811 research outputs found
Endoscopic ultrasonic curette-assisted removal of frontal osteomas
Indications for endoscopic resection of fronto-ethmoidal osteomas have been progressively expanded thanks to optimization of surgical exposure and the development of dedicated instruments. Curved cutting drills are still suboptimal to treat hard osseous neoplasms of the frontal sinus. We present two patients affected by frontal osteoma treated with an endoscopic procedure using an ultrasonic bone curette. The ultrasonic bone curette may be considered an effective tool to reduce soft tissue manipulation, optimize surgical time and accelerate the healing process. However, the technique requires significant shape innovations to reach the lateral recesses and to manage pure intrasinusal lesions
Solitary fibrous tumour of the supraglottic larynx.
Solitary fibrous tumour (SFT) is a rare, benign, mesenchymal neoplasm that usually arises in the pleura, but rarely involves other sites outside the serosal space (mediastinum, lung, liver, thyroid gland); larynx involvement is very rare with only sporadic cases reported in the literature. We report a case of SFT in a 41-year-old woman with supraglottic laryngeal invovlement; symptoms included dysphonia and mild odynophagia lasting 2 years, and fibre-optic laryngeal evaluation showed a sub-mucosal mass involving the left supraglottis and medial wall of the pyriform sinus. MRI represents the gold standard tool for differential diagnosis (with schwannoma, paraganglioma and haemangioma) and correct staging, while immunohistochemical and cytomorphologic analysis (bcl-2 and CD34 positivity in 90% of cases) is needed for definitive diagnosis. Surgery is the main treatment (endoscopic and open conservative technique), and its goal is a balance between safe oncological resection and good preservation of laryngeal functions; in this particular case an open laryngeal approach was scheduled due to the size of the tumour. Prognosis is good and in only a few cases (especially in pleural SFT) does the biological behaviour take a malignant course
Synthesis and characterization of multiferroic BiMnO
We report on the high pressure synthesis of BiMnO, a manganite
displaying a "quadruple perovskite" structure. Structural characterization of
single crystal samples shows a distorted and asymmetrical coordination around
the Bi atom, due to presence of the lone pair, resulting in
non-centrosymmetric space group Im, leading to a permanent electrical dipole
moment and ferroelectric properties. On the other hand, magnetic
characterization reveals antiferromagnetic transitions, in agreement with the
isostructural compounds, thus evidencing two intrinsic properties that make
BiMnO a promising multiferroic material.Comment: 4 pages, 3 figure
Factors influencing CAD/CAM accuracy in fibula free flap mandibular reconstruction
La tecnologia CAD/CAM (Computer-Aided Design/Computer-Aided Manufacturing) ha migliorato sia i risultati funzionali che morfologici nella chirurgia ricostruttiva mandibolare. L\u2019obiettivo del nostro studio \ue8 stato quello di valutare questo tipo di tecnologia ed i fattori che possono influenzare la sua precisione. Un totale di 26 casi di ricostruzione mandibolare con lembo libero di fibula, utilizzando tecnologia CAD/CAM sono stati operati presso l\u2019Unit\ue0 Maxillofacciale della Fondazione IRCCS Ca\u2019 Granda Ospedale Maggiore Policlinico di Milano, da giugno 2014 a febbraio 2018. Abbiamo valutato l\u2019accuratezza confrontando i files STL di pianificazione chirurgica virtuale (obiettivo pianificato) con il file STL di una scansione TC postoperatoria precoce (risultato postoperatorio ottenuto). Entrambi i file STL sono stati importati su Geomagic Studio 2016 (Geomagic Gmbh). In base alla posizione della placca di ricostruzione (punto di riferimento fisso), abbiamo confrontato la deviazione sul condilo sinistro, gonion sinistro, gnathion, gonion destro e condilo destro, per calcolare l\u2019errore medio di deviazione. L\u2019errore medio di deviazione varia da 0,6 mm a 2,2 mm. Solo 2 dei 26 casi analizzati avevano un errore medio uguale o superiore a 2 mm (7,7%). L\u2019area mediana (symphysis-gnathion) ha mostrato una variazione pi\uf9 bassa (1,05 \ub1 0,92 mm) mentre l\u2019area di gonion ha mostrato maggiore variazione (la variazione media del gonion destro e sinistro era rispettivamente di 1,6 mm e 1,46 mm). Nessuno dei possibili fattori (tempi di ricostruzione, malignit\ue0 o benignit\ue0, sito o dimensione del difetto) che potrebbero influenzare la precisione del CAD/CAM, ha mostrato un\u2019influenza significativa. La tecnologia CAD/CAM nella ricostruzione microvascolare dei difetti mandibolari mediante lembo libero di fibula minimizza gli errori umani ed \ue8 considerato come un intervento chirurgico indipendente dall\u2019operatore con alto grado di accuratezza e riproducibilit\ue0.Computer-aided design/computer-aided manufacturing (CAD/CAM) technology has im-proved the functional and morphological results of mandibular reconstructive surgery. The purpose of this study was to objectively assess this technology and factors affecting its accuracy.Fibula