What do I need to know about x-rays?

X-rays (actually called radiographs) are needed in dentistry to detect conditions that are not seen with the eyes. You might wonder why something that is not seen with the eyes could possibly be important. A cavity might be located between teeth and when it is small, it cannot be seen just by looking at the teeth. X-rays allow the dentist to find cavities between teeth when they are small. This early detection means less tooth structure has to be removed when the decay is removed. This is less time consuming for the patient as well as less costly. Early detection of problems is the best way to maximize the chance of successful treatment in all parts of medicine, and dentistry is no exception. X-rays also help to detect problems under the gums or in the bone where they cannot be seen until they become much more serious.

Health Canada has guidelines for helping the dentist to decide how often x-rays should be done, but ultimately that decision is made on an individual basis for each patient. Several factors help the dentist decide when to do x-rays. For detection of cavities, the dentist considers factors like how well the patient brushes his or her teeth. Does the patient floss, and if so, how often? What kind of exposure to sweets does the patient have? What medications is the patient using? Some medications reduce salivary flow which puts the teeth at a higher risk of decay. Researchers tell us that the most accurate predictor of decay in the next couple of years for a particular patient is how much decay has been encountered by that patient in the last couple of years. How much root exposure does the person have. Exposed roots are much more likely to decay than enamel covered parts of the tooth. For detection of bony problems, there are other factors to consider. As well, if the patient is experiencing pain, depending on what kind of pain, the dentist may need an x-ray to decide what is causing the pain. A problem cannot be treated until it is understood what the problem is and which tooth or other structure in the mouth is causing the pain.

As well, sometimes x-rays are needed to monitor growth. The body forms all if its teeth properly so much of the time that often people forget that there can be developmental problems like teeth that do not form (congenitally missing teeth). It is important for a dentist and a patient to know when a tooth is congenitally missing. Often when wisdom teeth are expected (usually in the late teenage years), a large x-ray that allows the dentist to see all of the lower face is done to see the position of the expected wisdom teeth. This allows planning for whether the particular mouth has enough room for the wisdom teeth or if and when they might need to be removed. This large x-ray (called a panoramic radiograph) cannot be used to detect small cavities because its level of sharpness is not nearly of the quality of the smaller x-rays. Again, x-rays are commonly used in dentistry for prevention of problems or for solving problems before they become much larger.

Radiation is to be minimized because too much radiation can by unhealthy. Radiation used for dental radiographs is small. In the late 1950’s, the radiation needed to expose a dental film was about 6 times what it is today. This large reduction in the radiation needed to expose a dental film has mostly to do with advances in film technology. In the last few years with the addition of digital x-ray equipment in some offices, radiation is only one tenth as high as it is to produce today’s film x ray. So, with the latest technology (digital or filmless technology), only 1/60 of the radiation is needed to produce a dental image now as compared to the late 1950’s. You might wonder why the person taking the x-ray always leaves the room when the energy is released. This is because there is a process whereby the dentist weighs the expected benefits of doing the x-ray against the risks of doing the x-ray. Since the person operating the x-ray machine will realize no benefit at all from having the x-ray done, he or she removes himself or herself from the x-ray beam.

Some people refuse recommended x-rays. This makes proper (timely) diagnosis of some problems in the mouth impossible. Many dentists will dismiss a patient from the practice if they will not accept recommended x-rays after explanation regarding the need for the x-rays being recommended is fully explained. Simply put, the long term maintenance of your teeth is compromised when needed x-rays are not done. Be sure to discuss the reasons for recommended x-rays with your dentist if you have a question about the usefulness of what is suggested.


This article was written by Dr. Mike Christensen and published in the Daily Miner and News, and Enterprise. Local Kenora News Publicatons (1998-2006)