Accuracy of customized abutment data superimposition according to the extent of scanning area.

PURPOSE: To evaluate the accuracy of superimposition of customized abutment library data onto scanned abutment data according to the extent of the scanning area. MATERIALS AND METHODS: A patient model was fabricated by a 3D printer (Probo, DIO Implant), and a customized abutment was fabricated using a four-axis milling machine (ARUM 4X-100, Doowon). The customized abutment library data were generated using a laboratory scanner (E3, 3Shape) for superimposition after intraoral scanning. A cone-shaped structure was embedded into the library data at the center of the connection part. The customized abutment was placed on the model, and the model was scanned using a laboratory scanner to produce reference data. Three different test group datasets were generated using intraoral scanner and computer-aided design software: (1) fully scanned customized abutment; (2) insufficiently scanned proximal surface; and (3) insufficiently scanned margin, assuming challenging intraoral conditions. The library data were superimposed onto each test group; thereafter, the distance and angle between the reference and test group data were analyzed by using the embedded cone. Statistical analysis was performed using one-way analysis of variance followed by post hoc Tukey test for multiple comparisons. RESULTS: There were no statistically significant differences between the mean distance and angle of the test group data (with three different scanning areas) and the reference data. CONCLUSION: The superimposition technique can be used clinically, not only when the scan is complete, but also when the proximal surface and margin of the customized abutment have been scanned incompletely.

Polymer Solution Route for Synthesis of Nano-Sized, SiO2 Based Ceramic Powders.

Nano-sized SiO2 based powders were fabricated by a polymer solution technique. Nitrate metal sources and Ludox series silica sol were dissolved in D.I. water and then polyvinyl alcohol solution was added as a polymeric carrier. The metal cations were dispersed well in the solution and a homogeneous polymeric network was formed. The organic-inorganic precursor gels were turned to a porous powder with expanded volume through an explosive oxidation reaction during calcination process. The polymer molecular weight, polymer content and heating rate affected the particle agglomeration and size. The reaction between oxygen and unstable metal cations resulted in a vigorous exothermic reaction and simultaneously the reaction created extensive voids, which accompanied soft powders. The porous powders were crystallized at relatively lower temperature, and easily ground to a very fine powder having nano-sized particles. The crystalline development was also dependent on the polymer type, and the weak hydrogen bonding by optimum polymer content promoted homogeneous entrapment between the -(OH) hydroxyl groups and cations, which are solvates by water molecules.

Fabrication of In Vitro Cancer Microtissue Array on Fibroblast-Layered Nanofibrous Membrane by Inkjet Printing.

In general, a drug candidate is evaluated using 2D-cultured cancer cells followed by an animal model. Despite successful preclinical testing, however, most drugs that enter human clinical trials fail. The high failure rates are mainly caused by incompatibility between the responses of the current models and humans. Here, we fabricated a cancer microtissue array in a multi-well format that exhibits heterogeneous and batch-to-batch structure by continuous deposition of collagen-suspended Hela cells on a fibroblast-layered nanofibrous membrane via inkjet printing. Expression of both Matrix Metalloproteinase 2 (MMP2) and Matrix Metalloproteinase 9 (MMP9) was higher in cancer microtissues than in fibroblast-free microtissues. The fabricated microtissues were treated with an anticancer drug, and high drug resistance to doxorubicin occurred in cancer microtissues but not in fibroblast-free microtissues. These results introduce an inkjet printing fabrication method for cancer microtissue arrays, which can be used for various applications such as early drug screening and gradual 3D cancer studies.

Three-dimensional migration of neutrophils through an electrospun nanofibrous membrane.

The study of immune cell migration is important for understanding the immune system network, which is associated with the response to foreign cells. Neutrophils act against foreign cells before any other immune cell, and they must be able to change shape and squeeze through narrow spaces in the extracellular matrix (ECM) during migration to sites of infection. Conventional in vitro migration assays are typically performed on two-dimensional substrates that fail to reproduce the three-dimensional (3-D) nature of the ECM. Here we present an in vitro method to simulate the 3-D migration of neutrophils using an electrospun nanofibrous membrane, which is similar to the ECM in terms of morphology. We examined the properties of neutrophil movement and the effects of gravity and the presence of IL-8, which has been widely used as a chemotactic attractant for neutrophils. The number of neutrophils passing through the nanofibrous membrane were higher, and their movement was more active in the presence of IL-8. Also, we confirmed that neutrophils could migrate against gravity toward IL-8 through a nanofibrous membrane.