I recently had someone ask me to evaluate an x-ray taken by another dentist. As you can see (in the image posted below), there’s clearly an amalgam filling (the bright white spot). You can also clearly see the cavity just to the left of the filling. What you can’t clearly see is what decay is developing below the mercury filling. That’s one of the problems with traditional x-rays.
You can’t see small decay on radiographs. By the time you see it (as with the decay in this particular image), the decay is large. X-rays really only see minerals, so only when the tooth has been decayed to the point there are no minerals, then the x-rays will look different. Waiting until that happens results in more pain and possible extractions (or root canals if you go to a dentist that believes in those).
CT Scans will more clearly show decay under the filling and other small areas of decay (and the patient isn’t exposed to the large quantities of radiation an x-ray produces).
However, based on the decay next to the amalgam filling, and because decay under a poorly placed amalgam filling is very common, there is an above average chance that there is currently decay under the filling, as well.
What else can this one image tell us? Because there’s a large cavity in the tooth beside the silver filling, the patient probably has a diet that is conducive to decay (acidic carb diet). To reduce the chances of future decay, changing to a diet that’s lower in acid (water such as Essentia can help: Essentia Water Review), rinsing your mouth regularly after eating, and adhering to a proper dental care regimen can make a world of difference.
PS: Thanks to the patient for allowing me to reprint this image and show a good example of decay around an amalgam filling. If you have particular questions about the x-ray, please leave a comment and I’ll do my best to get you a good answer.