In general, all medical/dental procedures (and really, anything we do) carry both risks and benefits. The internet and media generally focus on the risks of radiation, but the substantial benefits are often ignored.
The government considers the risk associated with a yearly radiation dose limit of 50,000 µSv for a radiation worker to be acceptable. That amount of radiation is comparable to 25 head CTs = 2,500 cross country flights = 100 months of background radiation = 250,000 dental x-rays = 500,000 bananas. The following is an infographic that depicts the relative amount of radiation found in certain everyday activities. Each icon depicts 0.1 µSv of radiation.
One of the most common questions I get as a dentist for kids is, “Are x-rays necessary?” I usually give an answer that explains that it allows us to see if there is a cavity between the teeth and how big the cavity is. This article is meant to clarify that answer with some photos so you can see what I mean!
Now, this is not to say that every good looking tooth is going to have an area of large decay (most don’t). But, it helps to show why, even when the teeth appear to be in good health, we will sometimes ask for x-rays.
PS, We usually will take x-rays every 1 year because that is about how long it takes for the average cavity to develop.