--- title: "Cephalometric X-Ray in Orthodontics UK | Ceph Analysis" url: https://virtualconsultant.online/guides/cephalometric-x-ray-orthodontics-uk description: "A ceph X-ray reveals your skeletal jaw pattern, incisor angles, and facial profile. Learn when one is needed, what ANB means." updated: 2026-08-25T00:00:00Z publisher: Virtual Consultant Online --- Cephalometric X-Ray Diagnosis Skeletal Pattern Radiograph # Cephalometric X-Ray in Orthodontics UK A cephalometric X-ray — commonly called a ceph — is a standardised lateral (side-on) skull radiograph used in orthodontic diagnosis and treatment planning. It allows precise measurement of the skeletal, dental, and soft tissue relationships that underpin your bite and facial profile. [Start Photo Assessment](https://virtualconsultant.online/evaluations/quote) [Compare Costs](https://virtualconsultant.online/costs) ## What is a cephalometric X-ray? A cephalometric radiograph — often abbreviated to ceph — is a standardised lateral skull X-ray taken with the patient positioned in a cephalostat: a device that holds the head in a precise, reproducible position with the teeth in occlusion (or at rest) and the Frankfort plane (a reference line from the ear to the lower orbital rim) roughly horizontal. The standardised positioning is what makes the radiograph clinically useful — because the projection geometry is reproducible, measurements taken on serial cephs over time can be directly compared, allowing growth monitoring and assessment of treatment change. In the UK, cephalometric radiographs are taken using a dedicated cephalostat attached to or separate from the dental X-ray unit. Modern machines produce digital images that can be analysed using specialist software such as Dolphin Imaging, Nemoceph, or OrthoAnalyzer. ## What a cephalometric X-ray shows The lateral ceph displays the hard and soft tissue structures of the skull and face in profile. Key structures visible include the cranial base (providing reference landmarks such as Sella and Nasion), the maxilla (upper jaw) and mandible (lower jaw) and their spatial positions, the upper and lower incisor teeth and their angulation relative to the jaw bones, the molar teeth, the airway (pharyngeal space), and the soft tissue profile including the nose, lips, and chin. Because bone, tooth structure, and soft tissue all have different radiodensities (X-ray opacity), each can be distinguished and used for landmark identification and measurement. The soft tissue profile is particularly useful for planning aesthetic outcomes in jaw surgery cases and for assessing lip competence. ## Key measurements and what they mean Cephalometric analysis involves identifying anatomical landmarks and measuring the angles and distances between them. The most clinically important measurements in UK orthodontic practice include: SNA angle — the angle at Nasion between the cranial base line and the maxillary line; normal is approximately 81 to 83 degrees, with higher values indicating a prognathic (forward) maxilla and lower values a retrusive upper jaw. SNB angle — the equivalent measurement for the mandible; normal is approximately 78 to 80 degrees. ANB angle — the arithmetic difference between SNA and SNB; this is the most important single measurement as it quantifies the skeletal discrepancy between upper and lower jaws. ANB of 2 to 4 degrees indicates Class I, greater than 4 degrees indicates Class II (lower jaw behind upper), and less than 2 degrees or negative indicates Class III (lower jaw ahead or upper jaw retrusive). MMPA (Maxillary-Mandibular Planes Angle) — describes the vertical skeletal pattern, distinguishing high-angle (anterior open bite tendency), average, and low-angle (deep bite tendency) facial types. Upper incisor to maxillary plane angle — normal is approximately 109 degrees; proclined incisors increase this, retroclined decrease it. FMIA (Frankfort-Mandibular Incisor Angle) — used to assess lower incisor position. ## When a cephalometric X-ray is needed Not all orthodontic patients need a ceph. It is most valuable when a skeletal discrepancy is suspected or confirmed, when jaw surgery (orthognathic surgery) is being considered or planned, when there is uncertainty about the degree of incisor proclination or retroclination, during or after growth modification treatment (such as functional appliances or headgear) to measure skeletal change, for monitoring jaw growth over time in growing patients, and when quantifying soft tissue profile for surgical planning. A ceph is a standard component of orthodontic records for patients receiving comprehensive fixed appliance treatment in secondary care (hospital or specialist practice), particularly where an NHS treatment plan requires prior approval. For mild cases managed by primary care dentists or direct-access orthodontists with clear aligners, a ceph is often not required. ## Radiation dose — how safe is it? The radiation dose from a lateral cephalometric radiograph is very low. Effective dose is typically in the range of 2 to 6 microsieverts (microSv) for digital systems, and up to 10 microSv for older film-based systems. To put this in context, background radiation in the UK is approximately 2,700 microSv per year — equivalent to around 2.7 mSv. A single ceph represents roughly one to three days of background radiation exposure. The ICRP and UK radiation protection guidelines (IRMER) apply the ALARA principle — that radiation exposure should be as low as reasonably achievable — which means a ceph should only be taken when clinically justified. For patients with known thyroid sensitivity, a thyroid collar may be used where it does not obscure essential anatomical landmarks. Digital systems have significantly reduced doses compared to film-based cephalometry. ## When a cephalometric X-ray is NOT needed A ceph is not required for mild, purely dental cases with no skeletal discrepancy — for example, mild crowding in a Class I patient where the diagnosis is clear from clinical examination and a dental panoramic radiograph (OPG). It is not routinely needed for short-term or cosmetic clear aligner treatment targeting mild alignment issues. Patients with mild spacing or minor tooth rotations do not usually need cephalometric analysis. The decision to take a ceph should follow the