Usually, the mandibular canine only has one root and one root canal. However, there has been a noticeable increment in evidence showing variations in its morphology, such as the presence of two roots and two root canals. The aim of this article was to present a case of a mandibular canine with two roots and two root canals and to review the available literature on this anatomic variation. Root canal treatment of tooth #43 with such morphology was performed in a 47-year-old woman. Careful inspection of the preoperative radiograph indicated the presence of more than one canal. The 12-month follow-up showed normal periapical tissues, with no pain or tenderness. Literature review revealed that the overall prevalence of such root canal configuration is 5.7%, with a strong preference for female sex (87.5%). Although mandibular canines with two roots and two root canals are not common, clinicians should always anticipate the presence of possible variations. Therefore, timely diagnosis and meticulous exploration of such mandibular canines allow for planning of an individualized treatment protocol, tailored to their peculiar morphology, focused on avoiding excessive weakening or even perforation of the roots.

BackgroundThis study aimed to describe the anatomy of maxillary canines from a Western Mexican sub-population using micro-computed tomography (micro-CT).Material and MethodsMaxillary canines (n=32) were scanned at 19.6µm voxel resolution. Number and location of canals, the distance between the cemento-enamel junction and apex, occurrence of accessory and lateral canals, presence of oval canals, number of foraminas as well as two- (area, perimeter, roundness, aspect ratio, major and minor diameters) and three-dimensional (volume, surface area, and SMI) analysis were performed. Data of two-dimensional analyses at 5 different apical levels was statistically compared using Kruskal-Wallis tests (α=0.05).ResultsOverall, 31 specimens had one root with a main canal (Vertucci type I). Mean distance from the apex to the cemento-enamel junction was 16.32±2.27. Apical foraminas were present in 14 specimens (43.75%). No statistical differences were found in the two-dimensional analyses between the foramen and the 1 and 2mm apical levels (P >0.05).ConclusionsMaxillary canines presenting one root canal were present in a high percentage of cases (96%). The prevalence of long oval canals was <12% at the apical third and at least 37% of the sample showed more than one point of exit in the last apical 3mm. Key words:Maxillary canine, micro-computed tomography, root canal anatomy.

This case demonstrates that once the increased thickening of the canal walls, incrementing the root length, apical closure and the total resolution of the apical lesion are observed, the main canal of a previously treated tooth with an RR procedure can be filled.

BackgroundThis paper analyzed the distribution of treatments for permanent teeth with necrotic pulps and open apices according to the stage of root development.Material and MethodsDental records from all root canal procedures performed in permanent teeth with necrotic pulps and open apices over a period of 14 years by residents of the Speciality of Endodontics, University of Guadalajara, Mexico, were analized.ResultsRecords from 206 treatments were mainly divided into the following 3 different stages according to criteria described by Cvek: stage IV (n = 79, 38.3%), stage V (n = 66, 32%) and stage III (n = 53, 25.7%). Few cases involved the initial stages of root development (stages I and II) (n = 8, 3.8%). Such teeth were submitted to four different treatments: MTA apical barrier (n = 69), Ca(OH)2 replacements (n = 34), gutta-percha (n = 67) and a plug of Ca(OH)2/gutta-percha (n = 36). The teeth with intermediate root development (Cvek stage III) showed a predilection for the MTA apical barrier and Ca(OH)2 replacement techniques (P ≤ 0.001). Furthermore, the stage of root development did not influence the apical extent of the root filling.ConclusionsThe finding of permanent teeth with necrotic pulp and open apices is not exclusive to young patients with an open apex. Moreover, teeth with fragile, irregular and divergent apical morphologies, such as Cvek’s stages´ I and II, were not common and may be considered to be unusual findings. The diverse endodontic procedures were reliable regardless of the stage of root development. Key words:Incomplete root formation, Open apex, Epidemiological studies, Root development.

The present paper aims to evaluate the performance of a multi-branch gas-liquid pipe separator by means of 3D computational fluid dynamics. This type of separator is attractive for deepwater subsea hydrocarbon fields due to its compactness and reduced weight when compared against traditional gravity vessel separators. The focus of this paper is on studying the internal flow dynamics, the separation efficiency, and the performance with changing and transient operating conditions. Numerical simulations were performed on a numerical prototype of the separator using the inhomogeneous mixture model and assuming that both phases are continuous. Sensitivity analyses were performed on gas volume fraction, outlet pressures, and considering slug flow at the inlet with periods of 2 s and 8 s. The separation efficiency was quantified by calculating the liquid carry-over and gas blowby. For most of the operational conditions studied, separation occurred primarily in pipe branches closer to the inlet while those closer to the outlet exhibited a static liquid level. Reducing the gas outlet pressure caused the height of the liquid in the branches to be reduced. The inlet gas volume fraction did not affect significantly the separation performance, the flow distribution, nor the liquid level inside the separator. Separation efficiencies were not affected significantly with the presence of slugs; however, the liquid level in the branches oscillated significantly. The results and numerical models produced by this study could potentially be used to improve the understanding of this type of separators and improve its efficiency and system-level design. Keywords Gas-liquid separation • Subsea processing • Computational fluid dynamics List of symbols Variables Δy Thickness of cell closest to wall (m) u * Friction velocity (m/s) t Time (s) U Velocity vector U Velocity component (m/s) p Pressure (Pa, bara) g Gravitational acceleration (m/s 2) M p Momentum interphase (N/m 3) C D Drag coefficient d og Oil-gas interfacial length (m) t Turbulent viscosity (Pa s) k Kinetic energy (m 2 /s 2) p k Turbulent production (kg/m s 3) Greek symbols ρ Density (kg/m 3) μ Dynamic viscosity (Pa s) Volume fraction Turbulent dissipation rate (m 2 /s 3) Subscripts o Oil g Gas OG Outlet of gas OL Outlet of liquid p Generic phase "p" j Generic spatial coordinate i Generic spatial coordinate m Mixture Superscripts o Oil g Gas Abbreviations CFD Computational fluid dynamics GCU Gas carry under * M. Diaz