OBJECTIVE: The current study aims to elucidate the two-way fluid-structure interaction (FSI) analysis of the blood flow and the effect of stenosis on hemodynamic parameters.
METHODS: A patient-specific 3D model of the left coronary artery was constructed based on computed tomography (CT) images. The blood is assumed to be incompressible, homogenous, and behaves as Non-Newtonian, while the artery is considered as a nonlinear elastic, anisotropic, and incompressible material. Pulsatile flow conditions were applied at the boundary. Two-way coupled FSI modeling approach was used between fluid and solid domain. The hemodynamic parameters such as the pressure, velocity streamline, and wall shear stress were analyzed in the fluid domain and the solid domain deformation.
RESULTS: The simulated results reveal that pressure drop exists in the vicinity of stenosis and a recirculation region after the stenosis. It was noted that stenosis leads to high wall stress. The results also demonstrate an overestimation of wall shear stress and velocity in the rigid wall CFD model compared to the FSI model.
MATERIALS AND METHODS: Forty Turkom-Cera ceramic disks (10 mm × 3 mm) were prepared and randomly divided into four groups. The disks were wet ground to 1000-grit and subjected to four surface treatments: (1) No treatment (Control), (2) sandblasting, (3) silane application, and (4) sandblasting + silane. The four groups of 10 specimens each were bonded with Panavia-F resin cement according to manufacturer's recommendations. The SBS was determined using the universal testing machine (Instron) at 0.5 mm/min crosshead speed. Failure modes were recorded and a qualitative micromorphologic examination of different surface treatments was performed. The data were analyzed using the one-way analysis of variance (ANOVA) and Tukey honestly significant difference (HSD) tests.
RESULTS: The SBS of the control, sandblasting, silane, and sandblasting + silane groups were: 10.8 ± 1.5, 16.4 ± 3.4, 16.2 ± 2.5, and 19.1 ± 2.4 MPa respectively. According to the Tukey HSD test, only the mean SBS of the control group was significantly different from the other three groups. There was no significant difference between sandblasting, silane, and sandblasting + silane groups.
CONCLUSION: In this study, the three surface treatments used improved the bond strength of resin cement to Turkom-Cera disks.
CLINICAL SIGNIFICANCE: The surface treatments used in this study appeared to be suitable methods for the cementation of glass infiltrated all-ceramic restorations.
METHODS: Sixty-five extracted maxillary incisors were decoronated, its canal was artificially flared and randomly categorized into group tFRC (tapered FRC post) (n = 22), mFRC (multi-FRC post) (n = 21), and DIS-FRC (direct individually shaped-FRC (DIS-FRC) post) (n = 22), which were further subdivided based on cementation resin. The posts were cemented and a standardized resin core was constructed. After thermocycling, the samples were loaded statically and the maximum load was recorded.
RESULTS: The load capacity of the maxillary central incisor was influenced by the different FRC post system and not the resin cement (p = 0.289), and no significant interaction was found between them. Group mFRC (522.9N) yielded a significantly higher load capacity compared to DIS-FRC (421.1N). Overall, a 55% favorable fracture pattern was observed, and this was not statistically significant.
CONCLUSION: Within the limitation of the study, it can be concluded that prefabricated FRC posts outperform DIS-FRC posts in terms of the load capacity of a maxillary central incisor with a simulated flared root canal. The cementation methods whether a self-adhesive or self-etch resin cement, was not demonstrated to influence the load capacity of a maxillary central incisor with a flared root canal. There were no significant differences between the favorable and non-favorable fracture when FRC post systems were used to restored a maxillary central incisor with a flared root canal.
METHODS: Silanated, titanated and pure NBT at 5% were incorporated in PMMA matrix. Neat PMMA matrix served as a control. NBT was sonicated in MMA prior to mixing with the PMMA. Curing was carried out using a water bath at 75°C for 1.5h and then at 100°C for 30min. NBT was characterised via Fourier transform-infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and Brunauer-Emmett-Teller (BET) analysis before and after surface modification. The porosity and fracture toughness of the PMMA nanocomposites (n=6, for each formulation and test) were also evaluated.
RESULTS: NBT was successfully functionalised by the coupling agents. The TCA exhibited the lowest percentage of porosity (0.09%), whereas silane revealed 0.53% porosity. Statistically significant differences in fracture toughness were observed among the fracture toughness values of the tested samples (p<0.05). While the fracture toughness of untreated samples was reduced by 8%, an enhancement of 25% was achieved after titanation. In addition, the fracture toughness of the titanated samples was higher than the silanated ones by 10%.
CONCLUSION: Formation of a monolayer on the surface of TCA enhanced the NBT dispersion, however agglomeration of silanated NBT was observed due to insufficient coverage of NBT surface. Such behaviour led to reducing the porosity level and improving fracture toughness of titanated NBT/PMMA composites. Thus, TCA seemed to be more effective than silane.
CLINICAL SIGNIFICANCE: Minimising the porosity level could have the potential to reduce fungus growth on denture base resin to be hygienically accepTable Such enhancements obtained with Ti-NBT could lead to promotion of the composites' longevity.