de Paula Silveira Alessandra C, Chaves Sacha B, Hilgert Leandro A, Ribeiro Ana Paula D
Graduate student, School of Health Sciences, University of Brasília, Brasília, Brazil.
Associate Professor, Department of Genetics and Morphology, Institute of Biology, University of Brasília, Brasília, Brazil.
J Prosthet Dent. 2017 Mar;117(3):386-392. doi: 10.1016/j.prosdent.2016.07.017. Epub 2016 Sep 24.
The precision of fit of chairside computer-aided design and computer-aided manufacturing (CAD-CAM) complete crowns is affected by digital impression and restorative material.
The purpose of this in vitro study was to evaluate by microcomputed tomography (μCT) the marginal and internal adaptation of composite resin and ceramic complete crowns fabricated with 2 different intraoral cameras and 2 restorative materials.
Ten extracted human third molars received crown preparations. For each prepared molar, 2 digital impressions were made with different intraoral cameras of the CEREC system, Bluecam and Omnicam. Four groups were formed: LB (Lava Ultimate+Bluecam), EB (Emax+Bluecam), LO (Lava Ultimate+Omnicam), and EO (Emax+Omnicam). Before measuring the precision of fit, all crowns were stabilized with a silicone material. Each unit (crown + prepared tooth) was imaged with μCT, and marginal and internal discrepancies were analyzed. For the 2D analysis, 120 measurements were made of each crown for marginal adaptation, 20 for marginal discrepancy (MD), and 20 for absolute marginal discrepancy (AMD); and for internal adaptation, 40 for axial space (AS) and 40 for occlusal space (OS). After reconstructing the 3D images, the average internal space (AIS) was calculated by dividing the total volume of the internal space by the contact surface. Data were analyzed with 2-way ANOVA and quantile regression.
Regarding marginal adaptation, no significant differences were observed among groups. For internal adaptation measured in the 2D evaluation, a significant difference was observed between LO and EO for the AS variable (Mann-Whitney test; P<.008). In assessment of AIS by the 3D reconstruction, LB presented significantly lower values than the other groups (Tukey post hoc test; P<.05). Bluecam presented lower values of AIS than Omnicam, and composite resin crowns showed less discrepancy than did ceramic crowns.
The marginal adaptations assessed in all groups showed values within the clinically accepted range. Moreover, the composite resin blocks associated with the Bluecam intraoral camera demonstrated the best results for AIS compared with those of the other groups.
椅旁计算机辅助设计与计算机辅助制造（CAD-CAM）全冠的贴合精度受数字印模和修复材料的影响。
本体外研究的目的是通过微型计算机断层扫描（μCT）评估用2种不同的口内相机和2种修复材料制作的复合树脂和陶瓷全冠的边缘及内部适合性。
选取10颗拔除的人类第三磨牙进行牙冠预备。对于每颗预备好的磨牙，使用CEREC系统的不同口内相机Bluecam和Omnicam制作2个数字印模。形成四组：LB（Lava Ultimate+Bluecam）、EB（Emax+Bluecam）、LO（Lava Ultimate+Omnicam）和EO（Emax+Omnicam）。在测量贴合精度之前，所有全冠均用硅酮材料固定。每个单元（全冠+预备牙）用μCT成像，并分析边缘和内部差异。对于二维分析，对每个全冠进行120次边缘适合性测量、20次边缘差异（MD）测量和20次绝对边缘差异（AMD）测量；对于内部适合性，进行40次轴向间隙（AS）测量和40次咬合间隙（OS）测量。在重建三维图像后，通过将内部空间的总体积除以接触面积来计算平均内部间隙（AIS）。数据采用双向方差分析和分位数回归进行分析。
关于边缘适合性，各组之间未观察到显著差异。对于二维评估中测量的内部适合性，在AS变量上，LO和EO之间观察到显著差异（曼-惠特尼检验；P<.008）。在通过三维重建评估AIS时，LB组的值显著低于其他组（Tukey事后检验；P<.05）。Bluecam的AIS值低于Omnicam，复合树脂全冠的差异小于陶瓷全冠。
所有组评估的边缘适合性值均在临床可接受范围内。此外，与Bluecam口内相机相关的复合树脂块在AIS方面显示出比其他组更好的结果。
