A living tooth is classified by science as an organ because it is
made up of multiple tissue types, each with an essential function. These tissue types are:
Enamel--the
body's hardest mineralized surface, which seals and protects the interior.
Dentin--a bony
substance which serves as a cushion for chewing forces.
Pulp--blood
vessels and nerves which nourish and give perception to the tooth.
Cementum--the
hard outer surface of the tooth where there is no enamel.
Periodontal ligament--the
connective tissue that attaches to both the cementum and the jawbone anchoring the tooth.
It takes 14 months for a tooth to be completed in a human. The process
of tooth formation is called "a tiny marvel of design and construction" (Scientific American, August 2005, page 37).
Six to seven weeks after conception when the human head is being formed, tooth development begins. There are four steps that
have been identified in the design and engineering of human teeth:
1. Mouth surface cells at the tooth location thicken slightly and
gene activity within the cells send signals to underlying tissue which surround the surface cells. This forms a tooth bud.
This is done by week seven or eight after conception.
2. The thickened surface cells become a cap, and at the center of
this cap a structure forms called an enamel knot. This knot sends signals to all other cells to direct their growth. This
is accomplished by the ninth week after conception.
3. The developing tooth has a bell shape with cells forming on the
top that will become enamel and cells under that which will become dentin. This is completed by the fourteenth week.
4. Roots develop, completing their formation six to twelve months
after birth.
It is difficult to comprehend how all of these cells know how to
do what they do and when to do it. Scientists have been intercepting the signals mentioned above, and they are now trying
to see if they can grow human teeth artificially to replace false teeth. Sending signals and controlling construction timing
is a function of intelligent and purposeful design -- not chance.
