Dentists use two main methods of examination to assess dental and oral health - clinical examination and radiographic examination.
Clinical examination or evaluation entails visually examining all aspects of your mouth: teeth, gums, tongue and palate (roof of your mouth). During this evaluation, a dentist may ask you to close or clench your teeth together to see how your teeth connect with each other. A dentist may also ask you to bite down on something, gently tap your tooth or teeth with an instrument (percussion), or put gentle pressure on an area(palpation). All these are tests to see what kind of reaction is elicited. Depending on the type of reaction, the dentist can devise a plausible explanation for the reaction and/or other symptoms the patient may be experiencing.
This hypothesis is then verified with the taking of X-rays or radiographs. Depending on the type of dentist you visit - each one has his or her own specialty - you may have several different X-rays taken. Each type of X-ray is meant to help a dentist or dental specialist visualize the various structures underneath the gum line and inside tooth structures - the kinds of things you can't see on visual examination alone.
Below is a list of commonly used X-rays and their role in helping the dentist and/or dental specialist assess you for treatment.
1) Panorex or Panoramic X-ray - As the name implies, this is a wide-view picture of your mouth. The X-ray machine will start on one side and cycle around your face to the other side, taking a continual wide-screen picture from one temporomandibular joint to the other. This X-ray is very helpful in determining the position of wisdom teeth, the health and quality of bone and position of nerves in the lower jaw. A Panorex will also show all teeth present, including those that are unerupted or impacted. A Panorex of a child will look quite chaotic because there are the adult teeth "hiding" above the present baby teeth.This X-ray will also show the position and placement of tooth roots.
2) Periapical X-ray (P.A.) - This type of X-ray provides dentists with a close-up view of any particular tooth or teeth. If an area of tooth decay or other concern is indicated on a Panorex, usually a periapical will be taken next to confirm the structures of the area in question. Next to the Panorex, the P.A. X-ray is the most commonly used radiograph.
3) Bitewing - Bitewings are so called because the wing-shaped film is held in place by biting down. Like P.A. X-rays, bitewings take detailed pictures of specific teeth. Bitewings are helpful in examining areas between teeth, including bone quality, quantity and cavities.
4) Occlusal - This type of X-ray is usually only used for children between the ages of 3 and 8. This X-ray provides a view of the entire upper or lower jaw. It helps dentists visualize how the adult teeth are developing and how they are likely to erupt.
5) Cephalometric - This type of X-ray is commonly used by orthodontists and oral surgeons when deciding a treatment plan that involves moving the teeth or jaws. This film is a "side view," or profile of your head. It allows dentists and oral surgeons to see the position of the teeth in a biting position, and examine the health of the temporomandibular joint as well. This X-ray helps them determine where they should target their movement treatment and address any profile issues that will happen as a result of jaw or tooth movement.
6) Digital X-rays - Many of the above X-rays require the use of films and X-ray machines. With the advances of the 21st century, many dental offices are now taking advantage of digital X-rays, for which there is no X-ray radiation or plastic films involved. Digital X-rays are stored in a computer with the patient's file and can be brought up on a screen at a moment's notice for evaluation. This option also helps minimize the amount of space required to file standard X-rays.
7) Cone Beam CT scan - This particular scan has become especially useful in evaluating the roots of teeth and may be recommended by an endodontist (root canal specialist) if the patient is experiencing pain following a root canal procedure. The C.B. CT will show the endodontist if there were any roots left untreated during the procedure and allows them to study the shape of those roots. Some roots can converge or meet another root and others curve, making successful root canal treatment tricky.
Many people have raised concerns over the amount of radiation that is used to take standard dental X-rays (not including the digital X-rays and the CT scan). There has never been a reported case of illness developing because of the radiation associated with dental X-rays. In fact, the amount of radiation used in the taking of dental X-rays is one-twentieth of the standard medical scans.