principle of clinical justification — it should only be performed if the information it provides will change or refine the treatment plan. ## How is a cephalometric X-ray taken? The process is quick and straightforward. You will be asked to stand or sit with the side of your head facing the X-ray source and detector. Ear rods (ear pegs) are gently placed in both ear canals to fix your head position, and a nose rest positions the face. You will be asked to bite your teeth together gently (or rest them in natural occlusion) and to relax your lips. The exposure takes a fraction of a second. The resulting image is immediately available digitally for the orthodontist or radiographer to review. If a growth comparison series is being taken (two cephs months or years apart), the same machine and positioning protocol must be used to ensure comparability. ## Useful related pages [CBCT vs OPG X-Ray in Orthodontics](https://virtualconsultant.online/guides/cbct-vs-opg-xray-uk) [Orthodontic Treatment Records](https://virtualconsultant.online/guides/orthodontic-records-uk) [Orthodontic Treatment Planning Process](https://virtualconsultant.online/guides/orthodontic-treatment-planning-process-uk) [Jaw Surgery and Orthodontics](https://virtualconsultant.online/guides/jaw-surgery-orthodontics-uk) [How Orthodontic Mechanics Work](https://virtualconsultant.online/guides/how-orthodontics-works-uk) This guide is for general information only. It is not a diagnosis, treatment plan, or substitute for advice from a registered dentist or orthodontist. ### Compare next steps [Orthodontist Near Me](https://virtualconsultant.online/locations/orthodontic-treatment-near-me) [Clear Aligners Near Me](https://virtualconsultant.online/treatments/clear-aligners-near-me) [Invisalign Near Me](https://virtualconsultant.online/locations/invisalign-provider-near-me) [Browse Locations](https://virtualconsultant.online/locations) ### Ready for a clearer starting point? Upload guided photos and receive an indication of likely treatment options and pricing before booking appointments. [Get an Online Quote](https://virtualconsultant.online/evaluations/quote) ### Frequently Asked Questions What is a ceph X-ray used for in orthodontics? A cephalometric radiograph is used to measure the skeletal and dental relationships of the jaws and teeth in profile. It tells the orthodontist whether a discrepancy between upper and lower jaws is skeletal (bone position) or dental (tooth position only), how the incisors are angulated, what the vertical facial pattern is, and — when taken as part of a series — how the jaws are growing or changing in response to treatment. Is a cephalometric X-ray safe? Yes. The radiation dose is very low — typically 2 to 6 microsieverts for a modern digital ceph, equivalent to one to three days of natural background radiation. The IRMER regulations in the UK require that every X-ray is clinically justified before it is taken, so your orthodontist will only request a ceph if the clinical information it provides is genuinely needed for your diagnosis or treatment planning. When will I need a cephalometric X-ray? You are most likely to need a ceph if your orthodontist suspects or has confirmed a skeletal jaw discrepancy (Class II or Class III), if jaw surgery is being considered, if you have a significantly deep or open bite, if you are having growth monitoring during functional appliance treatment, or if you are being treated as part of a comprehensive NHS or hospital orthodontic plan. For minor cosmetic aligner treatment, a ceph is usually not required. What does the ANB angle mean? The ANB angle is the difference between the SNA and SNB angles — it quantifies the anteroposterior (front to back) relationship between the upper jaw (maxilla) and lower jaw (mandible). A normal ANB is 2 to 4 degrees. Greater than 4 degrees indicates a Class II skeletal pattern (lower jaw relatively behind upper), which is associated with overjet and protrusion. Less than 2 degrees or a negative value indicates a Class III skeletal pattern (lower jaw ahead of upper), associated with underbite or edge-to-edge bite. The ANB is one of the most important numbers in an orthodontic diagnosis. Will I need a cephalometric X-ray for aligner treatment? Not necessarily. If your case is mild to moderate and involves straightforward crowding, spacing, or minor rotations without a significant skeletal discrepancy, a ceph is unlikely to be required. More complex aligner cases — particularly those involving bite correction, significant overbite or overjet reduction, or skeletal camouflage — may benefit from cephalometric analysis to ensure the treatment plan is biomechanically safe and that the incisor movements proposed are within acceptable limits. How long does a cephalometric X-ray take? The exposure itself lasts a fraction of a second. The full process — positioning in the cephalostat, taking the image, and reviewing the digital result — typically takes two to five minutes. Because the image is digital, the orthodontist or radiographer can review it immediately on screen and begin cephalometric analysis without any delay for film processing. In a hospital or specialist orthodontic practice, tracing and analysis may be done digitally using specialist software on the same appointment or shortly after. Explore your options Quick links Not sure where to start? Use these quick links to explore orthodontic treatments, typical costs, and helpful guides that explain what different options involve. Whether you're researching braces or clear aligners, comparing pricing, or just getting a feel for what comes next, you can browse at your own pace and come back when you're ready to request a quote. 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Upload guided photos and get a tailored recommendation for your teeth and bite. [Start Photo Assessment](https://virtualconsultant.online/evaluations/quote) [Find an Orthodontist](https://virtualconsultant.online/locations) Citation details Title Cephalometric X-Ray in Orthodontics UK | Ceph Analysis Publisher Virtual Consultant Online Published 2026-05-28 Updated 2026-08-25 URL [https://staging.virtualconsultant.online/guides/cephalometric-x-ray-orthodontics-uk](https://staging.virtualconsultant.online/guides/cephalometric-x-ray-orthodontics-uk)