X-rays, also known as radiographs which are an essential part of any dental care treatment plan. They are diagnostic, but they can also be preventative, by helping a dentist diagnose potential oral care issues in a patient’s mouth before they become a major problem. An x-ray is a type of energy that passes through soft tissues and is absorbed by dense tissue. Teeth and bone are very dense, so they absorb X-rays and appear white where as in gums and cheeks X-rays pass more easily through it and appear black.
X-rays are divided into two main categories
- Intraoral.
- Extraoral.
Intraoral is an X-ray that is taken inside the mouth. An extraoral X-ray is taken outside of the mouth. Intraoral X-rays are the most common type of radiograph taken in dentistry. They give a high level of detail of the tooth, bone and supporting tissues of the mouth.
These X-rays allow dentists to:
- localisation of the cavities and to know the extent of the cavity
- Look at the anatomy of roots and crown before removing an impacted tooth.
- Check the health of the bony area around the tooth
- Determine if periodontal disease is an oral care issue
- See the status of developing teeth
- Otherwise, monitor good tooth health through prevention
- To know the extent of the lesions which involve the bone.
- During endodontic therapies
- Determine if unerupted teeth are missing
- Determine how many teeth are present in the mouth
- Diagnostic x-ray
- See if familial dental anomalies are present
- Find cavities between and on the teeth
- Check on previous endodontic treatments
- Determine the cause of oral swelling
- Evaluate injuries to the teeth after trauma.
Intra oral radiographs
Intraoral X-rays are the most common type. They give a high level of detail. The various types of intraoral X-rays show different aspects of the teeth:
1.Bite-wing X-rays (right) highlight the crowns of the back teeth. Dentists take one or two bite-wing X-rays on each side of the mouth. Each X-ray shows the upper and lower molars (back teeth) and bicuspids (teeth in front of the molars). These X-rays are called "bite-wings" because you bite down on a wing-shaped device that holds the film in place while the X-ray is taken. These X-rays help dentists find decay between back teeth.
2. Periapical X-rays highlight only one or two teeth at a time. A periapical X-ray looks similar to a bite-wing X-ray. However, it shows the entire length of each tooth, from crown to root.Depending on your oral health and dental history your dentist may recommend a full-mouth radiographic surveya, or FMX. This includes every tooth, from crown to root to supporting structures. They are X-rayed using both bitewing and periapical radiographs.
3 .Occlusal X-rays (right) are larger than most X-rays. They highlight tooth development and placement in children. Each X-ray shows nearly the full arch of teeth in either the upper or lower jaw
Extra oral radiographs
Extraoral X-rays are less detailed than intraoral X-rays. For this reason, they are usually not used for detecting cavities or flaws in individual teeth. Most commonly used extraoral radiographs re
1.Panoramic X-raysshow the entire mouth on a single X-ray. They include all teeth on both upper and lower jaws. This type of X-ray requires a special machine. The tube head that emits the X-rays circles behind your head while the film circles across the front. That way, the full, broad view of the jaws is captured on one film. Because the machine moves in a set path, you have to be positioned carefully. Devices attached to the X-ray machine hold your head and jaw in place. All this may look and feel intimidating, but the process is very safe. It often uses less radiation than intraoral X-rays.
2. Cephalometric projectionsare X-rays taken of the entire side of the head. They are used to look at the teeth in relation to the jaw and the person's profile. Orthodontists use cephalometric projections to determine the best type of orthodontic treatment.
3. Cone-beam computed tomography (CT) provides three-dimensional images. You stand or sit while the machine rotates around your head. The beam is cone-shaped, instead of fan-shaped as in a standard medical CT. A cone-beam scan uses less radiation than a medical CT scan but far more than any standard dental X-ray. The cone-beam CT is particularly useful for dental implant selection and placement.
4.Standard computed tomography (CT) usually must be done in a radiologist's office or a hospital. Typically, you will lie down while the image is taken. The radiation exposure is higher for this type of CT than for a cone-beam CT. A standard CT scan may be done to determine size and placement location for implants.
Digital Radiographs
Digital radiographs are one of the newest X-ray techniques. Standard X-ray film is replaced with a flat electronic pad or sensor. The image goes into a computer, where it can be viewed on a screen, stored or printed out. Digital X-rays taken at different times can be compared using a process that highlights differences between the images. Tiny changes therefore can be caught earlier. Used properly, digital X-rays use about half the radiation of conventional film.
'How often X-rays should be exposed
Many people require regular X-rays to keep track of their oral health. How often should X-rays be done? The answer depends on your medical and dental history and the current condition of your mouth. Some people may need X-rays as often as every six months. People who visit the dentist regularly and have excellent oral health may need X-rays only every three years or so.
To see how often you or your family members might need X-rays, check out this chart. It is based on information from the American Dental Association and the U.S. Food and Drug Administration.
Who needs more frequent or regular X-rays?
- Children and teenagers — Children and teens who have a history of many cavities may need X-rays every six months or every year, depending on age. So may those who have a high risk of decay for other reasons. X-rays also help to keep track of tooth development.
- Adults with many fillings, crowns, bridges or other restorations — X-rays help the dentist find decay beneath your fillings and crowns or in new places.
- People with periodontal (gum) disease — X-rays can reveal signs of bone loss. If this has happened, then you may need periodontal (gum) surgery.
- People with dry mouth, also called xerostomia —Saliva helps keep your mouth and teeth healthy by regulating the acid levels (pH) in the mouth. In a dry mouth, the pH decreases. This causes the minerals in the teeth to break down, resulting in more cavities. Many medicines can cause dry mouth. It also can be a result of cancer treatment or a long-term disease.
- Smokers — Smoking increases the risk of bone loss around the teeth and periodontal disease.
- Users of chewing tobacco — Chewing tobacco is sweetened with sugars and can lead to more cavities.
X-ray Safety
For children
Since X-rays expose children to radiation, many parents are worried about the risk of conditions like cancer. The American Academy of Pediatric Dentistry reassures parents that the amount of radiation that's received during a dental X-ray is extremely small. Today's X-ray equipment lets dentists focus the X-ray beam on the area of interest to reduce radiation exposure. Protective equipment like lead body aprons and shields also keep your child safe during their procedure.Since children with a low risk of tooth decay don't need X-rays as often, practicing good oral hygiene at home can help minimize the need for X-rays. X-rays for children have many important uses. If you're concerned about X-rays, consider your child's dentist's advice can be compared using a process that highlights differences between the images. Tiny changes therefore can be caught earlier. Used properly, digital X-rays use about half the radiation of conventional film.