Objective

To compare the mechanical and biological features of a polymethylmethacrylate (PMMA) disc for CAD/CAM prostheses (test samples, TG) with a traditional resin (control samples, CG).

Methods

Mechanical analysis was performed using Dynamic Mechanical Analysis (DMA) and Brillouin's micro-spectroscopy. Human keratinocyte morphology and adhesion were analyzed by scanning electronic microscopy (SEM), cytotoxicity by the MTT assay, apoptosis by flow cytometry and p53, p21 and bcl2 gene expression by real time PCR.

Results

TG exhibited a higher elastic modulus than CG (range 5100–5500 ± 114.3 MPa vs 3000–3300 ± 99.97 MPa). The Brillouin frequency was found at ω_B= (15.50 ± 0.05) GHz for TG and at ω_{B_1} = (15.50 ± 0.05) GHz and ω_{B_2} = (15.0 ± 0.1) GHz for CG where two peaks were always present independently of the sample point. SEM analysis revealed that keratinocytes on TG disks appeared to be flattened with lamellipodia. Keratinocytes on CG disks rose above the substrate with cytoplasmatic filaments. MTT viability data at 3 h and 24 h showed TG was significantly less cytotoxic than CG (p < 0.001). No significant differences emerged in apoptosis on CG and TG. Real-time PCR showed p53 expression increased after 3 h by about 9-fold in keratinocytes on TG (p < 0.001) and about 5-fold in those on CG (p < 0.001). High p53 expression persisted after 24 h on both disks. No significant variations were observed in p21 and bcl2 expression at any time-point.

Significance

PMMA resins, as used in CAD/CAM technology, displayed suitable biocompatible and mechanical properties for removable prostheses.

中文翻译：

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用于数字可移动假体的CAD / CAM PMMA树脂的生物力学表征

客观的

为了比较用于CAD / CAM假体的聚甲基丙烯酸甲酯（PMMA）盘（测试样品，TG）与传统树脂（对照样品，CG）的机械和生物学特性。

方法

力学分析是使用动态力学分析（DMA）和布里渊微镜进行的。通过扫描电子显微镜（SEM）分析人角质形成细胞的形态和粘附，通过MTT测定法分析细胞毒性，通过流式细胞术分析细胞凋亡，并通过实时PCR分析p53，p21和bcl2基因表达。

结果

TG的弹性模量比CG高（范围5100–5500±114.3 MPa和3000–3300±99.97 MPa）。布里渊频在ω发现_乙=（15.50±0.05）GHz的用于TG和在ω _{B_1} =（15.50±0.05）GHz和ω _{B_2}= CG的（15.0±0.1）GHz，其中始终存在两个与采样点无关的峰。SEM分析表明，TG盘上的角质形成细胞似乎已被片状脂膜弄平。CG盘上的角质形成细胞上升到具有细胞质细丝的基质上方。在3小时和24小时的MTT生存力数据显示，TG的细胞毒性明显低于CG（p <0.001）。CG和TG的凋亡无明显差异。实时PCR显示，TG后3小时后，p53表达在TG的角质形成细胞中增加了约9倍（p <0.001），而在CG时则增加了约5倍（p <0.001）。两个磁盘上24小时后，高p53表达仍然存在。在任何时间点均未观察到p21和bcl2表达的显着变化。

意义

CAD / CAM技术中使用的PMMA树脂对可拆卸假体具有合适的生物相容性和机械性能。