Naina Himaja, Nandini Vidyashree V, Kumar Dilip M, Marimuthu Russia, Boruah Shiney, Raj Naveen S
Prosthodontics, Sri Ramaswamy Memorial (SRM) Kattankulathur Dental College and Hospital, Chengalpattu, IND.
Cureus. 2024 Jul 20;16(7):e64971. doi: 10.7759/cureus.64971. eCollection 2024 Jul.
Aim The aim of this study is to evaluate and compare the microhardness and polymerization shrinkage of polymethyl methacrylate reinforced with residual zirconia. Materials and methods A total of 360 resin samples were fabricated, with dimensions of 12 mm × 12 mm × 3 mm and 12 mm × 8 mm × 6 mm. Zirconia dust (40% by weight) was added to 180 of these samples. The study included four groups: Group A (autopolymerizing acrylic resin), Group H (heat-polymerizing acrylic resin), Group ZA (autopolymerizing acrylic resin with zirconia dust), and Group ZH (heat-polymerizing acrylic resin with zirconia dust). Each group consisted of 90 samples, with 45 samples used for evaluating microhardness and 45 samples for assessing polymerization shrinkage. Results Group ZH exhibited the highest microhardness at 6.06 ± 0.31 GPa. It also recorded the lowest shrinkage values, measuring 52.11 ± 3.21 mm³. Tukey's honestly significant difference test revealed that microhardness was significantly higher in Group ZA (4.53 ± 0.29 GPa) compared to Group A (3.51 ± 0.25 GPa). However, Group H (5.42 ± 0.26 GPa) demonstrated greater hardness than Group ZA. Regarding shrinkage, the addition of zirconia dust resulted in reduced values, with Group ZA (73.93 ± 3.55 mm³) showing less shrinkage compared to Group A (91.9 ± 6.38 mm³). Similarly, Group ZH (52.11 ± 3.21 mm³) had lower shrinkage than Group H (66.71 ± 5.97 mm³). Group A exhibited the highest shrinkage among all the groups. Conclusion Within the limitations of this study, it can be concluded that there is an increase in hardness and a decrease in shrinkage values of the resin with the addition of zirconia dust in heat and autopolymerizing acrylic resin used for the fabrication of provisional restorations. Zirconia-incorporated heat-activated resin showed superior microhardness and decreased shrinkage values. Although the addition of residual zirconia to autopolymerized samples demonstrated better hardness, it was observed that pure heat-polymerized samples showed greater hardness. Reusing computer-aided design and computer-aided manufacturing powder waste can cut down on economic losses and aid in environmental sustainability.
目的 本研究旨在评估和比较残余氧化锆增强的聚甲基丙烯酸甲酯的显微硬度和聚合收缩率。
材料与方法 共制备了360个树脂样本，尺寸为12 mm×12 mm×3 mm和12 mm×8 mm×6 mm。其中180个样本添加了40%（重量）的氧化锆粉尘。该研究包括四组：A组（自凝丙烯酸树脂）、H组（热凝丙烯酸树脂）、ZA组（含氧化锆粉尘的自凝丙烯酸树脂）和ZH组（含氧化锆粉尘的热凝丙烯酸树脂）。每组由90个样本组成，其中45个样本用于评估显微硬度，45个样本用于评估聚合收缩率。
结果 ZH组的显微硬度最高，为6.06±0.31 GPa。其收缩率值也最低，为52.11±3.21 mm³。Tukey真实显著差异检验显示，ZA组（4.53±0.29 GPa）的显微硬度显著高于A组（3.51±0.25 GPa）。然而，H组（5.42±0.26 GPa）的硬度高于ZA组。关于收缩率，添加氧化锆粉尘导致收缩率值降低，ZA组（73.93±3.55 mm³）的收缩率低于A组（91.9±6.38 mm³）。同样，ZH组（52.11±3.21 mm³）的收缩率低于H组（66.71±5.97 mm³）。A组在所有组中收缩率最高。
结论 在本研究的局限性内，可以得出结论，在用于制作临时修复体的热凝和自凝丙烯酸树脂中添加氧化锆粉尘会使树脂的硬度增加，收缩率值降低。含氧化锆的热激活树脂显示出优异的显微硬度和降低的收缩率值。虽然向自凝样本中添加残余氧化锆显示出更好的硬度，但观察到纯热凝样本的硬度更大。重复使用计算机辅助设计和计算机辅助制造的粉末废料可以减少经济损失并有助于环境可持续性。
