Abstract：
OBJECTIVE: Denture fabrication has shifted from traditional heat-processed and auto-polymerizing materials to computer-aided design and computer-aided manufacturing (CAD-CAM) milled and printed materials. The monomer in traditional materials can induce an allergic reaction in some patients. With the rise in the edentulous population and increasing demand for the fabrication of dentures, these newer materials should be studied for monomer leaching. The purpose of this study was to evaluate the ratio of residual monomer in materials being used for denture bases: CAD-milled polymethylmethacrylate (PMMA), printed denture base resin, heat-processed PMMA, and auto-polymerizing PMMA comparatively.
METHODS: Milled, printed, heat-activated, and auto-polymerizing denture base specimens (n = 3 for each group, each test run three times) were fabricated according to manufacturer recommendations. Specimens were first immersed in deuterated chloroform (CDCl3), a deuterated organic solvent, to evaluate monomer leaching and to observe physical properties of the materials. NMR spectroscopy was used to evaluate the dissolution of materials and residual monomer to crosslinked polymer ratios at 1, 4, and 9 days. A second group of specimens was then immersed in deuterium oxide (D2O) to evaluate if the residual monomers would leach out of the system. The solution was then analyzed using nuclear magnetic resonance (NMR) spectroscopy for 1 month. The deuterated forms of chloroform (CDCl3) and water (D2O) were used to enable sample characterization by NMR.
RESULTS: While the heat-processed, auto-polymerizing, and milled specimens possessed residual monomers, no significant monomer leaching was noted in the printed specimen, while immersed in CDCl3. Similarly, the printed specimen was most resistant to dissolution, as compared to the rest; dissolution of the specimen is indicative of little to no cross-linking. No detectable dissolution of monomer was seen when all specimens were immersed in D2O for up to 1 month.
CONCLUSIONS: Residual monomers were not found in the printed denture material in this study in either CDCl3 or D2O, whereas CAD-milled and traditionally processed denture bases still have residual monomers within their respective systems when immersed in organic solvent. None of the specimens tested leached monomers into D2O.
METHODS: Milled, printed, heat-activated, and auto-polymerizing denture base specimens (n = 3 for each group, each test run three times) were fabricated according to manufacturer recommendations. Specimens were first immersed in deuterated chloroform (CDCl3), a deuterated organic solvent, to evaluate monomer leaching and to observe physical properties of the materials. NMR spectroscopy was used to evaluate the dissolution of materials and residual monomer to crosslinked polymer ratios at 1, 4, and 9 days. A second group of specimens was then immersed in deuterium oxide (D2O) to evaluate if the residual monomers would leach out of the system. The solution was then analyzed using nuclear magnetic resonance (NMR) spectroscopy for 1 month. The deuterated forms of chloroform (CDCl3) and water (D2O) were used to enable sample characterization by NMR.
RESULTS: While the heat-processed, auto-polymerizing, and milled specimens possessed residual monomers, no significant monomer leaching was noted in the printed specimen, while immersed in CDCl3. Similarly, the printed specimen was most resistant to dissolution, as compared to the rest; dissolution of the specimen is indicative of little to no cross-linking. No detectable dissolution of monomer was seen when all specimens were immersed in D2O for up to 1 month.
CONCLUSIONS: Residual monomers were not found in the printed denture material in this study in either CDCl3 or D2O, whereas CAD-milled and traditionally processed denture bases still have residual monomers within their respective systems when immersed in organic solvent. None of the specimens tested leached monomers into D2O.
摘要：
目的：义齿制造已从传统的热处理和自动聚合材料转向计算机辅助设计和计算机辅助制造（CAD-CAM）铣削和打印材料。传统材料中的单体可以在一些患者中引起过敏反应。随着无牙人口的增加和假牙制造需求的增加，这些较新的材料应该进行单体浸出研究。这项研究的目的是评估用于义齿基托的材料中残留单体的比例：CAD研磨的聚甲基丙烯酸甲酯（PMMA），印花义齿基托树脂,热处理PMMA，和自聚合PMMA比较。
方法：铣削，已打印,热激活，和自动聚合义齿基托标本(每组n=3，每个测试运行三次)是根据制造商的建议制造的。首先将样品浸入氘代氯仿（CDCl3）中，氘代有机溶剂，评估单体浸出和观察材料的物理性质。NMR波谱用于评估在1、4和9天时材料的溶解和残余单体与交联聚合物的比率。然后将第二组样品浸入氧化氘(D2O)中以评估残余单体是否会从系统中浸出。然后使用核磁共振(NMR)光谱分析溶液1个月。氘代形式的氯仿(CDCl3)和水(D2O)用于通过NMR表征样品。
结果：当热处理时，自动聚合，和碾磨的标本有残留的单体，在打印的样本中没有发现明显的单体浸出，而浸入CDCl3。同样，打印的样本最耐溶解，与其余部分相比;样品的溶解表明几乎没有交联。当将所有样品浸入D2O中长达1个月时,没有观察到单体的可检测的溶解。
结论：在本研究中，CDCl3或D2O的印刷义齿材料中均未发现残留单体，而CAD研磨和传统加工的义齿基托在浸入有机溶剂中时仍在其各自的系统内具有残留单体。测试的样品均未将单体浸出到D2O中。
方法：铣削，已打印,热激活，和自动聚合义齿基托标本(每组n=3，每个测试运行三次)是根据制造商的建议制造的。首先将样品浸入氘代氯仿（CDCl3）中，氘代有机溶剂，评估单体浸出和观察材料的物理性质。NMR波谱用于评估在1、4和9天时材料的溶解和残余单体与交联聚合物的比率。然后将第二组样品浸入氧化氘(D2O)中以评估残余单体是否会从系统中浸出。然后使用核磁共振(NMR)光谱分析溶液1个月。氘代形式的氯仿(CDCl3)和水(D2O)用于通过NMR表征样品。
结果：当热处理时，自动聚合，和碾磨的标本有残留的单体，在打印的样本中没有发现明显的单体浸出，而浸入CDCl3。同样，打印的样本最耐溶解，与其余部分相比;样品的溶解表明几乎没有交联。当将所有样品浸入D2O中长达1个月时,没有观察到单体的可检测的溶解。
结论：在本研究中，CDCl3或D2O的印刷义齿材料中均未发现残留单体，而CAD研磨和传统加工的义齿基托在浸入有机溶剂中时仍在其各自的系统内具有残留单体。测试的样品均未将单体浸出到D2O中。
