delivers it directly to the plasma.

Question 21

Q21: if there is a decrease in plasma calcium levels, the parathyroid hormone acts to release calcium in the plasma. It can do this fast and slow, how does the slow process work.

Answer 21

It works by bone dissolution and shifts remodelling to favour resorption.

Question 22

Q22: trapped osteoclast are known as osteocytes, are osteocytes vital or non vital?

Answer 22

They are vital