The purpose of X-Rays
One of the most useful tools that I have in my office is an x-ray or a radiograph. Radiographs allow me to see things that I cannot see such as small cavities, bone defects under gums, or wisdom teeth that have not come out into the mouth. Radiographs combined with visual and tactile senses allow me to do a through exam to check the overall health of the mouth. Unfortunately x-rays get a bad rap because of bad science reporting on dental x-rays. However, dental x-rays are safe as the dosage of radiation is low. For this article to compare radiation levels received by dental x-rays, I will compare it to the average daily dose of radiation a person receives in South Louisiana which is as most of my readers know at sea level. The three types of x-rays that I use are intraoral, panoramic, and three dimensional x-rays. Each type gives me a specific type of information to make good recommendations for my patients.
Intraoral x-rays are the most common x-ray that is used in my office, and probably the type that most people are familiar. These are the x-rays where the dental assistant or the hygienist puts a small device or piece of film in your mouth, has you bite onto it, and then pushes a button. Thirty years ago, the most common type of intraoral x-ray was a film x-ray manufactured with Kodak technology and one exposure of that was the equivalent of 2 days of background radiation. In my office, I use a digital sensor because it uses much less radiation and is much easier to keep track of and to show my patients what I am doing. The dose from one of these x-rays is the equivalent of half a day of background radiation. Usually for a patient’s first visit where I need to do a full check on each tooth, I like to take 18 x-rays which is a full mouth set or FMX for short and this is the equivalent of 9 days of regular background radiation. The FMX is usually taken every 3 to 5 years depending on the health of the teeth and the patient’s history of oral disease such as cavities or gum disease. Also I will like to take sets of 4 intra oral x-rays at the regular cleaning check ups and this is a decent indicator of oral health. These images are called bitewings. For patients who get cavities regularly, I like to get bitewings every 6 months so that we can treat the cavity while it is small whereas if a patient has not had a cavity in the past 2 years, I like to take them once per year. By using digital technology, the biggest benefit of intraoral x-rays is comparing x-rays year after year to see what has changed and what has remained the same.
The next type of x-ray that I take often in my office is a panoramic x-ray or a pano for short. Pano’s are useful because they only take 10 seconds to take and they give me an image of the entire mouth. The patient stands in the x-ray unit, and bites down on a small piece of plastic that helps line the front teeth with the sensor. The x-ray unit rotates around the head completely getting a two dimensional image of the jaws and only uses about the equivalent of radiation exposure from one day. While I cannot see smaller cavities on a panoramic x-ray, I can see bigger cavities as well as the full roots of teeth which is needed if I have to extract a tooth. Pano’s are primarily used in children so that dentists can assess growing and make sure that all the teeth are coming in properly and in the correct order. I find these x-rays very useful as well when I have a patient who is unable to take the full series of intraoral x-rays either due to gagging or pain. Finally, I find these images useful when a new patient wants to talk about necessary treatment as I can help the patient formulate a great plan from having a good full view of the mouth.
The last type of x-ray that I use is a three dimensional x-ray or a CBCT which stands for cone beam computed tomography. CBCT’s are the newest type of dental x-ray though they have been out for around 20 years. The biggest issue with intraoral and panoramic x-rays are that they are 2D (i.e. flat) images of a 3D structure (the jaw). CBCT’s were originally developed and became popular as a way to plan implants as a good 3D image of the bone is needed to decided where and how to place an implant. With modern technology, I can take a CBCT and scan a stone model into my computer and merge the two. By doing this, I can plan out implants and decide how and where to place them exactly by using my 3D printer to make guides for the implant placement. These x-rays though have become more useful in root canals as it helps dentist find all of the nerve without having to take 2 or 3 intraoral x-rays. These images are also useful for braces as dentist can see where all the bone and teeth are and plan out tooth movement on a computer along with stone models. The amount of radiation exposure varies quite a bit with these machines with smaller images of 2 to 3 teeth being around half a day of exposure and images of both jaws and the joint might be 5 days of exposure.
X-rays are a critical part of dentistry and have made the diagnosing and treating of dental disease much more predictable. Taking a few low radiation dose x-rays on a routine basis can help prevent the dentist from needing to take more x-rays in the future as well as save money from fixing problems before they become larger. If you are in need of a complete exam to check for issues in your mouth, please call us at 504-392-5104 and we will help you out.