Alfaro David P, Ruse N Dorin, Carvalho Ricardo M, Wyatt Chris C
Faculty of Dentistry, The University of British Columbia, Vancouver, Canada.
J Prosthodont. 2015 Jul;24(5):381-6. doi: 10.1111/jopr.12274. Epub 2015 Mar 5.
The aim of this study was to compare the internal fit of lithium disilicate crowns fabricated using digital technology with those fabricated by conventional means.
Forty-five lithium disilicate crowns were fabricated: 15 using digital impression and computer-aided design/computer-aided machining technique (group 1), 15 from the same digital impressions, but using a conventional die and laboratory fabrication process (group 2), and 15 using a conventional poly (vinyl siloxane) (PVS) impression and laboratory fabrication process (group 3). Tooth #15 was prepared for all-ceramic restoration on an ivorine typodont, which was digitized and a replica milled in zirconia to serve as master model. The master zirconia model was used for the impression procedures. Duplicate dies of the master zirconia die were made in polyurethane, enabling the internal fit of each crown to be evaluated using X-ray microcomputed tomography. The total volume of the internal space between the crown and die, the mean and maximum thickness of this space, and the percentage of the space that was at or below 120 μm thickness was calculated for each group and statistically tested for significant difference using one-way ANOVA, with post hoc Scheffé analysis.
Group 1 crowns resulted in a smaller volume of internal space (12.49 ± 1.50 mm(3)) compared to group 2 (15.40 ± 2.59 mm(3) ) and to those of group 3 (18.01 ± 2.44 mm(3)). The mean thickness of the internal space for group 1 (0.16 ± 0.01 mm) and for group 2 (0.17 ± 0.03 mm) was significantly lower than that of group 3 (0.21 ± 0.03 mm). The average percentage of the internal space of a thickness of 120 μm and below was different between the three groups: 46.73 ± 5.66% for group 1, 37.08 ± 17.69% for group 2, and 22.89 ± 9.72% for group 3. Three-dimensional renderings of the internal space were also created.
The results of this study suggested that pressed and milled IPS e. max crowns from LAVA COS digital impressions had a better internal fit to the prepared tooth than pressed IPS e.max crowns from PVS impressions in terms of total volume of internal space, average thickness of internal space, and percentage of internal space at or below 120 μm.
本研究旨在比较使用数字技术制作的二硅酸锂全冠与传统方法制作的二硅酸锂全冠的内部适合性。
制作45个二硅酸锂全冠：15个采用数字印模和计算机辅助设计/计算机辅助加工技术制作（第1组），15个来自相同的数字印模，但采用传统代型和实验室制作工艺（第2组），15个采用传统的聚（乙烯基硅氧烷）（PVS）印模和实验室制作工艺（第3组）。在一个象牙色人工牙列模型上对15号牙进行全瓷修复预备，将其数字化，并在氧化锆中铣削一个复制件作为母模。母氧化锆模型用于印模程序。在聚氨酯中制作母氧化锆代型的复制代型，以便使用X射线微计算机断层扫描评估每个全冠的内部适合性。计算每组全冠与代型之间内部空间的总体积、该空间的平均厚度和最大厚度，以及厚度在120μm及以下的空间百分比，并使用单因素方差分析进行统计学显著性差异检验，采用事后Scheffé分析。
与第2组（15.40±2.59mm³）和第3组（18.01±2.44mm³）相比，第1组全冠的内部空间体积较小（12.49±1.50mm³）。第1组（0.16±0.01mm）和第2组（0.17±0.03mm）内部空间的平均厚度显著低于第3组（0.21±0.03mm）。三组之间厚度为120μm及以下的内部空间平均百分比不同：第1组为46.73±5.66%，第2组为37.08±17.69%，第3组为22.89±9.72%。还创建了内部空间的三维渲染图。
本研究结果表明，就内部空间总体积、内部空间平均厚度以及厚度在120μm及以下的内部空间百分比而言，来自LAVA COS数字印模的压制和铣削IPS e.max全冠与预备牙的内部适合性优于来自PVS印模的压制IPS e.max全冠。
