Ask The Experts: Getting the Right Bitewing
- Victoria Romans
- Oct 23, 2012
Ask The Experts: How do I get the right bitewing with the wingers?
From your question, I’m assuming that the winger is some type of bite tab attached to your film or sensor. I’m also interpreting the question “how to get the right bitewing” as how do I take it correctly to get a great image with no overlap, since overlapping crowns is the major error of concern on a bitewing.
Poor bitewing images usually have overlapped crowns so you are not able to see the interproximal spaces clearly. This seems to be the most common problem in most dental offices because the assistant does not understand its cause. And it is a very simple fix.
So what actually causes overlapping? Answer: Incorrect horizontal x-ray beam. The x-ray beam must be directed at the patient’s teeth so that the x-ray (cone) is perpendicular or at a right angle to the buccal surface. X-rays travel in a straight line, so as they exit the cone, they must hit the teeth at a right angle. If the cone is aiming slightly distal to mesial, or mesial to distal and not perpendicular, overlapping will occur. If the x-ray beam is not perpendicular, the x-ray beam will superimpose part of one tooth over the adjacent tooth so the contact is not visible. Correcting the horizontal tube angle, even slightly will correct this. If you are using some type of bite tabs with no aiming rings, you must set this angle correctly yourself. You must look at the shape of the patient’s dental prior to placement of the cone.
Every patient has a different shaped arch, either u-shaped v-shaped, or square-shaped. This shape will determine how you will place the cone so the x-rays (which travel in a straight line) will hit the teeth at a right angle. If correct horizontal tube angle, no overlap will occur.
The video “How to Do Bisecting Angle” has a great section on taking bitewing with bite tabs. It is toward the end on that video. I recommend viewing it.
For those of you using Dentsply-Rinn aiming rings, The FILM placement must be positioned parallel to the teeth. This will position the bar and aiming ring perpendicular to the teeth, promoting correct horizontal cone placement.
So in summary, remember it is incorrect horizontal x-ray beam that cause overlapping. By changing it ever so slightly can improve your bitewing radiograph. Hope this answers your question.