Dental x-rays use either film or digital technology, which is becoming more common in dental offices. Other emerging technologies are also being explored. Cone beam CT (computed tomography) technology is one new method of radiography being used in dentistry for a variety of reasons.
Guidelines exist on the proper use of x-rays in dental care. They help dentists decide which patients need what kind of x-rays. The benefits of taking x-rays should outweigh the risks of exposure to radiation. As well, as few x-rays should be taken as possible so that exposure to radiation is minimal.
The need for x-rays depends on whether patients are at high or low risk for dental decay (cavities) and gum disease and whether their teeth have been filled or received root canal treatment. Age is another consideration. Children may have different dental x-ray needs than teenagers or adults.
X-rays can be useful when:
However, dental x-rays are not usually used to screen for dental disease.
The guidelines promote the safe use of radiographs. Minimal exposure to radiation is key. For this reason, using lead lined aprons and collars, faster dental film and digital radiography has been encouraged. All reduce the amount of radiation exposure to the patient.
The dentist decides which x-rays should be taken for each patient. The decision is based on a visual examination of the mouth. If dental disease is obvious, then a full series of x-rays can be taken within the mouth. These x-rays provide a significant amount of information. It is impossible to learn as much just bylooking at the mouth. If problems in the mouth are few or the patient is coming in for a six or 12 month check up, fewer x-rays are taken.
The most common x-rays done within the mouth are called bitewing x-rays. They look for cavities between teeth. They also check bone levels around teeth to assess gum disease. The decision to use these x-rays is based on the patient’s risk of developing cavities between the teeth. If the risk is low, x-rays will be takenlessoften. Bitewing x-rays are taken by placing dental film inside the mouth, next to the teeth.
Periapical or root end x-rays are taken when the entire tooth or teeth in question needs to be seen. These are often done to check teeth that have large fillings, crowns, or root canal treatment. Pain or swelling associated with the teeth may be another reason for taking x-rays. These x-rays can help find infection and check bone levels around the teeth. Root end x-rays are taken by placing dental film inside the mouth next to the tooth or teeth in question.
Another type is the panoramic x-ray, which is taken outside of the mouth. It provides a great deal of information regarding the teeth, surrounding bone and the upper and lower jaws. It also shows the structures of the lower and middle aspects of the face. A panoramic x-ray can help show the position of wisdom teeth. It can reveal problems such as cysts or tumours in the jaws. The position and eruption of children’s teeth can also be checked.
However, it is not as accurate as bitewing and root end x-rays in checking for cavities or gum disease.
Cephalometric x-rays, used for orthodontic assessment, show a side view of the head and jaws. These are useful in determining a patient’s stage of development and predicting growth.
Digital dental radiography has become more popular in the last ten years. Many dentists have switched from film to digital radiography. Instead of looking at x-rays on a viewing box, images appear on a computer screen. X-rays can be seen almost immediately after they have been taken. This helps patients understand their situation and treatment options. As well, much less radiation is involved in taking digital x-rays compared to film.
Digital radiography allows for magnification, enhancement, and other manipulation of images. Less time is required to send the x-ray to other dental offices or for insurance purposes. With digital radiography, there is no need for the chemicals and equipment used in film developing. Finally, digital radiography allows for better record keeping, as these x-rays are stored electronically.
Cone beam CT (computed tomography) x-rays are proving useful to dentists. This technology is relatively new in dentistry, having emerged over the past five years.
Computed tomography takes x-rays that show thin sections of the body. For dental purposes, the thin slice images are taken of jaws, teeth and supporting structures.
Computed tomography shows a three dimensional view. Previously with conventional x-ray technology, only two-dimensional images were possible. This technology is mainly used in radiology centres, orthodontic and oral surgery offices.
The amount of radiation used for cone beam CT x-ray images is significantly less than that used in conventional CT imaging. However, it does require more radiation than bitewing, root end or panoramic x-rays. In addition, the clarity and detail of cone beam CT x-rays are not as good as x-rays done within the mouth. For this reason, cone beam CT x-rays are not used to diagnose cavities or gum disease. However, improvements are expected over the next several years.
New advances in dental radiography are gaining popularity. However, traditional dental x-rays are still more common. Dental x-rays should be taken only when needed to keep exposure to radiation low as possible. On the other hand, x-rays can provide significant information to prevent, diagnose and treat dental disease. Digital radiography will most likely take over in dentistry just as it has in medicine.