Dental X-Rays Explained: What Are the Different Types and Are They Safe?
“Do I really need another X-ray?” It is a perfectly reasonable question – and one we are always happy to answer.
At Boston House Dental Clinic, dental X-rays form one part of a much bigger diagnostic picture. Your dentist also uses clinical examination, your dental and medical history, digital photography and, where appropriate, digital intraoral scanning to understand what is happening in your mouth.
The clever thing about an X-ray is that it lets us see what our eyes cannot.
Decay can hide between apparently healthy teeth. Infection can develop around a tooth root. Bone supporting the teeth can change without being visible when you smile. But that does not mean everybody should have X-rays at every appointment.
In the UK, every medical or dental X-ray exposure must have a clinical justification: the expected diagnostic benefit must outweigh the small radiation risk. Current regulations also require exposures to be optimised so the dose is as low as reasonably practicable for its intended purpose.mIn other words: we take the X-ray we need – not an X-ray simply because we can.
So, what are all the different types?
First: what is a dental X-ray? X-rays are a form of ionising radiation. They pass through different tissues to different degrees, allowing us to create an image of structures beneath the surface. Teeth, fillings, bone, decay and other structures interact differently with X-rays, which is why your dentist can obtain information that simply isn’t available from looking inside your mouth. Modern dental radiography can produce very detailed images using relatively low radiation doses. UK guidance and national diagnostic reference levels exist specifically to help practices optimise exposures. And despite the terminology, not all dental imaging actually uses X-rays. More on that shortly.
Intraoral X-rays: the ones we take at Boston House
“Intraoral” simply means that the small image receptor or sensor is positioned inside your mouth. At Boston House Dental Clinic, these are the dental X-rays we take on site.
There are several types.
Bitewing X-rays – the detective between the teeth
If your dentist asks you to bite onto a small sensor or holder, there is a good chance we are taking a bitewing X-ray. Bitewings are particularly useful for looking between the back teeth – areas that can be difficult or impossible to inspect fully with the naked eye. This type of X-ray captures the crowns of the upper and lower teeth in the same area, allowing the dentist to assess the areas between the teeth as well as the surrounding bone. Depending on the size and positioning of the sensor and the size of your mouth, each bitewing will usually show around two to four teeth from each arch.
They can help us identify:
- Decay between teeth
- Decay around existing restorations
- The condition of fillings and crowns
- Changes in the bone supporting the teeth
Bitewings are particularly useful for monitoring patients according to their individual risk of dental decay. And that last point matters. There is no universal rule saying everyone needs bitewing X-rays every six or twelve months. The appropriate interval depends on clinical findings, age, previous disease, caries risk and other individual factors. UK selection criteria explicitly reject taking dental radiographs simply as routine screening without individual clinical justification.
Periapical X-rays – looking at the whole tooth
A periapical X-ray shows an individual tooth or a small group of teeth from the crown right down to the tip of the root and surrounding bone.
Think of the difference this way:
A bitewing asks: “What is happening between these teeth?”
A periapical asks: “What is happening to this entire tooth and around its roots?”
We may use one when investigating:
- Toothache
- Suspected infection
- An abscess
- Trauma
- Root problems
- Bone changes
- Root canal treatment
- A tooth before certain restorative procedures
They are particularly useful when the problem may be underneath the gum or around the root, where even the world’s most enthusiastic dentist cannot see directly.
Occlusal X-rays – less common, but still useful
An occlusal radiograph captures a larger area of the upper or lower jaw than a standard periapical image. Dentists use them less commonly in routine adult dentistry today, but they can have particular diagnostic uses, including assessing tooth position or certain areas of the jaw. As with every dental radiograph, the clinical question determines whether it is appropriate.
What about panoramic X-rays or an OPG?
Now we move outside the mouth. A panoramic radiograph, often called an OPG, produces a broad two-dimensional image of the teeth, jaws and surrounding structures. Rather than putting a sensor beside an individual tooth, specialist equipment rotates around the patient’s head. An OPG can be useful when a dentist needs a much wider overview, for example when assessing:
- Wisdom teeth
- Multiple teeth
- General jaw anatomy
- Certain orthodontic cases
- Some surgical treatment planning
- Broader dental or bony pathology
Boston House does not take panoramic X-rays on site. If your dentist decides that this type of imaging is clinically necessary, we refer you to an appropriate external imaging provider.
What is a cephalometric X-ray?
A cephalometric radiograph, often shortened to a “ceph”, is another type of extraoral X-ray. It usually produces a side-on image of the skull, jaws and teeth and is particularly associated with orthodontic assessment and treatment planning. Again, this is specialist extraoral imaging rather than something we perform routinely at Boston House. Where clinically required, we arrange external imaging.
