Bone Physiology2

7/31/2019 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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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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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.

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Bone Physiology2