EXPERIMENTAL EVALUATION OF INTRAORAL SCANNERS IN EDENTULOUS MANDIBLES

Aim: the main difficulties for intraoral scanners (IOS) are found in the edentulous mandibles. The reduced bucco-lingual surface, the limited height of the bone crest and the mobility of the soft tissues generate criticalities for the acquisition of the digital impression. The purpose of this study is to evaluate the comparison between digital and analog impressions in these particular conditions. Methods: two scans were obtained for the 11 subjects. The first intraoral scan was carried out with intraoral scan (Omnicam DentsplySirona) and the second was acquired by digitizing a plaster model, obtained from an impression taken with an analogue method, the best choice in these cases. All scans were converted to standard tessellation language (STL). The STL files obtained for each patient were superimposed by means of the GEOMAGIC Control X software, to evaluate the comparison. The average distance values obtained through the Geomagic 3D software constitute our primary outcome measure. 1 sample t-test was used to prove the hypothesis that the average distances of the points obtained between the two files are relevant (α = .05). Results: concerning the scans ability to reproduce the analog impression the intraoral scans carried out with a intraoral scan generated files with single measurements in terms of minimal distance between objects far from scans obtained with analogue methods (t =-7.29, P < .001). Conclusion: regarding the results obtained, it was possible to conclude that the STL files deriving from digital impressions are significantly different from those deriving from analog impressions, highlighting a difference between the two methods

DIGITAL TECHNOLOGIES IN COMPLETE REMOVABLE DENTURE: A CASE SERIES

Aim: complete removable denture has been the last prosthetic procedure to follow the digitization because of drawbacks into the intraoral scans of edentulous arches; in addition, it is impossible to record muco-compressive impressions through IOS. So, a full digital procedure is not yet conceivable. We considered the possibility of an “hybrid” protocol thanks to a specific software. The hybrid protocol requires traditional techniques for the anatomical impression followed by laboratory scan of casts and wax. Methods: the software consists in two synergic programs: - Ruthinium Digital Preview allows to have a picture of the prosthetic project and change it previously, thanks to two calibrated photographs. - Ruthinium Denture Guide is a 3D software that helps laboratory work into denture production, particularly to a correct setting of acrylic teeth. The planned dental setting is printed in a template. Template and base plate, both 3D printed, are connected thanks to a structure that ensures the designed occlusal scheme. Results: the collected clinical cases did not allow a statistic analysis about patient and clinical satisfaction through evaluation questionnaires. Conclusion: it looks like that patients appreciate the prosthetic rehabilitation previsualization and in particular being actively involved in aesthetic choices. Clinically, it appears to be a shorter need for touch-ups at the last appointment; probably because of the 3D tooth position planning

Transient deformations in the Suez-Sinai area from GPS observations

We analyze data from four GPS campaigns carried out between 1997 and 2002 on a network of 11 sites in the Suez-Sinai, the area of collision between the African and the Arabian plates. This is the key area to understand how and in which way Sinai behaves like a sub-plate of the African plate and the role played between seismic and geodetic (long term) deformation release. Our analysis shows that, on average, the Suez-Sinai area motion (in terms of ITRF00 velocities) matches African plate motion (NNR-NUVEL-1A model). However, the baseline length variations show transient deformations in Sinai and across the Gulf of Suez, reaching up a maximum value of about 1.5 cm in five years. Since current geodynamical models do not predict significant tectonic deformation in this area, we worked under the hypothesis that a contribute may be due to post-seismic relaxation. Under this hypothesis, we compared the baselines length variations with the post-seismic relaxation field associated with five major local earthquakes occurred in the area, testing two different viscoelastic models. Our results show that the transient deformations are better modelled for viscosity values of 1018 Pa s in the lower crust and 1020 Pa s in the asthenosphere. However, since the modelled post-seismic effect results modest and a certain amount of the detected deformation is not accounted for, we think that an improved modelling should take into account the lateral heterogeneities of crust and upper mantle structures

Strain rate relaxation of normal and thrust faults in Italy

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Static stress drop as determined from geodetic strain rates and statistical seismicity

