Roberto Felici

Accuracy of Three Electronic Apex Locators Compared with Digital Radiography: An Ex Vivo Study

INTRODUCTIONnThis study compared (1) the accuracy of three different electronic apex locators (EALs) in detecting the apical foramen ex vivo under clinical conditions; (2) the accuracy of digital radiography and EALs in determining the working length (WL) with visible control under a microscope; and (3) the precision of #10, #15, and #20 K-files in electronic measurements.nnnMETHODSnThe length of 101 extracted human teeth was measured with three different EALs (Endex [Osada Electric Co, Tokyo, Japan], ProPex II [Dentsply-Maillefer, Ballaigues, Switzerland], and Root ZX [J. Morita Co, Tustin, CA]), with radio videography (RVG) and compared with the actual length. An endodontic training kit (Pro-Train; Simit Dental, Mantova, Italy) was used during the experimental procedures.nnnRESULTSnStatistical analysis showed that Endex and ProPex II were more accurate than Root ZX in determining the WL. The paired sample t test showed no statistically significant difference between the accuracy of the two radiographic planes examined. The t test showed no significant difference between the three different K-file sizes measurements.nnnCONCLUSIONSnEndex and ProPex II were more accurate than Root ZX in determining the actual WL. Instrument sizes of hand files did not affect the accuracy of EALs. EALs showed to be more accurate in determining the WL than RVG.

Accuracy of three electronic apex locators in anterior and posterior teeth: an ex-vivo study.

INTRODUCTIONnThe aim of this study was to determine in anterior teeth, bicuspids, and molars (1) the accuracy of 3 different electronic apex locators (EALs) in detecting the apical foramen and (2) the accuracy of digital radiography in determining the working length (WL), compared with visible control under a microscope.nnnMETHODSnBy using radiovideography (RVG), we measured the lengths of 120 root canals with 3 different EALs (Endex, ProPex II, and Root ZX) and compared them with the actual lengths. The accuracy of EALs and RVG was related to each dental category. An endodontic training kit (Pro-Train) was used during experimental procedures.nnnRESULTSnStatistical analysis showed that the 3 EALs and RVG were less accurate in anterior teeth and molars than in bicuspids. The paired-sample t test showed no statistically significant difference between mesiodistal plane and buccolingual plane digital radiography in all groups.nnnCONCLUSIONSnThe 3 EALs tested were more accurate in detecting the apical foramen in bicuspids than in both molars and anterior teeth. Radiographic measurements were not reliable for determining WL in all dental groups in both radiographic planes.

Operando Structural Characterization of the E-ALD Process Ultra-Thin Films Growth

Spanning from nanoelectronics to new solar energy materials, technological development in the recent years requested highly controlled nanostructured surfaces, ultra-thin films, and 2D structured materials. In general, although very favorable from a full life cycle assessment (FLCA) standpoint, electrodeposition hardly allows to obtain the high order required by recent technologies. In particular cases, the electrodeposition enables the deposition of atomic layers by means of surface limited reactions (SLRs). By exploiting SLRs, it is possible to define layer-by-layer deposition scheme of different atomic layers; we refer to these schemes as electrochemical atomic layer deposition (E-ALD) and when the growth of the film is epitaxial with the substrate, the techniques are called electrochemical atomic layer epitaxy (ECALE). Aiming at characterizing structure and growth of materials grown by means of E-ALD, surface analysis techniques apply better. In particular, surface X-ray diffraction (SXRD) with high brilliance synchrotron sources enables the operando structural analysis in electrochemical environment. In recent years, several works on the operando surface characterization by means of SXRD have been reported. Thanks to novelties in the field of operando SXRD experiments, semiconducting systems were studied, such as single and multilayer of CdS and Cu2S.

Oxidation of CO on Pd(1 0 0): on the structural evolution of the PdO layer during the self sustained oscillation regime

Abstract Under particular temperature and gas conditions the reactivity of the Pd(1 0 0) surface toward CO oxidation exhibits oscillatory behaviour. Here we examine the surface structure of this model catalyst and show that the periodic pattern is more complex than previously reported and that superimposed on the overall oscillation much faster structural variations are present. By examining the structure of the sample surface at high temporal resolution we conclude that the structure of the oxide layer present at the surface evolves continuously toward a more disordered phase in agreement with the Mars-Van Krevelen reaction mechanism.

Self-organization of porous anodic alumina films studied in situ by grazing-incidence transmission small-angle X-ray scattering

Self-ordered porous anodic alumina (PAA) films are studied extensively due to a large number of possible applications in nanotechnology and low cost of production. Whereas empirical relationships between growth conditions and produced oxides have been established, fundamental aspects regarding pore formation and self-organization are still under debate. We present in situ structural studies of PAA films using grazing-incidence transmission small-angle X-ray scattering. We have considered the two most used recipes where the pores self-organize: 0.3 M H2SO4 at 25 V and 0.3 M C2H2O4 at 40 V. During anodization we have followed the evolution of the structural parameters: average interpore distance, length of ordered pores domains, and thickness of the porous oxide layer. Compared to the extensively used ex situ investigations, our approach gives an unprecedented temporal accuracy in determination of the parameters. By using of Al(100), Al(110) and Al(111) surfaces, the influence of surface orientation on the structural evolution was studied, and no significant differences in the interpore distance and domain length could be observed. However, the rate of oxide growth in 0.3 M C2H2O4 at 40 V was significantly influenced by the surface orientation, where the slowest growth occurs for Al(111). In 0.3 M H2SO4 at 25 V, the growth rates were higher, but the influence of surface orientation was not obvious. The structural evolution was also studied on pre-patterned aluminum surfaces. These studies show that although the initial structures of the oxides are governed by pre-patterning geometry, the final structures are dictated by the anodization conditions.