|Year : 2022 | Volume
| Issue : 2 | Page : 47-52
Prosthetic and dental implant patient's biosafety during MRI procedure: A survey based study on awareness among professionals
Jitendra Rao1, Anshdha Shah1, Kalpana Singh2, Bhawana Tiwari3
1 Department of Prosthodontics, FODS, King George's Medical University, Lucknow, Uttar Pradesh, India
2 Department of Biochemistry, King George's Medical University, Lucknow, Uttar Pradesh, India
3 Department of Prosthodontics, ESIC Dental College, New Delhi, India
|Date of Submission||16-Feb-2022|
|Date of Decision||25-Apr-2022|
|Date of Acceptance||18-Jun-2022|
|Date of Web Publication||23-Aug-2022|
Dr. Anshdha Shah
Department of Prosthodontics, FODS, King George's Medical University, Lucknow, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Aims and Objectives: The survey was conducted to evaluate the awareness among dentists and radiologists regarding the safety and interactions of dental materials in relation to magnetic resonance imaging (MRI). Materials and Methods: A questionnaire was circulated among professionals of the North Indian population as Google forms to assess their awareness regarding the safety of dental implants in MRI field, and the results were calculated by the same application. Results: A majority of the professionals seemed to be well-informed regarding the magnetic nature of materials used as dental implants. However, there were mixed opinions regarding the biosafety of different dental materials used for prosthetic restoration of implants or as prosthesis that maybe attached to oral structures. Conclusion: The present survey revealed that the most professionals possess the knowledge and awareness about biosafety of dental materials, there still a further need to increase awareness to avoid dilemmas in routine practice.
Keywords: Artifacts, biosafety, dental implants, magnetic resonance imaging, prosthetic materials
|How to cite this article:|
Rao J, Shah A, Singh K, Tiwari B. Prosthetic and dental implant patient's biosafety during MRI procedure: A survey based study on awareness among professionals. J Interdiscip Dentistry 2022;12:47-52
|How to cite this URL:|
Rao J, Shah A, Singh K, Tiwari B. Prosthetic and dental implant patient's biosafety during MRI procedure: A survey based study on awareness among professionals. J Interdiscip Dentistry [serial online] 2022 [cited 2022 Oct 4];12:47-52. Available from: https://www.jidonline.com/text.asp?2022/12/2/47/354452
| Clinical Relevance to Interdisciplinary Dentistry|| |
- It will useful to dentists of all specialities to help clear the doubts of patients with implants or prosthetic component of the mouth
- Useful information for the radiologist
- Dentists can choose the components which are more suitable for patients that may need to undergo MRI.
| Introduction|| |
The variety of imaging modalities available for the head and neck region, for both medical and dental purposes, includes panoramic radiography, ultrasound, computed tomography (CT), cone-beam computed tomography, magnetic resonance imaging (MRI), and positron emission tomography. Among them, CT and MRI are the more popular entities.
MRI uses a powerful magnetic field, radio waves and a computer, to create images of tissues and organs throughout the body. The powerful magnetic field aligns atomic particles called protons that are present in most of the body tissues, especially the soft tissues. The applied radio waves then cause these particles to produce signals that are picked up by the receiver within MR scanner. Usually, MRI uses a magnetic field of 1–1.5 Tesla (T) and a more powerful MR scanner may use 3 T.
Based on the magnetic field strength, the types of MRI are as follows:
- Low field MRI scanners – 0.23–0.30 T
- High field MRI scanners – 1.5–3.0 T
- Ultra-high MRI scanners – 5.0–7.0 T.
MRI in patients with metallic foreign objects is often contra-indicated, as the object may be dislodged due to the presence of a magnetic field. Various dental restorations and several types of dental prostheses consist of different metals and metal alloys that may interact with MRI.
