Influence of needle design and irrigation depth in the presence of vapor lock: A computational fluid dynamics analysis in human oval roots with apical ramification.

This paper aims to study the removal of a vapor lock located in the apical ramification of an oval distal root of a human mandibular molar, simulating different needles and irrigation depths with computational fluid dynamic. A geometric reconstruction of the micro-CT of the molar shaped up to a WaveOne Gold Medium instrument was used. A vapor lock located in the apical 2 mm was incorporated. Geometries with positive pressure needles (side-vented [SV], flat or front-vented [FV] and notched [N]) and the EndoVac microcannula (MiC) were created to run the simulations. Irrigation key parameters (flow pattern, irrigant velocity, apical pressure, wall shear stress) and vapor lock removal were compared among the different simulations. Each needle behaved differently that is, FV removed the vapor lock from one ramification and had the highest apical pressure and shear stress values; SV removed the vapor lock in the main root canal but not in the ramification and reached the lowest apical pressure from the positive pressure needles; N was not able to completely remove the vapor lock and showed low apical pressure and shear stress; MiC removed the vapor lock from one ramification, had negative apical pressure and the lowest maximum shear stress. The main conclusion is that none of the needles showed complete removal of vapor lock. MiC, N, and FV were able to partially remove the vapor lock from one out of the three ramifications. However, SV needle was the only simulation that showed high shear stress with low apical pressure.

Clinical usefulness of serum angiotensin converting enzyme in silicosis.

INTRODUCTION: Silicosis is an irreversible and incurable disease. Preventive measures to eliminate exposure are the only effective way to reduce morbidity and mortality. In such situations, having a biomarker for early diagnosis or to predict evolution would be very useful in order to improve control of the disease. The elevation of serum angiotensin-converting enzyme (sACE) in silicosis has been described in previous studies, although its relationship with severity and prognosis is not clear. AIMS: To determine the levels of sACE in a cohort of patients with exposure to silica dust with and without silicosis, and to assess their impact on the prognosis of the aforementioned patients. METHOD: Prospective observational study on patients treated in a silicosis clinic from 2009 to 2018. sACE levels and pulmonary function tests were performed. Radiological progression was assessed in patients who had already had 2 X-rays of the thorax and / or two CT scans with at least a 1-year interval, from the time of inclusion in the study. RESULTS: A total of 413 cases of silicosis were confirmed, as well as 73 with exposure to silica dust but without silicosis. The mean sACE level for healthy subjects was 27.5±7.3U/L, for exposed patients without silicosis it was 49.6±24.2U/L, for simple silicosis it was 57.8±31,3U/L and for complicated silicosis it was 74.5±38.6U/L. Patients with a higher sACE generally progressed radiologically during follow-up (73.3±38.0 vs. 60.4±33.7; p<.001) and so the category of silicosis changed (73,9±38.1 vs. 62.5±34.6; p<.021). CONCLUSIONS: sACE was elevated in patients with silicosis, and the greater its severity, the higher it was, which is associated with disease progression measured radiologically or as a category change of silicosis.

Positive and negative pressure irrigation in oval root canals with apical ramifications: a computational fluid dynamics evaluation in micro-CT scanned real teeth.

AIM: To compare using computational fluid dynamics (CFD) the flow pattern, irrigant velocity, apical pressure and shear stress produced by negative (MiC) and positive pressure with different types of needles (side-vented (SV), front-vented (FV) and notched (N)) at two insertion depths in the apical ramification of oval root canals. METHODOLOGY: The micro-CT of a mandibular molar with an oval root canal with an apical ramification was used for computational analysis after preparation and geometric reconstruction. Geometries with the needles in two positions (1 and 3 mm from WL) were created to run the simulations. Key parameters of irrigation were displayed with CFD and compared. RESULTS: The penetration depth of the needle in the root canal strongly influenced shear stress and apical pressure. The three needles revealed that the highest shear stress, velocity and apical pressure were 1 mm from the WL and generated medium velocities. In N simulations, the fluid flow did not reach the apical ramification and the lowest shear stress values for positive pressure needles were found. The predominant axial component for FV revealed a different pattern of irrigation with high shear stress values and higher apical pressures than those exerted by other needles. SV simulations had generalized fluid flow in most of the main canal, the highest shear stress values and lower apical pressure than the threshold determined for risk of extrusion. MiC was associated with low velocity, shear stress and apical pressure. CONCLUSION: The SV needle demonstrated a combination of low positive pressure and high shear stress; while N had the lowest shear stress and FV the highest apical pressure. MiC generated fluid flow in part of the apical ramification with negative apical pressure values but low shear stress and velocity.

Preparation of antioxidant active films based on chitosan: diffusivity study of α-tocopherol into food simulants.

New active films based on chitosan and polycaprolactone blends and containing α-tocopherol were designed for food packaging applications. Mechanical properties, stability against temperature and swelling degree in 50 % ethanol (v/v) were evaluated. Migration kinetics of α-tocopherol from the developed films into butter and food simulants [50 % ethanol (v/v), 95 % ethanol (v/v), and isooctane] at different temperatures were studied. α-Tocopherol was quantified in the food simulants by means of high performance liquid chromatography with diode-array detection at 292 nm. The proposed method exhibited a good sensitivity with a limit of detection of 0.1 mg/L. The kinetics release of α-tocopherol was characterized by determining the partition and the diffusion coefficients by using a mathematical modeling based on Fick's Second Law. The diffusion coefficients obtained ranged between 1.03 × 10(-13) and 2.24 × 10(-12) cm(2)/s for 95 % ethanol (v/v) at 4 and 20 °C, respectively. Developed films maintained the antioxidant activity for more than 20 days.

DNA barcoding of the genus Lepidion (Gadiformes: Moridae) with recognition of Lepidion eques as a junior synonym of Lepidion lepidion.

DNA sequences of cytochrome c oxidase I gene (COI) from Lepidion spp. were employed to test the efficiency of species identification. A sample of 32 individuals from five Lepidion species was sequenced and combined with 26 sequences from other BOLD projects. As a result, 58 Lepidion DNA sequences of the COI gene belonging to eight of the nine recognized Lepidion species were analysed. Sequences were aligned and formed seven clades in a Bayesian phylogenetic tree, where Lepidion lepidion and Lepidion eques grouped jointly. The Kimura 2-parameter genetic distances, among congeners were, on average, 4.28%, 16 times greater than among conspecifics (0.27%). The main diagnostic meristic data of Lepidion spp. were compiled and a detailed morphological revision of the congeneric species L. eques and L. lepidion was made. The eye diameter was significantly different between L. eques and L. lepidion (P < 0.001). The number of anal fin rays ranged from 45 to 51 in L. lepidion and from 47 to 54 in L. eques, but no significant differences were obtained in the mean values of this variable (P = 0.07). According to the morphological and genetic analyses, the results strongly suggest that the Mediterranean codling L. lepidion and the North Atlantic codling L. eques are conspecific, making L. eques a junior synonym of L. lepidion.