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Looking into the Smile: X-rays in Dentistry

Updated: Mar 6

X-rays are a technique used in dentistry to obtain images of teeth and other structures in the facial region. This is possible because they are electromagnetic waves capable of passing through the tissues to then form an image on a film. In this article we will look at two of these X rays common in dentistry, the intraoral radiograph and the OPG X ray.


Why are dental X rays necessary?

Radiographs are one of the most used complementary examinations in the dental office because they are an instrument that provides valuable information to the dentist, they support the clinical examination, allowing an accurate diagnosis to subsequently establish the most appropriate treatment plan for the situation presented by the patient.

Considering the above, we can affirm that radiological examinations allow the dentist to study the oral condition of the patient with greater detail and precision. In addition, it should be taken into account that many times the presumptive diagnosis changes after performing an X-ray, since factors that could not be seen with the naked eye during the oral examination become evident.

At the same time, they are a support for the dentist when showing the patient the pathologies and lesions of their teeth and surrounding bone, and motivating them to correct the habits that have caused them.



X ray image examined by the dentist
Dentist examines an X ray of a patients Teeth

Among the dental characteristics that can be observed with an X-ray are: the anatomy of the crown of the teeth and roots, the level and quality of the bone that surrounds and supports the teeth, the presence or absence of lesions or fractures, among other factors that will be mentioned later. In short, radiographs are a very useful diagnostic tool to assess the condition of dental tissues, periodontium (support for the teeth), alveolar bone and some facial structures.


Dental X rays Interpretation

As you well know, when you look at an X-ray you will see that there are white, black and other grey structures. This can be interpreted as follows:

● Radiopacity - White - Structures that are dense, such as amalgam restorations, look white.


● Radiolucency - Black- Structures that are hollow and contain air look black under normal conditions, as is the case with maxillary sinuses. Blackness or 'shadowing' can also be observed in teeth when they present pathologies such as cavities or lesions next to the root. The reason for this is that a cavity is a hole in the tooth. There there is not as much tooth structure present the x-rays are able to travel through to the film easier. The more of the film that is exposed by the x-rays the blacker the image


● Under normal conditions the teeth usually have a greyish colour. They are not completely white but they are not black either because they are not a hollow structure.


Types of dental X rays

Not all radiographs used in dentistry are the same or have the same purpose, as each one is designed to evaluate a specific area and provide different information about each patient. Among the main ones we have the intraoral radiographs and the OPG X ray:


Intraoral radiographs.

As its name indicates, the image is taken inside the patient's mouth by means of a film of a few centimetres. Depending on the technique this film is held with a plastic holder or has a paper flap which is bitten. In this group are:

- Bitewing: They show the crown area of the upper and lower teeth (usually 3-4 teeth top and 3-4 teteh on the bottom). It is usually intended for the posterior area, especially that of the molars and premolars, where visual access is more difficult during clinical examination.

It is used to visualize more accurately the junction areas between adjacent teeth, known as interproximals. Very small caries (tooth decay) that are not clinically visible just by looking at the tooth with eye sight in the mouth can be detected. The benefit of picking up these cavities when they're small is that means more of the tooth is preserved, and less likely the tooth will become sore and need a root canal treatment.

- Periapical: It usually shows 2 or 3 complete teeth, which allows us to evaluate them from the crown to the root. In addition to tooth decay, it allows us to determine the presence of dental abscesses, periapical lesions, internal resorptions, bone loss, etc. These are also very useful during root canal treatment to check the progress of the treatment.

- Palatal or occlusal: They capture all the upper or lower teeth together in a single shot. These are less common and require a much larger film.


The Intraoral X ray Machine will usually be found in the dental surgery room
Intraoral X ray Machine

Extraoral dental X-Rays.

- Panoramic: Orthopantomogram also known as an OPG X ray, is a 2D image of the upper and lower jaws, including any teeth. OPGs are indicated to assess the number of teeth (it allows to know if there are supernumerary teeth) and their position, so it is useful for orthodontic planning, and wisdom tooth assessment.

