The dentist’s job is to detect and treat problems in the mouth which may include disease such as caries (tooth decay) or periodontal (gum) disease, as well as problems such as cysts or tumors – which occur less frequently but can be serious when they do.
The first-line diagnostic tool is the dentist’s own eyes and he will examine the patient’s mouth in the light of experience looking for tell-tale signs of problems, such as white or brown patches on teeth which could mean decay is present, or for red and swollen gums indicating periodontal disease. The use of a dental probe helps detect minute cavities and softened areas of tooth surface whilst transillumination (shining a light through teeth) is sometimes another helpful diagnostic tool.
The Need For Dental Radiography
It is not always possible, however, to see decay present in inaccessible areas of the teeth. So the invention of radiography or use of X-rays in order to “see” through hard tooth tissue has been of immense importance in improving the early detection of dental decay. Where decay is present in a tooth it eats away at the tooth substance, first the enamel layer and then dentine, causing these to become less dense and therefore able to allow X-rays to pass through more easily.
It is these areas of relative radiolucency that show up the presence of cavities, and the earlier it can be spotted the less damage will have taken place and the easier it is to restore the tooth.
On an radiograph, the denser areas such as the teeth will show up white whilst less dense parts or spaces will appear darker.
Thus the use of dental x-rays is an essential, part of the diagnostic process and can detect hidden dental abnormalities such as;
- decay in between teeth or under old fillings,
- unerupted misplaced or extra teeth,
- root resorption,
- tooth fractures, or
- bone loss from between teeth.
The dentist’s knowledge enables him to examine X-rays and pinpoint problems which otherwise might have gone unnoticed. From this information he is able to draw up a plan of treatment which might be relatively simple or might involve complex sequential treatment for teeth, gums, or the jaw.
So, Who Needs X-rays?
X-rays can be used to identify a problem, such as pain – In which case the symptoms determine their need and timing. They are also used as a matter of occasional routine and prior to certain treatments.
‘Routine’ radiographs are taken to identify any problems BEFORE they are visible to the dentist’s eyes. How often these are taken depends on the requirements for each individual and is to an extent a matter of judgement.
Where patients include children who are prone to dental caries it may be prudent to take bitewing X-rays every six months to enable early treatment of decay between teeth where it commonly occurs. In the older patient it may be adequate to take a comprehensive set of radiographs at the first examination and then only certain follow-ups later as and when deemed necessary. It is a case of weighing up the patient’s past history, signs and symptoms, age, and risk of disease.
Radiographs are essential for orthodontists, since they need to ascertain the positions of teeth developing within the jaws. This is to enable them to work out the necessary tooth movements needed to straighten and align teeth.
Other examples of the role of X-rays in dental treatment include:
- In root canal treatment – X-rays are used to determine the length of the roots, to enable the dentist to clean and fill them to this required length. Radiographs are also used to check the final treatment.
- Prior to implant treatment to determine, amongst other things, the amount of available bone tissue.
- Prior to wisdom tooth extraction, for example to identify any complicating factors.
- Before crown or bridge work to help ensure the health of the anchoring teeth.
As they represent a 3D object on a 2D image, X-rays are far from perfect, and have several downsides in terms of diagnostic capabilities. The future will lie with more 3D imaging technology. But these are currently impractical for most day-to-day dental needs. So for now, X-rays offer the best imaging option for the majority of dentists and patients.
Types of Dental Radiographs
The most commonly used ones are:
- “Bitewings” – These are used to check the crowns of your back teeth, primarily to identify any decay.
- “Peri-apical” – This takes in the full length of a few teeth. Thus they can be used to diagnose problems along the root and and the tips of the teeth.
- “Panoramic” dental radiographs give a wider view of the whole jaw. They are useful for orthodontic and implant planning, but less so for spotting decay.
Safety of X-rays
There are understandable concerns for health regarding X-rays which are ionizing radiation and can damage body cells. It is all a matter of degree however, and the benefits from diagnostic X-rays far outweigh any potential risk since the dose is so small.
There is a natural background radiation in our environment to which we are all exposed anyway, and dental X-rays add very little extra exposure, especially when digital. The exposure is so small that X-rays can be taken during pregnancy when necessary.
As radiation effects on the body are cumulative, however, it is essential to minimize exposure. Dentists take great care to do this by using minimal doses, only taking them when needed and using up-to-date films and machinery (which emits much lower radiation).
Digital versus traditional X-rays
The traditional type of X-ray or radiograph uses a film suitably positioned to receive the X-rays just like the film in a camera. The film has to be processed using chemicals in order to fix the image for viewing. The more recent introduction of digital radiography, however, uses an electronic sensor to capture the information after X-rays are passed through the teeth or jaws, and then this is decoded and presented on a screen by a computer.
Just as digital photography has largely replaced the traditional use of film for taking family snapshots, so digital radiography is generally superseding the use of traditional X-ray films.
The advantages of digitals are that the picture is available almost immediately without the need to wait for films to be developed, and in addition that the exposure times are generally much shorter producing less exposure for the patient. Digital X-rays demand only about 80% of the dose that would be necessary with traditional types of radiography, making them very safe indeed. The images produced can sometimes be enhanced or manipulated to provide the maximum diagnostic benefit.
Also, since there is no need to develop films, the need to dispose of potentially harmful chemicals is avoided.
The procedure for taking digital x-rays is similar to the traditional one, but a computer analyses and displays the image on a screen and a hard copy can be printed out.
Digital radiography may not be suitable for very young children since the sensor apparatus may be too bulky, but in such cases a very sensitive film is used to limit the X-ray dose to the absolute minimum.
Modern X-ray procedures involve only a very minimal health risk in themselves and allow dentists to pick up on a whole range of problems that can affect the mouth and jaws, often well before the problem would otherwise become apparent.
This means that early treatment can be instigated with much greater chances of success and the need for less in the way of heroic restorative or prosthetic procedures.
Next time your dentist says “I think we’ll just take a couple of X-rays” be assured that he is doing his very best to spot any problems before they become too serious and has your interests at heart.