2,919 research outputs found
Il trattamento delle malocclusioni di II classe divisione 1 in dentizione mista con dispositivi preformati di guida all’eruzione
No full textScopo del lavoro
La finalità è stata quella di valutare le variazioni scheletriche e dento-alveolari indotte da un dispositivo preformato di guida all’eruzione (Occlus-o-Guide®) nel trattamento di una malocclusione di II classe divisione 1 in dentizione mista.
Materiali e metodi
E.D.I., di sesso femminile e di anni 9 e mesi 6, presentava una malocclusione di II classe scheletrica divisione 1 deep bite, II classe molare a dx e I classe molare a sx, overjet di 5 mm, overbite di 6 mm; le arcate dentali mostravano affollamento degli elementi dentali, soprattutto all’arcata inferiore. La paziente presentava inoltre una recessione gengivale su 4.1. Il piano di trattamento aveva previsto l’utilizzo di un Occlus-o-Guide® della serie G (misura 5) per 2 ore diurne in modo attivo e tutte le notti in modo passivo. Una volta ottenuta la correzione del rapporto molare, l’Occlus-o-Guide® è stato utilizzato dalla paziente solo durante la notte per stabilizzare il risultato ottenuto e guidare l’eruzione degli ultimi elementi dentali.
Risultati e conclusioni.
Al termine del trattamento, della durata di tre anni, la paziente presentava rapporti di I classe a destra e sinistra sia canina che molare, un overjet ed un overbite nella norma, l’assenza di affollamento, una corretta intercuspidazione ed un miglioramento della recessione gengivale su 4.1. L’Occlus-o-Guide® può quindi essere utilizzato con successo in dentizione mista nella correzione delle II classi divisione 1: in particolare se il trattamento inizia prima dell’eruzione dei canini e termina con l’eruzione dei premolari il risultato è stabile nel tempo, e se le fibre collagene non sono ancora formate anche la correzione delle rotazioni e degli affollamenti si mantiene stabile. Il trattamento precoce con Occlus-o-Guide® è semplice, di breve durata e nella maggior parte dei casi non è necessaria una seconda fase di trattamento ortodontico. Infine è possibile risolvere una malocclusione utilizzando un solo dispositivo, in quanto una volta terminata la fase attiva di trattamento, l’Occlus-o-Guide®, divenuto passivo, può essere ulteriormente utilizzato per la fase di contenzione
Evaluation of restoration results on the Antonino and Faustina temple in Rome through seismic transmission tomography: comparison of P-wave velocities before and after restoration
No full textThe use of 3-D and 2-D seismic tomography for assessing the physical integrity of building panels
No full textThis paper describes an application of 3-D seismic tomography for evaluating the inner structure of some building panels. The measurements were performed on two building panels that had been expressly constructed using the building techniques of the ancient Romans. The study was made to assist the design of restoration work on ancient Roman monuments, and walls in particular. The aim of the survey was to assess whether the seismic tomography technique could be used to determine the elastic properties of brick walls and how these might vary when the walls are subjected to different loads. Different loads were applied to both building panels and seismic tomographic images were obtained for each loading. By noting the changes in elastic properties, it was hoped to predict the onset of cracks or fractures. For the first wall, images were obtained for two load phases. On the second wall, the experiment was conducted for only one loading. The study showed that it was possible to identify the internal variations in seismic velocity caused by the applied loads and to predict the zones that were going to fracture. The inversion algorithm used was based on the LSQR method
Seismic refraction, isotropic and anisotropic seismic tomography on an ancient monument (Antonino and Faustina temple 141 A.D.)
No full textEvaluation of restoration results on the Antonino and Faustina Temple in Rome through seismic transmission tomography: Comparison of P-wave velocities before and after restoration
No full textTo evaluate the state of preservation of two columns of the Pronao of the Antonino and Faustina temple in the Roman forum (Rome, Italy - 141 A.D.), 2D seismic tomography was used. In this paper we describe the results of seismic transmission tomography before and after restoration, comparing sections of the two restored columns. The aim of this work was to test the validity of seismic tomography to guide the restorer during the restoration. We assessed the value of using this method to determine elastic properties in terms of P-wave velocity and, consequently, identify zones with little cracks and fractures, and detect improved dynamic characteristics after the restoration. Considering the dimensions nad shape of the studied objects, particular field and acquisition techniques were adopted. To obtain high-resolution tomograms, we used piezoelectric sensors with high cut-off frequency and short sampling intervals for the recorder unit; furthermore a particular recording technique was used to avoid reading errors (double trigger). The investigated sections are divided into cells, whose dimensions are calculated using Fresnel theory and a priori information. To invert the data we used the Least Square Inversion (LSI) method modified with variable damping factors, taking into account the mean slowness of the marble as constraint. The results of comparing P-wave velocities indicate that transmission tomography is able to detect differences in the elastic properties that occur before and after restoration. These results provide information to evaluate the degree of restoration needed, and to guide and help to improve the work of the restorer
The use of 3D and 2D seismic tomography for assessing the physical integrity of building panels.
No full text
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