Staining with fluoride or tetracycline

I got a comment the other day:

What about fluoride? I know that too much fluoride in the public drinking water stains children’s teeth a mottled grey, from the inside out.

While tetracycline staining and cosmetic dentistry seem interesting leads in a similar vein and which I discuss at the end of this post, I don’t think fluoride staining will work. I shamelessly offer my layman’s reasons why because something I write may spark something else in the commenter or others . . .

Or annoy the right expert enough to be drawn in . . .The US Centers for Disease Control and Prevention offers a primer on fluoride staining, or Dental Fluorosis.
These photographs from their site show mild and severe forms of the condition.  

I will leave aside the need to establish that fluorides as with any other stain candidate will not harm the elephant.

First, fluoride only stains the enamel or the outer, exposed layer of immature teeth and not the underlying dentin, which makes up a lot of a tooth. Elephant tusks do have enamel, but most is worn away by use. Mature tusks (and ivory) are mostly dentin and would likely be untouched by fluoridation.

Second, we dose ourselves with fluorides continuously by imbibing trace amounts with our drinking water.

Continuously adding fluoride even to just strategic drinking holes in the elephants’ habitat would be expensive. More problematic, it would require a continuously maintained infrastructure of monitoring and replenishment liable to corruption or inattention.

Also, even if it is proven that the umpteen other species using the water hole could tolerate the needed fluoride doses, I think an elephant tusk staining solution affecting other species would be unethical and controversial enough to be unworkable.

The staining solution, I believe, will involve something ingested by elephants in discrete doses at long and possibly irregular intervals. Even if fluorosis did stain dentin, a cursory run around the web suggests that we couldn’t induce and maintain fluoride staining this way.

The antibiotic tetracycline in a long term regime of discrete dosages does permanently stain both the enamel and dentin of immature teeth. Certain derivatives such as minocycline used to combat extreme acne stains adult teeth as well as other tissues and fluids. Using an antibiotic is a political non-starter, but if the staining mechanism of tetracycline could be found or replicated in a benign substance, I think it’d be a likely avenue for research. This article in Pharmacology Weekly is a summary of tetracycline staining. They discussed minocycline separately.

Another lead to pursue:Cosmetic dentists worry about discoloration of teeth and how to bleach them to a pleasing white. I contacted one and referred him to the blog. I asked him how he would go about staining teeth a distinctive color permanently through and through. He replied thoughtfully, but could offer no suggestions. Maintained by another cosmetic dentist, this site gives an idea of what cosmetic dentistry encompasses.