Two critical items in the energetic budget of a seismic province are the strain rate, which is measured geodetically on the Earth’s surface, and the yearly number of earthquakes exceeding a given magnitude. Our study is based on one of the most complete and recent seismic catalogs of Italian earthquakes and on the strain rate map implied by a multi-year velocity solution for permanent GPS stations. For 36 homogeneous seismic zones, we used the appropriate Gutenberg Richter relation based on the seismicity catalog to estimate a seismic strain rate, which is the strain rate associated with the mechanical work due to a co-seismic displacement. The volume storing most of the elastic energy is associated with the long-term deformation of each seismic zone, and therefore, the seismic strain rate is inversely proportional to the static stress drop. The GPS-derived strain rate for each seismic zone limits the corresponding seismic strain rate, and an upper bound for the average stress drop is estimated. These results demonstrated that the implied regional static stress drop ranged from 0.1 to 5.7 MPa for catalog earthquakes in the moment magnitude range [4.5–7.3]. These results for stress drop are independent of the “a” and “b” regional parameters and heat flow but are very sensitive to the assumed maximum magnitude of a seismic province. The data do not rule out the hypothesis that the stress drop positively correlates with the time elapsed after the largest earthquake recorded in each seismic zone

Integrazione di rilievi batimetrici e laser scanner aereo nell'area dei Colli Albani

The Colli Albani are a Quaternary volcanic complex located about 15 km SE of Rome, comprised in an area of latitudes 41.6-41.9 N and longitudes 12.5-12.9 E. It has recently developed particular interest in the geophysical community for some peculiar characteristics imputable to a residual volcanic activity. In the framework of a project financed by the Department of the Civil Protection devoted to the study of the Colli Albani deformations, we have recently realized a bathymetric survey of the Albano lake and an airborne laser scanner survey of the Albano and Nemi craters. The present work is composed by two phases. In a first phase the accuracy of the DEM achieved by the laser scanner is verified through a comparison with a GPS kinematic survey. In particular, our aim is to test if the use of DEM in different formats, TIN or Grid, could lead to meaningful differences in terms of accuracy and precision. In a second phase of the work, we merged the LIDAR and bathymetric data with the purpose to achieve a complete digital terrain model of the area that could allow in the next future geo-morphological analyses of the whole volcanic structure

Modeling ground deformations of Panarea volcano hydrothermal/geothermal system (Aeolian Islands, Italy) from GPS data.

Panarea volcano (Aeolian Islands, Italy) was considered extinct until November 3, 2002 when a submarine gas eruption began in the area of the islets of Lisca Bianca, Bottaro, Lisca Nera, Dattilo and Panarelli, about 2.5 km east of Panarea Island. The gas eruption decreased to a state of low degassing by July 2003. Before 2002 the activity of Panarea volcano was characterized by mild degassing of hydrothermal fluid. The compositions of the 2002 gases and their isotopic signatures suggested that the emissions originated from a hydrothermal/geothermal reservoir fed by magmatic fluids. We investigate crustal deformation of Panarea volcano using the GPS velocity field obtained by the combination of continuous and episodic site observations of the Panarea GPS network in the time span 1995-2007. We present a combined model of Okada sources which explains the GPS results acquired in the area after December 2002. The kinematics of Panarea volcano show two distinct active crustal domains characterized by different styles of horizontal deformation, supported also by volcanological and structural evidences. A subsidence in the order of several mm/yr is affecting the entire Panarea volcano and a shortening of 10-6 yr-1 has been estimated in the Islets area. Our model reveals that the degassing intensity and distribution are strongly influenced by geophysical-geochemical changes within the hydrothermal/geothermal system. These variations may be triggered by changes in the regional stress field as suggested by the geophysical and volcanological events that occurred on 2002 in the Southern Tyrrhenian area

Adjuvant hyperthermic intraperitoneal chemotherapy (HIPEC) in patients with colorectal cancer at high risk for the development of peritoneal metastases. A matched case-control study

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Gate-source distance scaling effects in H-terminated diamond MESFETs

In this paper, an analysis of gate-source and gate-drain scaling effects in MESFETs fabricated on hydrogen-terminated single-crystal diamond films is reported. The experimental results show that a decrease in gate-source spacing can improve the device performance by increasing the device output current density and its transconductance. On the contrary, the gate--drain distance produces less pronounced effects on device performance. Breakdown voltage, knee voltage, and threshold voltage variations due to changes in gate-source and drain-source distances have also been investigated. The obtained results can be used as a design guideline for the layout optimization of H-terminated diamond-based MESFETs