The effect of 1.5 T and 3 T magnetic resonance imaging on microleakage of amalgam restorations

Abstract

The aim of this article is to compare the effects of 1.5 T and 3 T MRI on microleakage of amalgam restorations. A total of 90 extracted molar teeth were used in this study. Amalgam was used to restore standard Class V preparations (5 × 3 × 2 mm). Following the restoration, the teeth were divided into three groups according to magnetic resonance imaging (MRI) protocol (Group I: Control, Group II: 1.5 T MRI, and Group III: 3 T MRI). A total of 6,000 thermal cycles at 5°C–55°C were applied on all samples. Microleakage values were measured in millimeters using the ImageJ program. Microleakage values were higher in the gingival region compared to the occlusal region in all groups and the differences were statistically significant (p < .05). Microleakage values were not statistically different among the groups in the occlusal region (p > .05), while there were statistically significant differences among the groups with respect to microleakage values in the gingival region (p < .01). The highest mean microleakage amount in the gingival region was measured in Group III (1.192 ± 0.941 mm). This was followed by Group II (0.519 ± 0.813 mm) and Group I (0.347 ± 0.726 mm), respectively. Within the limitations of this in vitro study, we observed that higher microleakage values in amalgam restored teeth in which were exposed to MRI procedure. We also found that the teeth exposed to the stronger magnetic field showed higher microleakage amount.

No Increased Mercury Release from Dental Restorations at 1.5T, 3T, or 7T MRI

“…In searching the literature, it became apparent that research on this issue was limited not only at 7T but also at lower field strengths, particularly 3T. [5][6][7][8][9][10][11][12][13] The only studies investigating the effects of 3T MRI on dental amalgam evaluated microleakage rather than mercury excretion based on dye visualization under light microscopy 8,12,13 or evaluated isolated amalgam or amalgam within hydroxyapatite disks instead of human dental restorations. 10,11 The correlation between these findings and mercury release from dental restorations is unknown.…”

“…This was of particular interest to us, as our institution had recently installed a 7T unit for clinical use. In searching the literature, it became apparent that research on this issue was limited not only at 7T but also at lower field strengths, particularly 3T 5–13 . The only studies investigating the effects of 3T MRI on dental amalgam evaluated microleakage rather than mercury excretion based on dye visualization under light microscopy 8,12,13 or evaluated isolated amalgam or amalgam within hydroxyapatite disks instead of human dental restorations 10,11 .…”