How do you Read X-rays?

An X-ray is an image made up of several white, grey and black overlapping shadows. The image that you see, depends on how many X-rays are able to pass through and hit the film, the more dense objects (e.g. metal) let fewer beams pass through and the whiter the image appears in that area.

A whiter area is known in dentist speak as a ‘radiopaque’ area. Blacker areas on the film have not stopped any X-rays (e.g. air) and these areas are known as ‘radiolucent’. If the image is grey, then some of the X-rays but not all, passed through. Of course X-rays are not just white, black and grey but a spectrum of shades (depending on how many X-rays pass through) that go to form the image.

This is important to know as the dentist may refer to the area as 'an area of darkness' but will often forget he is talking to a patient and not a radiologist and say “I can see a periapical radiolucency associated with that tooth”, meaning, ‘I can see an area of darkness around the end of that tooth,’ indicating infection into the nerve, a classic sign that the tooth needs root canal or to be extracted.

The darkness of the image is also affected by the strength of the X-ray beam itself, the type of film used and the way in which the X-ray is developed. All these aspects are controlled by the dentist to ensure a clear and accurate picture of the area in question (as always, at the lowest possible dose).

How does the Dentist Read X-rays?

I think it is important to explain to my patients exactly what it is that I am looking for and I point out anything of note or that may be of interest along the way.

When I show a patient something on an X-ray, their first reaction is to say something like, “How the heck did you see that?” Dentists of course are trained to spot even tiny abnormalities- it all starts with knowing what you are looking for and very importantly where to look! We will go over some of the more common things in the next few articles to give you a good idea- I know if I was having treatment I would be interested in exactly what was going on in my mouth and why!

When looking at traditional X-rays it is important to have an X-ray viewer to display the film on. This bright light allows the X-rays to be seen clearly and to be properly assessed. Sometimes magnification can also be a great help to make sure you don’t miss anything and I will often use my dental loupes with magnification for just this purpose. If your dentist uses digital X-ray technology, this isn't necessary. The the image will be displayed on the computer screen for you to see and you have the advantage of being able to change the contrast, zoom in and manipulate the image to aid the diagnosis or help explain the treatment.