What is a Dental X-ray?

A dental X-ray, or radiograph as it’s also known, is a procedure used to produce images of the inside or outside of a patient’s mouth. X-rays are used to provide a clearer picture of the health of the teeth, roots, gums and bones. Among other things, X-rays can detect tooth decay and bone loss, issues that a simple oral exam would unlikely pick up.

How Do Dental X-rays Work?

X-rays are a penetrating form of high-energy electromagnetic radiation. This energy can travel through or be absorbed by human tissue. After travelling through a dental X-ray machine tube and then human tissue, the photons (electromagnetic particles) reach a receptor at the other side. This receptor is traditionally a sheet of film which is processed in chemicals to then produce the X-ray images. Becoming more popular is the use of digital receptors which are able to process the images straight to a computer.

What Do Dental X-rays Show?

X-ray beams weaken as they travel through human tissue. The thicker the tissue, the fewer photons that make it through to the receptor. An X-ray image will show denser areas of the mouth, such as enamel and dentine, as light-coloured (radiopaque). Less dense areas, such as the pulp and gums, show up darker (radiolucent). Dental X-rays can spot the early signs of a cavity by the appearance of radiolucent (darker) patches in areas which should normally be white, such as the dentine.

Dark spots that appear between the roots of the teeth can show potential active bone loss or gum disease. Areas that are particularly white on an X-ray image are most typically fillings or crowns, as these are more radiopaque than even enamel.

Are Dental X-rays Safe?

Dental X-rays sit between ultraviolet radiation and gamma rays on the electromagnetic spectrum. The level of radiation given off by a dental X-ray and absorbed by a patient is minimal and lasts only a fraction of a second. Dental X-rays are therefore considered a very safe procedure. Advances in technology and the ability to target X-ray beams on smaller areas of the mouth have made the process safer.

It is important that the whole dental team is aware of radiation safety. The National Radiological Protection Board, Guidance notes for dental practitioners on the safe use of X-ray equipment (2001) should be used for guidance. A patient always has the choice of whether to proceed with a dental X-ray. Likewise, a dentist has a choice of whether to provide care to patients who refuse an X-ray. When this occurs, good documentation in the patient’s records is essential.

How Many Dental X-rays Are Too Many?

It is common for new patients to receive an X-ray during their first dental examination. The number of X-rays a patient requires thereafter will depend on individual medical and dental history. Some patients might require an X-ray every 6 months while others will only require one every couple of years. Examples of patients who might require more frequent X-rays include children, smokers, patients with gum disease and patients with lots of fillings.

Dental X-Ray UK Regulations

Dental staff in the UK are required by law to be IRMER trained. This applies to everyone involved in taking and/or processing radiographs. Practices are now also required to register with the HSE if they use radiographic equipment. The Ionising Radiation (Medical Exposure) Regulations 2017 (IRMER) relates to the protection of the patient and specifies that individuals are informed in advance of the risks of any ionising radiation exposures they receive.

There should be a clearly defined person at each dental practice responsible for implementing both IRMER and IRR99 legislation. This is often the practice manager. The Ionising Radiation Regulations of 1999 (IRR99), relates to the protection of workers, the public and the equipment aspects of patient protection.