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Routine dental X-rays are not backed by evidenceβ€”experts want it to stop

By: Beth Mole
14 October 2024 at 19:11

Has your dentist ever told you that it's recommended to get routine dental X-rays every year? My (former) dentist's office did this yearβ€”in writing, even. And they claimed that the recommendation came from the American Dental Association.

It's a common refrain from dentists, but it's false. The American Dental Association does not recommend annual routine X-rays. And this is not new; it's been that way for well over a decade.

The association's guidelines from 2012 recommended that adults who don't have an increased risk of dental caries (myself included) need only bitewing X-rays of the back teeth every two to three years. Even people with a higher risk of caries can go as long as 18 months between bitewings. The guidelines also note that X-rays should not be preemptively used to look for problems: "Radiographic screening for the purpose of detecting disease before clinical examination should not be performed," the guidelines read. In other words, dentists are supposed to examine your teeth before they take any X-rays.

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Radiation should be able to deflect asteroids as large as 4 km across

24 September 2024 at 17:37
Image of a large, circular chamber covered filled with a lot of mechanical equipment, all of which is lit by blue internal glows and covered with massive, branching trails of lightning.

Enlarge / Sandia National Labs' Z machine in action. (credit: Randy Montoya)

The old joke about the dinosaurs going extinct because they didn't have a space program may be overselling the need for one. It turns out you can probably divert some of the more threatening asteroids with nothing more than the products of a nuclear weapons program. But it doesn't work the way you probably think it does.

Obviously, nuclear weapons are great at destroying things, so why not asteroids? That won't work because a lot of the damage that nukes generate comes from the blast wave as it propagates through the atmosphere. And the environment around asteroids is notably short on atmosphere, so blast waves won't happen. But you can still use a nuclear weapon's radiation to vaporize part of the asteroid's surface, creating a very temporary, very hot atmosphere on one side of the asteroid. This should create enough pressure to deflect the asteroid's orbit, potentially causing it to fly safely past Earth.

But will it work? Some scientists at Sandia National Lab have decided to tackle a very cool question with one of the cooler bits of hardware on Earth: the Z machine, which can create a pulse of X-rays bright enough to vaporize rock. They estimate that a nuclear weapon can probably impart enough force to deflect asteroids as large as 4 kilometers across.

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