Dentists use x-ray vision as their super power to help maintain your optimum oral health and assist with accurate diagnosis.
Why take dental x-rays (radiographs)?
You may have had some x-rays (radiographs) taken when you went for a dental visit. Radiographs are a valuable way for your dentist to properly assess and diagnose the state of your oral health.
By external observation only, it is not possible to see what’s happening between your teeth, under your gums or inside your tooth.
What information can dental radiographs provide?
Dentists can learn a lot from radiographs, including information about:
- Decay between teeth that is not otherwise visible
- Problems with existing fillings, root canals, crowns or bridges
- Presence and severity of gum disease and associated bone loss
- Infections including abscesses and around the tooth root tip, cysts and tumours
- Tooth development including the presence of emerging teeth, extra teeth, missing teeth, impacted teeth which may need removal
- Proximity of teeth to nerves and sinuses
- Traumatic injuries to teeth and bone fractures
- Whether there is sufficient bone for procedures such as implants
How does digital radiography work?
In the past, dental radiographs were taken on film and developed in the surgery in developing solution and set with a fixing solution. It was a time consuming process and sometimes the dentist discovered that the image was under or over exposed, blurry or not in the correct area. Very frustrating for both the dentist and the patient!
Digital radiography is a form of x-ray imaging, where digital x-ray sensors are used instead of traditional photographic film. The sensor is placed in your mouth next to the area that the radiograph will show.
When the x-rays pass through the mouth, the teeth and bones block more of the ray than the gums and soft tissues, so the teeth appear lighter on the final radiograph. Areas of tooth decay and infection look darker because they let more of the rays through.
The great advantage of digital radiography is that the images are able to be viewed on a screen immediately without having to wait while film processes. The size of the displayed digital image can be manipulated so a particular area can be focused on. The contrast on the digital image can be adjusted to more clearly view an area of interest. The digital radiograph can also be easily transmitted to other health professionals such as dental or medical specialists whom you may be referred to.
Are digital radiographs safe?
Dental radiographs are one of the lowest radiation dose studies performed. The use of digital X-rays reduces radiation by as much as 80%. Although an x-ray machine looks quite large, the x-rays come out of a small cone. This limits the rays to an area less than 7 centimetres in diameter. X-ray machines also are well shielded. Very little radiation exposure occurs beyond the diameter of the beam.
A routine examination which includes 4 bitewing radiographs is about 0.005 mSv, which is less than one day of natural background radiation. It is also about the same amount of radiation exposure from a short plane flight (around 1-2 hrs).
All dental surgeries that have and use x-ray equipment:
- must have licences for the equipment,
- must have regular inspections to ensure the equipment is in proper working order and
- are subject to legal conditions established by the state government.
As with all aspects of life, a process of risk management needs to be applied. As part of the decision about whether to take a radiograph, your dentist takes into account a range of factors such as your past and present oral health, the state of your mouth, your health, risk of disease, any symptoms of oral disease and proposed dental treatment.
Always inform your dentist if you are, or may be pregnant. Taking radiographs while a patient is pregnant is usually kept to a minimum and, by preference, delayed until after the baby is born. However, some dental conditions such as acute infections or injury may necessitate the use of radiographs during pregnancy. As a general rule, the middle trimester is the most stable period for having dental work done. Protective measures, such as a lead apron, are used as an added precaution when taking radiographs at this time.
Why do the dentist and assistant leave the room when radiographs are taken?
This is because of the number of radiographs they take on a regular daily basis. By stepping out of the room, they are limiting the amount of accumulated radiation they receive.
What kinds of radiographs are there?
Firstly are intra-oral radiographs. These are taken inside the mouth using a sensor. They include bitewings and periapical (PA) radiographs.
The most commonly used radiographic procedures in general dentistry are bitewings and periapical radiographs, although OPGs are being used more routinely.
Bitewing radiographs display images of both the upper and lower back (posterior) teeth. This type of radiograph shows how the teeth make contact with each other (interproximally) and whether there is decay at these contacts. It also shows some detail of the bone between your teeth roots.
Periapical radiographs provide an image of the whole tooth, from the crown to the root tip in the bone. These radiographs are especially useful in determining the extent of decay in a tooth and whether there is a problem in the bone surrounding the tooth.
The second type of radiographs are extra-oral radiographs which are taken outside the mouth. These include OPGs (orthopantomograms) and CBCT (Cone Beam Computed Tomography) scans. You can see why the names of these procedures are usually abbreviated!!
With the introduction of digital radiography in dentistry, many dental practices now have their own extra-oral machines. This enables them to take OPGs and even CBCTs “in house”. Diagnostic and planning discussions can happen at the same appointment after the radiographs have been taken which eliminates the need for multiple visits.
OPGs, sometimes called panoramic radiographs, show a wide 2 dimensional view of your whole jaw including your teeth, jaw bones and joints, nasal and sinus area. This type of image can be used for multiple purposes including checking on the position of teeth and their roots prior to extractions or orthodontic treatment, the health of jaw joints and sinuses, how teeth relate to each other (occlusion), determining bone loss as a consequence of gum disease, making initial examinations for implant suitability.
CBCTs (sometimes called Cone Beams) are used when regular dental radiographs are not sufficient. They use x-rays, projected outwards in the shape of a cone, to produce 3 dimensional images of your teeth, soft tissues, nerves and bones can be produced in a single scan. The scan uses this combination of x-rays and computer systems to create virtual ‘slices’ of the body without the need for invasive surgery, taking multiple images of teeth, bones and soft tissue.
A dental CBCT may be used by dentists and oral surgeons for a number of purposes including:
- Dental implant investigation and planning
- Evaluating abnormalities of the teeth, jaws and face
- Assessment of the cleft palate
- Diagnosis of cavities, root canals and dental trauma
- Detecting cysts or tumours
- Proximity of teeth to nerves and sinuses
How often should x-rays be taken?
Dentists have a responsibility towards the health of their patients and to weigh up the benefits of accurate diagnosis and health maintenance against unnecessary exposure to radiation.
Frequency of radiation depends on your oral health, long term whole body health and immediate situation. If your oral health is stable, you will probably require radiographs less often than a person with a tendency to decay. Or, if your long term health is stable, you will probably require radiographs less often than a person with certain acute health conditions. Finally, if you are undergoing certain types of dental treatment such as root canal therapy, you may require radiographs at several consecutive appointments.
And if you are concerned about dental x-rays for any reason, speak to your dentist about it and the reasons for any proposed dental radiographs.
What happens to the radiographs after they are taken?
Any radiographs that your dentist takes of your teeth or refers you to have taken, form part of your clinical records that your dentist has compiled. The radiographs are a visual record of your oral health and they are a valuable benchmark to assess disease or healing over a period of time. Combined with clinical notes, photographs, letters to and from other practitioners, radiographs help to give a comprehensive record of your oral health.
Digital dental radiography has become a valuable tool to work for the benefit of patients. It provides important information that can help your dentist maintain, diagnose and plan effective treatment that aims to improve your oral health outcomes all your life.
Now that’s a super power!