And then there is CBCT – dentistry in 3D
Cone Beam Computed Tomography (CBCT) is a more advanced type of dental X-ray examination that produces three-dimensional information. Rather than a flat image, CBCT allows clinicians to examine anatomical structures in three dimensions. It can be extremely useful in selected cases, including aspects of:
- Implant planning
- Oral surgery
- Impacted teeth
- Endodontics
- Complex anatomy
- Certain pathological conditions
However, CBCT generally involves more radiation than conventional dental radiography, and therefore requires particularly careful justification and optimisation. UK national diagnostic reference levels include specific benchmarks for dental CBCT examinations. Boston House does not perform CBCT scans in the practice. Where a CBCT is clinically justified, we refer patients to an external specialist imaging provider.
We will leave the fascinating world of CBCT there for now, because it deserves a blog of its own. Coming soon: What Is a CBCT Scan and Why Might Your Dentist Recommend One?
Not everything we use to “see” your teeth involves radiation. This is an important distinction.
Digital dental photography
Dental photography uses ordinary visible light – not ionising radiation. Photographs can provide an excellent visual record of:
- Teeth and gums
- Tooth wear
- Cracks or fractures visible clinically
- Gum recession
- Existing restorations
- Cosmetic concerns
- Changes during treatment
- They are also enormously helpful when explaining something to a patient.
After all, “Here is the area I’m concerned about” is generally more useful than pointing vaguely towards a molar and hoping everybody is picturing the same thing. Photography can also help document a starting point and allow comparison over time.
Is there a downside?
Photography cannot see through teeth or bone. A beautiful high-resolution photograph of a tooth cannot tell us everything about decay hidden between teeth, the tip of a root or the bone surrounding it. That is why photographs and X-rays are complementary rather than interchangeable.
What about our 3Shape intraoral scanner?
This is another very useful piece of the diagnostic puzzle. Our 3Shape intraoral scanner creates a detailed digital 3D representation of the surfaces of your teeth and gums. And again: it does not use ionising radiation. Digital scans can help us record and monitor things such as:
- Tooth wear
- Gum recession
- Tooth movement
- Changes in tooth shape
- The relationship between teeth
- Restorative and orthodontic treatment
If we scan you at different points in time, those digital records can help us compare changes. An X-ray, photograph and intraoral scan therefore do different jobs. One does not simply replace the others.
What happens if I don’t have a dental X-ray?
If an X-ray is not clinically necessary, there is no benefit in taking one. But when your dentist does recommend an X-ray, declining it can sometimes mean accepting greater diagnostic uncertainty. For example, we may not be able to see:
- Early decay between teeth
- The full extent of decay
- Infection around a root
- Changes in supporting bone
- Certain problems beneath existing restorations
- Some abnormalities that are hidden clinically
That does not mean an X-ray automatically finds every dental problem either. The best diagnosis usually comes from combining your history, symptoms, clinical examination and the appropriate imaging.
But are dental X-rays safe?
This is where perspective helps. No exposure to ionising radiation should be described as completely risk-free. That is precisely why UK regulations require dental X-rays to be justified and optimised. However, radiation doses from conventional dental X-rays are generally very low. UK government patient-dose information gives a single bitewing dental X-ray as less than 0.01 mSv, equivalent to less than about 1.5 days of natural background radiation. A panoramic dental X-ray is listed at approximately 0.01 mSv, also around 1.5 days of natural background radiation.
Putting that into perspective
Putting that into perspective
| Exposure | Typical effective dose |
| Single dental bitewing | <0.01 mSv |
| Panoramic dental X-ray | ≈0.01 mSv |
| Chest X-ray | ≈0.02 mSv |
| London–Washington return flight* | ≈0.089 mSv |
*The flight figure is an example modelled cosmic-radiation dose and varies with route, altitude, flight duration and conditions. UK government radiation guidance gives approximately 89 μSv (0.089 mSv) for the example London-Washington return journey. So a single bitewing involves considerably less radiation than that example transatlantic return flight.
It is a useful comparison, but not a reason to become casual about dental X-rays. The principle remains the same: only expose when there is a clinical benefit.
ALARP: a rather unexciting acronym with an important job
British radiation protection loves an acronym, and one worth knowing is ALARP: As Low As Reasonably Practicable
Under IR(ME)R, patient exposures must be optimised so that doses are kept as low as reasonably practicable while still achieving the intended diagnostic purpose. In practical dentistry that means considering things such as:
- Whether an X-ray is actually required
- Selecting the appropriate type of X-ray
- Appropriate exposure settings
- Correct positioning
- Good-quality equipment
- Quality assurance
- Avoiding unnecessary repeat exposures
Modern digital imaging and techniques such as appropriate beam collimation can also contribute to reducing patient dose. UKHSA guidance has long recommended rectangular collimation for intraoral radiography because it can significantly reduce exposure compared with a larger circular beam.
Why doesn’t the dentist wear a lead apron?
This one understandably puzzles patients. You are sitting next to the X-ray machine while your dental professional moves away before pressing the exposure button.
It can look rather suspicious. “Hang on – where are YOU going?” The answer is occupational exposure.
