On the Mechanical Properties of Hybrid Dental Materials for CAD/CAM Restorations.

Two hybrid dental materials available for computer-aided design and manufacturing (CAD/CAM) dental restorations have been selected to explore their potential. On the one hand, the scarcely investigated polymer-based material Vita Enamic® (VE) and, on the other hand, the leucite-based material IPS Empress® CAD (EC). Their micro-structure and mechanical performance were analyzed in two environments: directly as received by the manufacturer (AR), and after immersion and storage in artificial saliva (AS) for 30 days to determine the influence of the saliva effect. To avoid an inappropriate selection of materials for clinical use, a full understanding of their mechanical behavior is essential. Therefore, this investigation aims to determine the micro-structural and chemical composition by field emission scanning electron microscopy (FE-SEM) and X-ray fluorescence analysis, establishing the density, micro- and nano-hardness, the nano-elastic modulus, and the flexural strength and fracture toughness (by introducing a femto-laser notch to replicate a real crack). In addition, fracture surfaces of the broken samples were analyzed to correlate the failure micro-mechanisms with their mechanical properties. Results indicate that while the crystalline phase of the materials is very similar (composed of SiO2 and Al2O3), the micro-structure and mechanical behavior is not. The material EC, with finer micro-structure, exhibits a higher mechanical performance but with greater variability of results. Furthermore, the material VE, with a 25 vol.% polymer phase, shows a mechanical performance similar to enamel and dentin and therefore more similar to human behavior.

Saliva Influence on the Mechanical Properties of Advanced CAD/CAM Composites for Indirect Dental Restorations.

This study aims to evaluate the microstructural and mechanical properties of three commercial resin-based materials available for computer-aid design and manufacturing (CAD/CAM)-processed indirect dental restoration: LavaTM Ultimate Restorative (LU), 3M ESPE; Brilliant Crios (BC), COLTENE and CerasmartTM (CS), GC Dental Product. The three types of resin-based composite CAD/CAM materials were physically and mechanically tested under two conditions: directly as received by the manufacturer (AR) and after storage under immersion in artificial saliva (AS) for 30 days. A global approximation to microstructure and mechanical behaviour was evaluated: density, hardness and nanohardness, nanoelastic modulus, flexural strength, fracture toughness, fracture surfaces, and microstructures and fractography. Moreover, their structural and chemical composition using X-ray fluorescence analysis (XRF) and field emission scanning electron microscopy (FESEM) were investigated. As a result, LU exhibited slightly higher mechanical properties, while the decrease of its mechanical performance after immersion in AS was doubled compared to BC and CS. Tests of pristine material showed 13 GPa elastic modulus, 150 MPa flexural strength, 1.0 MPa·m1/2 fracture toughness, and 1.0 GPa hardness for LU, 11.4 GPa elastic modulus; 140 MPa flexural strength, 1.1 MPa·m1/2 fracture toughness, and 0.8 GPa hardness for BC; and 8.3 GPa elastic modulus, 140 MPa flexural strength, 0.9 MPa·m1/2 fracture toughness, and 0.7 GPa hardness for CS. These values were significantly reduced after one month of immersion in saliva. The interpretation of the mechanical results could suggest, in general, a better behaviour of LU compared with the other two despite it having the coarsest microstructure of the three studied materials. The saliva effect in the three materials was critically relevant for clinical use and must be considered when choosing the best solution for the restoration to be used.

Relationship of fat distribution with adipokines in patients with acquired immunodeficiency virus infection.

BACKGROUND: The aim was to examine the relationship of fat distributions with adipokines concentrations in HIV-infected patients. METHODS: This was a cross-sectional analysis of 36 HIV (free of lipodystrophy) infected patients. Dual-energy X-ray absorptiometry was used. RESULTS: In the multivariate analysis, basal adiponectin concentration was a dependent variable, whereas waist to hip ratio and abdominal fat mass were independent predictors in the model (F = 5.1; P < 0.05). Adiponectin concentration decreases by 5.541.2 µg/ml (CI 95%: 8,071.9-3,029.1) for each unit of waist to hip ratio and 561.9 ng/ml (CI 95%: 918.2-213.4) for each kilogram of fat mass of abdominal area. In the multivariate analysis, basal leptin concentration was a dependent variable, whereas waist circumference remained an independent predictor in the model (F = 6.3; P < 0.05), with a direct correlation. Leptin concentration increases by 0.067 ng/ml (CI 95%: 0.001-0.12) for each centimeter of waist circumference. CONCLUSIONS: Leptin and adiponectin are related with adiposity in HIV-infected patients.

Tumor multilobular óseo: Presentación de dos casos en perros / Multilobular tumor of bone: Report of two cases in dogs

The multilobular tumor of bone (MTB) is considered as a slow-growth malignant tumor, which generally occurs on the cranium and facial bones of dogs, although it has been reported in other domestic animals. This study presents two cases of MTB in dogs. The first case was manifested in an 8-year-old male Bull Terrier, while the second one affected a 5.5-year-old female German Shepherd. Both animals were submitted for post-mortem examination. MTB diagnosis was confirmed by histopathological examination. The aim of this report was to describe the main clinical-pathologic features of MTB, such as its slow, diffuse and deforming growth pattern, as well as the histomorphological image peculiarities that are unmistakable from other tumors such as chondrosarcoma and osteosarcoma, that should be considered as differential diagnoses. Up to date, this is the first report of canine MTB in Mexico.

El tumor multilobular óseo (TMO) es considerado como tumor maligno de crecimiento lento, que ocurre generalmente en el cráneo y en los huesos faciales del perro, aunque también se ha registrado en otras especies animales. Aquí se presentan dos casos de TMO en perros. El primero ocurrió en un Bull Terrier, macho, de ocho años de edad, el segundo en Pastor Alemán, hembra, de 5.5 años. Ambos animales fueron remitidos para su examen post-mortem. El tumor multilobular óseo fue confirmado por histopatología. El objetivo de este trabajo fue describir las principales características clínico-patológicas del TMO en perros, como su crecimiento lento, difuso y deformante, al igual que las peculiaridades histomorfológicas de la imagen, que son inconfundibles con otros tumores; por ejemplo, condrosarcoma y osteosarcoma, que deben considerarse dentro de los diagnósticos diferenciales. Éste es el primer informe de TMO canino en México.