Fluoride Action Network

Yes, you can brush your teeth too much

Source: The Toronto Star | January 19th, 2004 | By Rachel Ross
Location: Canada, National

You brush and brush your teeth, hoping to prevent decay. But nothing stops your teeth from slowly turning brown.

It seems to get worse the more you brush, in fact.

It could be that the problem is in the paste.

Most major brands of toothpaste contain some form of fluoride: usually sodium fluoride. It’s an ingredient that has long been billed as a powerful cavity fighter by the dental community. But as with most things in life, too much of a good thing can be a very bad thing indeed.

Fluoride is all around us. It’s in the food we eat and it’s added to the tap water we drink. It is, in fact, impossible to avoid altogether. Fortunately, dentists say a certain amount of fluoride is beneficial for your teeth ˜ it makes the enamel stronger.

The main ingredient in tooth enamel is a mineral called hydroxyapatite, said Dr. Hardy Limeback, head of preventive dentistry at the University of Toronto. It’s a sensitive mineral: even a weak acid can make it rather soluble. Unfortunately, the bacteria that live in your mouth basically make acid for a living. These bacteria feed on tiny food particles left behind from your last meal and produce acids that slowly dissolve the hydroxyapatite. Loose enough hydroxyapatite and your teeth will get soft and vulnerable.

Flouride can replace the missing mineral, though. The chemical reaction involves replacing the hydroxyl group in hydroxyapatite with flouride to form fluorapatite, Limeback said.

Fluorapatite is much more resistant to the acids produced by your mouth-borne bacteria. So a limited amount of the mineral will make your teeth more resistant to decay. Too much fluoride, however, can be disastrrous for your teeth and bones.

Limeback has done a lot of research about fluoride over the years and has often come out against fluoridating the water supply.

“We’ve discovered that having more fluorapatite in bone and in tooth structure makes the tissue, the bone and teeth more brittle,” Limeback said.

The problem is well-documented in areas of India and China, he said, where there are very high levels of fluoride in the water supply ˜ sometimes as much as 20 times higher than the levels of water fluoridation found in North America. Adults with prolonged exposure to such high levels of fluoride often develop deformed bones that break easily.

“The skeleton is often really badly affected,” he said.

The condition, called endemic fluorosis, isn’t common here. But a lesser variant, known as dental fluorosis, is on the rise in Canada and the United States. Dental fluorosis ˜ basically a corroding of the teeth ˜ occurs when children ingest so much fluoride that the cells that form tooth enamel are harmed. These damaged ameloblast cells make enamel that’s weak, porous and lacking in minerals.

Dental fluorosis also leaves the teeth looking rather mottled. At first whiter flecks appear on the teeth. But given enough fluoride, those whitest flecks will turn brown. Sometimes the teeth actually start to disintegrate, leaving behind rough, jagged edges.

Pictures of severe dental fluorosis are quite dreadful: so many dark brown patches and rough edges. They remind me of the pictures of horrific cavities we were all shown in grade school to convince us to brush everyday ˜ with fluoride, of course.

How ironic.

Don’t get me wrong ˜ it’s still important to brush your teeth. Toothpaste is more than just fluoride in a tube. Toothpastes also contain an abrasive (usually hydrated silica), which helps to scrub your teeth clean.

“The physical structure of silica is tough enough to clean the teeth and remove extrinsic stains, and yet soft enough to not damage the enamel and dentine,” said Joyce Law, a spokesperson for Procter & Gamble’s toothpaste division.

(Some people use a simple combination of fluoridated water and baking soda because they prefer the abrasive action of sodium bicarbonate.)

Sodium lauryl sulfate is another common ingredient in manufactured toothpastes. Pick up a bottle of bubble bath and you’ll find it in there too. It’s a common detergent that provides a nice foam for carrying away debris. Such a detergent also makes it easier for the fluoride to re-mineralize your teeth.

Ingredients such as zinc citrate prevent plaque from hardening, or calcifying on their teeth. Tetrasodium pyrophosphate performs a similar function ˜ it stops the calcium and magnesium in your saliva from locking on to your pearly whites.

Anti-bacterial agents, such as triclosan, are also used in some toothpastes to kill off the little things that make the enamel-weakening acid.

My point: there’s lots of important tooth care agents in toothpaste, but some people might want to opt for a brand that doesn’t have fluoride.

“If they’ve had no fillings most of their lives, they have good oral hygiene and eat a proper diet that doesn’t include abusing white flour and white sugar, then they are likely at low risk for cavities and probably don’t need the toothpaste with fluoride,” Limebacker said.

Young children, in particular, should have limited exposure to fluoride. It’s in those early years of tooth development that excessive fluoride can be particularly detrimental to enamel.

For kids who can’t be trusted not to eat the minty paste, Tom’s of Maine makes non-fluoridated varieties.

Kind of makes you question the merit of bubblegum flavoured toothpaste for kids.

We’re supposed to be discouraging them from eating the paste, not making it tasty.