You may have a small number of clinically justified dental X-rays. Dental professionals could potentially take thousands of X-rays throughout their careers, so UK radiation-safety rules require practices to control and restrict staff exposure. The practice has radiation risk assessments, Local Rules and defined arrangements for operating X-ray equipment safely. CQC specifically looks at how dental practices protect patients, staff and members of the public and requires practices to follow applicable radiation legislation and UK guidance. This includes the concept of a controlled area around X-ray equipment during an exposure.
The precise arrangements depend on the equipment, room, risk assessment and advice from the practice’s Radiation Protection Adviser rather than simply one universal painted line on the floor. So when your dental professional steps to the designated safe position, they are not escaping from something dangerous to you. They are following radiation-protection procedures designed for somebody who works around X-ray equipment day after day.
Where is my lead apron?
Another excellent question. For conventional dental radiography, UK guidance does not recommend routinely putting a lead apron on every patient. Guidance states that there is no justification for routine patient lead-apron use in dental radiography because an apron does not protect against radiation scattered internally within the body. There are limited circumstances in which specific protection may be appropriate, and these should follow professional and Medical Physics Expert advice. So if you have previously had dental X-rays without a heavy lead apron, that does not mean somebody forgot it. Modern radiation protection focuses primarily on justification, optimisation, restricting the beam and using appropriate equipment and exposure settings rather than automatically covering every patient in lead.
Who makes sure dental X-rays are used safely?
There is rather more behind that little button than you might imagine. In England, dental radiography is governed principally by the Ionising Radiations Regulations 2017 (IRR17) for protection of workers and the public and the Ionising Radiation (Medical Exposure) Regulations 2017 – IR(ME)R – for medical exposures of patients.
The CQC enforces IR(ME)R in England and considers dental radiography under its requirements for safe care, treatment, premises and equipment.
Practices must have appropriate arrangements covering areas including trained duty holders, radiation-protection advice, risk assessments, Local Rules, equipment testing, quality assurance and appropriate clinical justification. CQC guidance also expects practices to follow the College of General Dentistry’s Selection Criteria for Dental Radiography when deciding when dental radiographs are appropriate.
So the decision to take an X-ray should never simply be:
“It’s been a year – time for another one.”
It should be:
“Will this image give us clinically useful information that justifies the exposure?”
So, which dental imaging do I actually need?
There isn’t a standard answer – and that is exactly the point. One patient may need bitewings to monitor decay risk. Another may need a periapical image because of discomfort around a particular tooth. Someone planning complex treatment might need an OPG or CBCT through an external imaging provider. Another patient may need no X-rays at all at that appointment.
At Boston House Dental Clinic, we combine clinical examination with appropriate digital intraoral X-rays, dental photography and 3Shape digital scanning, selecting imaging according to each patient’s clinical needs. Where a patient requires more specialist extraoral imaging – such as a panoramic X-ray, cephalometric radiograph or CBCT – we refer to an appropriate external scanning provider rather than performing these examinations at the clinic. The aim isn’t to take more images. It is to take the right image, at the right time, for the right reason.
FAQs
How often should you have dental X-rays?
There is no single interval appropriate for everyone. Your dentist considers your age, dental history, decay and gum-disease risk, symptoms, previous X-rays and clinical findings. UK guidance requires radiographs to be selected according to individual clinical need rather than taken automatically at fixed intervals.
Are digital dental X-rays safer than old-fashioned X-rays?
Digital systems can contribute to efficient low-dose imaging, but “digital” does not automatically make every exposure lower. Dose depends on the equipment, detector, exposure settings, beam size and technique. The important principle is optimisation: obtaining adequate diagnostic information with the lowest reasonably practicable exposure.
Can I refuse a dental X-ray?
Yes. Your dentist should explain why an X-ray is being recommended, its benefits and relevant risks so you can make an informed decision. However, declining clinically necessary imaging may limit what your dentist can safely diagnose or the treatment they can appropriately provide.
Does an intraoral scanner expose me to radiation?
No. Our 3Shape intraoral scanner uses optical scanning technology rather than ionising X-rays. It creates a digital 3D representation of the visible surfaces of your teeth and gums.
Why does the dental team leave the area when taking an X-ray?
Dental staff potentially perform many exposures throughout their working lives. Radiation-protection arrangements therefore minimise their cumulative occupational exposure. Practices establish controlled areas and safe working procedures based on risk assessment, Local Rules and professional radiation-protection advice.
Do I need a lead apron for a dental X-ray?
Not routinely. UK dental radiation-protection guidance states that routine lead aprons for patients are not justified for conventional dental radiography. Specific circumstances may require different precautions based on professional advice.
Is a CBCT the same as a normal dental X-ray?
No. Conventional dental X-rays generally produce two-dimensional images. CBCT produces three-dimensional information and can be extremely valuable for specific clinical questions, but it generally involves a higher radiation exposure and therefore requires specific justification. We’ll cover CBCT properly in a separate Boston House article.