Based on their magnetic susceptibility, various dental materials may be classified as – ferromagnetic, diamagnetic, and paramagnetic.,
Ferromagnetic materials are strongly attracted to a magnet, for example, Chromium oxide, cobalt, ferrite (iron), Gadolinium, Nickel, rare earth magnet, magnetite, and yttrium.
Paramagnetic materials are not very strongly attracted to a magnet, for example, magnesium, tin, platinum, palladium, titanium, aluminum, and molybdenum. Hence, a patient with titanium implant may safely undergo MRI without any dislodgement of implant and minimum to no artifacts on the image.,
Diamagnetic materials are those which are repelled by a magnet, for example, zinc, copper, bismuth, silver, and gold.
During an interaction two entities affect each other, similarly, when a dental material is exposed to an MRI field, it may get affected by the field as well as it may affect the resultant image.
Effects of magnetic resonance imaging on dental materials and appliances
- Thermal heating – tissue injury may occur due to heating of a prosthetic appliance
- Dislodgement – the magnetic field attracts the iron-containing substance and may cause the dislodgment of such an object
Effects of dental materials and appliances on magnetic resonance imaging
Artifact generation - The magnetic field and radio frequency pulses interact unfavorably with dental materials. Metals do not generate an MRI signal, hence, causing blacking of the image/artifact generation. The presence of metals results in severe variations in the static magnetic field due to susceptibility variations between metal and surrounding tissue. The magnetic field variations cause large resonant frequency variations. When the field changes rapidly with position, there is significant dephasing of the signal, resulting in signal loss.
With an increase in the population belonging to the older age group, there is an increased indication for the use of MRI for the diagnosis of various conditions. The same population is also prone to undergo dental treatment with increasing age, especially the replacement of missing teeth with dental implants. Thus, dentists as well as radiologists need to be aware of the interactions between MRI and dental materials such as titanium alloy, casting alloy, and zirconium.
The dentists as well as the radiologists need to be aware of the effects that MRI may cause on the biomaterials fixated in the human body and the alterations that these biomaterials may cause to the quality of the image.
The current survey was performed to evaluate the knowledge and awareness among dentists and radiologists regarding interactions between dental materials and MRI.
| Materials and Methods|| |
A knowledge and awareness survey was performed among actively practicing dentists and radiologists in the form of a questionnaire. This survey was carried out among the professionals of the North Indian population. The questionnaire was circulated in the form of a link to the Google form page. The Google form questionnaire comprised seven close-ended questions. The questionnaire was circulated to only those who had been in clinical practice for at least 1 year.
The percentage of clinicians replying to each option for every question was calculated.
| Results|| |
The form was circulated among 100 doctors (dentists and radiologists combined). 87 individuals responded to the form, 62 of these individuals were general dentists (BDS), 23 were postgraduate dentists, and 2 of them were radiologists [Figure 1]. The results were analyzed and represented in the form of bar diagrams and pie charts using Microsoft Excel 2019. The number of subjects that chose a particular option as the correct one was depicted in these diagrams.
89.2% (72) of the doctors agreed that a titanium implant can be used as the best replacement for missing teeth whereas 10.8% (9) did not agree with this view, 4 doctors did not attempt the question [Figure 2].
|Figure 2: Q1 Can biomaterial consisting of Titanium implant be the best replacement for missing teeth?|
Click here to view
71.8% (61) of doctors said that patients with dental implants can safely undergo MRI, 21.2% (18) stated otherwise. 7.1% (6) were not sure whether a patient with dental implant could safely undergo MRI [Figure 3].
|Figure 3: Q2 Do you think patients with dental implant can safety undergo MRI? MRI: Magnetic resonance imaging|
Click here to view
81.2% (69) of the population said that titanium was non-ferromagnetic in nature and 18.8% (16) said that it was a ferromagnetic material. Two individuals chose not to attempt the question [Figure 4].