It can also be used to identify periapical pathologies and lesions such as cysts and granulomas, anomalies in the dental roots, and changes to the jaw bones.


OPG X ray Machine
OPG X ray machine in the dental clinic


In this case the image is taken thanks to a machine that rotates around the patient's head, thus capturing the maxillary and mandibular bones and the upper and lower teeth in a single shot.

It should be noted that dental X ray OPG is not the ideal technique for detecting tooth decay, unless they are very deep and advanced. It is preferable to opt for periapical or bitewing radiographs depending on the case.

- Dental CT Scans: CT stands for Computed Tomography. This is a more advanced technique in which thousands of images are taken from different angles of the patient's mouth, which are sent to a computer that generates a virtual image in 3 dimensions. Commonly known as Cone Beam CT, or CBCT. These images give much greater detail than an OPG which is only 2D. CBCT is useful for dental implant planning because it details not only the height of the bone, but the width as well. Complex root canal also benefits from CBCT imaging.

- Cephalometric X-ray: This is a 2D image taken from a profile view. It's usually indicated before orthodontic treatment, as it allows us to know the general state of the bones of the skull and the proportions between them, and at the same time detect skeletal problems.


The choice and indication of each X-ray should be made responsibly, depending on the needs of each patient and for the diagnosis to be made at a given time. And above all, taking care that it produces more benefits than risks for the patient. This is known as ALARA principle. As Low As Reasonably Achievable.


Are dental X rays safe?

It is important to mention that the indication for each radiographic study should not be made arbitrarily, but on the contrary, it should be fully justified. This is because during its performance the patient is exposed to ionizing radiation that can produce adverse effects on the body if performed repeatedly.

Despite the fact that dental X rays radiation dose is very low, the more times the patient is exposed to X-rays during their treatments, the greater the chances of developing some adverse effect, since radiation doses are cumulative, i.e. they add up.

To give some perspective however, the radiation received from having an OPG X ray is less than you would receive from taking an international flight! Check out the table below from the Agency of Clinical Innovation. You can see here that an OPG X ray is not even equivalent to 1, 7 hour flight. You can find the full article here. Also as you can see, the OPG X ray and especially the regular intraoral X ray have vastly less radiation given in comparison to other X rays in the body.


A table showing the exposure of radiation in an OPG X ray or Intraoral X ray compared to Air Travel
Intraoral X ray and OPG X ray radiation compared to Air Travel

Are dental X rays safe during pregnancy?

Another detail that should be mentioned is that, although radiation in dental X rays is within the margins that are considered safe, it is still not recommended for pregnant women, since there is a risk of producing complications in the foetus, which, although minimal, should be taken into account.


X-rays, being a complementary examination, are indispensable in all dental specialties, not only in the diagnostic and treatment planning phase, but also in the immediate control of root canal treatment, restorations, fixed prostheses, implants, etc.

Therefore, except in some particular situations, its performance is absolutely necessary, it has also been studied that barriers such as lead aprons have no benefit to protecting the vulnerable thyroid.

There are also X-rays with digital technology in which the radiation transmitted during the procedure is lower than with traditional methods.


Dentista Dental Centre uses and recommends patients getting regular X-rays via our intraoral radiographs in our rooms, to check that there are no small cavities that need treatment. We also now have an OPG X ray available for patients who require any complex treatments involving planning. It is recommend to have an OPG screen every 5 years to pick up conditions that may be developing in the bones with no symptoms. This tool has helped dentists for years in helping diagnose problems whilst they are still too small to be seen with the naked eye. As the saying goes 'a stitch in time saves 9' and this is especially true for your teeth. Take advantage of modern technology and ask our dentists for a routine x ray next time you are in the dental clinic. Call us now for your Dentist Morley, Dentist Noranda!

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