Naji Ghassan Abdul-Hamid
Department of Prosthetic Dentistry, College of Dentistry, University of Baghdad, Bab-Almoadham, P.O. Box 1417, Baghdad, Iraq.
Int J Dent. 2020 Sep 9;2020:8432143. doi: 10.1155/2020/8432143. eCollection 2020.
The process of repairing the fractured nylon denture bases and addition of acrylic teeth to the previously worn nylon denture bases has not been widely studied. This study aims to assess the transverse strength of nylon denture bases repaired by various resin materials, different curing techniques, and types of surface treatments. . One hundred fifty thermoplastic nylon denture base samples were fabricated using plastic patterns measuring 65 × 10 × 2.5 mm (length, width, and thickness, respectively). These samples were then divided into three equal groups. Fifty samples were repaired by microwave heat-polymerization, fifty samples were repaired using the Ivomate autopolymerization, and the other fifty were repaired using light-polymerized acrylic resin. Each of these three groups was further divided into five subgroups of ten samples based on the type of surface treatment. The samples in the control group did not undergo any surface treatment, and the other four groups were chemically surface treated with monomer, acetone, ethyl acetate, and isopropanol, respectively. A three-point bending test was used to calculate the transverse strength values of the samples. Fourier transform infrared (FTIR) analysis was conducted to determine the component of functional groups between the polyamide nylon base and poly(methyl-methacrylate) PMMA repair materials. A polarizing microscope was utilized to investigate the mode of failure at the fracture surfaces. . The collected data were analyzed with one-way ANOVA and Sidak's multiple comparison test to show the differences among different groups. For surface treatments, the highest transverse strength values were obtained by monomer-treated samples (18.29 N/mm); however, the lowest values were obtained in non-surface treated samples (5.58 N/mm). While for repair techniques, the highest transverse strength values were obtained by microwave processing, followed by Ivomate and then the light-cured polymerization. The means were found to be significant ( < 0.001). FTIR analysis shows the presence of hydrogen bonding which is due to the ester and amid groups which enhance the bond strength of the surface-treated samples. The interface of the polarizing microscope images revealed a cohesive fracture within repair materials rather than the adhesive nature. . The microwave-polymerized resin was considered as the most effective repair technique along with monomer chemical etchant which creates a tight adhesion between PMMA and nylon denture base in comparison to other groups.
修复断裂的尼龙义齿基托以及在先前磨损的尼龙义齿基托上添加丙烯酸树脂牙的过程尚未得到广泛研究。本研究旨在评估采用各种树脂材料、不同固化技术和表面处理类型修复的尼龙义齿基托的横向强度。使用尺寸为65×10×2.5毫米（分别为长度、宽度和厚度）的塑料模具制作了150个热塑性尼龙义齿基托样本。然后将这些样本平均分为三组。50个样本通过微波热聚合进行修复，50个样本使用Ivomate自凝树脂进行修复，另外50个样本使用光固化丙烯酸树脂进行修复。根据表面处理类型，这三组中的每一组又进一步分为五个亚组，每组10个样本。对照组的样本未进行任何表面处理，其他四组分别用单体、丙酮、乙酸乙酯和异丙醇进行化学表面处理。采用三点弯曲试验计算样本的横向强度值。进行傅里叶变换红外（FTIR）分析以确定聚酰胺尼龙基托与聚（甲基丙烯酸甲酯）PMMA修复材料之间官能团的成分。利用偏光显微镜研究断裂表面的失效模式。收集的数据采用单因素方差分析和Sidak多重比较检验进行分析，以显示不同组之间的差异。对于表面处理，经单体处理过的样本获得了最高的横向强度值（18.29 N/mm）；然而，未进行表面处理的样本获得的值最低（5.58 N/mm）。而对于修复技术，微波处理获得了最高的横向强度值，其次是Ivomate自凝树脂，然后是光固化聚合。发现均值具有显著性（<0.001）。FTIR分析表明存在氢键，这是由于酯基和酰胺基增强了经表面处理样本的粘结强度。偏光显微镜图像的界面显示修复材料内部为内聚破坏而非粘结破坏。与其他组相比，微波聚合树脂与单体化学蚀刻剂一起被认为是最有效的修复技术，它能在PMMA和尼龙义齿基托之间形成紧密的粘结。
