Thinking water fluoridation in developed countries was a good thing medically or for dentistry ended like 20 years ago. It took about another 10 years for most to accept it. It is now considered risky and provides no measurable benefit...any more... as the majority of people get plenty of fluoride from other sources. This is when people of developed countries have plentiful access to dental hygiene produces, which are loaded with fluoride, and dentist's care, which typically do routine fluoride treatments to children.

Since fluoride accumulates in your body with no metabolization, it doesn't leave your body after you ingest it, it just keeps accumulating. Over time this can cause several health problems and dental problems. These take a very lot to become extreme and most extreme examples that include sever impacts to learning and cognitive ability in children, for example, are taken from people who live in places where the fluoride levels in nature are naturally high and places where significant industrial fluoride pollution has been thoroughly recorded seriously impacting children, like in china.

The benefit of fluoridating water is mainly the momentary presence of fluoride, but secondarily, the slight benefit of the mineral to enamel development. In modern developed countries, the general public simply gets plenty of the mineral naturally from their normal diets. Yet, just in case, fluoride treatments are pretty routine where dental health care access is readily available, which might give a strong tooth development start, to help child.

When you brush your teeth, you are emerging your teeth in fluoride. This fluoride presence is well known to disrupt the metabolism the bacteria which cause cavities, through multiple specific metabolic mechanisms. Brushing with a fluoridated tooth paste is the most important modern tooth protection and it is very difficult to maintain without it with today's level of sugar consumption.

This means that those who preform proper hygiene, in developed countries with access to dental care and diverse nutritious food, get plenty of fluoride, without consuming purposely, but only naturally! If these are met, then it should currently be assumed that they would get no benefit, but only health and dental risk, from consuming fluoride put in their water supply.

This distinction is why we get conflicting options on fluoridating water. Water fluoridation is dangerous to us, but still a huge benefit to impoverished or less developed countries. It is probably still pushed heavily towards such countries as a cheap and easy benefit, with a large impact. So large, that it probably does hold a place with some of the most historically beneficial medical achievements of the 20th century, which continues to do so today... in other countries. This is probably comparable to the Polio vaccine, as we don't use the "oral" version of the Polio vaccine, because it is risky for vaccine derived Polio. Yet, those in charge think it is worth the risks and the oral Polio vaccine is so much cheaper and easy to transport compared to the kind of Polio vaccines we get, that it makes large humanitarian campaigns feasibly obtainable, to vaccinate impoverished populations and developing nations, with little health care access.

Some of the most recognizable studies showing the benefits of water fluoridation were from in Canada, just a few decades ago, but hygiene products and brushing techniques improved quite a big since then and likely became more generally used by the public (even if mostly thanks to TV marketing of dental hygiene product). Dental healthcare access likely expanded greatly since then, even in the short amount of time.