A escassez de recursos naturais, o aumento de necessidades energéticas, os incentivos recentes em termos legislativos e uma preocupação crescente com as questões ambientais, desencadearam uma procura crescente de fontes alternativas de energia. Este estudo pretende analisar a viabilidade económica de um sistema fotovoltaico (FV) de produção de eletricidade para autoconsumo, no Campus Politécnico de Viseu. A avaliação foi efetuada, tendo por base a criação de 3 cenários para a potência de ligação do sistema FV, com métricas tradicionais (valor atual líquido e payback)e complementada com o recurso a técnicas de opções reais (árvores de decisão), que permitem integrar, na avaliação, fontes de incerteza e flexibilidade operacional. Em termos globais, o investimento revela interesse económico e o payback é inversamente proporcional ao valor da tarifa suportada na aquisição de energia à rede.
Resumen: Objetivo: Determinar los comportamientos de salud bucal, la prevalencia de lesiones dentales, el nivel de información sobre los procedimientos de primeros auxilios en el caso de la avulsión dental y el conocimiento de los protectores bucales en una muestra de atletas portugueses. Materiales y métodos: estudio transversal de 1048 atletas del distrito de Viseu, Portugal. Se utilizó un cuestionario auto administrado que incluyó datos demográficos y preguntas sobre: I) hábitos de higiene bucal, II) ocurrencia de traumatismos orofaciales, III) uso de protectores bucales y IV) conocimiento de los atletas sobre el manejo de primeros auxilios en caso de avulsión dental. La comparación entre diferentes variables se realizó mediante la prueba de chi-cuadrado con el nivel de significancia establecido en p≤0.05. Resultados: La edad promedia de la muestra (76,24% hombres) fue de 18,14±8,17 años. En general, los resultados demostraron un bajo uso de hilo dental (25,48%) y un alto número de atletas (21,94%) que no habían visitado un dentista en más de un año. La prevalencia de trauma dental fue de 5,06% y las lesiones dentales más comunes que experimentaron los atletas fueron las fracturas de corona (60,38%). Casi la mitad de los participantes (45,23%) informaron que no sabían cómo actuar después de una avulsión dental. La tasa de uso de protectores bucales fue muy baja (9,73%). Hubo una relación significativa entre la prevalencia de lesiones dentales y el uso de protectores bucales (p=0,000; V de Cramer=0,145). Conclusión: la prevalencia de trauma dental en nuestra población fue baja. Un número bajo de atletas usa un protector bucal y hay una falta de conocimiento sobre temas de trauma dental. Programas de prevención y acciones de promoción entre esta población son importantes y deben ser adoptados.Palabras Clave: Traumatismos de los dientes; avulsión de diente; protectores bucales; odontología preventiva; Atletas.
Objectives: Commercial photocurable polymers used in dental additive manufacturing still have mechanical limitations. The incorporation of graphene may provide interesting advantages in this field. This study aimed to evaluate in vitro the effect of adding graphene nanoparticles to a 3D-printed polymethylmethacrylate dental resin in terms of surface roughness, flexural properties, and hardness. Methods: A 3D-printed dental resin (Dental Sand, Harz Lab) was loaded with four different graphene nanoplatelet (Graphenest) concentrations: 0.01wt%, 0.1wt%, 0.25wt%, and 0.5wt%. The neat resin was used as the control group. The surface roughness was measured with a contact profilometer using bar-shaped specimens (50x10x4mm). The flexural strength of specimens (80x10x4mm) from each group was calculated using the 3-point bending test in a Universal Test Machine. Hardness shore D was measured using a manual durometer on round-shaped specimens (12x6mm). Data were evaluated using the Kruskall-Wallis test followed by post-hoc Bonferroni corrected pairwise inter-group comparisons. Statistical significance was set at p<0.05. Results: Graphene improved 3D-printed PMMA resin hardness with statistical significance at a concentration of 0.01wt% (p=0.043). Surface roughness increased with graphene concentrations above 0.01wt%, with statistically significant differences at 0.25wt% (p=0.006) and 0.5wt% (p=0.005) concentrations. Flexural properties worsened with increased graphene concentrations, and these differences were significant in the concentrations of 0.25wt% (p=0.028) and 0.5wt% (p=0.006). Conclusions: The use of graphene as a mechanical reinforcement nanomaterial seems to be viable at low concentrations without prejudice to the surface roughness of a 3D-printed polymethylmethacrylate resin.
This retrospective study evaluated the survival rate of short, sandblasted acid-etched surfaced implants with 6 and 8 mm lengths with at least 120 days of follow-up. Data concerning patient, implant and surgery characteristics were retrieved from clinical records. Sandblasted and acid-etched (SLA)-surfaced tissue-level 6 mm (TL6) or 8 mm (TL8) implants or bone-level tapered 8 mm (BLT8) implants were used. Absolute and relative frequency distributions were calculated for qualitative variables and mean values and standard deviations for quantitative variables. A Cox regression model was performed to verify whether type, length and/or width influence the implant survival. The cumulative implant survival rate was assessed by time-to-event analyses (Kaplan–Meier estimator). In all, 513 patients with a mean age of 58.00 ± 12.44 years received 1008 dental implants with a mean follow-up of 21.57 ± 10.77 months. Most implants (78.17%) presented a 4.1 mm diameter, and the most frequent indication was a partially edentulous arch (44.15%). The most frequent locations were the posterior mandible (53.97%) and the posterior maxilla (31.55%). No significant differences were found in survival rates between groups of type, length and width of implant with the cumulative rate being 97.7% ± 0.5%. Within the limitations of this study, the evaluated short implants are a predictable option with high survival rates during the follow-up without statistical differences between the appraised types, lengths and widths.
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