Bone Physiology2
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Transcript of Bone Physiology2
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Osteoblasts
Arise from osteoprogenitor cells(pluripotent mesenchymal
cells) under the effect of many growth factors
- Cytokines- Bone morphogenetic protein
- Fibroblast growth factor(FGF)
- Insulin like growth factor(IGF)
- Transforming growth factor (TGF-beta)
Osteoblasts express cell surface receptors that bind many
hormones like (parathyroid hormone,Vit D, estrogen),
cytokines, growth factors, extracellular matrix proteins.
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Osteocytes
Derived from hematopoietic progenitor cells that also gives
rise to monocytes and macrophages.
The cytokines and growth factors crucial for osteoclasts
differentiation and maturation are- Interleukin ( IL-1, IL-3, IL-6, IL-11, Tumor necrosis factor
Granulocyte and macrophage colony stimulating factor)
- They work by stimulating osteoclast progenitor cells or byparticipating in a paracrine system in which osteoblast and
marrow stroma cells take part.
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Clinical Implications Of
Hormonal Imbalance
InOrthodontics
Guided By:Dr.(Mrs). P.V. HazareyProf & H.O.DDr.Sunita ShrivastavaProf & Guide
Presented By
Parikshit.R.Rao
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Thyroid Hormones (Mechanism Of Action)
Calorigenic action : stimulates heat production by increasing
oxygen uptake in all the tissues.
CVS : myocardial cells are under the influence ofsympathetic nerve and the receptors are beta receptors which
increase in response to thyroid hamones.
. CNS : contributes in myelination in axons of cortical neurons,branching and development of dentrites and vascular bed of
brain.
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Protein metabolism :
Anabolic effects : Increases the secretion of enzymes necessary
for catalyzing reactions for formation of various proteins.
Eg : Ketoglutarate
glutamate dehydrogenase ( influenced by hormones)
Glutamate
Catabolic effects :
Ketoglutarate Glutamate
Proteases and peptidases(deamination)
Aminoacids
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Carbohydrate metabolism : Has got opposing actions in physiologicaldoses.
- Increases peripheral glucose uptake through insulin like action.
- Increases blood glucose level :1 Glycogenolysis : Glycogen
phosphorylase (action is enhanced by Camp )
Free glucose
2 Gluconeogenesis : which includes both glycolysis and citric acid cycle
On Vitamins : necessary for conversion of beta carotene to
Vit A and of Vit A to retinene.
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Lipid metabolism : increases number of LDL receptors andthus promotes cholestrol metabolism.
Growth and development : promotes protein synthesis and also
causes increased release and action of Growth Hormone.
Functions of CalcitoninOn Bones : lowers osteoclastic activity due to direct action ofharmone on the bone (increases alkaline phosphatase synthesisfrom the osteoblasts).
Maintains calcium level of bones in pregnant women.
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Features affecting our treatment.
Delayed wound healing ( lack of endothelial growth factor,
decreased collagen synthesis )
Delayed tooth movement ( osteoclast activity, blood flow)
TREATMENT
- Thyroxine should be administered
50g per day for 3 weeks,
100g per day for next 3 weeks
finally increase to 150g per day and continue as a single
dose.
Hypothyroidism
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Features affecting our treatment.
Osteoporosis (Mobilization of bone proteinsdecreases the mass).
Pain threshold is less.
TREATMENT
Carbimazole
- 0-3 weeks 40-60mg daily
- 4-8 weeks 20-40mg daily
- Maintenance 5-20mg daily for 18-24 months.
Hyperthyroidism
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Functions of Parathormone
It increases bone resorption by increasing the osteoclastic acivity.
Helps to convert Vit D into its active form calcitriol.
It acts on renal tubules to increase calcium reabsorbtion.
REGULATION OF PTH SECRETION
- Higher serum calcium level inhibits PTH secretion.
- Higher calcitriol level inhibits PTH secretion.
- Plasma phosphates and magnesium level also affect the PTH
secretion.
PARATHYROID HORMONE
(MECHANISM OF ACTION)
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Features affecting our treatment.
Delayed tooth movementTreatment time may be prolonged.
