RESUMEN
The aim of this study is to visualize and characterize by ultra-high-speed imaging (UHSI) the failure phenomena at the resin-ceramic bonding interface of lithium disilicate (LiSi2) samples bonded with gold-standard protocol (Monobond Plus [MB]) and the nontoxic one (Monobond Etch & Prime [MEP]) subjected to mechanical loading. Unprecedented frame rate, image resolution, and recording time were reached by using the most advanced UHSI camera. The finite element analysis (FEA) of the proposed mechanical test confirmed that the specific design of our samples enables a combined shear and compression stress state, prone to test the bonding interface while being close to physiological stresses. Ten LiSi2 samples were pretreated by gold standard (MB, n = 5) and self-etching primer (MEP, n = 5). Axial compression loading gradually increased until catastrophic failure was performed. As shown by the FEA, the angle between the bonding interface and load direction leads to shear-compression stresses at the resin-ceramic bonding interface. Failure was recorded by UHSI at 300,000 fps. All recorded images were analyzed to segregate events and isolate the origin of fracture. For the first time, thanks to the image recording setup, it was observed that debonding is the first event before breakage, highlighting that sample fracture occurs by interfacial rupture followed by slippage and cohesive failure of materials. Failure mode could be described as mixed. MEP and MB showed similar results and behavior.
Asunto(s)
Recubrimiento Dental Adhesivo , Cementos de Resina , Propiedades de Superficie , Ensayo de Materiales , Silanos , Ácido Fluorhídrico , Cerámica , Porcelana Dental , Análisis del Estrés DentalRESUMEN
OBJECTIVES: Ceramic veneers restorations may undergo damages, such as cracks, fractures, or debonding. Full-field measurements must be carried out in order to visualize and analyze the strain fields. This paper demonstrates that digital holography permits to investigate the mechanical behavior under stress of a natural incisor and a natural incisor reconstructed with CAD/CAM ceramic veneer. METHODS: The facial surface of a maxillary central incisor is prepared to receive a monolithic ceramic reconstruction manufactured using a chairside computer-aided design and computer aided manufacturing (CAD/CAM) system (Cerec AC® system, Sirona Dental System®, Bensheim, Germany). One incisor is kept intact for comparison. The samples are sectioned longitudinally to obtain a planar observation of the region of interest. A mechanical indentation head and digital holographic set-ups permit a full-field, contact-less and single-shot measurement of the three-dimensional displacement fields at the surface of the tooth sample when subjected to load. Stain fields are then estimated and comparison of the results between two samples can be carried out. RESULTS: 3D displacement, fields and strain fields are measured and highlight the behavior of the region of interest in three directions of space for the ceramic veneer and the natural incisor. The strain maps reveal the local behavior, especially the concentration or the sudden change in strain. The transition zones are clearly observed, particularly for the veneered sample. CONCLUSION: Digital holography highlights the localization of stress concentration zones in regions of interest and yields comparative analysis between samples with different tooth preparations. SIGNIFICANCE: holography permits to visualize and compare the mechanical response of the ceramic veneer and natural tooth. This helps choosing the mechanical properties of the bonding interface.
Asunto(s)
Holografía , Cerámica , Diseño Asistido por Computadora , Porcelana Dental , Análisis del Estrés Dental , Coronas con Frente Estético , Incisivo , Ensayo de MaterialesRESUMEN
OBJECTIVES: CAD/CAM ceramic occlusal veneers are increasingly used as therapeutic options. However, little is known about their mechanical behavior under stress, as the response of the prepared tooth that supports it. The aim of this article is to use for the first time 3D color holography to evaluate the behavior of a molar occlusal veneer under stress and the response of the prepared tooth. METHODS: The occlusal surface of a lower molar is prepared to receive a specific monolithic ceramic reconstruction manufactured with a chairside CAD/CAM system. Longitudinally cut samples are used to get a planar object observation and to "look inside" the tooth. A digital holographic set-up permits to obtain the contact-less and one-shot measurement of the three-dimensional displacement field at the surface of the tooth sample; stain fields are evaluated with low noise-sensitive computation. RESULTS: Figures show the strain fields with micro-strain units and highlight the behavior of the ROI (region of interest) in the three directions of space. The ROI are: the ceramic, the glue junction, the dentin enamel junction, dentin and enamel. The results show an excellent behavior of the restored tooth without areas of excessive stress concentrations, but also a significant involvement of the dentin enamel junction. SIGNIFICANCE: The ceramic occlusal veneer seems to behave in accordance with the biomechanical concepts ensuring the longevity of the reconstituted tooth. 3D holography is a highly recommended method for studying dental biomechanics.
