If you’ve had dental X-rays taken, you’re probably familiar with the small sensor or film placed inside your mouth to capture images of individual teeth. But there are two other types of dental scan – the OPG and CBCT – that work quite differently, capture far more information, and are used in specific clinical circumstances where standard intraoral radiographs alone aren’t sufficient.
Patients sometimes encounter these terms in treatment letters or consultations without a clear explanation of what they mean or why one has been recommended over the other. This article explains what OPG and CBCT dental scans are, how they differ, and how The Briars uses each of them in clinical practice.
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Before comparing OPG and CBCT dental scans, it’s worth understanding where standard intraoral radiographs – the small X-rays taken inside the mouth – sit in the picture. Despite being the most familiar type of dental imaging, they remain the first choice for most diagnostic purposes, and this is worth explaining clearly.
Intraoral radiographs are taken at close range, with the sensor or film placed directly adjacent to the tooth being imaged. This proximity produces exceptionally detailed images – fine enough to detect early decay between teeth, subtle changes in bone levels around the roots, and small lesions that would be invisible on a larger, more distant scan. For the routine diagnostic work that forms the majority of dental radiography, nothing surpasses them for resolution and diagnostic accuracy.
At The Briars, intraoral radiographs are always the preferred starting point. For patients who find them uncomfortable – whether due to a sensitive gag reflex, a small mouth, or sensory difficulties – the clinical team will always explore solutions before considering alternatives. Distraction techniques, repositioning, and patient-led pacing all help in most cases. For patients where the gag reflex is a significant barrier, Richard Lilleker uses acupuncture as an adjunct to help manage the reflex during X-ray taking – an approach that makes intraoral radiography achievable for patients who might otherwise assume it isn’t possible for them.
The reason this matters in the context of OPG and CBCT scans is that both are employed when intraoral radiographs are insufficient or impractical for a specific clinical purpose – not as routine replacements for them.
OPG stands for orthopantomogram – a panoramic X-ray that captures the entire dentition, both jaws, the temporomandibular joints, and the surrounding bone structures in a single, wide image. The patient stands or sits with their chin resting in a support, and the X-ray machine rotates around the head to produce the panoramic view. It is quick, comfortable, and requires nothing to be placed inside the mouth.
The OPG’s strength is breadth. In a single image, a clinician can see all the teeth, their roots, the level of the surrounding bone, the position of unerupted or impacted teeth, and an overview of the jaw anatomy. It is a useful survey tool – particularly for assessing wisdom teeth, gaining an overview of the entire dentition when intraoral radiographs would be impractical, or when a patient is genuinely unable to tolerate intraoral imaging.
Its limitation is detail. Because the OPG captures a wide area from a distance, the resolution of individual tooth structures is lower than an intraoral radiograph. It is less reliable for detecting early caries between teeth, and fine detail around individual roots or small lesions can be difficult to assess with confidence. It is a broad picture rather than a close-up – clinically useful in the right context, but not a substitute for intraoral radiography when detail matters.
CBCT – Cone Beam Computed Tomography – is an entirely different category of imaging. Where both intraoral radiographs and OPG produce two-dimensional images, CBCT produces a detailed three-dimensional reconstruction of the structures being scanned. This is the fundamental distinction, and it is what makes CBCT invaluable for complex treatment planning.
During a CBCT scan, a cone-shaped beam of X-rays rotates around the area of interest – this can be a single tooth, a section of the jaw, or the full dental arches depending on the field of view selected. The resulting data is processed to create a three-dimensional model that can be viewed from any angle and in cross-section, giving the clinician a level of anatomical detail that no two-dimensional image can match.
CBCT allows precise measurement of bone volume and density, identification of the exact position of nerves, sinuses, and other anatomical structures, and detection of pathology that would be invisible or ambiguous on conventional radiographs. The images are reviewed and reported by a specialist radiologist – an important step that ensures findings are interpreted with the appropriate expertise, and one that reflects the clinical rigour with which CBCT is used at The Briars. Our dedicated article on why CBCT scans need specialist reports explains this process in more detail.
The differences between OPG and CBCT dental scans can be summarised across five dimensions that matter clinically.
Dimensionality is the most significant. OPG produces a flat, two-dimensional panoramic image. CBCT produces a true three-dimensional dataset. For treatment planning that depends on understanding the precise anatomy of a specific site – where a nerve runs, how much bone is available, what lies adjacent to a proposed implant position – two dimensions are simply not sufficient.
Detail and resolution follow from this. Intraoral radiographs remain the superior choice for fine diagnostic detail around individual teeth. OPG sacrifices some of that detail for breadth. CBCT offers exceptional three-dimensional detail within its field of view, but is used selectively because its radiation dose is higher than either of the two-dimensional alternatives.
Radiation dose is a relevant consideration in any radiographic decision. All three types of imaging use ionising radiation, and the clinical justification for each scan must outweigh the associated dose. Intraoral radiographs carry the lowest dose. OPG is moderate. CBCT carries the highest dose of the three, which is why it is prescribed only where the clinical need for three-dimensional information is clearly established – not as a routine investigation.
Field of view differs meaningfully between OPG and CBCT. OPG always captures the full dental panorama. CBCT can be prescribed with a small, medium, or large field of view depending on what needs to be assessed, which allows the dose to be kept as low as reasonably achievable while still capturing the required information.
Clinical application is where the distinction becomes most practically useful, which leads naturally to how The Briars uses each.
At The Briars, the choice between OPG and CBCT dental scans – and indeed whether either is needed alongside or instead of intraoral radiographs – is always a clinically justified decision made on an individual patient basis.
OPG is used selectively. The most common clinical indications are the assessment of wisdom teeth – where the panoramic view allows the position, angulation, and relationship of impacted third molars to the inferior dental nerve to be assessed – and situations where a patient is genuinely unable to tolerate intraoral radiography despite the team’s best efforts to make it manageable. It provides a useful overview in these specific circumstances, but it is not a routine part of the new patient examination at The Briars.
CBCT is used where three-dimensional information is essential to safe and precise treatment planning. The primary application at The Briars is dental implant planning — every implant case is planned using CBCT imaging to assess bone volume and density, identify the position of anatomical structures, and guide the creation of surgical plans and custom guides. It is also used in more complex endodontic cases, surgical planning, and where standard radiography has identified something that requires further three-dimensional investigation.
Both the OPG and CBCT scanner are housed on site at The Briars, meaning that when advanced imaging is required, it can be carried out as part of your treatment journey at the practice rather than requiring referral elsewhere. The clinical decision about which type of imaging is appropriate for your situation will always be explained to you clearly before any scan is taken.
If you have questions about dental radiography or about the imaging involved in a treatment being planned for you, our team is always happy to explain the reasoning. The Faculty of General Dental Practice publishes guidance on dental radiography that provides useful independent context for patients who would like to understand more about how imaging decisions are made.
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