Angiogenesis and osteogenesis at incorporation process of onlay bone graft.

PURPOSE: The roles of angiogenesis and osteogenesis in autologous and allogenic bone grafts and the use of platelet-rich plasma (PRP) as a modifier were investigated. MATERIALS AND METHODS: Forty rabbit mandibles received onlay grafts of fresh autologous and frozen allogeneic bone. PRP was added on the right side. After intervals of 3, 7, 14, 28, and 56 days, the animals were euthanized. Hematoxylin and eosin staining was used to measure the quantity and area of osteoblasts. Sections stained with toluidine blue showed newly formed bone area. In sections with Weigert-van Gieson staining, the number of vessels and their lumens was quantified. The quantity and area of cellular arrangements expressing CD31 and the area of vessels were obtained. RESULTS: Quantities of osteoblasts and their areas, newly formed matrices, and vessels and their lumen areas were obtained and identified by immunomarking with CD31. In general, values for these were higher in rabbits with allogeneic bone grafts and on the sides where PRP had been added. There was a variable significance between categories and days. It was confirmed that osteogenesis was intensified when angiogenesis was consolidated. CONCLUSIONS: Angiogenesis was important for greater osteoblast differentiation and bone matrix synthesis, ensuring consolidation of onlay grafts with the receptor bed. Allogeneic grafts and PRP intensified these processes.

Pattern of osteogenesis during onlay bone graft healing.

OBJECTIVE: The aim of this paper was to analyze how healing occurs between onlay bone graft and the mandible cortex. STUDY DESIGN: Autologous and allogeneic corticocancellous bones, harvested from the ilium wing, were grafted at each mandible side of 40 rabbits. One side received platelet-rich plasma (PRP). Killings occurred at 3, 7, 14, 28, and 56 days. Tissues were stained by hematoxylin-eosin and toluidine blue. New bone area was measured at different regions of sections stained with toluidine blue. Wilcoxon test was used to analyze differences among regions and Bonferroni test to analyze the influence of PRP, graft nature, and days. RESULTS: Osteogenesis was higher at the lateral region (P < .05). PRP tended to improve bone neoformation, which was higher at the allogeneic graft. Statistical significance among the different categories of variables-grafts, use of PRP, and days of observation-did not have a linear behavior. A linear behavior of statistical tests was not detected. Bone new formation increased until the 14th day (P < .05). CONCLUSIONS: Onlay grafts heal due to osteogenesis which occurs at the lateral region and between the cortex and host mandible. Allogeneic grafts and PRP tend to improve bone formation.

Effects of freezing on bone histological morphology.

Allograft bone has been widely used for reconstruction of different portions of the skeleton. The fragment of bone harvested must be kept under low temperatures. The cryopreservation also contributes to decrease the antigenic potential of the tissue. Although this technique is considered safe, there is little information about the morphological modifications that the medullary and cortical portions of bone suffer after freezing. Hence, the aim of this study was to investigate the morphology of bone tissue after freezing under different temperatures and periods. Twelve rabbits were used to analyze the effects of two temperatures, -20 degrees C and -70 degrees C, during four periods of time: 30, 60, 90, 120 days. Tissues were analyzed by HE, picro-sirius stains and also by Feulgen's reaction, through qualitative and morphometric ways, considering the area occupied by cells and nuclei, medullary and cortical portions, as well as by collagen expression at cortical. The differences among the treatments were analyzed by Tukey s test, at 5% significance level. Bone freezing increased cellular and nuclear areas at cancellous bone and diminished nuclear area at the cortical bone. Cortical bone collagen suffered denaturation proportionally to temperature decrease and to freezing duration. These alterations compromised the morphology of tissues after 90 or 120 days of freezing at the temperature of -70 degrees C. Cells necrosed during freezing, contributing to reduce bone antigenicity.

Evaluation of factors that can modify platelet-rich plasma properties.

OBJECTIVE: The aim of this article is to discuss a protocol for obtaining platelet-rich plasma (PRP) and evaluate which factors, derived from its preparation method and from whole blood, modify PRP cytometry and coagulation time. STUDY DESIGN: Whole blood, harvested from 50 rabbits, was centrifuged at 300g for 10 minutes. Supernatant was recentrifuged at 5000g for 5 minutes. PRP was clotted with calcium chloride. Whole blood and PRP cytometry were obtained through automatic measurement. The amount of erythrocyte- and platelet-poor plasma drawn from whole blood was measured. Hematocrit, platelet and leukocyte count, mean corpuscular volume (MCV) and mean platelet volume (MPV), mean, standard deviation, and median were also calculated at whole blood and PRP. PRP coagulation time was also analyzed. Mean values between groups were analyzed using Student t test. Correlations were evaluated using Pearson's correlation coefficient. The significance level was set at P < .05. A linear regression was performed to investigate the relationship among the correlated variables. RESULTS: From whole blood, 2.68 mL of erythrocytes and 5.72 mL of platelet-poor plasma (PPP) were removed. PRP platelet count was 2,324,080 cells/microL. Whole blood hematocrit influenced the amount of cells and PPP removed, as well as PRP platelet count. PRP platelet count was dependent on whole blood hematocrit and platelet count, and does not interfere in PRP coagulation time. A linear interaction was confirmed between the variables that presented significant Pearson correlation. CONCLUSIONS: The protocol evaluated produces a good PRP. Whole-blood parameters can predict PRP features. Whole-blood hematocrit is an important variable for PRP preparation and PRP cytometry characterization. PRP platelet count is dependent upon whole-blood platelet count.

A (RES) significação da cidadania na construção do Estado e da sociedade brasileira / The new meaning of citizenship in the construction of the state and brazilian society

O significado de cidadania foi construído no decorrer do proceso de formação do Estado brasileiro, de forma a justificar e consolidar a estrutura econômica e política vigente. Nesta perspectiva, seu conceito esteve, durante muito tempo, traduzido em benefícios concedidos, em detrimento da participação popular. A partir da década de 80, com a implantação da constituição Cidadã, foi conferido à cidadania um caráter mais ativo e de direitos conquistados, requerendo uma mobilização da sociedade brasileira. No entanto, apenas a formulação legal não foi suficiente para a efetivação do controle social. Assim, uma reflexão sobre a construção dos valores e sentidos atribuídos à cidadania no processo de formação do Estado brasileiro parece-nos importante, pois acreditamos ser este um dos passos para a efetivação da participação popular e conseqüente consolidação do Sistema Único de Saúde.

Efeitos emocionais da perda dos dentes em adultos / Emotional effects of tooth loss in adults

Este estudo tem como objetivo identificar as possíveis mudanças emocionais em adultos causadas pela perda dentária. Foram aplicados questionários em 100 pacientes edêntulos totais ou parciais, sendo ou não usuários de prótese. Os resultados mostraram que a população em estudo apresentou alterações emocionais e físicas após a perda dos dentes. 63% dos entrevistados tiveram a auto-estima afetada e em 70% observou-se dificuldade em aceitar a ausência dos dentes. Concluiu-se que a perda dentária repercute no bem-estar emocional do paciente, além de debilitar a aparência e algumas atividades cotidianas.