Evaluation of mechanical properties of platelet-rich fibrin membrane for implant surgery: An analysis in vitro.

The aim of this study was to evaluate and compare the mechanical resistance of platelet-rich fibrin (PRF) membrane when submitted to resistance traction on longitudinal axis. Blood collection of a healthy individual was collected with an amount of 300 mL and divided into 30 tubes containing 10 mL each one. The samples were divided into three groups, according to the g-force protocols: (1) F200 g: (2) F400 g; (3) F800 g. Membranes of each g-force group were divided into subgroups, according to waiting time after centrifugation: (T0) immediate use and (T30) use after 30 min. Considering these intervals of time, the concentrate was removed from tubes and inserted in a PRF metallic box to confection of the membrane. The PRF membranes were submitted to mechanical tension on a universal testing machine and obtained to a resistance force of each membrane. The centrifugation time showed no statistically significant difference for membrane resistance for any force applied (P > 0.05; Student's t-test). For T0 group results demonstrated no influence for membrane resistance (P = 0.357; Student's t-test), therefore T30 showed statistically significant difference (P = 0.040; Student's t-test) for membrane resistance for centrifugation forces applied, with highest value when applied greatest force. The findings suggest that the waiting time for centrifugation could be determined according to demand of application, and for immediate use of the membrane, the centrifugation did not influence the resistance, on the other hand, after 30 min, the application of higher force resulted in a membrane with considerable resistance.

Etiopathogenic features of severe epistaxis in histological samples from individuals with or without arterial hypertension.

There is a consensus that arterial hypertension (AH) is associated with stroke. Therefore, this study aimed to evaluate the histology of the microvasculature associated with the mucosa of the posterior nasal cavity to identify possible factors related to vascular weakening and rupture. Histological sections were obtained from hypertensive and normotensive individuals, regardless of epistaxis. Our results showed that the group with AH had: (a) smaller median diameter of the lumen of arteries and arterioles; (b) increased thickness of the intimal arteries and arterioles, slight inflammatory infiltrate, and rupture of internal elastic lamina; (c) greater thickness of the middle tunica in arterioles; (d) lower percentage of histological sections with non-injured intimal layers in capillaries, arterioles, and small arteries; (e) lower percentage of histological sections with intact media tunic and/or myocytes juxtaposed in arteries and arterioles; (f) no difference between the diameters of small arteries or arterioles. The intima was thicker in individuals with severe epistaxis than in the normotensive group, but it did not differ from the AH group. Thus, hypertension may cause structural lesions in the vascular layers, and in the absence of tissue repair and the persistence of AH, these lesions may favour vascular rupture, especially during hypertensive peaks.

Methodological variations affect the release of VEGF in vitro and fibrinolysis' time from platelet concentrates.

Blood Concentrates (BCs) are autologous non-transfusional therapeutical preparations with biological properties applied in tissue regeneration. These BCs differ in the preparation method, in fibrin network architecture, growth factors release as well as in platelet/cell content. Methodological changes result in distinct matrices that can compromise their clinical effectiveness. The present study evaluated the influence of different g-forces and types of tubes in the release of vascular endothelial growth factor (VEGF) from platelet-rich fibrin (PRF) as a function of time. The PRF-like samples were obtained with three g-forces (200, 400, and 800 x g) for 10 minutes in pure glass tubes or in polystyrene-clot activator tubes. Scanning and Transmission electron microscopy was used to morphometric analyzes of PRF's specimens and flow cytometry was used to quantify VEGF slow release until 7 days. Our results showed that platelets were intact and adhered to the fibrin network, emitting pseudopods and in degranulation. The fibrin network was rough and twisted with exosomic granulations impregnated on its surface. An increase in the concentration of VEGF in the PRF supernatant was observed until 7 days for all g forces (200, 400 or 800 xg), with the highest concentrations observed with 200 x g, in both tubes, glass or plastic. Morphological analyzes showed a reduction in the diameter of the PRF fibers after 7 days. Our results showed that g-force interferes with the shape of the fibrin network in the PRF, as well as affect the release of VEGF stored into platelets. This finding may be useful in applying PRF to skin lesions, in which the rapid release of growth factors can favor the tissue repair process. Our observations point to a greater clarification on the methodological variations related to obtaining PRF matrices, as they can generate products with different characteristics and degrees of effectiveness in specific applications.

Utilização de fibrina leucoplaquetária autóloga para reinserção de implante com perda de estabilidade primária em cirurgia guiada ­ relato de caso / Use of autologous platelet rich fibrin to reinsert an impl with loss of primary stability in guided surgery ­ case report

Com o avanço da tomografia computadorizada, a reabilitação oral com implantes osseointegráveis em pacientes edêntulos totais tornou-se mais segura e rápida, tendo como ferramenta softwares capazes de converter imagens em protótipos e guias cirúrgicos tridimensionais previamente planejados, tornando o momento cirúrgico menos traumático. Com a otimização das técnicas cirúrgicas, protéticas e de imagem, criou-se a cirurgia guiada, caracterizada por nova filosofia envolvendo a reabilitação por implantes. Mesmo com o avanço tecnológico, a perda da estabilidade primária pode ocorrer, levando, em muitas situações, ao comprometimento do caso. Este artigo tem como objetivo principal mostrar através de um relato de caso todas as etapas que passam pelo planejamento, técnica cirúrgica e pós-operatório da cirurgia guiada, demonstrando o potencial da fibrina leucoplaquetária autóloga como auxiliar no reparo para recuperação de implantes com perda da estabilidade primária (AU).

Due to the evolution of computer tomography advance, oral rehabilitation using bone integrated implants in totally edentulous patients became safer and faster, using software capable of converting images into tridimensional prototypes and surgery guides previously planned, making the surgery less traumatic. The optimization of surgerical, prosthetics and image techniques resulted on guided surgery characterized by a new philosophic view over implant rehabilitation. Even with advanced technology the loss of primary stability may occur compromising the success of the treatment. This article aims at demonstrating through a case report every step related to guided surgeries including planning, surgical techniques, and postoperative, focusing on the autologous fibrin buffy as auxiliary in the optimized fix during recoveries from implants without primary stability (AU).

Avaliação do funcionamento e identificação de pontos críticos de controle, em bancos de leite humano do Distrito Federal / Evaluation of the operation and control critics points identification, in banks of human milk of the Distrito Federal

A importância do aleitamento materno exclusivo até aos seis meses de vida é indiscutível e para garantir o acesso e a disponibilidade do leite humano aos neonatos foram implantados aos Bancos de Leite Humano (BLHs), que se constituem em centros especializados em aleitamento materno. O Brasil conta com uma rede de 163 BLHs, dos quais 11 se localizam no Distrito Federal; as normas de funcionamento destas unidades são estabelecidas pela Fundação Oswaldo Cruz (FIOCRUZ). O presente trabalho teve como objetivo avaliar as condições de funcionamento, a adequação às normas estabelecidas pela FIOCRUZ e a identificação de pontos críticos de controle em oito BLHs de hospitais da rede pública do Distrito Federal. De acordo com os dados obtidos, observou-se que os maiores problemas ocorrem no período de escassez de leite, pois a maioria dos BLHs não segue rigorosamente os critérios de qualidade físico-química (acidez) e microbiológica. Quanto à operacionalização, verificou-se que as diretrizes dos BLHs se fundamentam nas Boas Práticas de Fabricação (BRASIL, 1997) e não na Análise de Perigos e Pontos Críticos de Controle APPCC, evidenciados ao se constatar a inadequação da área física, o fluxo não unidirecional e a possibilidade de contaminação cruzada.