Wang Yun-Ju, Chu Tien-Min G, Lin Wei-Shao
Department of Prosthodontic Dentistry, Hsinchu Cathay General Hospital, Hsinchu City, Taiwan.
Department of Biomedical Sciences and Comprehensive Care, Indiana University School of Dentistry, Indianapolis, IN.
J Prosthodont. 2023 Apr;32(S1):61-67. doi: 10.1111/jopr.13581. Epub 2022 Aug 17.
To investigate the translucency parameters of traditional, milled, and 3D-printed denture base materials at 3 different thicknesses and the color masking ability of each material against a metallic background between different thicknesses.
A traditional heat-polymerizing polymethylmethacrylate (PMMA) (H-Lucitone) material was used as the control group. Two milled pre-polymerized resin blocks (M-Lucitone and IvoBase) and five 3D-printed denture base materials (P-Lucitone, Dentca LP, Dentca OP, Formlabs, and Kulzer) were used as experimental groups. A total of 240 samples, (n = 30, per material) were fabricated to a final specimen dimension of 12×12 mm and in thicknesses of 1.0, 2.0, and 3.0 mm (n = 10 per thickness/material) according to the manufacturers' recommendations. The color coordinates (L*, a*, b*) in CIELab color space for all specimens placed against a white, black, and metallic background were measured with a spectrophotometer. The translucency parameters (TP ) at each thickness and the color differences between 1 mm and 2 mm (dE ) and between 2 mm and 3 mm (dE ) against the metallic background were calculated with the CIEDE2000 color matrix. Comparisons between the groups for differences in TP were made using One-way ANOVA separately for each thickness. Comparisons of groups and materials for differences in dE and dE were made using Two-way ANOVA and Fisher's Protected Least Significant Differences (α = 0.05).
The TP decreased with increasing thickness in all 8 material groups. All 3D-printed materials, except P-Lucitone, had higher TP than milled pre-polymerized resin materials (M-Lucitone and IvoBase), and traditional heat-polymerizing PMMA (H-Lucitone) material (P<.001) at all thicknesses. In the 1 mm and 2 mm thickness, heat-polymerizing acrylic resin (H-Lucitone) had the lowest TP , and in the 3 mm thickness, milled acrylic resin (M-Lucitone and IVOBase) had had lowest TP (p < 0.001). All material groups had significantly lower values of dE than dE (p < 0.001). The color differences dE were significantly lower in H-Lucitone, M-Lucitone, P-Lucitone, and IvoBase groups than in other materials, while the color difference of dE was significantly lower in H-Lucitone, P-Lucitone and Dentca LP than other materials (p < 0.001).
The results from this study provide clinicians and dental technicians with information regarding the selection of denture base materials to achieve desired color masking outcomes, according to available prosthetic space. Thicker prostheses significantly improved the color masking abilities of denture acrylic resins against a metallic background. In a thickness of 1 and 2 mm, the heat-polymerizing acrylic resin had a lower translucency parameter and better color masking ability. When the prosthesis thickness reached 3 mm, the milled acrylic resin had a lower translucency parameter and better color masking ability. When compared to the heat-polymerizing resin and milled acrylic resin materials, except for one 3D-printing resin (P-Lucitone), the color masking abilities of the remaining 3D-printing resin materials were low, regardless of prosthesis thickness.
研究传统、铣削和3D打印义齿基托材料在3种不同厚度下的半透明参数，以及每种材料在不同厚度下对金属背景的颜色掩盖能力。
使用传统热聚合聚甲基丙烯酸甲酯（PMMA）（H-Lucitone）材料作为对照组。两个铣削预聚合树脂块（M-Lucitone和IvoBase）和五种3D打印义齿基托材料（P-Lucitone、Dentca LP、Dentca OP、Formlabs和Kulzer）作为实验组。根据制造商的建议，共制作240个样本（每种材料n = 30），最终样本尺寸为12×12 mm，厚度为1.0、2.0和3.0 mm（每种厚度/材料n = 10）。使用分光光度计测量所有样本在白色、黑色和金属背景下的CIELab颜色空间中的颜色坐标（L*、a*、b*）。使用CIEDE2000颜色矩阵计算每种厚度下的半透明参数（TP）以及在金属背景下1 mm和2 mm之间（dE）和2 mm和3 mm之间（dE）的颜色差异。对于TP差异，分别对每种厚度使用单因素方差分析进行组间比较。对于dE和dE差异，使用双因素方差分析和Fisher's Protected Least Significant Differences（α = 0.05）进行组和材料间的比较。
在所有8个材料组中，TP随厚度增加而降低。除P-Lucitone外，所有3D打印材料在所有厚度下的TP均高于铣削预聚合树脂材料（M-Lucitone和IvoBase）以及传统热聚合PMMA（H-Lucitone）材料（P <.001）。在1 mm和2 mm厚度时，热聚合丙烯酸树脂（H-Lucitone）具有最低的TP，在3 mm厚度时，铣削丙烯酸树脂（M-Lucitone和IVOBase）具有最低的TP（p < 0.001）。所有材料组的dE值均显著低于dE（p < 0.001）。H-Lucitone、M-Lucitone、P-Lucitone和IvoBase组的颜色差异dE显著低于其他材料，而H-Lucitone、P-Lucitone和Dentca LP的dE颜色差异显著低于其他材料（p < 0.001）。
本研究结果为临床医生和牙科技术人员提供了有关根据可用修复空间选择义齿基托材料以实现所需颜色掩盖效果的信息。较厚的修复体显著提高了义齿丙烯酸树脂对金属背景的颜色掩盖能力。在1和2 mm厚度时，热聚合丙烯酸树脂具有较低的半透明参数和较好的颜色掩盖能力。当修复体厚度达到3 mm时，铣削丙烯酸树脂具有较低的半透明参数和较好的颜色掩盖能力。与热聚合树脂和铣削丙烯酸树脂材料相比，除一种3D打印树脂（P-Lucitone）外，其余3D打印树脂材料的颜色掩盖能力较低，与修复体厚度无关。
