I'm going to also throw anecdotes into the bucket: three dentists completely missed a cavity on one of my rear molars (wisdom teeth) until I mentioned pain, and then they poked around physically and said, "oh yeah, that's a big one."
What kind of dental x-rays they took? Panoramic (shows the whole row of teeth in one image), CBCT (volumetric 3D) or intraoral (a digital sensor or film was put inside your mouth)?
Not OP, but I have only ever had the type of dental x-ray where they stick the L-shaped plastic into your mouth and make your bite down while they take photos. I had no idea there were others.
The original machine I used looked like a TSA body scanner but for your head. Somehow it hit plates that were developed into an image the dentist could present to me.