|Figure 4: Q3 What is the nature of the dental implant material (Titanium)|
Click here to view
13.1% (11) of the doctors thought that MRI can cause dislodgement of dental implants whereas 78.6% (66) thought that MRI could not cause dislodgment of dental implant and 9.5% (8) were not sure. The question was not attempted for 3 forms [Figure 5].
|Figure 5: Q4 Do you think that the MRI can cause dislodgement of dental implants? MRI: Magnetic resonance imaging|
Click here to view
35.3% (30) individuals thought that the presence of dental implants will compromise the image quality of MRI and cause artifacts whereas 50.6% (43) thought that the image will not be compromised and 15.3% (13) were not sure. One individual did not respond to the question [Figure 6].
|Figure 6: Q5 Do you think that presence of dental implants will compromise image quality and cause artifact in MRI? MRI: Magnetic resonance imaging|
Click here to view
41.7% (35) of professionals believed that implant-supported crowns and bridges would cause image distortion in MRI and 45.2% (38) did not share this opinion and 15.5% (13) were not sure. Three people did not respond to the question [Figure 7].
|Figure 7: Q6 Do you think implant-supported crown and bridge (Gold, Nickel-based alloy, zirconium) cause image distortion in MRI. MRI: Magnetic resonance imaging|
Click here to view
42.4% (37) doctors said that cobalt-chromium (Co-Cr) alloy causes distortion of MRI and 32.9 (28) said that no distortions will be seen and 24.7% (21) individuals were not sure. One of the doctors did not attempt the question [Figure 8].
|Figure 8: Do you think the presence of Cobalt–Chromium alloy cause image distortion in MRI? MRI: Magnetic resonance imaging|
Click here to view
| Discussion|| |
Dental implants have become one of the most desirable methods to replace missing teeth for esthetic and functional purposes. Most of the clinicians in our study also had similar views regarding tooth replacement. Dental implant or a root form implant is a screw-shaped metallic device resembling the anatomic root of the tooth and hence replaces the root of the tooth within the alveolar bone. An abutment is then screwed onto the implant which supports the prosthetic crown that replaces the crown portion of the tooth. The dental implant is mainly composed of commercially pure titanium (CpTi) and Ti-6Al-4V, and both of these materials are biocompatible with alveolar bone and gingiva and are capable of undergoing osseointegration. Any biomaterials inducted into the body interact with the tissues as well as the environment. These interactions and responses depend on the properties of the material as well as its quantity of exposure in the oral cavity.
When a biomaterial is introduced into the human body, the patient is bound to have certain doubts about it, and it is the responsibility of the clinician to clarify the dilemma before procedures such as MRI. In dentistry, these objects can be crowns, metal posts, orthodontic braces, screws and plates used for fracture fixation, and dental implants. Most of these entities can be removed if required, but it may not be feasible to remove objects such as fixation screws and plates in every situation. It is not advisable to remove a dental implant from an osseointegrated site.
It is a generalized misnomer among people that metallic objects should not be introduced into the magnetic field of an MRI. This statement though true to some extent does not apply to all metals equally. Different metals have a different magnetic nature and response in the body.
Titanium being a paramagnetic (non-ferromagnetic) material remains unaffected by the magnetic field of MRI. Sullivan et al. evaluated the safety of MRI of metallic implants (stainless steel wires, titanium, and vitallium plates) and reported that none of the materials showed either deflection/dislodgement or a significant temperature change, suggesting the safety of dental implants in MRI. The current survey shows that the majority of the dentists were aware of the ferromagnetic nature of dental implants and its resultant safety in MRI. Marincas et al., reported a temperature elevation of <1°C in dental implants when placed in a magnetic field of 3T.
The other aspect that needs to be considered is the clarity of the image obtained, as presence of metallic objects causes artifacts on the image. The artifacts occur due to the presence of a ferromagnetic material in the magnetic field which causes the magnetic signal to be lost thus, creating an artifact on the image.
