With each issue, Trib+Health brings you an interview with experts on issues related to health care. Here is this week's subject:

Ryan Quock serves as vice chair of the Department of Restorative Dentistry and Prosthodontics, as well as associate professor of Restorative Dentistry at the UT Health Science Center at Houston. There he studies fluoride therapies, as well as other components of caries management.

Editor's note: This interview has been edited for length and clarity.

Trib+Heath: The question of whether or not it is safe for communities to add fluoride to their water supply has become a topic of discussion in many Texas cities, such as Austin and San Marcos. Why do you think this is and is there a cause for concern?

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Ryan Quock: I guess the short answer to the second question is that fluoride added by authorities to the community water supplies, in the recommended concentrations for the prevention of dental caries, is not a cause for health concern. That’s sort of the first thing.

As to why there is concern in various communities, I’m guessing this is not really a new thing. We’ve sort of observed this for years, that there has consistently been a percentage of the population who have concerns about adding anything to our water supply, and fluoride has become a focus of some of their concern.

One could only speculate, and I’m sure you’ve looked at the various websites and other media they’ve put out there regarding their concern for systemic health. Perhaps the scientific evidence doesn’t support the vast majority of the concerns or claims that are made by those that would oppose the addition of fluoride to the community water supplies. Again, I think it needs to be emphasized that in the specific concentrations that are recommend for the prevention of dental caries, it’s very safe.

Trib+Heath: Are there any common misconceptions you hear about the effects of fluoride in your work? If so, what do you think spurred these misconceptions?

Quock: It’s one of those really tricky things to share the common ones because, on the one hand, from a scientific perspective and from a public health perspective, fluoride very clearly is very effective for preventing dental caries. That includes very, very, very small concentrations in the water supplies. On the negative aspect, or the other side of the coin, not really negative, but there is really no evidence that fluoride causes any sort of adverse effect for the patient, when in those small quantities in the water supply.

So you’ve got a set of data and facts related to data in support of fluoride, but then there seems to be an unlimited supply of proposed adverse effects that opponents of water fluoridation would have. I feel like I get introduced to new proposed adverse effects all the time. People say that it causes problems with thyroid. People say it causes every cancer known to man, pretty much. People say that it causes neurological issues. Whatever your imagination could come up with, I’ve heard various things. So really kind of it gets to a point where it becomes difficult to address all of them because people make a claim, but there’s no scientific data to support the claim.

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Trib+Heath: What is your recommended fluoride intake and why?

Quock: The Institute of Medicine is a pretty respected body that makes recommendations for intake of all sorts of different nutrients and chemicals and what not. They actually have a recommendation for what an upper limit would be for how much you should get of various elements, and fluoride is one of those. I don’t have a specific recommendation. I’d say follow the Institute of Medicine’s recommendation. And the way they do it is they tell you how many milligrams, or even fractions of a milligram, per kilogram of the weight of the person per day is safe for consumption.

I can fairly safely say that if a person is drinking water that has the optimal level of fluoride for preventing dental caries, they’re not going to get anywhere near that sort of safe range for fluoride as recommended by the Institute of Medicine.

I think the bottom line is a person is going to more likely experience the adverse, toxic effects of drinking too much water before they experience any adverse effects of the fluoride that’s in the water — because we’re speaking of less than 1 part per million of fluoride in the water supply. For every million molecules of water you’re consuming, you’re only consuming one or less than one molecule of fluoride, if you look at it in a mathematical sense.

Trib+Heath:  Are there benefits to adding fluoride to water versus getting it from other sources, such as toothpaste or mouthwash with fluoride in it?

Quock: The bottom line is that the way that fluoride prevents tooth decay, dental caries is by topical exposure to the teeth, once they’ve erupted in your mouth. There’s a small benefit that systemic fluoride offers during development, but primarily we all benefit from a daily exposure of our teeth to fluoride. So, actually, in an ideal world everyone would be brushing with fluoride toothpaste on a daily basis, a couple times a day, if not more, and just taking really good care of themselves.

The tricky part is that not all patients have access to toothpaste, and not all patients have access to a dentist, so then you begin entering a public health dilemma. Well, these folks who either geographically or socioeconomically are stranded and don’t have access to the things that many middle class and upper class people have access to and take for granted, what are you going to do for those people?

And so, that’s where water fluoridation becomes so valuable. It provides nice, consistent exposure, if consumed on a regular basis, for those teeth, to the really small quantities of fluoride on a regular basis. It’s able to reach a wider demographic than just trusting people on their own to go get toothpaste or on their own go to the dentist. Those things are a little more expensive, and they require a little bit more effort.

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From a practitioners' point of view, we just know from experience, we are already dealing with a highly self-selective population that comes into our offices in the first place. Then amongst those people who have put a priority on their oral health, a good number of them still don’t do the sort of things daily that they need to do, with toothpaste or what not, to take care of their teeth.

Trib+Heath: Have you found cases of people receiving too much fluoride from their daily dental routine paired with water consumption?

Quock: When we look at adverse effects for too much consumption, digestion of fluoride, the most common adverse effect—and this is how they calculated out the levels, to avoid this—is fluorosis.

Fluorosis manifests in teeth as really faint white spots and in some extreme cases maybe some brown spots, maybe some pits in the enamel. Usually in these cases, during the years in which those teeth are developing, they haven’t erupted yet. So a young child, practically speaking under the age of 10, had consumed amounts of fluoride on a regular basis well exceeding the amount recommended by the Institute of Medicine.

We’re talking about maybe they’re drinking a water supply that is super fluoridated — typically we’re talking about well water that has more than the recommended amount of 0.7 parts per million in the water. In some places, the well water has 10 parts per million or 20 parts per million. In those cases, as the teeth are developing, the fluoride integrates into the teeth and causes these discolorations.

They’re typically purely cosmetic. In fact, folks with fluorosis, because they have fluoride integrated into their tooth structure, are actually less prone to dental decay. That’s how we found out about the benefits of fluoride. A dentist in Colorado back at the turn of the last century noticed that his patients in one community experienced a lot less dental decay than patients in another community. The only difference that he found when he narrowed it down was the decay-resistant community presented fluorosis in their teeth, and their well water contained a lot more fluoride in it than the community that had dental decay, and they had less fluorosis.

That’s the most prevalent form. Historically therefore, here in Texas for example, in the dental community, whenever we have a patient come in and we see a lot of fluorosis in their teeth, the first question we ask is “Where are you from?” Because in the past, a lot of folks who came from the west part of the state would develop fluorosis because the well water in that part of the state was naturally very, very high in fluoride.