Hi everyone and welcome to this vide, I'm Prateek a dentist and specialty doctor and in this video
we're going to be looking at the most common types of radiographs or x-rays that we take in dentistry.
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channel. So if we look at the types of x-rays that we take in dentistry they can broadly be divided
into two categories - we have intra-oral radiographs i.e where the film is placed inside the mouth and
we also have extra-oral radiographs where the film is outside the mouth. Let's first look at
intra-oral radiographs as these will form the basis for most of the work you do in practice. So firstly
we have bitewing radiographs. Bitewing radiographs are routinely done for patients as part of their
caries assessment - we do one for the left side and one for the right side. Typically they're done in a
horizontal manner however they can be done in a vertical manner if necessary. There are two main
reasons bitewings are very helpful. The first one is to diagnose caries - this may be interproximal
caries or it could be caries underneath restorations. Additionally bitewings are very
helpful in assessing bone levels this includes healthy bone levels but also very early bone
loss that may be seen in periodontal disease. Next we have periapical radiographs, or around the apex.
The aim of a periapical radiograph is to show you more detail surrounding the apices of teeth. There
are many reasons we may do periapical radiographs. We often do them to diagnose periapical pathology
surrounding a tooth and then subsequently if we embark upon endodontic treatment. We often use
peripheral radiographs to assess our endodontic treatment. Aside from endodontic treatment
periapical radiographs are helpful in a number of other areas. In patients with periodontal disease,
peripheral radiographs help us assess the bone levels in more moderate to severe bone loss cases.
Additionally we can use peripheral radiographs in order to localise ectopic teeth and this
would be done using a parallax technique. Finally periapical radiographs can also be very helpful
if we are looking at the root morphology prior to extracting a tooth - this is particularly useful
with third molar teeth. Next we have occlusal radiographs in which case we can have a maxillary,
or an upper occlusal, or we can have a mandibular, or a lower occlusal. For an occlusal radiograph, the
patient will usually have the film between their teeth so they will bite down on the film in a
horizontal place. We can use occlusal views for a range of reasons some of these include localising
ectopic teeth or impacted teeth, identifying salivary calculi, for example in the submandibular
gland we may do a lower occlusal. They can also be helpful to identify foreign bodies or other
pathology within the jaw, for example cysts. Because the patient places the film between their teeth
occlusals can be quite useful in patients who have trismus. So there we've looked at the intra-oral
radiographs that includes bitewing radiographs, periapical radiographs and occlusal radiographs.
Let's now look at the extra-oral radiographs. The most common extra-oral radiograph that you're
likely to come across is a panoramic film or an OPT, DPT or OPG. Panoramic films involve the patient
standing with their teeth on a bite fork and a machine rotating around their head so it gives us
a full overview of the patient's dentition as well as surrounding anatomy including the jaws.
They don't necessarily provide the detail that an intra-oral film would provide however they give
an overall view of the patient's dentition for example patients who may not tolerate
intra-oral radiographs due to the size of the film or they've got a bad gag reflex. An OPT can provide
us with sufficient detail often to carry out treatment however OPTs are particularly useful
in assessment of third molars prior to extraction in order to look at the interaction between the
wisdom tooth and the inferior alveolar nerve. OPT is also very useful in order to assess fractures
of the mandible as well as other pathologies such as cysts. An advantage with OPT often a lot of the
new machines will allow you to use sectional OPTs so you could do a left, you could do a right view,
you could just get the TMJs or you could cut the TMJs off. This is quite helpful when we consider
the radiation dose being exposed to the patients. The impact on the parotid glands is larger than
other surrounding structures and therefore if you can avoid exposing them to radiation this
is of benefit to the patient. I will be doing a separate video looking at the anatomy of an OPT
so that you'll feel more comfortable interpreting the imaging. Next we have oblique lateral films.
Oblique lateral films can be useful particularly in children in order to help with diagnosis where
they can't tolerate an intra-oral film. An oblique lateral would usually involve the child being sat
at 90 degrees on their chair with their face put against a sensor. Then we have the beam
coming at an angle obliquely to their jaw this will then ideally capture both sides in terms of
the posterior teeth. Along with assessing things like caries, oblique laterals can be used to
identify other jaw pathology and unerupted teeth. Next we have posteroanterior films or PA films.
These can either be of the skull or of the mandible. We can use the PA skull to assess
fractures of the skull vault or other pathology such as bone abnormalities like Paget's disease.
For this type of imaging the patient sits facing the x-ray film, they tip their head slightly and
their forehead and the tip of the nose should be touching the film. The x-ray tube is then placed
behind the patient horizontally in line with the base of the skull. This then captures the image
which will let us look at things like the sinuses, cranium, any of the fractures. For a PA mandible
the patient sits in the same way however we lower the level of the x-ray tube keeping it
in the horizontal to the level of the mandibular rami. This will provide us with more information
relating to the mandible. We typically get PA mandibles when we're assessing fractures of the
mandible. Generally in any fracture case we want to be getting two views from different directions
and this will allow us to assess displacement of a fracture. For example if you consider an OPT, as
we may say to patients, x-rays are two-dimensional images of a 3D structure so on an OPT the mandible
may look fine but when you take a PA mandible you can actually see it's displaced in a direction
you couldn't see on the OPT. Next we have the occipitomental view and again we typically take
this view in order to assess fractures of the mid face or any pathology associated with the sinuses.
So because we tend to assess fractures with this view we tend to take two different views
at different angles. To take the occipitomental view the patient will be facing the image receptor.
Rather than having their head tilted forwards, they'll be tilted backwards such that their
chin touches the image receptor. We then line up the x-ray tube at a horizontal to the occiput
behind them. This will then capture the OM zero degrees view then in order to take another view
we would simply move the x-ray beam to a certain angle typically something like 30 degrees to the
horizontal and so the beam would be coming at a higher angle and we get a slightly different
view. We can then look at these two views and this will help us identify any fractures and
any displacement. And finally we have cephalometric imaging or lateral ceph these are taken using a
special machine called the cephalostat. Lateral cephs are mainly used in orthodontic treatment planning
and the progression of treatment. You could take lateral cephs along the patient's journey and
compare their initial imaging to their final imaging to see the change that has occurred.
There is other imaging such as CT scans and CBCT scans which I won't be touching on in this video.
My recommendation is this video is an extremely important and helpful textbook that you can get
and this is the Essentials of Dental Radiography and Radiology that's now in its sixth edition.
This is probably the only book you need to learn about imaging within dentistry. If you
did find this video useful please make sure to share it with others and let me know of
any other topics that you would like me to cover - until the next video, take care!