The primary component of the dental implants is Grade IV CpTi (Ticp), which has a very small proportion of ferromagnetic component (Iron) –0.05%, hence, producing minimal to no artifacts. Dental crowns on the other hand are made from a variety of base metals such as nickel, cobalt, chromium, molybdenum, and copper. A porcelain fused to metal crown comprises of nickel and Co-Cr alloy whereas a metal-free crown is made of zirconium and sodium aluminum silicate. Dental implants made of titanium pose no danger to the patient during MRI scans and implant-supported zirconium crowns can also be safely allowed during MRI scans. Implant-supported porcelain fused to metal crowns are usually safe although removal of long-span metal bridges or metal fused to porcelain bridges may be considered. The patient may feel a pull on the prosthetic component if nickel content is high in the crown and dislodgment may occur, however, an implant-supported crown made completely porcelain is safe to undergo MRI scanning. Metals such as gold, nickel, and Co-Cr are ferromagnetic metals that cause artifacts on the images but zirconium being nonferromagnetic does not cause any artifacts on an MRI. Klinke et al. carried out an in vitro study in which he reported that ceramics used in dentistry do not cause any artifacts but the majority of the metal alloys used cause artifacts. They also reported artifacts caused by certain composites containing Ytterbium trifluoride.
The dental and medical professionals framing the study population for the current survey exhibited a lack of knowledge of effect of implant (titanium) and implant-supported crowns (gold, nickel alloy, zirconium, Co-Cr) and bridge on the image quality of MRI. Costa et al. performed a retrospective study, where they identified 70 MRI scans with artifacts due to the presence of metallic objects. Objects responsible for the artifacts were identified as dental crowns (Gold) or titanium implants or metallic orthodontic appliances. They reported that 78% of artifacts were caused by orthodontic appliances, 18% by titanium implants and 4% metallic (gold) crowns. This indicates that though dental implants themselves cause minimal to no artifacts the implant-supported crowns that consist of metal may cause the formation of slight artifacts.
Blankenstein et al. reported that steel causes a wide range of artifact sizes (10–74 mm) and titanium, Co-Cr and ceramic produced an artifact of <20 mm.
Smeets et al. reported that zirconium implants cause significantly smaller artifacts as compared to titanium implants. Hilgenfeld et al. studied the artifacts produced by different types of metal crowns over titanium and zirconium implants. The fewest artifacts were found with the Zr crown and a Zr implant, slightly larger artifacts were seen with PFM precious alloy, porcelain fused to Zr and Zr alone with a titanium implant. Unfavorable artifacts were seen with crown containing nonprecious alloys and titanium implant.
In the current survey, it was observed that most dentists and radiologists though aware of the effects of MRI on dental implants, lacked complete knowledge on the effects of the dental implants and materials on the image quality of MRI.
Mathew et al. conducted a survey among dentists to evaluate their awareness about MRI and their interactions with restorative dental materials and concluded similar results that suggested that a majority of dentists perceived that dental materials can produce artifact in MR imaging. The patients undergoing MRI, especially with titanium implants should be educated and motivated to avoid fear while undergoing the scanning. The safety of the implant should be mentioned by the manufacturing company at the time of packaging.
| Conclusion|| |
Patients with dental implants can safely undergo MRI without any adverse effects to the patient. Majority of the dental materials such as titanium, titanium alloys, zirconium dioxide, nickel–titanium, and gold alloys cause low-to-moderate artifacts and stainless steel and Co-Cr alloys cause significant artifacts. Responses by various professionals suggest that the majority of them have appropriate knowledge about the magnetic nature of the dental implants as well as its biosafety in context with MRI. Even with limitations in the study such as small study population lack of open-ended questions about specific opinions of clinicians, mixed reviews regarding the effect of different metals on MR image quality suggest that there is scope for further increasing knowledge and awareness about the dental materials and how they interact with MRI to be able to make decisions in practice without dilemmas.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]