Thoughts about Tooth Enamel
The minerals that make up teeth provide another
example of phenomenally detailed design.
by Henry L. Richter, PhD
I was captivated by a recent article in Chemical and Engineering News (C&EN October 26, 2020, Page 24) entitled “What’s that stuff? – Dental Enamel”. Whenever the word “design” is used, it demands thinking about a designer. Here is yet another example of the exquisite design in our bodies. In our book Spacecraft Earth, David Coppedge and I explore some examples of the exquisite design we find from the universe itself down to the lowly atom. Here we are looking at teeth.
Quoting from the C&EN article:
In simple terms, tooth enamel is kind of like a rock. It’s made up of about 96% hydroxyapatite, says dentist Edmond Hewlett, from the University of California, Los Angeles School of Dentistry. Apatites are a group of calcium phosphate compounds with the generic formula Ca5(PO4)3X2. The identity of the X ion determines the specific type of apatite. For example, when X=F, you get fluorapatite, Ca5(PO4)3F, a pretty material that comes in all kinds of colors. Hydroxyapatite, usually colorless or white, is Ca5(PO4)3OH.
While all enamel is made of hydroxyapatite, it’s not the same inside and out. Enamels strength comes from how the hydroxyapatite is arranged, which scientists think reduces the risk of having a catastrophic crack propagate through enamel, (Dirk) Joester says. The outside of the enamel, which dentists refer to as the skin of the tooth, is also called aprismatic enamel. This layer, is only a few microns thick Hewlett says, and it has an amorphous form. “Like a solidified liquid crystal.”
The article goes on to describe how the enamel is deposited in several different forms, in layers consisting of minuscule rods several micrometers long, woven into sheets with layers at different angles to each other to give strength. And then, to add to the amazement, each rod consists of bundles of thousands of whisker shaped crystals of hydroxyapatite, only about 50 nanometers wide, says Pupa Gilbert who works on the properties of biomaterials at the University of Wisconsin, Madison. This gives the enamel additional strength. Furthermore, the crystals are not all lined up, but are misoriented, meaning that the crystals slowly change their orientation to one another. This makes the crystals more resistant to fractures.
About Those Cavities: Caring for Our Jewels
The structure is even more complex. In studying the material between the crystals, they found very small amounts of magnesium fluoride and magnesium carbonate. “What there is has a really dramatic impact on the properties of the crystals.” However, this material is soluble in acid which is not good news since that is often in your mouth. A low pH can dissolve the Mg between crystals, as well as the crystals themselves. This happens on a small scale and scientists do not know yet whether or not or how this causes cavities. Eating sugar leads to cavities. It’s not the sugar that causes cavities, but the bacteria that gobble up the sugar that attack the enamel.
When we get a dental cleaning, dentists scrape off the gunk which is called plaque off our teeth. 30 to 40% of this gunk is made up of dead bacterial cells and proteins from our saliva.The remaining 70% is active bacteria that convert the sugar sweets into harmful acids. Much of this is lactic acid which is what damages your teeth. When the pH is lower than 5.5, this starts to leach our the Ca2+ and PO43-, out of the enamel. As the enamel becomes weaker it breaks down, begins to crumble and that is when we get cavities.
Brushing with fluoride toothpaste can strengthen your teeth. The fluoride replaces the Ca2+ and PO43- lost from the leaching and can restore strength to the tooth. Fl– ions floating around your mouth can turn the hydroxyapatite into fluorapatite which is more resistant to acids. Is not all this a most marvelous design?
How Do Cells Know What to Build?
So what do we make of this? It is a wonder that we have teeth, and that they are located in just the right place to allow us to get and chew food. They are formed so the biting shape is in the front and chewing shape on the sides and back. They are hooked to a lower jaw which can move to allow the teeth to do their job. And the teeth themselves are of marvelous construction, coated with this substance – enamel, as hard as the hardest rocks, to protect them and keep their form and shape.
How are teeth made? We know that living cells are formed as the result of chemical synthesis orchestrated by the DNA/RNA in the cell. This synthesis continually takes place in each growing cell, producing just the right molecules and depositing them in the right place. How in the world do they do that?
Somehow the DNA/RNA in each cell knows what type of cell to produce, whether it be in an eye muscle, a kidney, or a tooth. In this case teeth are formed in the embryo and continue to grow in the infant until they emerge through the gums and show, ready to work. And new teeth start forming to become the adult teeth, which push the baby teeth out and become the permanent teeth for the rest of life (hopefully).
Somehow the cells know where they are and what function they perform. First, they produce the tooth pulp and roots, in just the right places. Some cells then recognize instructions that they are to produce the enamel, harvesting calcium and phosphate ions from the body fluids, making hydroxyapatite and depositing it in the right structure to produce the rock-hard enamel. And to know that this is tooth number 7 they are working on, out of 32 distinct kinds! How do they wind up in the right places on top and bottom and from front to back, with left-right symmetry, too?
Now, there are a lot of people who believe that this all came about as a result of undirected, random changes in living cells – through “evolution.” How in the world could unguided individual ‘accidents’ all add up to creating the genetic code that contains instructions for building teeth? How could they construct the machinery to produce different types of cells, depending where they are located? This idea cannot work, putting together one little change after another, building up to the extreme complexity that we see in living cells and structures like teeth. And then is the next miracle that I have a brain that can imagine all this and appreciate it.
Again, this shows very detailed design that is correct in every aspect. The only being capable of creating such exquisite design is the God of the universe Himself. Mysterious, marvelous designs are all about us, and we are fortunate to be created in such a way that we can observe all this and try (at least a little bit) to understand it.
Dr. Henry Richter was born in Long Beach, California, and served a short tour of duty in the U.S. Navy in World War II. From there he received a BS and PhD (Chemistry, Physics, and Electrical Engineering) from the California Institute of Technology in Pasadena California. Then he went to the Jet Propulsion Laboratory, which became part of NASA. While there he headed up the development of the free worlds first earth satellite, Explorer 1. He then oversaw the scientific instrumentation for the Ranger, Mariner, and Surveyor Programs. From JPL, he went to Electro-Optical Systems becoming a Vice President and Technical Director. Next was a staff position with UCLA as Development Manager of the Mountain Park Research Campus. He then owned an electronics manufacturing business and afterwards became the Communications Engineer for the L.A. County Sheriffs Department. Since 1977, he has been a communications consultant to Public Safety organizations. He is a life member of APCO, the IEEE, and the American Chemical Society. This year, he is the 2019 recipient of the Lifetime Achievement Award from the Radio Club of America, which he will be awarded this month at their annual banquet in New York City. His book America’s Leap into Space details the origins of rocketry and his own role in the launching of the first American satellite, Explorer 1, in 1958. Henry Richter is also author of Spacecraft Earth: A Guide for Passengers, with co-author David Coppedge (Creation Ministries International, 2016). Creation-Evolution Headlines is honored to have Dr Richter as a contribution writer. See his Author Profile for his previous contributions.