Asunto(s)
Cerámica/química , Diseño Asistido por Computadora , Coronas con Frente Estético , Holografía/métodos , Diseño de Prótesis Dental , Análisis del Estrés Dental , Humanos , Técnicas In Vitro , Ensayo de Materiales , Diente Molar , Estrés MecánicoRESUMEN
INTRODUCTION: "Critical Care Units" are intended to admit patients with multiple organ failure. The severity of patients admitted is variable. The aim of the study was to estimate the number of days that an optimum care organization could release, and therefore the additional admissions that would have been allowed. Estimates of earnings related to the various supplements were carried out jointly. METHODS: Reporting days associated or not with a resuscitation care during the year 2011 in an ICU of a university hospital (16 beds), optimized patient flow simulation, and computation of medical act inducing financial supplements. RESULTS: Six hundred and fifty-seven patients (SAPS II from 0 to 110, 41% ventilated more than 48hours, mortality=26%) were admitted representing 5095days (occupancy rate=87%). Two hundred and twenty-two patients (34%) did not trigger supplement for resuscitation care for 415days in the unit. Four hundred and thirty-five patients have triggered this supplement representing 4680days, including 3035days with resuscitation care and 1645 (35% of days valued resuscitation, 32% of total days) without any. The entire year 2011 has generated earnings of 3,980,192. Optimization of management would have allowed the admission of additional 235 to 295 patients and potential additional earnings from 524,735 to 1,063,804, depending on the occupancy rate chosen (80% or real 2011s) and the severity of discharged patients. CONCLUSION: Optimization of the patients flow between "Critical Care", Intensive Care and Continuous Monitoring Units would increase the number of patients admitted in "Critical Care" Units without any financial loss related to supplements.
Asunto(s)
Cuidados Críticos/economía , Cuidados Críticos/estadística & datos numéricos , Unidades de Cuidados Intensivos/economía , Unidades de Cuidados Intensivos/estadística & datos numéricos , Monitoreo Fisiológico/economía , Monitoreo Fisiológico/estadística & datos numéricos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Femenino , Francia , Humanos , Lactante , Recién Nacido , Tiempo de Internación , Masculino , Persona de Mediana Edad , Modelos Estadísticos , Insuficiencia Multiorgánica/terapia , Resucitación/economía , Resucitación/estadística & datos numéricos , Adulto JovenRESUMEN
OBJECTIVES: Hepatitis C virus (HCV) infection is a recognized public health issue in France. Institutional networks were created to improve healthcare practices and facilitate multi-disciplinary care for chronic diseases. The electronic medical file is one of the tools used by the networks to optimize patient care. METHODS: The main objective of this study was to determine what proportion of general practitioners in the Languedoc-Roussillon region of southern France would be interested in using the electronic medical files for patients with HCV infection. A random sample of 20% of the general practitioners in the region was selected and stratified by administrative district of practice. Among them, a telephone survey identified those interested in the hepatitis electronic medical files and following patients with hepatitis C. A more detailed questionnaire was sent to these interested physicians in order to obtain further information. RESULTS: Thirty-seven percent of the general practitioners concerned by the question followed patients with HCV infection. The advantages and disadvantages the physicians associated with use of these files were mostly related to the physician's age, attendance of continuing education courses and internet access. CONCLUSION: This study highlighted the fact that a significant number of general practitioners would be interested in accessing electronic medical files for patients with HCV infection. Considering these findings it might be useful to propose a working group including general practitioners and specialists in order to develop a concrete project for implementing electronic medical files for patients with HCV infection.