Intraoral radiographs

( 1 ) PERIAPICAL  Xray shows the entire tooth, including the root and surrounding bone and is useful in diagnosing an abscess, impacted tooth or bone loss due to periodontal disease. On each radiograph, the teeth from either the upper or lower jaw in one portion of the mouth are shown.

( 2 ) BITEWING  X-rays highlight the crowns of the teeth. On each radiograph, the upper and lower teeth in one portion of the mouth are shown, from the crown to about the level of the jaw. These require patients to hold or bite down on a piece of plastic with X-ray film in the center. Bitewing X-rays typically determine the presence of decay in between teeth, while periapical X-rays show root structure, bone levels, cysts and abscesses.They are also used to help diagnose cavities between the teeth, as these areas are not visible when looking directly in the mouth.

Periodically, a dentist may recommend a "full-mouth radiographic survey," or FMX. This means that every tooth, from crown to root to supporting structures, will be X-rayed using both bitewing and periapical radiographs.(See photo below). An FMX may be made if you are visiting a new dentist for the first time, or if no recent radiographs are available and the patient's overall dental health needs to be assessed.

FMX - Periapical & Bitewing Xrays

( 3 ) OCCLUSAL  X-rays are larger and highlight tooth development and placement. On each radiograph, nearly the full arch of teeth in either the upper or lower jaw is shown. These X-rays are taken with the X-ray machine either pointing straight down from near the nose (to take pictures of the upper jaw and teeth), or straight up from under the chin (to take pictures of the lower jaw and teeth).

Extraoral radiographs

Extraoral X-rays are made with the film outside the mouth. These can be considered the "big picture" X-rays. They show teeth, but their main focus is on the jaw or skull. Extraoral radiographs are used for monitoring growth and development, looking at the status of impacted teeth, examining the relationships between teeth and jaws and examining the temporomandibular joint or other bones of the face. Extraoral X-rays are less detailed than intraoral X-rays, so they are not used for detecting caries or flaws in individual teeth.

( 1 ) PANORAMIC RADIOGRAPHS (OPG)  show the entire mouth area — all teeth on both upper and lower jaws — on a single X-ray. This type of X-ray requires a special panoramic X-ray machine. What happens is that the tube head that emits the X-rays circles behind the patient's head, while the film simultaneously 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, the patient has to be positioned very carefully. And, because the beam and the film are both moving, any movement from the patient will blur the image on the screen. That's why such care is taken to keep the patient's head absolutely still in exactly the right position. The machines may have chin rests, forehead rests, and side head positioners, plus bite-blocks that patients will be asked to close their teeth around. All this may look and feel intimidating, but the process is very safe and often uses less radiation than intraoral radiographs. They are a good screening tool and used extensively for pre-orthodontic assessment of bone,to visualize impacted wisdom teeth (It is difficult to take an intraoral Xray of this area) as well as in pre-implant surgery bone height assessment. They show any abnormal growths or cysts in the jaw bone.

An OPG

( 2 ) TOMOGRAMS  are a special type of radiograph in which the dentist can focus in on one particular layer, or slice, of anatomy while blurring out all other layers. This allows dentists to see structures that may be difficult to see with standard X-rays. For example, the temporomandibular joint can be difficult to see. The condyle that makes up part of the joint is in the middle of a dense cranial base, so it is extremely difficult to X-ray. But by using a tomography technique called a temporomandibular joint projection, a straight "slice" that's lined up with the condyle shows that area more clearly.

( 3 ) CEPHALOMETRIC   projections are 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 profile of the individual. Orthodontists use cephalometric projections to plan their treatments. They will look at the entire face to determine the best way to get the teeth aligned in the right way for that particular person, according to the size of their teeth and jaws.

( 4 ) LATERAL-OBLIQUE:  To get a good view of the Temporo mandibular joint, a special kind of extra-oral Xray called the Lateral Oblique Xray might be required.This is generally not done at the dental clinic but with the radiologist on the dentist's recommendation.

Lateral Oblique Xray

( 5 ) COMPUTED TOMOGRAPHY  or CT scanning, usually is performed in a hospital, not the dentist's office, although a dentist may refer a patient for this test. With this process, the patient lies still in the CT machine while the X-ray beam rotates around. From the X-ray information, a computer creates a three-dimensional image of the interior structures. It is used to identify problems in the bones of the face, such as tumors or fractures.

SIALOGRAPHY  is a way of visualizing the salivary glands on a radiograph. Soft tissues, like gums and salivary glands, can't usually be seen on an X-ray because they are not dense enough to absorb enough X-rays to appear clearly on film. With sialography, the dentist injects a radiopaque contrast material directly into the salivary glands. This material shows up easily on film, allowing dentists to diagnose salivary gland problems, such as blockages or Sjögren's disease.