Can Dental X-Rays Show Cracked Teeth?
Since x-rays were discovered in 1895, they have progressively changed how dentists diagnose a variety of conditions, including cracked teeth. However, x-rays are not without limitations. Because an x-ray is a 2-dimensional picture of a 3-dimensional object, cracks may not be visible, depending on the angle at which the x-ray was taken, the size and location of the crack and the presence of existing dental work around the crack.
Tooth Cracks on Dental X-rays
A dental x-ray shows the three layers of a tooth. The outer layer of the tooth, the enamel, and the middle layer, the dentin, appear in various shades of light gray. The center of the tooth, the pulp, is home for the nerves and blood vessels. Pulp appears as a darker area on a dental x-ray. Existing dental work -- such as fillings and crowns -- appear light gray to white. A crack in a tooth appears as a dark line on an x-ray. However, existing dental work may block the crack from appearing on the image, especially if the dental work is metal or porcelain.
Cracks of the Tooth Crown
Dentists can often see cracks on the part of the tooth above the gum line -- the tooth crown -- when visually examining the mouth. When a large part of the tooth is cracked or broken off completely, a large dark area is seen on a dental x-ray. When the tooth is not broken off or chipped, a dark line is seen on an x-ray. This line may or may not appear, depending on the angle of the x-ray relative to the angle of the crack. If the crack does appear on an x-ray, the dentist will check to see if the crack involves only the enamel or has spread to the dentin and pulp. The depth of the crack affects the choice of treatment.
Cracks of the Tooth Root
A crack of the tooth root is harder to detect on a dental x-ray than a crack in the crown. If the x-ray was taken at an angle parallel with the crack in the root, the crack will appear as a dark, easily detected line. If not, the crack will appear as a poorly defined gray shadow. For the crack to show up on an x-ray, it may be necessary to get more than one x-ray of the area from different angles.
Vertical Root Cracks
Sometimes a tooth will crack lengthwise from the top of the tooth all the way to the bottom of the root. This is called a vertical root fracture. If the x-ray was angled just right, the crack may show up on an x-ray as a dark line. If not, the crack may not be visible on an x-ray unless an infection develops because of the crack. Infection appears on an x-ray as a dark circular shadow around the tip of the cracked tooth root.
- Modern Dental Assisting; Doni L. Bird and Debbie S. Robinson
- Radiology for Dental Auxiliaries, seventh edition; Herbert H. Frommer
- Oral Radiology Principles and Interpretation, second edition; Paul Goaz and Stuart White
Registered dental hygienist Tami Farmer is a graduate of the Medical College of Georgia with more than 25 years dental experience. She is currently working in a private practice in the suburbs of Atlanta. She also writes continuing education courses for dental professionals and has won awards for her dental health presentations.