Copied and pasted from elsewhere, hope it's useful for all. posting a little on the ongoing MRI safety discussion based on my recent clinical experience. I had a patient who had e gvpilepsy in the childhood and who gets an MRI scan every year to ensure everything is all right. He had come to me with a request to change all of his ‘metallic’ restorations done by a previous dentist to ceramic ones. He said that his previous MRI scan was ‘unreadable.’
I were reluctant to believe him and hence searched for literature on dental restorations and MRI/CT. There is surprisingly little research that can be found. I’ll post a paper or two that I referred to sometime later. Later, I visited a radiologist with the query about MRI/CT safety of dental restorations. Here’s a summary of what he said to me and what I read in the papers:
1. The problem with metals and MRI is not much about the metal getting pulled out of body due to the magnetic field. Cardiac arterial stents are metallic and are completely embedded in soft tissues. Nothing untoward happens, since the amount of metal is small. The problem is that the brain MRI scan images get distortions when ferromagnetic metals are present near the head, and these distortions are huge ones. The radiologist showed me scan after scan after scan wherein the distortion had tendered the MRI unreadable, just like in my patient. Except most MRIs are not planned but are required as emergency investigations, typically after a stroke. Not much can be done about pulling out the dental restorations when a patient comes in on a gurney, having suffered a massive life threatening accident. Also, due to the close proximity of oral cavity to the base of cranium, a lot of vital arteries cannot be studied, a potentially fatal flaw in the scans in elderly stroke patients, which can mean the difference between life and death.
2. Titanium is MRI safe. The problem is that most of the devices contain titanium alloys, which may have traces of ferromagnetic metals, which can interfere with the image on scan. Even so, most of the titanium devices will not render the scan unreadable.
3. The worst offenders are porcelain-fused-to-metal crowns and orthodontic brackets. But a lot of things including metal posts, zirconium restorations and some brands of composites cause unreadable scans.
4. Amalgam— surprisingly — does not cause very much distortion. Ditto with e-Max.
5. CT scans also suffer from image distortion. But with CT scans, you can simply remove the slice that contains the dental restorations and read the cranium.
So what do I do now that I know these things? Firstly, I was shocked that such a significant matter is not even remotely referred to when we study restorative dentistry. I became aware of it only when I had a patient visiting me who suffered from the ill effects of dental metals. After this episode, I checked the restorative materials I use in my clinic to ensure their MRI safety. Also, nowadays I always inform the patient about the MRI safety of whatever restoration they are getting, with a mention of alternative materials that perform better on MRI. That way, my conscience is clear. It isn’t very easy for a patient to understand the significance of readability of MRI scan that may be needed in future in case of an accident. But I think it’s our duty to at least mention this point. Who knows, it may turn out to be the difference between life and death in some.
The radiologist I visited expressed that this topic must be taken seriously by dentists, specially since the potentially life threatening consequences are not borne by us.
And the next scan my patient underwent turned out to be readable.
