Dispositivos bioabsorvíveis de fixação em cirurgia bucomaxilofacial – revisão de literatura

The concerning regarding to the treatment of facial fractures has been reported since the antiquity to now a days. The literature shows the development of the techniques and materials used for this intention. There was a gradual alteration of the empiricists treatments to the ones based on scientific evidences. The materials described in the beginning vary from bandages, extraoral leather straps, gutters manufactured through horns of animals to metal used for closed and open fractures treatment. Through the technological advances used in the production of the fixation systems it started to use materials that were well accepted for the organism, as metallic system of plates and screws.  More recently another system was introduced in the market, the resorbable materials of fixation. Since then, many researches come being developed with intention to formulate a protocol, to test the new materials and to stand out its main indications and possible disadvantages. This paper has the aim to make a brief historical report about the evolution of the materials used in oral maxillofacial surgeries, and to review important topics related to resorbable plates and screws.A preocupação quanto ao tratamento das fraturas faciais é registrada desde a antiguidade até os dias atuais. A literatura demonstra o crescente desenvolvimento de técnicas e materiais utilizados para esse fim, constatando-se uma gradativa alteração dos tratamentos empíricos, baseados em evidências científicas. Os materiais inicialmente descritos variavam desde o uso de bandagens, tiras de couro extra-orais, calhas fabricadas através de chifres de animais até a utilização do metal no tratamento fechado e aberto das fraturas. Através dos avanços tecnológicos utilizados na produção dos sistemas de fixação, passou-se a utilizar materiais que fossem bem aceitos pelo organismo, como o sistema de placas e parafusos metálicos. Mais recentemente, outro sistema foi introduzido no mercado, os materiais de fixação bioabsorvíveis. Desde então, trabalhos vêm sendo desenvolvidos com o intuito de formular um protocolo de utilização, testar os novos materiais e ressaltar suas principais indicações e possíveis desvantagens. Este trabalho tem como objetivo fazer um breve relato histórico sobre a evolução dos materiais utilizados nas cirurgias maxilofaciais, além de revisar tópicos relevantes em relação às placas e parafusos bioabsorvíveis

Bone repair process in calvarial defects using bioactive glass and calcium sulfate barrier Processo de reparo ósseo em defeitos experimentais de calotas cranianas frente a utilização do vidro bioativo e da barreira de sulfato de cálcio

PURPOSE: To analyze bone repair process in Wistar rats' calvaria, with the use of two different biomaterials. METHODS: Forty two male Wistar rats were used, and four bicortical cranial cavities were created in each animal. The cavities were filled with: bioactive glass (BG); calcium sulfate barrier (CSB); bioactive glass covered with calcium sulfate barrier (BG/CSB); and autogenous blood clot (control). The animals were euthanized 7, 14, 21, 30, 60, 90, e 120 days after surgery. The scalps were removed and submitted to a routine process for histological preparation: staining with Haematoxylin and Eosin (HE). RESULTS: The BG was not completely resorbed; however, after 60 days, a decrease in size as well as a change in the morphological granule were observed. CSB was not observed in the last group (after 120 days). CONCLUSIONS: In Wistar rat calvaria bioactive glass, in an isolated form, negatively interfered in the bone repair process; the calcium sulfate barrier, in an isolated form, presented the capacity to maintain space, allowing the flow of osteogenic cells; the bioactive glass covered with calcium sulfate barrier association presented a better osteoconductive capacity when compared to isolated materials; calcium sulfate barrier was completely resorbed after 90 days; control cavities did not completely heal until 120 days after surgery.<br>OBJETIVO: Analisar o processo de reparo ósseo em calotas cranianas de ratos Wistar, frente ao uso de diferentes biomateriais. MÉTODOS: Foram quatro cavidades, bicorticais, nas calotas cranianas de quarenta e dois ratos Wistar machos. As cavidades foram preenchidas com: vidro bioativo (VB); barreira de sulfato de cálcio (BSC); vidro bioativo coberto com barreira de sulfato de cálcio (VB/BSC); coágulo sangüíneo (controle). Os animais foram mortos aos 7, 14, 21, 30, 60, 90 e 120 dias após a cirurgia. As calotas foram removidas e submetidas ao processo de rotina para confecções de lâminas coradas com Hematoxilina e Eosina (HE). RESULTADOS: O VB não foi totalmente reabsorvido, contudo, a partir dos 60 dias, observaram-se alterações no tamanho e forma dos grânulos. A BSC não foi observada no último grupo (120 dias). CONCLUSÕES: Em calotas cranianas de ratos Wistar, o vidro bioativo na forma isolada interferiu negativamente no processo de reparo ósseo. A barreira de sulfato de cálcio na forma isolada apresentou a capacidade de manutenção do espaço preenchido, permitindo a migração de células osteogênicas. A associação vidro bioativo coberto com barreira de sulfato de cálcio apresentou uma maior capacidade osteocondutora quando comparada aos materiais nas formas isoladas. A barreira de sulfato de cálcio foi totalmente reabsorvida após 90 dias; As cavidades utilizadas como controle não cicatrizaram completamente até o período de 120 dias

Evaluation of tissue response and genotoxicity of poly(L/D-lactic acid) disks implanted in rat calvarium

The aim of the present study was to evaluate local and cytotoxicity systemic tissue reaction in the skull of rats using the implantation of disks of poly (lactic L/D-acid) and evaluate its genotoxicity. 25 males Wistar rats were used, 20 animals underwent surgical procedures and had the discs implanted in the parietal bone, and 5 animals received postoperative medication in the same way, serving as a control group for genotoxicity. The results were subjected to statistical evaluation by analysis of variance (ANOVA). In histological evaluation, between periods of 90 and 120 days in the control group, a new formation at the edges of the defect was noticed. In the experimental group, there was new bone formation at the edges of the defect, migrating below the site occupied by the disk, an absence of inflammatory infiltrate. Regarding the evaluation of genotoxicity, a significant reduction in the frequency of polychromatic erythrocytes in relation to negative control or significant increase in the polychromatic erythrocytes with micronuclei was not detected. So, the material used in this study is biocompatible and well tolerated by the tissues studied, and found to be negative for chromosomal mutagenicity