Bioactive Materials Subjected to Erosion/Abrasion and Their Influence on Dental Tissues

Objective: The objective of this study was to evaluate the effect of erosion or erosion-abrasion on bioactive materials and adjacent enamel/dentin areas. Methods and Materials: Enamel and dentin blocks (4×4×2 mm) were embedded side by side in acrylic resin, and a standardized cavity (1.2×4×1.5 mm) was prepared between them. Preparations were restored with the following materials: composite resin (Filtek Z350, control); experimental composite containing di-calcium phosphate dihydrate particles (DCPD); Giomer (Beautifil II), high viscosity glass ionomer cement (GIC, Fuji IX); and a resin-modified GIC (Fuji II LC). The specimens were submitted to two cycling models (n=10): erosion or erosion-abrasion. The challenges consisted of five-minute immersion in 0.3% citric acid solution, followed by 60-minute exposure to artificial saliva. Toothbrushing was carried out twice daily, 30 minutes after the first and last exposures to acid. Dental and material surface loss (SL, in μm) were determined by optical profilometry. Data were analyzed with Kruskal-Wallis and Dunn tests (α=0.05). Results: Under erosion, for enamel, only the GIC groups presented lower SL values than Z350 (p0.05). For material, the GICs had significantly higher SL values than those of Z350 (p<0.001 for Fuji IX and p=0.002 for Fuji II LC). Under erosion-abrasion, the enamel SL value was significantly lower around Fuji II LC compared with the other materials (p<0.05). No significant differences were observed among groups for dentin SL (p=0.063). The GICs and Giomer showed higher SL values than Z350 (p<0.001 for the GICs and p=0.041 for Giomer). Conclusion: Both GIC-based materials were susceptible to erosive wear; however, they promoted the lowest erosive loss of adjacent enamel. Against erosion-abrasion, only Fuji II LC was able to reduce enamel loss. For dentin, none of the materials exhibited a significant protective effect

Percepción del desempeño docente y satisfacción de los estudiantes universitarios de las Ciencias de la Salud de la Universidad Nacional Hermilio Valdizán de Huánuco, 2013

Objective: To determine the relationship between perception of teacher performance and satisfaction of university students in health sciences at the National University of Huanuco Valdizán Hermilio in 2013 . Methods: The design was correlational, prospective, cross-sectional sample consisted of 385 students, who were applied interview guides and inventory of teacher performance, prior informed consent. Statistical analysis was by Spearman Rho contrast, relying on the SPSS V 20.0. Results: Most students demonstrate a level of “ optimal satisfaction “ [ 49.6 % ( 191 )] , followed by those who express a level “moderate satisfaction” [ 46.8 % (180 )] , and “dissatisfaction “ [ 3.6% ( 14 ) ] , respectively . Statistically significant correlation was found between the dynamic class [( Rho = 0.529 ) (p = 0.000) ] , class preparation - compliance program [( Rho = 0.606 ) (p = 0.000) ] , the criteria for assessment - rating [( Rho = 0.595 ) (p = 0.000) ] , respect for students [( Rho = 0.590 ) (p = 0.000) ] , subject mastery [( Rho = 0.610 ) (p = 0.000 )] , student motivation - interpersonal style [( Rho = 0.636 ) (p = 0.000) ] , approach to the profession [( Rho = 0.587 ) (p = 0.000) ] , with college student satisfaction . Conclusions: There is relationship between teacher performance and student satisfaction university, [( Rho = 0.704 ) (p = 0.000) ]El objetivo fue determinar la relación entre la percepción del desempeño docente y la satisfacción de los estudiantes universitarios de las ciencias de la salud de la Universidad Nacional Hermilio Valdizán de Huánuco, en el 2013. El diseño fue correlacional, prospectivo y transversal, la muestra estuvo constituido por 385 estudiantes; a quienes se les aplicaron las guías de entrevistas y el inventario del desempeño de los docentes, previo consentimiento informado. El análisis estadístico fue mediante el contraste Rho de Spearman, apoyándonos en el PASW V 20.0. Resultados: la mayoría de los estudiantes manifiestan un nivel de “satisfacción óptima” [49,6% (191)]; seguido de los que expresan un nivel “satisfacción moderada” [46,8% (180)]; e “insatisfacción” [3,6% (14)], respectivamente. Se encontró correlación significativa estadísticamente entre el dinamismo en clase, [(Rho = 0,529), (p = 0,000)]; preparación de la clase – cumplimiento del programa [(Rho = 0,606), (p = 0,000)], los criterios de evaluación – calificación [(Rho = 0,595), (p = 0,000)], respeto a los alumnos [(Rho = 0,590), (p = 0,000)], dominio de la materia [(Rho = 0,610), (p = 0,000)], motivación al alumno – estilo interpersonal [(Rho = 0,636), (p = 0,000)], enfoque a la profesión [(Rho = 0,587), (p = 0,000)], con la satisfacción del estudiante universitario. Conclusión: existe relación entre el desempeño docente y la satisfacción del estudiante universitario, [(Rho = 0,704), (p = 0,000)]

