Oral Medicine Technology, University Hospital Bonn, Bonn, Germany.
Department of Fixed Prosthodontics, Faculty of Dentistry, Fayoum University, Faiyum, Egypt.
BMC Oral Health. 2023 Jul 4;23(1):448. doi: 10.1186/s12903-023-03184-8.
This study aimed to evaluate and compare the marginal gap using two different methods and the internal fit of 3D printed and zirconia crowns.
3Y-TZP zirconia crowns (n = 20) were manufactured using subtractive milling (group M) and 3D printed (group P). The marginal gap was measured at 60 points using vertical marginal gap technique (VMGT). On the other hand, the silicone replica technique (SRT) was used to evaluate the internal fit and was divided into 4 groups: marginal gap, cervical gap, axial gap, and occlusal gap where the thickness of light impression was measured at 16 references. The numerical data was tested for normality using Shapiro-Wilk's test. They were found to be normally distributed and were analyzed using an independent t-test.
Using VMGT, group P had significantly higher mean marginal gap values of 80 ± 30 µm compared to group M = 60 ± 20 µm (p < 0.001). Also, with the SRT, the marginal gap of group P (100 ± 10 µm) had significantly higher values compared to group M (60 ± 10 µm). The internal fit showed significant difference between the tested groups except for Axial Gap.
Although milled crowns showed better results. The 3D printed zirconia crowns offer clinically acceptable results in terms of marginal adaptation and internal fit. Both VMGT and SRT are reliable methods for the assessment of the marginal gap.
本研究旨在评估和比较两种不同方法的边缘间隙，并比较 3D 打印氧化锆冠和氧化锆冠的内部适合性。
使用减法铣削（组 M）和 3D 打印（组 P）制造 3Y-TZP 氧化锆冠。使用垂直边缘间隙技术（VMGT）在 60 个点测量边缘间隙。另一方面，硅橡胶复制技术（SRT）用于评估内部适合性，并分为 4 组：边缘间隙、颈缘间隙、轴面间隙和咬合间隙，在 16 个参考点测量光固化硅橡胶厚度。使用 Shapiro-Wilk 检验对数值数据进行正态性检验。结果表明，数据呈正态分布，采用独立 t 检验进行分析。
使用 VMGT，组 P 的平均边缘间隙值为 80±30μm，明显高于组 M（60±20μm）（p<0.001）。此外，使用 SRT，组 P 的边缘间隙（100±10μm）明显高于组 M（60±10μm）。内部适合性除轴向间隙外，各测试组之间存在显著差异。
尽管铣削冠具有更好的结果，但 3D 打印氧化锆冠在边缘适应性和内部适合性方面具有临床可接受的结果。VMGT 和 SRT 都是评估边缘间隙的可靠方法。
