Journal, Explainers
How to read your own X-ray
Bright means dense, dark means missing. Once you know those two rules you can follow most of what your dentist is looking at.
You are entitled to look at your own radiographs, and you will get more out of an appointment if you do. Two rules get you most of the way.
Rule one: bright means dense
X-rays pass through soft material and are stopped by hard material. Anything that blocks them appears white. So enamel is the brightest thing in your mouth, dentine is a shade greyer, and the pulp chamber down the middle of each tooth is darker still because it is soft tissue.
Metal is brilliant white with hard edges, old amalgam fillings, posts, implant fixtures. Modern composite fillings are a soft grey and can be genuinely hard to spot, which is why we photograph as well as scan.
Rule two: dark means missing
Decay reads as a dark shadow inside a bright tooth, because the mineral has gone. On a bitewing view they usually appear as small dark notches at the contact points between teeth, the places a toothbrush cannot reach.
The same logic applies to bone. A dark halo around a root tip usually means infection has dissolved bone there. A bone level that has receded away from the crown means periodontal loss. Both are dark because something that used to be dense is not there any more.
A useful habit: ask to see last year’s film beside this year’s. Almost nothing in dentistry is alarming in a single image. Change over time is the signal.
What a panoramic view is for
The wide, curved image that shows the whole jaw is excellent for surveying, wisdom teeth, sinuses, jaw joints, anything unexpected. It is poor for detecting early decay, because everything is slightly blurred and overlapped. If someone tells you your teeth are decay-free based on a panoramic alone, that is not enough information.
On dose
A full digital series here is roughly the background radiation you absorb on a long flight. That is not zero, which is why we take them at intervals set by your actual risk rather than on a fixed schedule. If your last set was somewhere else and is recent, send it, we would rather read theirs than repeat ours.
Written by the clinical team at Roanlight Dental. General information only. It is not a substitute for an examination. Call (503) 555-0118 if something hurts.
