MRI Scanning with Braces, Aligners and Retainers: What You Need to Know

Fixed metal braces and MRI: the key facts

Fixed braces with stainless steel brackets and wires are classified as MRI conditional — not MRI contraindicated — at both 1.5 Tesla and 3 Tesla, which are the two field strengths used in the vast majority of UK NHS and private MRI scanners. MRI conditional means the appliance can be scanned safely provided specific conditions are met, rather than being absolutely prohibited. The MHRA (Medicines and Healthcare products Regulatory Agency) and international MRI safety standards such as ASTM F2503 classify most stainless steel orthodontic brackets and archwires as conditional at 1.5T, with many also cleared at 3T. The principal risk from fixed metal braces is not physical displacement — the force required to move bonded brackets is far greater than any field gradient in clinical MRI — but image artefact that degrades the diagnostic quality of images in the head and neck region.

Image artefact from metal: what it affects

Metal produces magnetic susceptibility artefact in MRI: areas of signal void, geometric distortion, and bright signal halos surrounding the metallic components. For fixed braces, this artefact principally affects the soft tissues of the oral cavity, the floor of the mouth, the maxillary sinuses, and the lower orbits. This means that MRI scans of the brain, spine, chest, abdomen, and limbs are rarely significantly affected by fixed brace artefact. Head and neck MRI — including scans for salivary gland pathology, TMJ assessment, lymph node evaluation, and nasopharyngeal lesions — is the area most affected. Radiologists are experienced in interpreting images with orthodontic artefact, and in many cases the diagnostic question can still be answered. Where artefact is predicted to be clinically significant, the referring clinician and radiologist will discuss whether bracket removal is warranted before the scan.

Should brackets be removed for MRI?

In most clinical situations, fixed brace brackets do not need to be removed before MRI. Removal is an irreversible step that prolongs orthodontic treatment and carries a financial cost; it should only be considered when the radiologist and clinician agree that artefact will genuinely prevent the scan answering the clinical question. This is rarely the case for MRI of structures remote from the teeth and jaws. For MRI of the oral cavity, parotid glands, mandible, or specific TMJ sequences where precise local anatomy is critical, removal may be discussed. If you are asked to have an MRI and have fixed braces, inform both your orthodontist and the MRI department in advance; do not arrange removal without discussion with both clinicians.

Clear aligners and thermoplastic retainers

Clear aligners — whether Invisalign, Spark, SureSmile, or any other thermoplastic brand — contain no metal components and are classified as MRI safe. They can remain in the mouth during scanning. Removable thermoplastic retainers (Essix style) are similarly metal-free and MRI safe. If you are wearing aligners or a removable retainer, inform the MRI team as standard practice, but there is no clinical reason to remove them specifically for MRI compatibility.

Bonded fixed retainers and MRI

Fixed bonded retainers are thin stainless steel wires bonded to the inner surface of the upper or lower front teeth. They are permanently in place and cannot be removed by the patient. These wires are stainless steel, so they produce image artefact in the same way as brace wires, particularly in the anterior mandibular and maxillary regions. You must declare your bonded retainer to the MRI team at booking or on your pre-scan questionnaire. In most cases, scanning proceeds normally with awareness that anterior artefact may be present. For lower jaw or anterior floor of mouth pathology, the radiologist will assess whether a different imaging modality such as CT or ultrasound would give cleaner images.

TAD mini-screws and MRI

Temporary anchorage devices (TADs) are small titanium miniscrews placed into the jaw bone to provide orthodontic anchorage. Titanium is paramagnetic rather than ferromagnetic, meaning it produces significantly less magnetic susceptibility artefact than stainless steel and has minimal interaction with MRI magnetic fields. TADs are MRI conditional and in practice cause very little image artefact. Declare them to the MRI team as you would any other orthodontic hardware.

Lingual braces and MRI

Lingual braces — fixed appliances bonded to the inner surface of the teeth — use stainless steel or gold alloy brackets and stainless steel wires. From an MRI safety perspective they behave similarly to conventional fixed labial braces: MRI conditional at 1.5T and 3T, with artefact concentrated around the teeth and oral cavity. The artefact distribution differs slightly from labial braces because the brackets are on the lingual surface, but the overall safety classification and imaging implications are the same.

Ceramic brackets and metal wires

Ceramic (tooth-coloured) brackets are made from aluminium oxide or zirconia and are non-metallic, producing no significant MRI artefact from the brackets themselves. However, ceramic bracket systems still use metal archwires — typically nickel-titanium or stainless steel — which produce artefact. The overall MRI safety classification of a ceramic brace system is therefore determined by the archwire, not the brackets, and is the same as for metal fixed braces: MRI conditional.

What to tell the MRI team

Always declare all orthodontic appliances on your pre-scan safety questionnaire. State the type of appliance — fixed braces, bonded retainer, clear aligners, TADs — and where possible the material. If you are unsure of the material, contact your orthodontic practice in advance and ask them to provide written confirmation of the appliance type and material for the MRI department. Most hospital radiology departments have a medical physics or MRI safety officer who can review the appliance specifications against the current MHRA safety database. Do not attend an MRI scan without declaring orthodontic hardware, even if you believe it is safe.

Useful related pages

This guide is for general information only. It is not a diagnosis, treatment plan, or substitute for advice from a registered dentist or orthodontist.