Teeth and bone are very dense, so they absorb X-rays, but gums and cheeks are much less dense, so X-rays pass through more easily. That’s why cheeks and gums appear dark and without detail on the x-ray film, but teeth show up much lighter. And fillings, which are even denser than bone, will show up as a solid, bright white area. Dental caries (cavities) will show up on an X-ray as a darker patch in a light tooth.
Dental X-ray images are among the most valuable tools a dentist has for keeping your mouth and teeth healthy. By understanding what the structures of the mouth look like normally on an X-ray film, dentists can diagnose problems in the teeth and jaws.
- Show areas of decay that your dentist may not be able to see with just a visual examination, such as tiny pits of decay that might occur between teeth
- Find decay that is developing underneath an existing filling
- Find cracks or other damage in an existing filling
- Alert the dentist to possible bone loss associated with periodontal (gum) disease
- Reveal problems in the root canal such as infection or death of the nerve.
- Help your dentist plan, prepare and place tooth implants, orthodontic treatments, dentures or other dental work
- Reveal other abnormalities such as cysts, cancer and changes associated with metabolic and systemic diseases (such as Paget’s disease and lymphoma)
- For children, radiographs are used to watch for decay and to monitor tooth growth and development. Dentists will use periodic X-rays to see whether a space in the mouth to fit all the new teeth, whether primary teeth are being lost quickly enough to allow permanent teeth to erupt properly, whether extra (supernumerary) teeth are developing or whether any teeth are impacted (unable to emerge through the gums). Often, major problems can be prevented by catching small developmental problems early and then making accommodations.
How Often Should Your Teeth Be X-rayed?
Even though no X-ray can be considered routine, many people require X-rays on a regular basis so that their dental condition can be monitored. Exactly how often this happens will depend on your medical and dental history and current condition.
Who needs more frequent or regular radiographs? They include:
- Children – Children need X-rays every six months because they are highly likely to develop decay. X-rays also help monitor tooth development.
- Adults with extensive restoration work, including fillings – All the conditions that helped create the caries to begin with continue, making it necessary to check for decay beneath existing fillings or in new locations.
- Anyone who drinks sugary sodas, chocolate milk or coffee or tea with sugar – Even mildly sugary beverages create an environment in the mouth that’s perfect for decay, so anyone who drinks these beverages regularly will need to have more regular X-rays.
- People with periodontal (gum) disease – Periodontal treatments may need to be stepped up if there are significant or continuing signs of bone loss.
- People who are taking medications that lead to dry mouth, also called xerostomia – Saliva helps keep the acid levels (pH) in the mouth stable. In a dry mouth, the pH decreases, causing the minerals in the teeth to break down, leaving them prone to caries. Medications that can decrease saliva are those prescribed for hypertension, antidepressants, antianxiety drugs, antihistamines, diuretics, narcotics, anticonvulsants and anticholinergics.
- People who have dry mouth because of disease, such as Sjögren’s syndrome, or because of medical treatments that damaged the salivary glands, such as radiation to the head and neck for cancer treatment.
- Smokers, because smoking increases the risk of gum disease and oral cancer.