Restenosis Investigation of Two-Stent Placement in the Artery Bifurcation with Different Stenting Techniques Using Computational Fluid Dynamics Analysis

The in-stent restenosis may still occur in patients with a coronary bifurcation stenting. The purpose of this study is to investigate the restenosis effect in the relationships between the bifurcation angles of the coronary artery and three types of stenting techniques (T-stenting, Culotte, and Kissing techniques), for comparing two kinds of arterial shapes using computational fluid dynamics (CFD) analysis. The finite element models of two types of the coronary arteries were reconstructed using stereolithography (STL) data of an artificial artery from reverse engineering laser scanning, and then each artery was further modified to add three kinds of the bifurcation angles, including 80°, 113°, and 142°. The low TAWSS of the two arteries were mainly concentrated at the LCX branch; a more essential discovery was that the low TAWSS area ration was in proportion to the bifurcation angle. The smallest low TAWSS of the T-stenting and Kissing techniques was detected in the arteries A and B, respectively. Both Culotte and Kissing techniques always showed a higher OSI than the T-stenting, and a high OSI was meaningfully located at the LCX branch. The CFD study concluded that the large bifurcation angle of an artery using a long stent at the LCX side branch with the T-stenting technique has a high risk of stenting restenosis

Maxillary Skeletal Expansion with Monocortical and Bicortical Miniscrew Anchorage: A 3D Finite Element Study

The aim of the present study is to use a 3D finite element analysis to investigate and compare the transverse displacement and stress distribution between stainless steel miniscrews and titanium alloy miniscrews used for monocortical and bicortical anchorage during miniscrew-assisted rapid maxillary expansions. Skull models were constructed to depict expansion after and before midpalatal suture opening at varying miniscrew insertion depths in four clinical scenarios: monocortical, monocortical deepening, bicortical, and bicortical deepening. Finite element analyses of miniscrew properties, including transverse displacement and von Mises stress distribution, were performed for each clinical scenario. Peri-implant stress was lesser in both bicortical anchorage models compared to both monocortical models. Transverse displacement in the coronal and axial planes was also greater and more parallel in both bicortical models compared to both monocortical models. Transverse displacement and peri-implant stress did not significantly differ between monocortical and monocortical deepening models or between bicortical and bicortical deepening models. From a biomechanical perspective, the bicortical deepening miniscrew anchorage is preferable to monocortical and monocortical deepening anchorage, because bicortical anchorage induces less stress on the peri-implant bone. Consequently, bicortical deepening anchorage should be considered the preferred option in challenging clinical scenarios in which strong anchorage is required for maxillary skeletal expansion