free flap mandibular reconstruction was performed in 26 cases us-ing CAD/CAM technology at the Maxillofacial Unit of Fondazione IRCCS Ca\u2019 Gran-da Ospedale Maggiore Policlinico, Milan, between June 2014 and February 2018. We evaluated the technology\u2019s accuracy by comparing the virtual surgical planning STL file (planned-target mesh) with the STL file from an early postoperative CT scan (postopera-tive-achievement mesh) in each case. The STL files were imported into Geomagic Studio 2016 (Geomagic GmbH). According to the position of the reconstruction plate (fixed reference point), we assessed deviations at the right condyle, right gonion, gnathion, left gonion and left condyle, calculating mean, minimum and maximum error values.Mean error values ranged from 0.6 to 2.2 mm; they were 65 2 mm in only 2 (7.7%) cases. The midline area (symphysis-gnathion) showed the least variation (1.05 \ub1 0.92 mm), and the gonion area showed the greatest variation (right and left means of 1.6 and 1.46 mm, respectively). Among all possible factors that could affect CADCAM accuracy, nothing showed significant influence, including the timing of reconstruction, site and size of the defect and malignancy status. CAD/CAM technology has a high degree of accuracy and reproducibility for microvascular reconstruction of mandibular defects using fibula free flaps, regardless of the defect site and length, use of a single- or double-barrel graft or timing of reconstructio
Commensurate structural modulation in the charge- and orbitally-ordered phase of the quadruple perovskite (NaMn)MnO
By means of synchrotron x-ray and electron diffraction, we studied the
structural changes at the charge order transition =176 K in the
mixed-valence quadruple perovskite (NaMn)MnO. Below we
find satellite peaks indicating a commensurate structural modulation with the
same propagation vector q =(1/2,0,-1/2) of the CE magnetic order that appears
at low temperature, similarly to the case of simple perovskites like
LaCaMnO. In the present case, the modulated structure
together with the observation of a large entropy change at gives
evidence of a rare case of full Mn/Mn charge and orbital order
consistent with the Goodenough-Kanamori model.Comment: Accepted for publication in Phys. Rev. B Rapid Communication
Implants outcome inserted in different sites
Oral rehabilitation by means dental implants has high standards of success. Recently, a new type of two-pieces spiral implants has been introduced in the market. Since few reports focus of the efficacy of this medical device as a reliable tool for oral rehabilitation, here a retrospective study is reported. In the period June-December 2017 one hundred and two spiral fixtures were inserted, half in females and 51 in males. The median age was 56 \ub1 8 (min-max 36-73 years). Forty-eight implants were inserted in upper jawbone and 54 in mandible. Two implants were lost and thus survival rate (SVR) is 99.9%. Then peri-implant bone resorption was used to investigate the clinical success (success rate, SCR) over time. No implants have a crestal bone resorption greater than 1.5 mm in the first year follow up. No studied variable has an effect on clinical outcome. In conclusion the studied implants have high SCR and SVR so that they are good tools for oral rehabilitation
Internal-strain mediated coupling between polar Bi and magnetic Mn ions in the defect-free quadruple-perovskite BiMnMnO
By means of neutron powder diffraction, we investigated the effect of the
polar Bi ion on the magnetic ordering of the Mn ions in
BiMnMnO, the counterpart with \textit{quadruple} perovskite
structure of the \textit{simple} perovskite BiMnO. The data are consistent
with a \textit{noncentrosymmetric} spacegroup which contrasts the
\textit{centrosymmetric} one previously reported for the isovalent and
isomorphic compound LaMnMnO, which gives evidence of a
Bi-induced polarization of the lattice. At low temperature, the two
Mn sublattices of the and sites order antiferromagnetically
(AFM) in an independent manner at 25 and 55 K, similarly to the case of
LaMnMnO. However, both magnetic structures of
BiMnMnO radically differ from those of LaMnMnO.
In BiMnMnO the moments of the sites form
an anti-body AFM structure, whilst the moments \textbf{M} of the
sites result from a large and \textit{uniform} modulation along the b-axis of the moments \textbf{M} in the
-plane. The modulation is strikingly correlated with the displacements of
the Mn ions induced by the Bi ions. Our analysis unveils a strong
magnetoelastic coupling between the internal strain created by the Bi
ions and the moment of the Mn ions in the sites. This is ascribed to
the high symmetry of the oxygen sites and to the absence of oxygen defects, two
characteristics of quadruple perovskites not found in simple ones, which
prevent the release of the Bi-induced strain through distortions or
disorder. This demonstrates the possibility of a large magnetoelectric coupling
in proper ferroelectrics and suggests a novel concept of internal strain
engineering for multiferroics design.Comment: 9 pages, 7 figures, 5 table
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