Study of temperature variation in cortical bone during osteotomies with trephine drills

Objective: The purpose of this study was to compare temperature variation during osteotomies with trephine drills under different irrigation conditions: without irrigation, external irrigation, and double irrigation. Materials and methods: Synthetic blocks of bone (type I density) were used for drilling procedures with an experimental computed machine, which measured the maximum temperature in the cortical bone during osteotomy with a bone cut that was 5\ua0mm in both diameter and depth. Three groups were formed depending on the irrigation conditions: no irrigation (G1), external irrigation (G2), and double irrigation (G3). Fifty drillings were performed for each group. Results: The average thermal increase in the groups was 21.7 \ub1 1.52\ua0\ub0C in G1, 14.2 \ub1 0.70\ua0\ub0C in G2, and 12.4 \ub1 0.75\ua0\ub0C in G3. The results presented statistically significant differences among all groups (\u3b1 = 0.05). Conclusion: The double irrigation technique resulted in a smaller increase in temperature in the cortical bone model, demonstrating a greater efficiency, which may be beneficial when compared to external irrigation alone. Clinical relevance: The trephine has been widely used in removing small blocks for bone graft, especially the posterior mandible, where the possibility of heating may be higher due to the density of cortical bone in this area. So it is important that the professionals select instruments that can reduce the risks of complications in the proposed treatment. \ua9 2014 Springer-Verlag Berlin Heidelberg

Avaliação da debulha mecânica em sementes de milho Evaluation of mechanical thrashing processing in corn seeds

No estado da Paraíba, as perdas de sementes e grãos de milho (Zea mays L.) provocadas principalmente pela colheita, debulha mecânica, beneficiamento e processos subseqüentes, são da ordem de 20%, acarretando prejuízos econômicos ao estado. Assim, estudaram-se as danificações decorrentes da debulha mecânica e da passagem das sementes de milho, variedades Cruzeta e Sertanejo, pelas diferentes etapas do beneficiamento. Para avaliar os danos provocados às sementes, utilizou-se uma debulhadora estacionária trabalhando a rotações de 520, 600 e 700 rpm, obtidas pela variação da aceleração do motor do trator ao qual a debulhadora se achava acoplada, como também das etapas promovidas pela UBS. Os danos foram avaliados visualmente e analisados em um delineamento estatístico inteiramente casualizado, com os tratamentos distribuídos em esquema fatorial. A variedade Cruzeta foi mais resistente aos impactos provocados pela debulha e pelo beneficiamento; o efeito do impacto na qualidade das sementes torna-se mais evidente com a elevação da velocidade do cilindro debulhador; a rotação de 600 rpm mostrou-se a mais indicada para a debulha do milho Cruzeta e Sertanejo.<br>In the State of Paraiba, the loss of seeds and grains of corn (Zea mays L.) caused, mainly by harvesting, mechanical thrashing and subsequent processes is about 20% resulting in economic loss to the state. In this context, the effect of mechanical damages during the thrashing and passage of corn seeds varieties -Cruzeta- and -Sertanejo- were studied, in the different stages of processing. To evaluate the damages caused to the seeds, a stationary thrasher was used working at 520, 600 and 700 rpm, obtained by the acceleration variation of the tractor to which the thrasher was attached. The damages were visually appraised and analysed in a completely randomized statistical design with the treatments distributed in a factorial scheme. -Cruzeta- variety was more resistant to the impacts caused by the thrashing and processing; the impacts on the seed quality became more evident with the elevation of speed of the thrashing cylinder; the 600 rpm rotation proved to be better for the thashing of Cruzeta and Sertanejo corn