Retainer im MRT – Belassen oder Entfernen?

Zusammenfassung

Die Magnetresonanztomographie stellt einen wesentlichen Bestandteil in der Diagnostik dar, nicht nur, da sie als nicht ionisierende Bildgebung den Patienten keiner Röntgenstrahlung aussetzt, sondern auch, da sie in ihrer Darstellung des Weichgewebes röntgenologischen Untersuchungen überlegen ist. Obgleich von der MRT aufgrund der strahlenfreien Bildgebung keine direkten Gefahren für den Patienten ausgehen, bedingt das statische und das hochfrequente Magnetfeld im MRT dennoch die Beachtung verschiedener Aspekte im Sinne der Patientensicherheit. Zahnärzten und Kieferorthopäden sind bei Entscheidungen mitbeteiligt, da sie häufig bezüglich der vom Patienten getragenen Restaurationen und Apparaturen konsultiert werden. Aus kieferorthopädischer Sicht stehen Retainer hierbei im Fokus, da sie anders als alle anderen kieferorthopädischen Apparaturen im Regelfall ein Leben lang in situ verbleiben und damit die MRT-Bildgebung bis ins hohe Alter limitieren können.

Wie die meisten dentalen Apparaturen bzw. Restaurationen bestehen nahezu alle Retainer aus ferromagnetischen Werkstoffen, welche sich durch das zur MRT-Bildgebung verwendete Hochfrequenzfeld erwärmen können. Aufgrund des statischen Magnetfelds wirken auf Retainer darüber hinaus sowohl Rotations- als auch Translationskräfte, über deren Ausmaß und Auswirkung auf die Patientensicherheit oft Unklarheit bei vielen Zahnärzten besteht. Neben beiden sicherheitsrelevanten Aspekten gilt zu beachten, dass Retainer, wie alle anderen metallischen kieferorthopädischen Apparaturen, Artefakte in der MRT verursachen. Diese können die Bildqualität erheblich limitieren und eine Diagnose erschweren.

Der folgende Artikel umfasst einen Überblick über die relevanten Punkte, die es vor der Entscheidung über eine eventuelle Entfernung des jeweiligen Retainers bei einer MRT-Aufnahme zu beachten gilt.

Abstract

Magnetic resonance imaging represents an essential component in diagnostics, not only because it does not expose the patient to X-rays as it is a non-ionizing imaging technique, but also because it is superior to X-ray examinations in its depiction of soft tissue. Although MRI does not pose any direct risks to the patient due to its radiation-free imaging, the static and high-frequency magnetic field in MRI nevertheless requires attention to various aspects in terms of patient safety. Dentists and orthodontists are involved in decision-making as they are often consulted regarding the restorations and appliances worn by the patient. From an orthodontic perspective, retainers are the focus here because, unlike all other orthodontic appliances, they usually remain in situ for the rest of the patient's life and can therefore limit MRI imaging into old age.

Like most dental appliances and restorations, almost all retainers are made of ferromagnetic materials that can be heated by the high-frequency field used for MRI imaging. Due to the static magnetic field, retainers are also subject to both rotational and translational forces, the extent and impact of which on patient safety is often unclear to many dentists. In addition to both safety aspects, it should be noted that retainers, like all other metallic orthodontic appliances, cause artifacts in MRI. These can significantly limit image quality and impede the diagnosis.

The following article provides an overview of the relevant points to consider before deciding whether to remove the respective retainer before an MRI scan.

Schlüssselwörter

Magnet Resonanz Tomografie - Artefakte - festsitzende Retainer - CAD/CAM - Twistflex

Key words

Magnetic resonance tomography - artifacts - fixed retainers - CAD/CAM - Twistflex

Publication History

Article published online:
07 December 2023

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