if its in the US, its probably that once you have the machine, and the tech, the cost of time and materials is probably less than 5 dollars, but they can bill the insurance $50-100. So they do it as often as they can, which under most insurance is covered one or twice a year. I could imagine it helping plan treatment for cavities, but for scaling? I doubt it...

They can feel cavities with their scaling tools. That's like half the reason why they train in school. They don't need a damn x-ray to do that. And they all say "We will not continue unless we do an x-ray" which just floors me. How is shooting x-rays in my skull even remotely healthy for my brain? I get we can tolerate x-rays, but jesus every damn time I switch dental practices or minimum once per year?