Treatment
Administration of Alfacalcidol (1 hydroxycholecalciferol) which is
hyfdroxylated in liver to calcitriol.
Hypo parathyroidism
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Features affecting our treatment
Increased bone resorption (increased osteoclastic
activity).
Decreased force levels .
Treatment
- Rehydration with normal saline (4-6 lit)
- Bisphosphonates (90mg i.v over 4 hours)
- Surgery.
Hyper parathyroidism
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Functions of Pituitary hormones
Growth Hormone : all actions are IGF mediated.
- Stimulates production of proteins,
- Increases blood sugar level.
- Increases lipolysis and thus FFA in the blood plasma.
- Increase calcium absorbtion from GIT and in turn increases
bone formation.
Prolactin :- Synthesis of milk in females.
- Opposes the action of pituitary gonadotrophins.
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Thyroid stimulating hormone :
- Synthesis of T3 and T4 harmones.
FSH, LH :
In males :
- formation of spermatozoan.- synthesis of testosterone from testis.
In females :
- help in estrogen synthesis.
- causes ovulation, formation and maintainance of corpus leuteum.
ACTH :
- Synthesis of adrenal hormones.
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Anti Diuretic hormone :
- increases permeability of distal tubules which increases water
reabsorption.- increases peripheral vasoconstriction and increases BP.
Oxytocin :
- Stimulates contraction of smooth muscle cells lining the
mammary glands and of the uterus.
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Clinical implications- Hypopituitarism :
- Tooth movement is slow.
Hyperpituitarism
Osteoporosis (Mobilization of bone proteins decreases the mass).
Increased osteoclastic activity.
Pain threshold is less.
Treatment
- Hypofuntioning :
Hydrocortisone (cortisol) 15mg on waking and 5mg
in the evening.- Hyper functioning : Dopamine agonist, sugery.
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Thymus
At birth thymus weighs 10-12 gms , during childhood and
adolscence 20-30gms but during old age it weighs arround 3-6gms.
With overgrowth of thymus, general bodily growth is accelerated.
Hypertrophy of the thymus may result in delayed eruption of the deciduous
teeth and poor tooth calcification.
The teeth may appear of bluish white color and of uneven size.
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Actions of adrenal cortex hormones
PROTEIN Metabolism : Increases protein break down.CARBOHYDRATE Metabolism : increases glucose 6 phosphatase
activity and thus increase glucose formation.
Electrolyte and water balance : has two antagonizing action
- increases water reabsorbtion and Na retention- antagonises the action of ADH
CNS : Increase in GC decreases the threshold of electrical exitation
of brain cells.
Resistance to stress .
Bone metabolism : Break down of bone matrix due to protein
catabolism , Decrease in Ca deposition because of increased Ca
excretion in urine.
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Clinical implications
In hypofuntioning condition 2 to 4 times the regular doseshould be given on the day of the appointment.
In hyperfunctioning condition treatment time should be
short per appointment, level of forces should be low.
Treatment
- Hypofuntioning :
Hydrocortisone (cortisol) 15mg on waking and 5mg in
the evening.
- Hyper functioning : phenoxybenzamine(10-20 mg orally
6-8 hourly) and prepare the patient for surgery.
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Hypothalamus
Makes up the 3rd ventricle of the brain, provides neurogenic control to
the pituitary gland which controls the target glands ie; thyroid,adrenals, gonads.
Tumors of hypothalamus may cause sexual precocity , dental age also
increases. Alveodental prognathism is present , dentition otherwise is
normal. Gingivitis is present.
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1 Interleukin-1beta and TNF- alpha production by human
monocytes cultured with L- Thyroxine and Thyrocalcitonin.
AJO-DO
1996 Oct 399-404
Mario Rossi
2 Effects of corticosteroids induced osteoporosis on
orthodontic tooth movement.
Ashcarft ,Tolley.
1992 Oct
AJO-DO
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3 Thyroid administration to reduce root resorption.
Eric L Loberg1994 No 5 395-400
Angle Orthodontics
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Conclusion
Recognition of endocrine dysfunction is of
considerable aid in determinig the method and
efficacy of treatment in various malocclusions.
An orthodontist who suspects an endocrinedysfuntion must insist on obtaining a diagnosis
from qualified source.