Transcript mineralization of teeth

Damion Francis MSc.
TMRI-ERU
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Chemical elements required by living organisms
other than C, H, O, N
Naturally occurring in foods and must be taken in
the diet
Comprise of 4% of the body weight
Classified according to the amount needed by the
body
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Macrominerals- required in large proportions by the
body (≥100mg)
Includes: calcium, phosphorus, magnesium, etc.
Microminerals (Trace elements)- required in
relatively small amount by the body
These include iron, zinc, cobalt and manganese
BONE
 Bone is made up of an inorganic mass of minerals
with a protein matrix (collagen)
 Major component is calcium and phosphate along
with a other minerals and trace minerals
 Concurring with biological theory increase in fruit
and vegetable intakes was associated with stronger
bones in several studies
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The exchange of Ca and P between the extracellular
matrix and body fluids are regulated by the
parathyroid hormone (PTH) and vitamin D
Bone has two growth phases:
 Formation of a protein matrix (collagen produced by
osteoblasts) which can be calcified
 Calcification (calcium phosphate is precipitated from serum)
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Remodeling involves the building of bone by
osteoblasts which are then broken down by
osteoclasts
Subsequently rebuilt by osteoblast mainly through
the production of hydroxyapatite (Ca10(PO4)6OH2),
the primary inorganic constituent of bone and teeth
The apatites develops and mature into calcified
crystals increasing bone density
Teeth
 Mineralization of cementum and dentin is similar to
bone
 Calcification of enamel differs from the above
mentioned
 Mineralization and matrix formation occur
alongside enamel development
 Mineral content of enamel is 95-97% with only a
trace of organic matrix
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Enamel development begins with the differentiation
of cells of the oral epithelium
Thickens to form a protruded inner enamel
epithelium
Results in formation of ameloblasts which secretes
enamel proteins such as amelogenin
Also involved in transport of calcium and phosphate
in enamel matrix
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Enamel proteins such as amelogenin mediate the
formation of hydroxyapatite crystals from calcium and
phosphate through enamel biomineralization
Protein fraction in developing enamel is an aggregate
of small proteins most of which are phosphoproteins
Once enamel is completely mineralized only
phosphopeptides remain (phosphorus and 1 or 2 aa)
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Adult body contains 1-1.5kg of ca
Function
 Deposit in soft tissue to harden them
 Plays part in controlling heart action, skeletal
muscle & excitability of the nerve
 Has role in blood clotting (prothrombin &
thrombin)
 Enzyme cofactor (pancreatic lipase)
 Chromosomal movement before meiosis
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Metabolism
Absorbed mainly in upper small intestine
 Facilitated by vit. D, proteins, acid pH
 Reduced by phytic acid, oxalic acid
 Transported as free ion or bound to
albumin
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Blood levels are regulated by PTH,
calcitonin (thyroid gland), and active vit. D
 storage deposit of calcium is bone
trabuculae in long bones
 Bones are metabolically active but can
calcium can be withdrawn when needed
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Approximately 250 – 1000mg of calcium
enters and leave the bone daily
 Homeostasis is maintained from dynamism
between blood levels and bone
 Diet and resorption contributes to the blood
levels which act as a reserve
 Osteoid formation is directly regulated by
amount of calcium from diet
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Calcium balance is obtained when there is sufficient
calcium absorbed to meet body requirements for
growth and tissue regeneration
Negative balance when insufficient consumed and
body mobilize calcium from bone to maintain
necessary blood levels
THREE HORMONE AND THREE ORGANS
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PTH
ACTIVATED VITAMIN D
CALCITONIN
BONE
KIDNEY
SMALL INTESTINE
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principal regulator of [Ca] in ECF by  [Ca] and 
[Pi]
If blood levels of iCa  0.1 mg/dl, secretion of PTH
is 
Kidney reacts quickly to changes in PTH  minute
to minute adjustments of blood Ca
PTH acts on distal nephron to  urinary excretion of
Ca
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steroid hormone
regulate specific gene expression following
interaction with its intracellular receptor
biologically active form is 1,25-dihydroxy vitamin
D3 (1,25-(OH)2D3, also termed calcitriol)
calcitriol functions primarily to regulate calcium and
phosphorous homeostasis
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Parafollicular cells of thyroid gland in response of
hypercalcaemia
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Decrease osteoclast activity
Stimulating a distal tubular - mediated calciuresis
Other hormones affect Ca balance - including
prostaglandins that mobilize Ca, various growth
factors, growth hormone, somatomedins, thyroid
hormones (decrease skeletal mass), sex steroids which
help maintain bone mass, adrenal cortical hormones
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Sources
dairy product, fortified flour, egg,leafy vegetable,
fish, cabbage, broccoli
Requirement
Adult 500mg/day, Pregnancy 1200mg/day
excreted in urine and feces
Deficiency
Rickets in children & Osteomalacia in adult
Food Calcium
Small Intestine
Body need
Acid pH
Vitamin C
Vitamin D
Lactose
Certain amino acids
Unabsorbed calcium
Alkaline pH
Oxalic acid
Phytic Acid
Some Fibers
Laxatives
Blood
Calcitonin (thyroid hormone)
Sufficient Vitamin D
Weight-bearing exercise
Teeth
Positive calcium balance
Feces
Parathyroid hormone
Inadequate/ excess vit. D
Bone immobilization
Bones
Urine
Negative calcium balance
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Inadequate intake, impaired absorption and
increased loss include:
Incomplete calcification of teeth
 Tooth and bone malformations
 Increased susceptibility to dental caries
 Excessive periodontal bone resorption
 Increased tooth mobility and premature
tooth loss
 Increased risk of hemorrhage
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Less than 500mg calcium associated with
higher risk of gingival detachment
 Decreased bone mineral density (cementum
and dentin)
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