Bone Biology Flashcards
what does bone turnover/remodelling allow?
replacement of brittle bone
what activity does bone turnover/bone remodelling require?
Osteoclast and osteoblast activity
what is b. remodelling regulated by?
Parathyroid hormone Calcitriol Calcitonin Sex hormones Growth hormone Hyoid hormone Cortisol
phases in b. remodelling?
Activation
Osteoclast recruitment and resorption
Reversal
Osteoblast recruitment and bone formation
Termination
where are osteoclasts recruited from?
mast cells and macrophages
Where are osteoblasts recruited from?
Blood supply
how does osteopetrosis display in body?
dense bone
unerupted teeth
impacted teeth
osteoclastic bone resorption occurs after extractions.
which dimension is the greatest amount of bone loss seen?
in the horizontal dimension
- labial facial aspect of ridge
- vertical ridge height loss on buccal
what is the clinical relevance of bone remodelling?
process takes 6 months and pose problem for some dental work
in pros how do we combat bone remodelling?
transitional dentures
drugs that affect bone remodelling?
NSAIDS
Bisphosphonates
steroids
denosumab and anti angiogenic drugs
how do bisphosphonates work?
- by binding to exposed bone mineral around resorbing osteoclasts
- Internalised by osteoclasts which disrupts their activity
Class of bisphosphonate
-Non – nitrogen containing e.g clodronate
How does it work?
Resemble pyrophosphate
incorporated into phosphate chain of ATP
unusable for energy production in osteoclasts
Class of bisphosphonate
- Nitrogen containing e.g alendronate
How does it work?
prevent the formation of key isoprenoid lipids in osteoclasts which anchor proteins to the cell membrane and without these cell death continues
What is MRONJ?
Exposed bone in the maxillofacial region or bone that can be probed that has persisted for more than 8 weeks
how to treat established lesions?
irrigation
antibiotics
remove sequestrate
stop bisphosphonate if safe
how do we manage pain in MRONJ
Analgesics
anaesthetic mouthwash
what does bleeding indicate in MRONJ
indicates healthy bone if bleeding at the bed of wound
when is the best time to give patients extraction when on denosumab?
just before they are due their 6month subcutaneous injection
how does angiogenic drug Everolimus work?
Serine theonine kinase that acts as an inhibtor of mammalian target of rapamycin
- Reduced growth of cells
what conditions do patients take high doses of steriods and therefore at higher risk of developing MRONJ?
COPD
Autoimmune Disease
why is long term use of NSAIDS a problem?
interference with prostaglandins
impacts bone bone healing
which drugs affect absorption of calcium from the stomach?
anti - seizure medication
which drugs increase renal excretion of calcium?
diuretics
which drugs reduce androgen and ostrogen levels?
breast and prostate cancer drugs
