Through the waterways

Through the water ways

We are 'non-big'

Good morning everyone, the world says 'Hello'!
No vulgarities please.
Muchlove everyone.

Tuesday, August 14, 2007

You knit me together in my mother's womb~ /10:11 PM

Psalm 139: 13-16

For you created my inmost being;
you knit me together in my mother's womb.

I praise you because I am fearfully and wonderfully made;
your works are wonderful,
I know that full well.

My frame was not hidden from you
when I was made in the secret place.
When I was woven together in the depths of the earth,

your eyes saw my unformed body.
All the days ordained for me
were written in your book
before one of them came to be.

People who say that life came about by accident probably are those who don't know their content well (or I dare say not at all). I'm supposed to specialise in teeth, and if you realise how much effort and planning takes place just to make a tooth 'begin', I'm pretty sure you'll agree that there is an intellegent designer.

Development of teeth

Deciduous teeth- begins at 20 weeks in utero (when you were the size of a green bean!)
Permanent teeth- Incisors to premolars: begins 20 weeks in utero- ends 10 months after birth. Molars: begins at 20 weeks in utero- ends 5 years after birth.

Imagine that! When you were the size of a green bean, your set of permanent teeth were being prepared in your mother's womb!

3 Developmental stages

1) Bud stage
Begins as epithelial ingrowth into the underlying connective tissue.

In other words, a bit of the gum on the surface pinches off and grows downwards and inwards.

2) Cap stage
The bud continues to proliferate. It becomes a cap shaped thing called the Enamel organ. The cap sits ontop of a lot of cells known as the Dental Papilla, which will in the future become the pulp. The cells surrounding the cap are known as the Dental Follicle and will become the future PDL. Dental Follicle provides nutrients to the developing tooth.

To simplify it: The pinched off part is called the enamel organ. The cells below it will one day become the pulp, and the cells surrounding it will become the fibres that help your tooth stick in the jaw.

3) Bell stage
Growth continues and the cap deepens into a 'bell' shape. The Dental Papilla begins deffrentiating into fibres and capillaries. The layer of enamel organ closest to the pulp is called the internal enamel epithelium. The layer of enamel organ on the periphery of the bell is called the external enamel epithelium. The cells of the dental papilla closest to the IEE begin to defferntiate into odontoblasts. The cells of the IEE begin to diffentiate into ameloblasts. Dentine and enamel formation commences.

The pinched off part grows bigger and the cells about it starts to transform into new kinds of specialised cells. Cells that make blood vessels, fibres, dentine and enamel. Then the dentine and enamel starts to form proper!

Dentinogenesis

1) Formation of uncalcified organic matrix

This stuff is known as predentine. Odontoblasts lay down dentine and pull away from the ADJ. Odontoblasts are therefore always located on the pulpal surface of the most recently formed predentine. Odontoblasts leave behind an extension as they recede, which later becomes enclosed in a dentinal tubule.

The cells making the dentine well... make it. They leave little bits of themselves in the dentine. Right now, the dentine is still soft.

2) Calcification

Takes place only when a fairly wide band of predentine has been formed. Starts in layers closest to the ADJ and advances pulpally. Globules of calcium salt are deposited in the matrix to make it hard.

This is just the longwided and complicated way of saying that the dentine becomes hard.

Amelogenesis

1) Organic matrix formation

Starts at the ADJ of each cusp tip or incisal edge after the first dentine is formed. Each ameloblast lays down a matrixnest to the newly formed dentine. Ameloblasts move away from the dentine, working in a line and thus enamel is deposited in layer.

Unlike dentine that is made to grow inwards. Enamel grow outwards.

2) Calcification

Calcification will begin in the first-formed matrix. The process is not uniform and there are periods of rest and sctivity. This causes incremental lines, the brown striae of retzius to form. Pits and fissures are formed where the growths from the various cusps unite. When the enamel formation of the cusps is almost complete, enamel formation at the cervical region begins. After enamel formation is completed, the ameloblasts atrophy and form the reduced enamel epithelium which degenerates upon tooth eruption.

Enamel grows hard as it is put down in layers... The cells on the enamel surface are washed away after the tooth comes into the mouth. Enamel once broken cannot grow back!

Root formation

Cementum formation

Only begins after the enamel and dentine formation has reached the future CEJ. Shape of the roots is mapped out by a growth from the IEE and EEE. This growth is called the hertwig's root sheath and i initiates dentine formation in the roots. Dentine formation continues as before. The root sheath starts to degenerate when the first layer of dentine has been laid down. As the root sheath breaks down, the connective tissue cells from the dental follicle come into contact with the root dentine and differntiate into cemetoblast. They deposite an organic matrix which is then calcified in layers. These are the incremental linesof salter. Cememtum grwoth continues throughout the life of the tooth.

After the happy dentine and enamel hit where the roots should begin, a membrane appears to shape the root. Dentine is laid down on this membrane which later dissapears. When it is gone, cells start forming cementum on the outside, which is a lifelong process.

b) PDL formation

Occurs at the same time as cementum is being laid down. Cells of the dental follicle deferentiate into fibroblasts and sythesize ground substance and fibres for the PDL. The fibres become embedded in the newly formed cementum and alveolar bone. They are constantly replaced as the toothe erupts.

Fibres that attach the tooth to the bone develop while the cementum is developing.

c) Alveolar bone formation

Develops from a V-shaped groove in the maxilla and mandible. The V-shaped groove contains toothbuds, alveolar nerves and blood vessels. Sone septae start to develop between the adjacent tooth buds. The bone then encloses the tooth buds to form the alveolus.

The jaw bone depresses and contains the developing teeth. It later seals up the teeth before the time of eruption.

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