Energetic particle influence on the Earth's atmosphere

This manuscript gives an up-to-date and comprehensive overview of the effects of energetic particle precipitation (EPP) onto the whole atmosphere, from the lower thermosphere/mesosphere through the stratosphere and troposphere, to the surface. The paper summarizes the different sources and energies of particles, principally galactic cosmic rays (GCRs), solar energetic particles (SEPs) and energetic electron precipitation (EEP). All the proposed mechanisms by which EPP can affect the atmosphere are discussed, including chemical changes in the upper atmosphere and lower thermosphere, chemistry-dynamics feedbacks, the global electric circuit and cloud formation. The role of energetic particles in Earth’s atmosphere is a multi-disciplinary problem that requires expertise from a range of scientific backgrounds. To assist with this synergy, summary tables are provided, which are intended to evaluate the level of current knowledge of the effects of energetic particles on processes in the entire atmosphere

Dimeric Proanthocyanidins on the Stability of Dentin and Adhesive Biointerfaces

A dentin biomodification strategy with selective proanthocyanidin (PAC)-enriched extracts reinforces dentin and dentin-resin interfaces. Enrichment of the extracts according to the degree of polymerization allows exploration of bioactive principles of PACs and structure-activity relationships. This study investigated the sustained dentin matrix biomodification and dentin-resin bioadhesion of 2 fractions consisting exclusively of B-type PAC dimers with or without a single galloyl motif (specifically, DIMERG and DIMERNG) and their precursor material, enriched grape seed extract (e-GSE; Vitis vinifera). The biomodification potential was determined by long-term evaluation of the apparent modulus of elasticity and collagen solubility (hydroxyproline release). Chemical characterization of the dentin matrix was performed by attenuated total reflectance-Fourier-transform infrared spectroscopy. The bioadhesive properties were assessed by a microtensile bond strength test at different time points, and macro-hybrid layers were produced to verify the degree of conversion of the adhesive resin. Fractions consisting of DIMERG, DIMERNG, and their precursor, e-GSE, increased the modulus of elasticity at all time points and reduced collagen degradation. Specimens treated with DIMERNG remained stable throughout 12 mo of storage, whereas a significant drop in the modulus of elasticity was observed for the DIMERG and e-GSE groups at 6 mo. The fractions and precursor did not affect the degree of resin conversion at the hybrid layer. Changes in infrared resonances corresponding to collagen cross-links in the dentin matrix occurred for all treatments. Higher bond strength was observed for dentin treated with e-GSE as compared with DIMERG and DIMERNG; all biointerfaces remained stable after 12 mo. Nongalloylated PACs mediate stable dentin biomodification, which includes protective activity against collagen degradation and reinforcement of the anchoring dentin matrix. Collectively, PACs with a higher degree of oligomerization offer a robust bioadhesion between the hydrophilic dentin matrix and the hydrophobic adhesive