Statement of problem

Magnetic resonance imaging (MRI) is a cross-sectional imaging technique that is widely used in the detection of pathologies in the head and neck region. However, information is lacking about the effect of MRI imaging on the clinical success of fixed partial dentures (FPDs).

Purpose

The purpose of this in vitro study was to analyze the effect of MRI on the physical properties and ceramic adhesion of FPD substructure materials.

Material and methods

Three hundred disk (12×1 mm) and 255 rectangular (4×2×2 mm) specimens were prepared with different fabrication techniques for 5 experimental groups: direct metal laser sintering (DMLS) with Co-Cr and Ti; casting with Co-Cr and Ni-Cr; and milling with ZrO₂. After ceramic application, the disk specimens were subjected to aging and divided into 3 subgroups (n=20) with exposure to 1.5-T and 3.0-T MRI brain scans for 30 minutes and no exposure (control). The shear bond strength (SBS) of the specimens was measured by using a universal testing machine. The rectangular specimens were exposed to MRI with the same procedure, and the nanostructure of the specimens was analyzed with the small-angle X-ray scattering (SAXS) method to detect the nanoscale structural effects of MRI. The average surface roughness (Ra) and Vickers microhardness (Vh) were also measured for complementary analyses. SBS, Ra, and Vh values were statistically analyzed by 1-way ANOVA and the Tukey honestly significant difference test (α=.05)_.

Results

The SBS (MPa) of casting groups (P<.001) and DMLS with the Co-Cr group (P<.05) were significantly affected by MRI exposures. The significant differences were seen on the Ra of casting (P<.001) and DMLS with Co-Cr (P<.05) and Ti (P<.01) groups. Also, the Vh of the casting with Co-Cr (P<.001) and Ni-Cr (P<.01) groups showed significant differences. The SAXS analysis indicated that the physical properties of materials were influenced by MRI exposure.

Conclusions

The results indicated that MRI applications affected the metal-ceramic adhesion of Co-Cr and Ni-Cr dental alloys produced by casting and the DMLS technique.

中文翻译：

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1.5-T和3.0-T磁共振成像对假体下部结构的陶瓷附着力和物理性能的影响

问题陈述

磁共振成像（MRI）是一种横截面成像技术，广泛用于检测头颈部区域的病变。但是，缺乏有关MRI成像对固定局部义齿（FPD）临床成功的影响的信息。

目的

这项体外研究的目的是分析MRI对FPD子结构材料的物理性能和陶瓷粘附的影响。

材料与方法

用5种不同的制造技术制备了300个圆盘（12×1毫米）和255个矩形（4×2×2毫米）的样品：5个实验组：用Co-Cr和Ti的直接金属激光烧结（DMLS）；用Co-Cr和Ti进行的直接金属激光烧结（DMLS）；以及用Cr2 +进行的激光烧结。用钴铬和镍铬铸造；ZrO ₂研磨。施加陶瓷后，将圆盘标本进行老化，并分成3个亚组（n = 20），分别暴露于1.5-T和3.0-T MRI脑部扫描30分钟且不暴露（对照）。通过使用万能试验机测量样品的剪切粘合强度（SBS）。以相同的步骤将矩形样品暴露于MRI，并使用小角X射线散射（SAXS）方法分析样品的纳米结构，以检测MRI的纳米级结构效应。还对平均表面粗糙度（Ra）和维氏显微硬度（Vh）进行了补充分析。通过1次方差分析和Tukey诚实的显着差异检验（α= .05）对SBS，Ra和Vh值进行统计学分析_。

结果

MRI暴露显着影响铸件组的SBS（MPa）（P <.001）和Co-Cr组的DMLS（P <.05）。铸件的Ra（P <.001）和Co-Cr（P <.05）和Ti（P <.01）组的DMLS的差异显着。同样，具有Co-Cr（P <.001）和Ni-Cr（P <.01）组的铸件的Vh显示出显着差异。SAXS分析表明，材料的物理性能受MRI暴露的影响。

结论

结果表明，MRI应用影响了铸造和DMLS技术生产的Co-Cr和Ni-Cr牙科合金的金属陶瓷附着力。